Category Archives: B-C

Cross Cultural Neuropsychology

Introduction

This chapter focuses on the Diagnostic Interview. A lot of this is basic “good interviewing practice” even if someone is not from another culture. These are the major points to keep in mind from this chapter

from Cross Cultural Neuropsychological Assessment, Theory and Practice, Chapters 8-9 by Victor Nell

Major Points

  • Think of the diagnostic interview as a real-life drama. You as the interviewer set the scene, beside the sequence facilitate the dialogue flow and intervene to maintain communication and level of intensity. With clients unaccustomed to testing it is the neuropsychologist’s main objective to put them at ease. There are several ways to do this–
  • The most important element is natural, personal warmth. They may have traveled a long distance, or are worried about catching a bus home, and communication may not be optimal. Obviously being genuine and warm, explaining who you are, why the interview is necessary, why it takes so much time etc. will help set the scene to make things flow more smoothly.
  • Learn how to maintain eye contact with client not the translator in a circumstance where the translator is being used. If the translator interacts with the neuropsychologist in a language that the client doesn’t understand, the client soon feels that the neuropsychologist has no interest in them.
  • When you ask a question the comment should be translated to the family in their language. Then instead of speaking the translation back to you, the translator repeats the answer, but this time in English (so of course now you, the neuropsychologist, understands!) But now the client doesn’t feel marginalized. What should happen when it’s done right is that the client should be replying directly to your questions and maintaining eye contact with you even if they are answering in their own language. (On page 149 there is a nice example of how to do this).
  • Teach the translator to translate both the client’s and the neuropsychologist speech into first person rather than using the indirect/third person approach. Translation should occur completely (don’t abbreviate what client says) and frequently. In other words, after the client says a sentence or two it should be translated. There is a sort of funny story at the bottom of page 149 that is abridged here: A South African psychiatrist has a nurse translator. The psychiatrist asks the client, “Are you hearing voices?” An animated conversation ensues between the client and the nurse translator, and the client becomes very excited and animated. The psychiatrist sits there listening attentively and after about 10 minutes, the nurse turns to the psychiatrist and provides him with the translation: “He says, Yes, doctor!”
  • You often have to get collateral information from a caregiver and you need to do it without slighting the client. At the beginning of the interview explain that people very often see the same things in different ways and that you will be putting the same question first to the client and then to the caregivers, not in order to check up on them but to see how other people in their lives are feeling about the same thing. Moving back and forth between the client and the caregivers is an essential aspect of the diagnostic interview. A good principle to follow is that there are no secrets and that everything will be discussed openly in the presence of client and family members. One danger to avoid is that the pace of the interview needs to be swift to maintain the energy level in the room.
  • Be sure to go to the primary source of information about a client rather than some senior person. In the analogy of a school system, don’t go to the principal, rather go to the teacher who sees the kid six hours a day. With an adult, it’s important to visit the patient’s job setting when discrepancy occurs between client files and the test results. If a client file says the client has excellent job performance but the test results suggest something very different, it’s time to do a site visit.
  • Client will want to talk about what is most important to them, perhaps the accident or hospital treatment, which of course is important but the interviewer may fail to get vital information such as educational background, achievements of the client and their family, and employment history. Use a standardized intake form which helps you get through the interview.

Body of the history

Intellectual And Social Accomplishments

Dr. Nell’s research suggests that it’s essential to have information not only about the client but about their parents and the highest standard they have passed in their life/career rather than the total years of schooling. The career level and place of residence of the parents give an idea of the enrichment at home or in client’s general environment. In the case of a child who sustained a brain injury early in life, the family background is often the only way of determining pre-morbid ability.

School Record

Construct a year-by-year table tabling grades and grade averages. Teacher comments can be misleading since most teachers try to be positive about a child. Often the child and the mother can remember where the child was placed before the accident and can compare this to present achievements. Try to get information about any kinds of classes that were failed and when this happened in relationship to the accident. Be sure to ask about behavior complaints at school or level of arousal and disinhibition. Also keep in mind a few other things: Is there a difference in information processing? Did the child begin to forget their homework assignments or develop any other sort of memory problem? What is the child’s playground behavior like?

Occupational History

For adult clients, often school is far behind them. Therefore occupational history has precedence in answering what life was like before the accident. For working class individuals whose job descriptions may not have changed much, the key thing that may have changed is their actual job earnings. In clients who come from third world countries, keep in mind informal businesses are numerous from roadside talking to door to door trinket sales. These should be fully recorded. There may be a lack of formal income records, yet a person may have made a lot of money. There is a great story at the top of page 154 about this.

Main Complaints

Keep in mind that spontaneous complaints have greater diagnostic weight than those that are elicited by direct questioning. Using broad, open-ended questions first to the client and then to the caregiver is essential. Once the main complaint/spontaneous complaints are elicited, it’s important to move beyond this information and probe additional information you suspect may be present such as problems with arousal, alcohol, temper, self-monitoring, and memory. Again, don’t ask leading questions: (e.g., rather than “Do you find you sleep more now than you did before?”, say “Have you noticed any changes in your sleeping habits since the accident?”) In order to probe without leading, you have to begin with what your client has brought to your interview. In a situation where there is a head injury, be sure to pay attention to the key issues discussed in Chapter 7 about classic dimensions of concussion syndrome (e.g., changes in arousal, personality, thinking).

Physical Complaints

Although some neuropsychologists leave this out, it’s an important area to ask questions about. Often the client will talk about their weak arm or a leg that hurts, but it’s important to ask about things like chronic pain. Not only does this affect their performance potentially, but it’s a primary area that needs to be addressed in a therapeutic setting. Oddly enough, sometimes a neuropsychological evaluation is completed and the evaluator never reports whether the client can walk unaided, has full use of both hands, or can see well enough to what TV. Although you may not be able to do a full sensory motor exam, you can still ask questions about these issues, look at their handwriting, ask them about their ability to feel hot and cold temperatures, or watch our client walk around the consulting room etc.

Chapter 9

This is a wonderfully interesting chapter for any neuropsychologist, (but especially for the pediatric neuropsychologist!) There is a nice discussion about Vygotsky’s work, the Zone of Proximal Development (ZOPED) and its applicability to testing. This is defined as the distance between a child’s actual developmental level during independent problem solving and the child’s level of potential development revealed by problem-solving under adult guidance or when working with more competent members of the child’s own age group. A very interesting discussion ensues about the role of mediated learning in acquiring cognitive schemes. The chapter goes into a discussion about psychometric testing and it’s classic “arms length procedure” where it standardized instruments are always read in a very specific way, nothing can be explained only repeated, and pat answers to client questions such as, “Whatever you think is best,” are given. Needless to say, clients from different cultures or different socioeconomic status may be put off by this type of formality. He discusses what South African psychologists contributed to the testing profession in that subject should have ample opportunity to learn to do the task involved in the test by preliminary exercises. He seems to say that this idea of practice and feedback came from Biesheuvel’s work in South Africa on the 1950s South African General Adaptability Battery (this was new and interesting!). The idea to take away is that guided learning experiences do indeed produce significant performance increase and that the distance between actual performance and performance after triggering in the zone of proximal development, might be a more reliable guide to an individual’s capacity to benefit from training rather than a simple performance measure that is applied indiscriminately to test-wise clients and those from socially and culturally different backgrounds.

A couple of other things to note: in Appendix 3 of this book, there is an interesting section on something he calls “Educating the Executive”. There are some informal activities he suggests to work on with a client from a different culture before beginning testing in order to establish if your client can do things such as identifying numbers, and has the visual acuity needed for the test you plan to administer. It’s rather interesting and is on page 232-234.

The remainder of the chapter goes into a couple of extended practice tasks to familiarize an individual from another culture about how to complete a task that they may not be particularly familiar with. Something called the Hick Box Reaction Time Test is described and a set of steps is offered to teach the task in a way to bring the client into the ZOPED. Next, he presents a practice task similar to the Rey Complex Figure. It’s an informal test and the picture is on page 168. Basically you have the client do this task and then afterward you discuss any discrepancies in their drawing from the copy. Essentially they learn how to construct a novel complex figure, you go over there are errors, how their drawing was different from the picture etc., and then provide other examples if necessary. At this point you give them the real ROCF and tell them not to rush but make a copy that looks exactly like the one you’ve given them. This assesses whether they can learn, benefit from this approach and he argues it may be a more beneficial or practical way to gain insight into their skills.

Cross Cultural Neuropsychology

(Nancy Viscovich)

A Core Test Battery

from Cross Cultural Neuropsychological Assessment, Theory and Practice, Ch. 10 by Victor Nell

“Test norming is a market-driven enterprise, and because the Wechsler tests have meticulous norms for North American and most Western countries, they provide a useful comparative platform for standardization in the developing countries.”

The World Health Organization Neurobehavioral Core Test Battery authors have urged that its 7 tests be included “as standard marker tests within larger batteries to allow cross-cultural comparisons between studies and countries.”

Included: 11/14 WAIS-III subtests 12/17 WMS-III 6 WHO-NCTB tests

WAIS-III

With more reversal items (until 2 correct responses are reached – basal), the WAIS-R maximum age of 74 increased to age 89 in WAIS-III. This leads to greater clinical utility in the diagnosis of mild to moderate mental retardation, and therefore of both traumatic and degenerative brain damage. WAIS –III has become more client friendly in non-Western settings – by using the reversal items, the patient can ease into the test in a non-threatening way (teach test demands, prepare for more difficult items later, etc.). So, while catering to the need to lower the test’s floor level, it caters to culturally different clients.

Some restructuring of what constitute the Index scores has led to more cultural fairness (e.g., Verbal Comprehension Index being excluded from the core test battery, since tests that carry heavy cultural baggage cannot be adapted by translation).

In the WMS-III, The Family Pictures subtest has not been taken up in the core test battery because the activities shown in the color pictures of these White middle class Americans will be incomprehensible to clients unfamiliar with daily life in the U.S.

How to prepare non-test-wise clients in the testing procedures

  • Extended Practice: It exists to level the playing field by helping the non-test-wise client to a point of familiarity with the test apparatus and the task demands that is equivalent to that taken for granted by the test author.

The emphasis on practice is on familiarization with the test materials or apparatus, and the test demands with regard to speed, accuracy, self-correction, and so on (task acquisition). It’s like active coaching. Extended practice is recommended for all clients who are not fully test-wise (e.g., individuals include victims of a failed educational school system).

  • Unpacking Hidden Meanings: This includes eye contact, saying things like “OK, let’s try another.” The test wise individual may pick up on these clues and self-correct. The non-test-wise client may not appear to be putting forth more effort because they are not picking up on these clues and self-correcting. You don’t want to attribute this behavior with low motivation, but lack of familiarity to hidden meanings. So prepare the client ahead of time and explain how you will respond and what is expected of them after they respond (e.g., cannot say right or wrong, will wait until time is up if no answer is given yet, etc.). Time limits can also be not understood. Explicit instructions about the kind of timing required is thus needed (for time limits of bonus time, need explanation).
  • Computer-Administered Tests: In non-Western cultures, computerized test administration may not be feasible because of poor reading skills, little familiarity of computers – can be intimidating to semiliterate, rural testees. Using two-button response boxes (with examiner being the one who controls the keyboard) may help with this (color coded for yes/no responses, for example).

A Core Neuropsychological Test Battery

Adults With Less Than 12 Years of Education:

  • Visuo-motor Abilities: Grooved Pegboard, Santa Ana Pegboard (WHO), Pursuit Aiming
  • Processing Speed: Simple Reaction time (problem for individuals in which deliberation is more important than speed & slower for individuals who are not test-wise).
    • Reaction times in South America & South Africa are substantially slower than in Europe. In this light, extended practice is required. To emphasize reaction time or need to work quickly, use a scenario that best fits that culture (e.g., street fight, confrontation with poisonous snake, etc). — reframing
    • Digits symbol or coding is a good diagnostic and predictive test because it parallels with everyday work place tasks – visual scanning, fine motor control, and incidental learning. It’s well suited for non-test-wise clients, even semiliterate individuals because the task is not to write #s, but to write novel symbols. For extended practice, make an additional copy of the test blank, using the last 3 rows: 2 for practice and the third for speeded practice.
    • Target detection tests- symbol detection better for non-test-wise clients because possible limited experience with letters and #s. No comments on adjusting – poorly standardized (per book).
  • Perceptual Organization
    • Picture Completion – non-test-wise client, missing part principle may not be immediately obvious. A common error is to name a missing part that is external to the given frame. Practice is thus essential in order to familiarize both adult and child with requirement that the missing part must be a significant element of the whole. Extended practice on tasks like Block Design are needed for semiliterates or those in more impoverished environments since they may have limited exposure to tasks tapping into these construction areas (e.g., Legos).
    • In Block Design it is important to provide additional practice items for the non-test-wise client for the embedded figures (the ones where the colors flow and each block is not easily defined to one particular quadrant). The current practice items are for non-embedded figures. So for non-test-wise client give Items 1-4 no matter what age and then give the example provided on page 187 of this book.
    • For object assembly you provide practice items for those unfamiliar with jigsaw puzzles. This is one of the better tests for non-test-wise clients.
    • Matrix Reasoning is well-suited to the instructional needs of non-test-wise clients.
  • Working Memory
    • Arithmetic subtest is good to be in core because everyday math is used by even those who are not well educated. It has 4 reversal items which provides excellent extended practice gradient for non-test-wise clients.
    • Digits forward is often easily grasped by even semiliterates. For digits backwards, however, extended practice is essential. The task should be explained with particular care, first asking the client to reverse the digits 1,2 and then 1, 2, 3. If difficulties emerge at this level, according to Lezak, it is helpful to point at an imaginary 1-2-3 series in the air in front of you, and then , pointing to the imaginary 3 on the right saying “Now you say 3 – (point to 3) –2 (point to 2) –1.” It can also be written down. Keep practicing until the client grasps the reversal principle. If giving spatial span, it should be done right after digit span so the client understands the concept.
  • Auditory Memory (Immediate and Delayed)
    • Verbal Paired Associates – provide extended practice. First give pair that is associated. Then give a pair that is not. For Logical Memory, outside of North America, it is important to avoid confounding narrative memory with the acquisition of what for the client is likely to be meaningless information or not “encoding” a concept that is meaningless to them.
    • Benton Visual Retention Test has high novelty for non-test-wise clients, and that additional practice is essential.
  • Visuomotor Abilities
    • Animal Pegs has been used for children from non-Western cultures (age 8+, from the WPPSI-R). It is more readily understood than grooved pegboard (no particular reasons noted in the book – my guess, familiarity with animals. It has good practice items.
  • Working Memory
    • Serial 7s: usually given to clients with 12 or more years of education. It can be used with semiliterates with caution. Begin with serial 3 for those with less education, explaining what has to be done and coaching them over 5 trials or until the task is performed fluently. If it seems too easy, switch to serial 7s.
  • Misc.
    • Trailmaking test cannot be given to those with less than 12 years of education even if they have good language skills and can say the alphabet.
    • Austin Maze Test – For non-test-wise clients with 12 or more years of education, this is a useful method for the examination of orderly learning with effective error utilization – the information yielded is comparable to the WCST.
  • Language
    • COWAT: letter fluency for those with 12 or more years of education.
    • Animal fluency for illiterate or semiliterate clients. Interpret with caution unless local norms are used.
    • Telephone #s to dictation: 7 digit #s are standard worldwide – can be routinely added to battery.
    • Token test – can use objects to help clarify instructions of what to do (see page 201). Just really provides extra practice to help them understand the directions.

Cranium, Ventricles, and Meninges

CRANIAL VAULT AND MENINGES

Foramina

Holes allowing cranial nerves, spinal cord, blood vessels to enter and leave cranial cavity

  • Foramen magnum– largest; at base of skull
  • Cervicomedullary junction – occurs at the level of foramen magnum; point where spinal cord meets medulla

Fossae

Compartments of the cranial cavity divided by ridges of bone

  • Anterior fossa – contains frontal lobe; divided from middle fossa by lesser wing of sphenoid bone
  • Middle fossa – contains temporal lobe; divided from posterior fossa by petrous ridge of temporal bone, as well as sheet of meninges
  • Posterior fossa – contains cerebellum and brainstem

Meninges

Final layers within skull are meninges and CSF

From inside to outside (PAD):

  • Pia– thin layer of cells
    • adheres to brain surface closely and follows gyri and depths of sulci
    • surrounds initial portion of each blood vessel as it enters brain surface, , then fuses with blood wall
  • Arachnoid– “spidery”
    • adheres to inner surface of dura
  • within arachnoid, CSF “percolates” over surface of brain
  • Dura– “hard”; 2 fibrous layers, which are fused with each other and adhere to the inner surface of skull except in two places (where one layer dips inward):
    • falx cerebri – flat sheet of dura suspended from roof of cranium; separates R and L hemisphere
    • tentorium cerebelli – tentlike sheet of dura covering upper surface of cerebellum; tentorium cerebelli and petrous portions of temporal bones divide posterior fossa from rest of cranial vault:
      • supratentorial: cavity above tentorium
      • infratentorial: cavity below tentorium

Spaces

Potential spaces formed by meninges; blood vessels within spaces can cause hemorrhage

  • Epidural space: b/w inner surface of skull and dura
    • Middle meningeal artery: branch of external carotid artery; supplies the dura
  • Subdural space: b/w dura and arachnoid
    • Bridging veins and dural venous sinuses—provide venous drainage from brain and meninges
  • Subarachnoid space: b/w arachnoid and pia
    • CSF and Major arteries (then penetrate into brain)
  • Spinal cord- enveloped by same 3 meningeal layers as exits through foramen of magnum; only difference is a layer of epidural fat in the spinal canal

VENTRICLES AND CEREBROSPINAL FLUID

Basic facts

  • Contain CSF
  • Two lateral ventricles, one in each hemisphere
  • Third within diencephalon
  • Fourth surrounded by pons, medulla, and cerebellum
  • Choroid plexus: inside ventricles; vascular structure that produces CSF; lined with epithelial cells
  • Ependymal cells: line inner walls of ventricles

Lateral Ventricles

  • Horns- extensions named after lobes or directions they extend
    • Frontal (Anterior) Horn- extends anteriorly from body of lateral ventricle into frontal lobe
    • Occipital (Posterior) Horn- extends back to occipital lobe
    • Temporal (Inferior) Horn- extends inferiorly and anteriorly into temporal lobe
  • Body- posterior to interventricular foramen of Monro, within frontal and parietal lobes
    • Atrium (Trigone): connects the body with the occipital and temporal horns
  • “C” shaped structures- follow curve of vent; caudate nucleus; corpus callosum, fornix, stria terminalis
  • Communicates with third ventricle via interventricular foramen of Monro

Third Ventricle

  • Walls formed by thalamus and hypothalamus
  • Communicates with fourth vent via cerebral aqueduct (aqueduct of Sylvius) which travels through midbrain

Fourth Ventricle

  • Roof formed by cerebellum
  • Floor formed by pons and medulla

Cerebrospinal Fluid

  • leaves fourth ventricle via: lateral foramina of Luschka and midline foramen of Magendie
  • Travels around brain and spinal cord in subarachnoid space
  • Reabsorbed by arachnoid granulations into dural venous sinuses (back into bloodstream)
  • Cisterns- widening of subarachnoid space to form large CSF collections

BLOOD-BRAIN BARRIER

Capillary endothelial cells

  • Brain capillary- tight junctures; cell transport required for passage of water soluble substances
  • Systemic capillary- capillary wall separated by clefts allowing passage of fluids and molecules
  • Choroid epithelial cells: form blood-CSF barrier; barrier between capillaries and CSF

Blood-brain and blood-CSF barriers separate arterial blood from brain parenchyma

  • Lipid soluble substances cross both (O2 and CO2)
  • Other substances conveyed in both directions through transport systems

Primary role of blood-brain barrier is to protect brain function from fluctuations in blood chemistry

  • Circumventricular organs: areas where blood-brain barrier is interrupted, allowing brain to respond to changes and secrete neuropeptides into system

Disruption of blood-brain barrier- caused by tumor, infection

  • Results in extravasation of fluids into interstitial space
  • Vasogenic edema- excessive extracellular fluid
  • Cytotoxic edema- excessive intracellular fluid within brain cells caused by cellular damage

HEADACHE

  • No pain receptors in parenchyma- pain caused by mechanical traction, inflammation, or irritation of other structures in the head that are innervated, such as blood vessels, meninges, scalp, and skull.
  • Side of headache often corresponds to side of pathology (but not always)

Vascular headache

Migraine (term also used to mean cluster headache)

  • Pathophysiology thought to involve inflammatory, autonomic, serotonergic, neuroendocrine, and other influences on blood vessel caliber in the head
  • 75% have + family history
  • Sx provoked by foods, stress, eye strain, menstrual cycle, changes in sleep
  • Aura: warning sx; visual blurring, shimmering, scintillating distortions, fortification scotoma (region of visual loss bordered by zigzagging lines resembling walls of a fort)
  • Often unilateral; if bilateral, warrants MRI to exclude vascular malformation or lesion
  • Pain is throbbing; exacerbated by light (photophobia), sound (phonophobia), or sudden movement
  • Nausea, vomiting, tender scalp may occur
  • 30 minutes to 24 hours duration; relief often after sleeping
  • Occur once every few years, to several times a week

Complicated migraine

  • Accompanied by transient focal neurologic deficits: sensory phenomena, motor deficits, visual loss
  • Migraine should be diagnosis of exclusion only after other causes (e.g., post-ictal headaches or cerebrovascular disease) have been ruled out

Treatment of migraine

  • Acute attacks: nonsteroidal anti-inflammatories, anti-emetics, serotonin agonists, ergot derivatives, rest in dark.
  • Preventive measures: avoid triggers, treatment with meds, hydration

Cluster headache

  • Less than 1/10 as common as migraine
  • Clusters occur once to several time per day over a few weeks then vanish for months
  • Pain is severe, described as boring sensation over one eye; lasts 30-90 minutes
  • Accompanied by unilateral autonomic sx (tearing, eye redness); Horner’s syndrome (ptosis, miosis, anhidrosis- covered in Ch. 13), unilateral flushing, sweating, nasal congestion
  • Treatment similar to migraine; inhaled oxygen effective in stopping attack

Tension headache (renamed tension-type headache)

  • Steady dull ache, described as band-like sensation
  • May be related to excessive contraction of scalp and neck muscles
  • Pathophysiological distinction between tension h/a and migraine has been questioned
  • Mild to mod h/a lasting few hours, but there is a chronic form
  • Treatment- muscle relaxation techniques; nonsteroidal anti-inflammatory; analgesics; TCAs

SEE TABLE 5.2 FOR OTHER CAUSES OF HEADACHE

Other causes

  • Any “explosive” onset of severe h/a should have CT – to rule out subarachnoid hemorrhage
  • Cerebral ischemia and infarction
  • Post-ictal period
  • Low CSF- from lumbar puncture or spontaneously; worse while standing, better when lying down
  • Increase CSF- neoplasms; worse when lying down
  • Meningitis-accompanied by fever, signs of meningeal irritation (stiff neck, light sensitivity)
  • Pseudotumor cerebri- elevated ICP with no mass lesion; common in adolescent females; tx w/ acetazolamide or shunt
  • Temporal arteritis (giant cell arteritis)- seen in elderly; vasculitis affects temporal arteries, including those supplying eyes; artery enlarged and firm; may lose vision

INTRACRANIAL MASS LESIONS

Mass– anything abnormal that occupies volume within the cranial vault (e.g., tumor, hemorrhage, abscess) Neurologic symptoms caused by:

  • compression and destruction of adjacent brain regions
    • local tissue damage (ex- lesion in primary motor cortex cause contralateral weakness)
    • distorts or irritates blood vessels, can cause headache
    • compression of blood vessels can cause ischemic infarction
    • erosion through blood vessel walls can cause hemorrhage
  • increased intracranial pressure
  • herniation: mass displaces structures so that they are shifted from one compartment to another
    • Mass effect- distortion of normal brain geometry due to mass lesion
    • Effacement- mild flattening of sulci next to lesion; seen on MRI but no symptoms
  • Other effects:
    • Disruption of blood-brain barrier leads to vasogenic edema
    • Compression of ventricular system obstructs CSF flow resulting in hydrocephalus
    • lesions produce abnormal electrical activity, causing seizures
    • Midline shift- shift in brain structures away from lesion
    • pineal calcification used to measure extent of shift at level of upper brainstem
    • displacement and stretching of upper brainstem impairs RAS

ELEVATED INTRACRANIAL PRESSURE

Elevated ICP can cause decreased cerebral blood flow and ischemia, though autoregulation of vessels compensates for modest increases in ICP

Symptoms/ signs of increased ICP

  • Headache- worse in morning because brain edema rises overnight from lying down
  • Altered mental status- *** most important indicator; irritability and depressed level of alertness and attention
  • Nausea and projectile vomiting
  • Papilledema- engorgement and elevation of optic disc; sometimes also see retinal hemorrhage
  • Visual loss caused by transient or permanent optic nerve damage
  • Diplopia caused by traction on CN VI, causing unilateral or bilateral abducens nerve palsies
  • Cushing’s triad- hypertension, bradycardia, irregular respirations

Treatment Goals

  • Reduce to safe level, giving time to treat underlying disorder
  • Measure through LP – BUT do not perform if severely elevated ICP because of risk of precipitating a herniation

BRAIN HERNIATION SYNDROMES

Herniation- mass effect severe enough to push structures into another compartment

 

Transtentorial Herniation-

herniation of medial temporal lobe, especially uncus, inferiorly through tentorial notch

  • uncal herniation– clinical triad:
    • blown pupil- compression of CNIII; dilated, unresponsive pupil; ipsilateral to lesion in 85% of cases
    • hemiplegia- compression of cerebral peduncles; can be ipsilateral or contralateral to lesion.
    • coma- distortion of midbrain reticular formation

Central Herniation

  • downward displacement of brainstem or cerebellar tonsils through foramen magnum
  • associated with any lesion causing increased ICP

Subfalcine Herniation

  • cingulate gyrus and other brain structures herniated under falx cerebri to other side of cranium
  • no clinical signs; may cause occlusion of anterior cerebral arteries

HEAD TRAUMA

Mild Head Trauma

Concussion – LOC; headache; dizziness; nausea; vomiting

Recovery usually complete, but can see postconcussive syndrome:

  • headaches
  • lethargy
  • mental dullness
  • lasts months after accident

Severe Head Trauma

Cause permanent injury to brain through:

  • Diffuse axonal shearing- damage to white matter and cranial nerves
  • Petechial hemorrhages- small spots of blood in white matter
  • Intracranial hemorrhage- symptoms can occur after delay of several hours after event
  • Cerebral contusion
  • Tissue injury from penetrating trauma
  • Cerebral edema, contributing to increased ICP

INTRACRANIAL HEMORRHAGE

Epidural Hematoma

Location

  • space between dura and skull

Cause

  • rupture of middle meningeal artery from fracture of temporal bone

Clinical features

  • increased ICP; pt may have lucid interval lasting hrs before lapsing into unconsciousness

Subdural Hematoma

Location

  • between dura and arachnoid

Cause

  • rupture of bridging veins

Clinical features

  • Two types
    • Chronic- slowly oozing blood collects; headache, cognitive impairment, unsteady gait, focal signs
    • Acute- high velocity impact injury

Subarachnoid Hemorrhage

Location Between arachnoid and pia

Cause

  • Two causes
    • Nontraumatic (spontaneous)- onset with severe headache; result of arterial aneurysm or bleed from AVM
      • Risk factors- hypertension, smoking, alcohol, sudden increase in BP
      • Clinical symptoms- headache, meningeal irritation, nuchal rigidity, cranial nerve, neuro deficits
      • Cerebral vasospasm- seen 1 week post; can lead to infarction
    • Traumatic: bleeding into CSF from damaged blood vessels due to contusions/ traumatic injury

Intracerebral or Intraparenchymal Hemorrhage

Location Within parenchyma in cerebral hemispheres, brainstem, cerebellum, spinal cord

Cause

  • Two types
    • Traumatic: contusions from skull ridgesl; coup/contrecoup injury; commonly frontal or temporal poles
    • Nontraumatic: caused by hypertension, brain tumor, vascular malformation
      • Most common- small penetrating blood vessels in basal ganglia; thalamus; cerebellum; pons

Intraventricular extension– extends from parenchyma to involve ventricles Intraventricular hemorrhage– arise from blood vessels in vents

Vascular malformations

  • Arteriovenous malformations: congenital abnormalities causing direct connection b/w artery and vein; tangle of abnormal blood vessels; hemorrhage is usually intraparenchymal; present with headache, seizure
  • Cavernous malformation: abnormally dilated vascular cavity lined by only one layer of vascular endothelium
  • Capillary telangiectasias- small regions of abnormally dilated capillaries; rarely give rise to hemorrhage
  • Venous angiomas- dilated veins; no clinical symptoms but associated with cavernous malformations

HYDROCEPHALUS

Excess CSF in intracranial activity

Caused by

  • Excess CSF production – rare; but can be seen with certain tumors (choroid plexus papilloma)
  • obstruction of flow in vents or subarachnoid space – more common
    • usually occurs at narrow points (foramen of Monro, cerebral aqueduct, fourth vent)
  • decrease in reabsorption due to damage or clogging of arachnoid granulations

Two categories

  • Communicating hydrocephalus- impaired CSF reabsorption in arachnoid granulations, obstruction of flow in subarachnoid space, or excess CSF productions
  • Noncommunicating hydrocephalus- obstruction of flow within ventricular system

Symptoms

  • Like any other cause of increased ICP- headache, nausea, vomiting, cognitive impairment, decreased vision
  • Dilation of vents compresses descending white matter pathways from frontal lobes leading to magnetic gait (feet barely leave floor) and incontinence
  • Infants- skull expands, leading to increase head circumference; bulging anterior fontanelle
  • Eye movement abnormalities- mild results in sixth nerve palsy (incomplete or slow abduction of eye in horizontal direction); severe results in inward deviation of both eyes

Treatment

  • Extraventricular drain- (ventriculostomy) fluid from lateral vents drained to bag outside head
  • Ventriculoperitoneal shunt- shunt tube passed from lateral vent into peritoneal cavity of abdomen
  • Third ventriculostomy- via endoscopy, blunt instrument perforates floor of third vent to allow CSF to drain

Normal Pressure Hydrocephalus – chronically dilated vents; measurement of CSF pressure not elevated Clinical triad of gait difficulties; urinary incontinence; mental decline (3 Ws: wet, wobbly, and wacky) Some improve after lumbar puncture (briefly) or VP shunt

Hydrocephalus ex vacuo – excess CSF in region where brain tissue lost due to stroke, surgery, atrophy, etc.

Common Congenital Causes in Children:

  • Neural tube defect (e.g., spina bifida/myelomeningocele)
  • Dandy-Walker syndrome
  • Aquaductal stenosis
  • Intraventricular Hemorrhage

PRIMARY CNS TUMORS

Adults Most common- glioblastoma, brain metastases (arise from neoplasms elsewhere in body that spread to brain) 30% infratentorial; 70% supratentorial

Pediatric Most common- astrocytoma, medulloblastoma, ependymoma 70% posterior fossa; 30% supratentorial Since many in posterior fossa, tend to cause hydrocephalus through compression/obstruction of fourth vent

Symptoms

  • Depend on size, location, rate of growth
  • Headache, signs of elevated ICP common at presentation
  • Seizures or focal symptoms depend on location

Benign– do not infiltrate or disseminate through nervous system Malignant– potential to spread; rarely spread outside CNS

Treatment

  • Surgical removal- should be > 90% tumor removal to have positive effect on outcome
  • Radiation therapy
  • Chemotherapy
  • Steroids to reduce edema

Types of Tumors

  • Gliomas- subdivided into several types, arise from glial cells
  • Meningiomas- arise from arachnoid villus cells
  • Pituitary adenomas- cause endocrine disturbance; cause bitemporal visual field defect by compressing optic chiasm
  • Schwannomas- most common on CN VIII; discussed Ch. 12
  • Lymphoma- arise in regions adjacent to vents; more common with increase in HIV infection
  • Pineal region tumor- uncommon; obstruct cerebral aqueduct causing hydrocephalus; compress midbrain

Pediatric Tumors

  • Cerebellar astrocytoma: grade I/IV; often cured by surgery alone
  • Medulloblastoma and ependymoma worse outcome

BACTERIAL INFECTIONS

Bacteria gain access through bloodstream, originating from infection elsewhere

Infectious meningitis

– infection of CSF in subarachnoid space

Symptoms- meningeal irritation: headache, lethargy, photophobia, phonophobia, fever, nuchal rigidity (neck muscles contract involuntarily, resulting in neck pain and resistance to neck flexion)

Diagnosis- symptoms may progress over hours or weeks; sample of CSF by lumbar puncture; CT before LP because removing CSF if there is a mass can cause herniation

Treatment- antibacterial therapy

Complications- seizures, cranial neuropathies, edema, hydrocephalus, herniation, infarcts, death

Brain abscess

expanding intracranial mass lesion, like brain tumor, but with more rapid course

Symptoms- lethargy, headache, fever, nuchal rigidity, vomiting, seizures; focal signs

Treatment- if small, treat with antibiotics; if large or progressive, treat with needle aspiration and antibiotics

Epidural abscess

– occur in spinal canal

Symptoms- back pain, fever; headache; signs of nerve root or spinal cord compression

Treatment-surgical drainage; antibiotics

Subdural empyema

collection of pus in subdural space, resulting from infection of nasal sinus or inner ear

Treatment- surgical drainage and antibiotics

 

Tuberculous meningitis

– seen with resurgence of TB

Symptoms- headache, lethargy, meningeal signs over course of weeks; inflammatory response in basal cisterns affecting circle of Willis and causing infarcts; coma and death if untreated

Treatment- combination of drugs

Populations at risk- IV drug users; HIV +; people where TB is endemic

Infections Caused by Spirochetes

  • Neurosyphilis- recent resurgence due to HIV;
    • Primary – cancer sores
    • Secondary – diffuse skin lesions
    • Tertiary –diffuse white matter infarcts causing dementia, behavioral change, delusion, psychosis, upper motor neuron weakness; Tabes dorsalis (involvement of spinal cord dorsal roots)

 

Lyme Disease- deer tick

Symptoms– early rash; later neurologic manifestations after several weeks (meningeal signs, emotional changes, memory and concentration problems, cranial and peripheral neuropathies); arthritis, cardiac abnormalities

Diagnosis- clinical features, LP, blood test

Treatment- IV ceftriaxone

VIRAL INFECTIONS

Viral meningitis

Less intense, rapid than bacterial; recovery occurs spontaneously in 1-2 weeks

Symptoms- headache, fever, lethargy, nuchal rigidity, meningeal irritation (Table 5.5, p. 147)

Diagnosis- blood tests, LP, EEG

Viral encephalitis – involves brain parenchyma; more severe symptoms Meningoencephalitis– meninges involved

Causes

  • Herpes – psychotic symptoms; focal signs; causes necrosis of temporal and frontal structures
  • Postinfectious encephalitis- several days after viral infection, diffuse automimmune demyelination of CNS
  • Herpes zoster- shingles, chicken pox
  • Transverse myelitis- caused by viral infections of CNS (spinal cord)

HIV-Associated Disorders of Nervous System

  • Aseptic meningitis- caused at time of seroconversion; associated with cranial neuropathies involving facial nerve
  • AIDS dementia complex- most common neurologic manifestation of HIV; treat with AZT in combo therapy
  • Progressive multifocal leukoencephalopathy (PML)- gradual demyelination of brain, leading to death in 3-6 months
  • Opportunistic viral, bacterial, funga, and parasitic infections: herpes, varicella-zoster, cytomegalovirus, TB, neurosyphylis, cryptococcal meningitis, toxoplasmosis
  • Primary central nervous system lymphoma- B cell lymphoma; second most common cause of mass lesions

Parasitic Infections

Cysticercosis– ingestion of eggs of pork tapeworm

Symptoms- organism migrates through bloodstream, forming small cysts in muscles, eyes, CNS; causes seizures, headache, lymphocytic meningitis; hydrocephalus if cyst obstructs

Radiologic appearance- small cysts in parenchyma with surrounding edema

Course- organisms eventually die leaving calcifications throughout brain (“brain sand”)

Diagnosis- clinical history; radiologic appearance; antibody tests

Fungal Infections

Can involve brain parenchyma and cause inflammatory response and/or CN deficits

 

Prion-Related Illnesses

Prion– protein-based infectious agent; able to transit illness from one animal to another although no DNA or RNA

Symptoms- diffuse degeneration of brain and spinal cord, multiple vacuoles with spongiform appearance

Types- Creutzfeldt-Jakob; Gerstmann-Straussler-Scheinker; kuru; fatal familial insomnia

  • Creutzfeldt-Jakob
    • rapidly progressive dementia, exaggerated startle response, myoclonus, visual distortion, ataxia
    • EEG: period sharp wave complex
    • progressive deterioration and death within 6-12 months
    • incubation period 2-25 years
    • there does appear to be some genetic susceptibility in one strain

LUMBAR PUNCTURE

Access to subarachnoid space of lumbar cistern

  • obtain samples of CSF
  • measure CSF pressure
  • remove CSF in normal pressure hydrocephalus
  • give drugs

Perform CT first to evaluate for increased ICP and avoid herniation Red blood cells in CSF can indicate subarachnoid hemorrhage or traumatic tap (due to needle puncture)

LP used for diagnosing infection, hemorrhage, neoplasms, meningitis, and multiple sclerosis

 

CRANIOTOMY

Burr holes drilled through skull, then joined together with small saw to remove bone flap; dura folded back to provide access to brain

 

Corticospinal Tract and Other Motor Pathways

MOTOR/SENSORY CORTEX, SOMATOTOPIC ORGANIZATION

Primary Motor Cortex

  • Precentral gyrus, Brodmann’s area 4

Primary Sensory Cortex

  • Postcentral gyrus, Brodmann’s areas 3, 1, 2

Somatotopic Organization of Primary Motor/Sensory Cortex

  • Adjacent regions on cortex correspond to adjacent areas on the body surface
  • Classically depicted by Motor and Sensory Homunculus
  • Not as clear-cut and consistent as originally believed

BASIC ANATOMY OF THE SPINAL CORD

Central Gray Matter

  • Butterfly-shaped
  • Surrounded by ascending/descending white matter columns (funiculi)
  • Dorsal (posterior) horn: primarily sensory processing; sensory neurons in the dorsal root ganglia have axons that bifurcate – one conveys sensory information from the periphery, the other carries the info through the dorsal nerve root filaments to dorsal aspects of the cord
  • Intermediate zone: contains interneurons and specialized nuclei
  • Ventral (anterior) horn: contains motor neurons that send axons out via ventral nerve root filaments
  • Can also be divided into nuclei/laminae

White Matter

  • Consists of Dorsal (posterior) columns and Ventral (anterior) columns
  • Thickest in the cervical levels where most ascending fibers have already entered the cord and most descending fibers have not yet terminated; sacral cord is mostly gray matter

Cervical and Lumbosacral Enlargements

  • Give rise to the nerve plexuses for the arms and legs
  • Has more gray matter at these levels, esp. in the ventral horns where lower motor neurons for arms and legs reside

Lateral Horn

  • Thoracic level
  • Contains intermediolateral cell column

SPINAL CORD BLOOD SUPPLY

Spinal Blood Supply

  • Arises from branches of the vertebral arteries and spinal radicular arteries
  • Vertebral arteries give rise to anterior spinal artery that runs along ventral surface supplying anterior 2/3 of the cord – anterior horns, anterior and lateral columns
  • Two posterior spinal arteries arise from vertebral/posterior inferior cerebellar arteries to supply dorsal surface supplying posterior columns and part of the posterior horns
  • The anterior and posterior arteries form a spinal arterial plexus that surrounds the cord
  • 31 segmental arterial branches, most from aorta to supply meninges, 6-10 of these radicular arteries
  • Great radicular artery of Adamkiewicz: major blood supply to lumbar/sacral cord, arising from left side T5-L3, usually between T9-T12
  • Mid-thoracic, T4-T8, between lumbar and vertebral arterial supplies, vulnerable zone of decreased perfusion, risk of infarction 2ndary thoracic surgery/other conditions of decreased aortic pressure
  • Batson’s plexus: epidural veins, don’t contain valves

GENERAL ORGANIZATION OF THE MOTOR SYSTEMS

Basic Facts

  • Elaborate network of multiple, hierarchical feedback loops
  • Cerebellum, basal ganglia, thalamic participation discussed in ch. 2, cortical regions in ch. 19
  • Upper motor neurons carry output to lower motor neurons in spinal cord and brainstem which project to muscles in the periphery
  • Descending upper motor neuron pathways divided into lateral and medial motor systems

Medial Motor Systems

  • Made up of 4 systems; control proximal axial girdle muscles involved in postural tone, balance, orienting movements of head, gait-related movements
  • Descend ipsilaterally or bilaterally
  • Unilateral lesions typically produce no obvious deficits
  • Tend to terminate on interneurons that project bilaterally – multiple spinal segments
  • Anterior corticospinal tract; vestibulospinal tracts; reticulospinal tracts; tectospinal tract

Lateral Motor System

  • Rubrospinal Tract
    • Small, uncertain clinical importance
    • May take over functions of corticospinal functions after injury
    • May play role in flexor (decorticate) posturing upper extremities
  • Lateral Corticospinal Tract
    • Most clinically important descending motor pathway; pyramidal tract
    • Controls movement of the extremities; lesions produce characteristic deficits for localization
    • Over ½ of the fibers originate in primary motor cortex (area 4) located in cortical layer 5
    • The rest from premotor and supplementary motor or parietal lobe (areas 3,1,2,5,7)
    • 3% of its neurons are Betz cells – giant pyramidal cells
    • Somatotopic representation-upper extremities medial to lower extremities
    • Lies in the posterior limb of the internal capsule
      • Internal Capsule
        • Corticospinal/corticobulbar fibers form part of it
        • Anterior limb separates head of caudate from globus pallidus and putamen
        • Posterior limb separates thalamus from globus pallidus and putamen
        • Genus transition between anterior and posterior limbs
        • Somatotopic map preserved– ace most anterior, arm and leg progressively posterior
        • Fibers projecting from cortex to the brainstem are called corticobulbar instead of corticospinal bc they go to the brainstem or “bulb”
        • Fibers compact so that lesions generally produce weakness of the entire contralateral body; occasionally more selective deficits
      • Cerebral peduncles
        • Internal capsule continues into midbrain cerebral peduncles (“Feet of the brain”)
        • Basis peduncle: white matter, ventral side
        • Middle 1/3 of basis peduncle: corticospinal/corticobulbar fibers, face/arm/leg axons go medial to lateral
      • Medullary Pyramids
        • Corticospinal fibers next descend through ventral pons forming scattered fascicles which collect on ventral surface to form medullary pyramids
        • Origin of imprecise pyramidal tract label
      • Cervicomedullary Junction
        • Transition from medulla to spinal cord
        • 85% of pyramidal fibers cross over in the pyramidal decussation to enter lateral white matter columns, forming the lateral corticospinal tract
        • Axons enter spinal cord gray matter to synapse onto anterior horn cells
        • Lesions above pyramidal decussation = contralateral weakness; below = ipsilateral weakness
        • Remaining 15% of fibers continue ipsilaterally and enter the anterior white matter columns to form the anterior corticospinal tract

AUTONOMIC NERVIOUS SYSTEM (ANS)

Basic Facts

  • Controls more automatic and visceral functions in contrast to somatic motor pathways just discussed
  • Autonomic efferents: peripheral synapse in ganglion btw CNS and effector gland/smooth muscle; in contrast to somatic efferents: anterior horn/cranial nerves project directly to skeletal muscle
  • While there are sensory inputs, the ANS itself consists of only efferent paths
  • Two main divisions: sympathetic (thoracolumbar) and parasympathetic (craniosacral)

Sympathetic

  • Arises from T1 to L2/L3
  • “Fight or flight” e.g., increasing BP, Hrt rate, bronchiodilation, pupil size
  • Preganglionic neurons: in the intromediolateral cell column in lamina VII, T1-L2/L3, travel short distance
    • Two Sets of Ganglia
      • Paired paravertebral ganglia: form sympathetic chain/trunk, bilateral, cervical to sacral
      • Paired prevertebral ganglia: in celiac plexus around aorta
  • Postganglionic neurons: travel long distances to reach effector organs; release mainly norepinephrine; one exception – sweat glands (acetylcholine)
  • Synaptic transmission mediated by acetylcholine (nicotinic receptors) released by preganglionic neurons
  • Outflow controlled directly/indirectly by higher centers
  • Also regulated by afferent sensory information including internal receptors (e.g., chemoreceptors)

Parasympathetic

  • Arises from cranial nerves and S2 to S4
  • “Rest and digest” e.g., increasing gastric secretions and peristalsis, decreasing Hrt rate and pupil size
  • Axons travel long distance to terminal ganglia within or near effector organs
  • Preganglionic fibers arise from cranial nerve parasympathetic nuclei and from sacral parasympathetic nuclei in the lateral gray matter of S2-S4 and intromedial cell column
  • Postganglion neurons release mainly acetylcholine (muscarinic cholinergic receptors)
  • Synaptic transmission mediated by acetylcholine (nicotinic receptors)
  • Outflow controlled directly/indirectly by higher centers
  • Also regulated by afferent sensory information including internal receptors (e.g., chemoreceptors)

KEY CLINICAL CONCEPTS

Upper vs. Lower Motor Neuron Lesions

  • Upper motor neurons of corticospinal tract project from cortex to lower motor neurons in the anterior horn of the spinal cord
  • Lower motor neurons in turn project via peripheral nerves to skeletal muscle
  • Signs of upper motor neuron lesions: muscle weakness and increased tone and hyperreflexia (spasticity), additional abnormal reflexes, e.g., Babinski; may initially be flaccid paralysis gradually developing into spastic paresis
  • Signs of lower motor neuron lesions: muscle weakness, atrophy, fasiculations (abnormal muscle twitches), hyporeflexia
  • Weakness can be caused by lesions at any level in the motor system

Weakness Patterns and Localization

  • Unilateral face/arm/leg: hemiparesis/plegia
    • No sensory deficits: contralateral; corticospinal/bulbar below cortex/above medulla; post. Limb internal capsule; basis pontis; mid 1/3 peduncle
    • With somatosensory/oculomotor/visual/higher cortical deficits: contralateral; primary motor cortex; corticospinal/bulbar above medulla
  • Unilateral arm/leg: contralateral above pyramidal decussation; ipsilateral below pyramidal decussation; arm/leg motor cortex; corticospinal lower medulla to C5
  • Unilateral face/arm: faciobrachial paresis/plegia; face/arm motor cortex
  • Unilateral arm: brachial monoparesis/plegia; contralateral arm motor cortex; ipsilateral peripheral nerves supplying arm
  • Unilateral leg: crural monoparesis/plegia; contralateral leg motor cortex; ipsilateral lateral corticospinal below T1, or peripheral nerves supplying the leg
  • Unilateral facial: Bell’s palsy/isolated facial weakness; common: ipsilateral facial nerve (CN VII); uncommon: contralateral face motor cortex or genu of internal capsule
  • Bilateral arm: brachial diplegia; medial fibers of corticospinal; bilateral cervical ventral horn; bilateral peripheral nerve/muscle d/o’s
  • Bilateral leg: paraparesis/plegia; bilateral leg motor cortex; lateral corticospinal below T1; cauda equina syndrome/bilateral peripheral nerve/muscle d/o
  • Bilateral arm/leg: quadraparesis/plegia; tetraparesis/plegia; bilateral arm/leg motor cortex; bilateral corticospinal lower medulla to C5; peripheral nerve motor neuron/muscle d/o’s – usually also affect the face
  • Generalized: bilateral entire motor cortex; bilateral corticospinal/bulbar anywhere from corona radiata to pons; diffuse d/o involving all lower motor neurons, peripheral axons, neuromuscular junctions, or muscles
  • Patterns not listed above: consider 2 or more lesions, unusual lesions, anatomical variants, or non-neurological

Cortices: Parietal and Temporal Lobes

TEMPORAL LOBE

Hippocampus

  • Some controversy as to whether or not it encodes (material-specific) or represents only a cognitive/ spatial map (memory)
  • Rat studies suggests spatial map (i.e., lesion here, no longer able to find platform on Morris milk maze based on spatial cues from env; also stimulation and single cell recordings support this)
  • Monkey studies show that removed hippocampus, impaired location but not object memory
  • Although some human studies do suggest that hippocampus is involved with spatial memory (i.e., our FIST study-RH specific; topographical amnesia & spatial disorientation shown in patient HM), it’s not just spatial memory (perhaps material specific to HS) based on human lesion studies (TLE, HM, etc.), electrical stimulation and WADA testing (TLE), ERP studies, etc
  • Do see amnesia following hippocampal removal, as specific as CA1 (RB) and HM; however, even though they had poor memory for landmarks, also poor performance on WMS LM, verbal PA, and several “non” spatial memory tasks

Amygdala

  • Associated with emotional CC, emotional memory (saliency), emotion; see emotion and memory notes

Heschle’s Gyrus

  • Primary auditory cortex

Insular

  • Primary taste cortex

Association Cortices

  • Following damage to inferior T regions, often see agnosia (unable to recognize classes of objects) or ventral stream of the what (see V-S notes)

Symptoms of Temporal Lobe Lesions

  • Disturbed auditory sensation/ perception
  • Disturbed selective attn of auditory/ visual input
  • Disorder of visual perception (agnosia)
  • Impaired organization & categorization of verbal material
  • Disturbed language comprehension (WA)
  • Impaired LTM (HM)
  • Altered personality and affective behaviors (amygdala)
  • Altered sexual behaviors

PARIETAL LOBE

Anterior Zone (distinct from B)

  • Somatic sensations and perceptions
  • Somatosensory strip/postcentral gyrus

Posterior Zone

  • Integrating sensory input from somatic & visual regions
  • Guidance of movements to points in space in relation to objects in space (what Milner & Goodale argues the “where” system is really all about)
    • Mountcastle et al. showed that tertiary parietal region receives afferents of sensory representations of body movement in space
    • This region has substantial efferents to BG, spinal cord with respect to proximal but not distal movements (distal more F lobe)
    • Lesions/damage to this region produces severe bilateral apraxia when limb movements are required
    • Motor control of left and right parietal cortex is asymmetrical
  • Recognizing & producing abstract stimuli (lesion in angular gyrus disrupt reading)
  • Integrative fx of tertiary cortex (sensory integration)- polymodal regions (several imputs from different modalities converge here)
  • Construction of spatial coordination system to represent visual & somatic spatial worlds
  • Involved with eye movement (show in monkeys neurons which are sensitive to movement of eyes especially visually relevant stimuli- i.e., complex cells which are responsive to specific angles of light- spatial orientation)

Deficits Associated with Parietal Lobe Damage

  • Decreased visual attention
  • Unable to perceive more than 1 stimuli
  • Unable to follow moving target
  • Decreased accommodation & convergence
  • Optic ataxia
  • Unable to maintain fixation
  • Gaze apraxia
  • Abnormal visual search

Syndromes Associated with Parietal Lobe Damage

  • Balint’s Syndrome
    • Paralysis of voluntary gaze
    • Optic ataxia
    • Stimultagnosia (unable to recognize more than one components of visual field at once- piecemeal perception)
    • Verbal intelligence, language and verbal memory intact
    • Due to bilateral PO lesions/damage
  • Gerstman’s Syndrome
    • Associated with left parietal lobe damage
    • Finger agnosia (can’t id fingers on hands)
    • R/L confusion
    • Agraphia (inability to write)
    • Acalculia (inability to perform math operations)
    • Unilateral neglect
    • Apraxia (associated more with left parietal lobe damage)
    • Topographical disorientation/decreased navigation-unable to judge distances
    • Also can see defcits in visual location (where) and depth perception
    • Drawing/ constructional deficits
    • Spatial attention

Theory of Parietal Lobe Functioning

  • Involved with map of object location which is viewer centered (guide movements) rather than objected centered (TL, size, shape, color, etc.)
  • Evidence:
    • Single cell recordings in monkeys
      • Posterior P receives combination of inputs (motivational, motor sensory)
      • Discharge is enhanced when attending to move or moving toward an object
    • Human ERP studies (P100, P200)
      • Largest to contralateral stimulis
      • See cells in P region responding before eye movements & if subjects told to pay attention to a particular spot in one visual field, ERP largest when stimulus is presented there rather than somewhere else
    • rCBF/ PET
      • Roland showed increased BF bilaterally to parietal regions when direct attention to visual target
      • Also shown with other studies

Clinical Psychology

CBT

  • cognitive distortions (Beck)
  • arbitrary inference, selective abstraction, overgeneralization, magnif/minim, personalization, dichotomous thinking
  • depression vs. anxiety (Beck)
  1. depression (cognitions- hopelessness, low s-e, failure) anxiety (anticipation of danger/harm)
  2. depression (negative themes) anxiety (uncertainty of future events question)
  3. both display demoralization, self-absorption, reduced cog capacity for pblm solving and task performance

RET vs Beck

  • RET holds irrational thoughts lead to maladaptive beh, CT holds thoughts are dysfx when they interfere with normal cog processing (can be rational); RET more beh focus; RET therapist more likely to challenge pt’s dysfx beliefs in CT pt encouraged to test out these beliefs on his/her own
  • Stimulus Control
  • narrowing: restricting target behavior to limited set of stim (e.g., fat person- only eat at kitchen table at mealtimes)
  • cue strengthening: linking beh that’s targeted for increase to specific cue or set of cues (e.g., student who rarely studies encouraged to study in certain, specified location, stim with that location will come to trigger study beh)
  • competing responses: identifying and eliminating responses that block desirable behs, or encouraging responses that block undesirable behs (e.g., poor studyer asked to id interference to studying- talking; targeted for elimination)

Stress inoculation Training

  1. cognitive preparation (ed as to how his/her faulty cog prevent appropriate and adaptive coping)
  2. skills acquisition (learning and rehearsing new skills, such as relaxation)
  3. practice (application of learned to real or imagined situations)

research shows useful in remediating aggressive beh and impulsive anger

paradoxical intention

Instructing clients to “do or wish for the very things they fear”- to circumvent anticipatory anxiety; used to treat insomnia

Client-Centered therapy

Carl Rogers

  • congruence: genuineness of therapist (words/actions)
  • incongruence comes about from conflict btwn self-concept and person’s experiences
  • self-actualization tendency: what guides/motivates us or capacity for natural growth, for constructive change, or for self-understanding; goal of therapy is to realize this capacity for self-actualization
  • client’s maladjustment due to discrepancy btwn real self and ideal self
  • therapist providing unconditional positive regard, empathy, genuineness results in change in client

Transactional Analysis

Erik Berne

  • aims to simplify client’s understanding of unhealthy interactions
  • goal is to get people to understand their patterns of behavior and to let their adult ego state take ctrl of transactions while integrating 3 ego states

Theory of Personality

Ego states

assumes 3 distinct ego states: child, parent, adult

Strokes

recognition of others (+/-); how transactions occur bwn ego states at 2 levels (social and covert)

Scripts

  • life plan:
  • developed through interactions with parents and others;
  • giving/receiving strokes- pattern; if unhealthy- maladaptive beh

life positions

  • I’m Ok, you’re Ok;
  • I’m Ok, you’re not Ok,
  • I’m not OK, you’re OK;
  • I’m not OK, you’re not OK

Transactions

  1. complementary: original communication met with appropriate response
  2. crossed: original communication elicits inappropriate ego state
  3. ulterior: confusion b/c one of communicators giving a dual message; basis of games (series of ulteriors)

Family therapy

Systems Theory

  • family is system of interacting relationships and transactional patterns
    • open system (open to outside influence)
    • closed system (resistant to change)- want to avoid this (goal of therapy)
  • properties of a family system:
  1. wholeness: all parts of system interrelated, if one part changes, all others do
  2. non-summativity: whole is greater than the sum of its parts
  3. equifinality: same end result occurs for the family no matter where one enters the system
  4. equipotentiality: one cause can lead to different results
  5. homeostasis: tendency for a system to restore the status quo in event of change/disruption of system (disruption- positive feedback)
  6. negative feedback: correct deviations in status quo to maintain homeostasis
  7. positive feedback: creating deviations in status quo to maintain homeostasis

Communication/Interaction Therapy

  • behavior is form of communication (verbal and non verbal); encourage positive communication btwn family members

double-bind communication

sometimes 2 aspects of same communication contradict each other (“I love you” while pushing child off lap)

metacommunication

report level is intended verbal statement, command level is implicit non-v message (metacommunication)

symmetrical or complimentary communication patterns

(former is = but more competition and conflict; other involves dominant/nondominant roles)

pseudo hostility

superficial bickering to avoid real conflicts; mystification: use denial to mask what’s really going on

Extended Family Systems Therapy

  • Bowen’s: incorporates members of extended family; encourages differentiation of self in all family members (primary goal)
  • 8 interlocking constructs:
  1. differentiation of self: ability to separate one’s intellectual & emotional fx; less able to do this- more fused with other family members
  2. triangulation: triad that causes conflict
  3. nuclear family emotional system: mech family uses to deal with tension and instability
  4. family projective process: projection of parental conflicts and general family dysfx onto children
  5. emotional cutoff: methods kids use to remove selves from emotional ties to their parents (avoidance of emotional involvement leads to lack of self-differentiation)
  6. multigenerational transmission process: escalation of family dysfx through several generations, leads to severe dysfx
  7. sibling position: birth order influences family fx: older children are expected to be responsible of younger
  8. societal regression: impact of societal stress on family system
  • Use genograms and triangulation techs

Minuchin’s structural family therapy

  • views family as an organism or structure
    • when structure’s dysfx processes maintained, family is underfunctioning
    • goal is to disrupt these processes and push family structure toward better fx’
    • improve family process with improve individual in family
  • family system
    • family is, rather than individuals
    • family structure (how family members relate to each other, sets of rules, values, etc.)
    • subsystems (parent-child relationship)
  • Boundaries: (enmeshment: overly unclear, diffuse boundaries- dependence; disengagement: overly rigid boundaries- isolation)
    • parent/child conflicts:
    • triangulation: each parent demands child to side with him/her against other
    • detouring: spouses reinforce deviant beh in child b/c it takes focus off of pblms they are having with each other
    • stable coalition: could join (one parent with child against other parent)
  • goals of therapy:
    • restructure family (inflexible)
    • joining (therapist blends with family system via mimesis- adopts family’s style/lang and tracking- id with family values and hx)
    • creates a family map (specific patterns in general family system can be assessed)
    • restructures the family via
      • enactment- use of role-playing to understand relationships/situations and then changed
      • reframing- family beh relabeled in more positive light
      • blocking- force family to act as they normally do to adopt new interactional patterns

Strategic family therapy

  • Jay Haley;
  • focuses on strategies a therapist uses to restructure a family’s problematic system
  • therapy seen as power struggle btwn client/family and therapist
  • therapist is to adopt strategy to reduce/eliminate family’s sx beh patterns
    • paradoxical interventions (instructing pt to engage in sx beh)
    • reframing (relabeling a beh to make it more amenable to therapeutic change)
    • circular questioning (intv tech to learn more about patterns in family relations)

Object-Relations Family Therapy

  • Psychodynamic principles
  • Interprets current relationships btwn family members
  • Focus on:
    • Transference
    • Early parent-child relationships
    • Insight is core for family change

Group Therapy

  • pioneers: Adler, Burrow, Moreno, Yalom
  • composition of group: most therapist want hetero/homogeneous balance
  • dev level, gender, IQ (most important), stability, size
  • stages of group therapy
  1. group members hesitant to divulge info; dep on leader for communication and approval; concerned with rules, structure, purpose of group
  2. members est place in group; communication becomes hostile and critical (esp toward therapist)
  3. members begin to trust each other and therapist more (cohesive)
  • role of group leader
    • knowledgeable about group dynamics; handle/manage conflicts
    • handle multiple transferences and countertransferences
    • encourage participation from all members
  • benefits of co-therapist
    • complement/support each other
    • broaden range of possible transferential relationships
    • M/F team advantages
  • benefits of group therapy
    • Increased sense of hope
    • Development of social skills
    • Universality (others have similar problems)
    • Sharing of info
    • Sense of cohesiveness and togetherness
  • confidentiality in group therapy
    • although not legally required for members, crucial for effective dev of group
  • group/indiv therapy both might be OK with borderlines and narcissistics

Psychoanalytic theory

Traditional Psychoanalysis

  • ego defense mech: keep unacceptable impulses from reaching consciousness
    • anxiety results if d.mech break down and fail to control

“psychic excitation” (entry of unconscious impulses into consciousness)

  • id governs primary process thinking (unconscious) and fx according to pleasure principle; bio drives: self-preservation instincts, libido, aggressive drives
  • ego governs secondary process thinking or conscious mental process; reality principle
  • superego: conscience, comes from internalization of societal and parental restrictions
  • goal of classical psychoanalysis:
    • engender insight into unconscious and
    • strengthen ego so behavior is more reality based;
    • improvement:
      • catharsis,
      • repeated interpretation leading to insight,
      • working through (assimilation of insights into personality)
    • parallel process: phenomenon where counselor responds to his/her supervisor in way that parallels manner in which a client responds to the counselor
  • reaction formation (OCD); displacement (phobias)
  • therapeutic alliance (allows pts to id with therapist as someone who can help replace id with ego)- switched to working alliance
  • four therapeutic steps: confrontation, clarification, interpretation, working through
  • Freud (Little Hans fear of horses- Oedipal complex, phallic stage)

Additional Psychodynamic Therapies

Jung’s Analytical Psychology

  • extroversion (disposition to fine pleasure in external things)
  • introversion (turning inward of the libido)
  • turn from extroversion of youth to introversion of adulthood mid life (40); associated with mid-life crisis/transition
  • personal unconscious contains repressed material while collective unconscious consists of archetypes (universally shared predispositions toward feeling, thinking, and perceiving)
  • used same processes as Freud: dream interpretation, associations, transference analysis
  • unconscious exists on 2 levels: individual/personal unconscious (arises from repression), collective conscious (arises from universally inherited neural patterns, and archetypes)

Adler’s Individual Psychology

  • pathological beh represents maladaptive and defensive attempts to overcompensate for feelings of inferiority
  • When a child adopts compensatory patterns of behavior as a defense mechanism, a socially-maladaptive life-style is the result if excessive; neurotic, psychotic, delinquent
  • goal of therapy is to help client replace mistaken style of life
  • masculine protest: every child experiences feelings of inferiority which motivate child to grow, dominate, and be supportive
  • organ inferiority: inferiority cmplx dev in connection with particular body part
  • goal of therapy: replace “mistaken style of life” with healthier/more adaptive one; like Freud- interpretation of dreams, resistances, transferences; also used role-plays (help pt dev new behs)
  • STEP and STET applications (Systematic Training for Effective Parenting/ Teaching)

neo-Freudians

(emphasize social, cultural determinants of personality)

Sullivan

  • emphasized importance of relationships through lifespan
  • parataxic distortions deals with current acquaintances as if they were significant others from past, causes neuroticism; – like transference
  • 2nd parataxic mode involves private/autistic symbols, person sees causal connections btwn events that aren’t actually related (helps dev self and reduce anxiety)
  • syntaxic mode involves symbols with shared meaning; emergest at end of 1st year of life (underlies lang acquisition)
  • 1st: prototaxic mode involves discrete unconnected momentary states (before lang dev; 1st few mos; SZ associated with this)
  • role of cognitive experience in personality dev; 3 modes of cog exp

Horney

  • focused on early relationships
  • certain parental behaviors (indifference, overprotection, rejection) cause child to experience basic anxiety (feelings of helplessness and isolation in hostile world)
  • defend against anxiety: movement toward others movement against others, movement away from others; healthy person uses all 3, neurotic- only 1

Fromm

  • focus on effects of societal structures and dynamics on personality
  • 5 Cs styles: receptive, exploitative, hoarding, marketing, productive (last allows person to realize his/her true human nature)

Ego Analysts

-Anna Freud, Hartmann -focus more on ego’s role in personality dev and pathology -ego-defensive fxs: resolution of conflict -ego-autonomous fxs: adaptive, non-conflict laden fxs (learning, memory, speech, perception) -non-defensive fx of ego & pathology results when ego loses its autonomy from id -re-parenting, focus on therapy -psychopathology occurs when ego loses its autonomy from the id

Object relations theory

  • As most psychodynamic based theories argue insight is core requirement for change (family change)
  • look at transferences resulting from early mother-child relationship in relation to current relationships btwn family members
  • Mahler, Winnicott, Kernberg, Fairbairn
  • focus on internal representations of self/others (introjects)
  • emotionally impoverished childhood env leads to pblms related to formation of introjects- leading to Itra/interP difficulty (splitting, unstable self-image)
  • psychological birth (occurs in 3rd year)- Mahler; self id and level of ego strength available to maintain representation of another person (object)
  • Kohut known for his work on narcissism: child dev grandiose self when child’s natural self-love (narcissism) is undermined by parent’s failure to satisfy child’s needs
  • re-parenting: focus of therapy

Cultural/ethnic considerations

-Latino’s and A-A stress family/extended family unit, less so individualism -A-A: more non-verbal, emotional, concrete, like structured, time-limited therapy

Cross’s model of Psychological Nigrescence (Identity development of blacks)

  1. pre-encounter: Euro-A worldvw (blame A-A for own pblms)
  2. encounter: personal/social event dislodges worldvw, search for A-A id
  3. immersion-emersion: struggles to destroy old id and clarify new; reject W, accept B
  4. internalization: resolves conflict btwn old/new worldvws: ideological flexibility, psych openness, self-confidence; moves toward non-racism
  5. internalization-commitment: able to integrate new id into old group, commitment to political actions to improve A-A condition

Latinos: patriarchal, family/sex roles rigid, personal approach to therapy

  • Cuento therapy focuses on using Spanish folktales in txt process
  • research shown that can impair formation of successful therapy interactions:
  • lang differences, class-bound values (middle class), and cultural-bound values (normal/abnormal)

Native Americans

  • Therapy is recommended to be non-directive, open, accepting
  • respect importance of elder tribe members, medicine people, legends
  • network therapy works (therapist serves as catalyst)

Asian-Americans

  • social/family roles well-defined and rigid
  • therapy not encouraged within the culture (address mental health issues in the family)

Gay/Lesbians

  • McLaughlin’s 8 stages of “homosexual identity formation”
  1. isolation
  2. alienation and shame
  3. rejection of self
  4. passing as straight
  5. consolidating a self id
  6. acculturation
  7. integration of self and public id
  8. pride and synthesis

Approach to therapy with diverse populations

  • eclectic orientation implies greater flexibility (good for ethnic groups)
  • informal approach also good with Latino’s (characteristic of culture)
  • need to focus on acculturation issues for any client from different culture
  • Views that impact therapeutic relationship:
  1. racial/cultural identification (degree to which client id with their cultural/racial background;
    1. The stronger the identification, stronger the desire for racially similar therapist, similar to MID model)
  2. attitude similarity (attitude similarity might be more critical than race)
  3. therapist sensitivity (racially sensitive/aware- helps therapeutic alliance)
  4. The presenting issue may determine whether racial/cultural identification is an important issue for therapy.
  • therapist’s sensitivity to cultural issues and level of ID with own cultural group are better predictors of efficacy than same ethnic group (pt/therapist)
  • etic approach: looking at cultures from outside using universally accepted means of investigations
  • emic approach: studying a culture from inside and seeing it as its own members do; should take this approach in therapy

Cultural encapsulation (Wrenn)

Model for therapist

  1. defines world in terms of own cultural beliefs/stereotypes
  2. minimizes/ignores cultural variations among clients
  3. unaware of own cultural biases
  4. defines counseling in dogmatically-accepted tech/strategies

Berry’s acculturation model (modes)

  1. integration: high retention of minority culture, high maintenance of mainstream culture
  2. assimilation: low retent. of minority culture, high maint. of mainstream culture
  3. separation: high minority culture, rejection of mainstream culture
  4. marginalization: low minority culture, low mainstream culture

The last two modes are more stressful

Hall’s communication styles

  • High-context c. (Af, As, L, NA; verbalizations shortened without loss of meaning, non-v messages)
  • Low-context c (W; verbalizations stressed and elaborate codes)

Minority Identity Development Model

  • 5 stages of id dev in oppressed minority group:
  1. conformity: to dominant cultural values; neg to own; prefer majority therapist
  2. dissonance: cultural confusion/conflict, challenge 1; prefer minority therapist
  3. resistance and immersion: actively rejects majority group and endorses minority, distrust, hatred strong; own race therapist
  4. introspection: conflict btwn personal autonomy and rigid constraints of 2
  5. synergistic articulation and awareness: resolves conflict; sense of self-fulfillment of cultural id; race of therapist doesn’t matter

Janet Helms identity development model for Whites

  • (similar to Minority Identity Development model); four interaction patterns: parallel, regressive, progressive, crossed:
  1. contact: limited contact with people of color; unaware of race/ethnic differences
  2. disintegration: increase contact leads to greater awareness of inequalities; emotional, psych, and moral confusion/conflicts
  3. reintegration: resolve conflicts- adopt W is superior and minorities inferior
  4. pseudo-independence: dissatisfaction with reintegration and re-examine beliefs
  5. immersion-emersion: embrace White identity, don’t reject minority, attempt to determine how they can feel proud of race without being racist
  6. autonomy: internalize non-racist White identity, realistic, understand strength/weaknesses of race, seek out cross-racial interactions

Gestalt theory/therapy

  • goal is to engender full awareness of self, env, and self-env interaction
  • leads to integration of whole/gestalt self
  • I statements, dream analysis, empty chair tech, here-and-now
  • Treat transference as fantasy and get client to focus on “here-and-now”

Boundary Disturbances

  • introjection: assimilating info, beliefs, and values without really understanding them (e.g., accept individualism without thinking about them b/c accepted by our culture).
  • projection: like in PA
  • retroflection: substitution of self for env, does to self what they’d like to do to others; chief mech underlying isolation
  • deflection: avoidance of contact or awareness by being vague, indirect , overly polite
  • confluence: boundary btwn self/env becomes too thin/permeable (doesn’t experience self as distinct)
    • merge self into beliefs, attitudes, feelings of others
  • isolation: more severe form of confluence, nonexistence boundary btwn self/env; importance of others for self is lost
  • all healthy unless person unaware they are doing it

Fritz Perl (theory of personality)

  • emphasizes boundary disturbances (such as introjection, defection, confluence)
  • results in person who is less ctrl by self, and more by self-image
  • consistency of self (promotes actualization, growth, awareness) and self-image (imposes external standards on self and impairs self-actualization and growth)
  • person’s interactions w/env determine which part of personality exerts most ctrl

Existential psychotherapy

  • focuses on individual and ultimate concerns of existence (death, isolation, meaningless, ultimately responsible for own lives)
  • normal or “existential anxiety” and neurotic anxiety (latter being when person tries to evade normal anxiety, loss of subjective sense of free will and inability to take responsibility for one’s own life)
  • goal of therapy is to reduce neurotic anxiety and to dev authentic/intimate relationship btwn therapist and client

Reality therapy

  • 1st developed by Glasser who was working with delinquent adolescents
  • psych problems are thought to be due to inability to responsibly/adequately meet one’s basic needs
  • Key issues are survival, belonging (affiliation), power, fun, freedom
  • success when failure identity is replaced by success identity
  • like Adler, applied to schools/institutions:
    • Schools Without Failure (SWF) program

Crisis Intervention, Brief Psychotherapy, Solution-focused therapy

Stages of crisis intervention

  • formulation (id of specific crisis and client’s rxns to it)
  • implementation (assessment of client’s life prior to crisis, setting of specific ST goals, implements of tech to achv these goals)
  • termination (progress in achieving these goals assessed)

Brief psychotherapy

  • time limits (<25 sessions);
  • therapeutic alliance (primary change strategy) in addition to
  • ability to stay focused on primary pblms,
  • willingness to adopt an active role,
  • flexibility in choice and application of intervention strategies;
  • selection of clients (acute onset sxs; good premorbid fx, high motivation, relate well to others)

Solution-focused therapy

  • goals:
    • move client toward a solution orientation
    • Change complaint narratives to solution narratives
  • techniques
    • exception question (ask when pblm wasn’t there- self-fulfilling prophecy);
    • scaling question (rate situation to see how problem is perceived by others);
    • formula tasks (rx for change);
    • miracle question (visualize goal);
    • skeleton key (unlocking solutions);
    • narratives and lang games

Psychometric issues

  • empirical criterion keying: choosing items for a test on basis of items’ ability to distinguish btwn grps (MMPI-2, Strong-Campbell Interest Inventory e.g.s)
  • MMPI-2
    •  ? >30- questionable;
    • T score of more than 60 for ? Responses- invalid profile
    • K (correction, suppressor V): person’s psychological defensiveness and guardedness (high- defensive)
  • Special scores on Rorschach:
    • contamination and inappropriate logic (most serious, psychopathology; 2/more impressions fused into single response, strained reasoning to justify stated characteristics);
    • deviant verbalizations (incorrect words or redundancies)
    • R has larger validity coefficients than MMPI with Exner system
    • The data comprising the Exner norms has been questioned
  • Strong-Campbell Interest Inventory
    • more valid for predicting occupational choice or satisfaction than job success
    • (based on Holland’s theory and research)- broken down into occupations;
    • predictive validity (0.30)
    • Occupational Themes: RIASEC
      • realistic
      • investigative
      • artistic
      • social
      • enterprising
      • conventional
  • Kuder Vocational Preference Record
    • Indication of interest in 10 broad areas: outdoor, mechanical, computational, scientific, persuasive, artistic, literary, musical, social services, clerical
    • based on broad categories and content validity (not empirical criterion keying- how it differs from SCII)
    • recently dev a child version (grades 6-12)

Potpourri

  • Howard’s research on # of therapy session/therapy outcome
  • 3 phases:
    • remoralization (1st few sessions; improve feelings of hopelessness and desperation);
    • remediation (symptomatic relief, about 16 sessions);
    • rehabilitation (3rd phase, gradual improve in various aspects of fx)
  • suicide risk Factors:
    • 15-24 age
    • primary prevention (intervention before onset of pblm)
    • client Vs thought to be best predictors of therapy outcome (high intelligence, openness, low defensiveness, high ego strength, high anxiety tolerance, moderate expectations about therapy).
    • therapist Vs thought to be good predictors of therapy outcome (therapist competence)
  • Treatments Vs: therapeutic alliance
    • paraprofessionals and professionals are equally effective in txt of certain pblm domains;
    • txt for kids/adolescents as effective as txt for adults;
    • therapy for elderly depressed effective
  • txt duration to effectiveness (linear up to 26 sessions, levels off)
  • treatment effect size of 0.85
    • average client at end of therapy is better off than 80% of controls
    • 66% of treated individuals compared to 34% of controls show improvement as a result of psychotherapy

CNS Cellular Organization and Communication

GENERAL INFO

  • Billions of cells in CNS (10-50 times more glial cells than neurons)
    • 12-15 billion neurons in cerebral cortex
    • 1 billion in spinal cord
  • Neurons operate w/in interconnected networks
    • number of connections between neurons ranges from 1,000 to 100,000 (average 10,000)
  • Share many characteristics with other cells of bodies, but also a number of differences:
    • Have dendrites and axons
    • Communicate primarily through axonal firing, not energy exchange and intercellular transport
    • Change their behavior with experience: they learn, remember, and forget
    • Formation and regeneration: traditional view is that neurons in brain do not regenerate and unless they suffer lethal damage, live as long as person; Peripheral neurons (sensory/motor neurons) can regenerate; RECENT animal research suggests that even neurons in brain and cord may be able to regenerate to certain extent

TYPES OF CELLS IN CNS

Neurons

(Classified either by morphology or function)

Morphological Classification

Defined by number of axons emanating from cell bodies

  1. Multipolar neurons (more than 2 axons)
  2. Bipolar
  3. Monopolar
  4. Interneurons: short axons or no axons that integrate neural activity w/in specific brain region

Functional Classification

  1. Motor neurons: make muscles contract
  2. Sensory neurons: respond directly to sensory info
  3. Interneurons: majority of neurons; receive input and send output to other neurons

Glial Cells

  • Glia cells (“nerve glue”) surround neurons
  • Much more numerous than neurons
  • Number of functions, including:
    • supply nutrients and oxygen to neurons
    • surround neurons to hold them in place
    • produce myelin
    • help form blood-brain barrier
    • act as housekeepers, metabolizing and removing dead neurons
    • during development, ‘radial glia’ guide migrating neurons
  • 4 types of glial cells in CNS
  1. Oligodendrocytes – form myelin of CNS (Schwann cells form myelin in PNS)
  2. Astrocytes – multiple support functions, including:
    1. provide structural support to neurons
    2. contribute to metabolism of synaptic transmission
    3. regulate ion balance
    4. support blood-brain barrier by covering blood vessels in CNS w/ “feet,” which holds the endothelial cells lining the blood vessels in place
    5. [also, astrocytes swell in rx to brain injury, which is responsible for many sxs of TBI]
  3. Ependymal cells – epithelial cells that line brain ventricles and central canal of spinal cord; assist in secretion and circulation of CSF
  4. Microglia – small cells that proliferate and act as scavengers when tissue destroyed

STRUCTURE AND FUNCTION OF NEURONS

Neurons vary in shape and size, but have 4 common features:

Cell body (soma)

  • Functioning and survival depends on integrity, since controls and maintains neuronal structure
  • Cell bodies are gray, so areas that are dense w/ cell bodies (eg, cortex) called ‘gray matter’
  • Protein synthesis can’t take place in axon, so all axon proteins come from cell body
    • some proteins destined to be secreted as transmitters; others maintain cell
  • Some cell components:
    • Cell Membrane: surrounds entire cell; semipermeable
    • Nucleus: w/in nucleus are chromosomes (composed of DNA which contain code for controlling growth and development of cell into maturity) and a nucleolus (produces ribosomal ribonucleic acid [rRNA] which participates in formation of protein)
    • Nissl Bodies: groups of ribosomes used for protein synthesis
    • Endoplasmic reticulum (ER): system of tubes for transport of materials within cytoplasm; can have ribosomes (rough ER) or no ribosomes (smooth ER). With ribosomes, the ER is important for protein synthesis
    • Golgi Apparatus: membrane-bound structure important in packaging peptides and proteins (including neurotransmitters) into vesicles
    • Microfilaments/Neurotubules: system of transport for materials within a neuron and may be used for structural support
    • Mitochondria: most cell processes require energy, which is manufactured by mitochondria; brain cells derive all energy from glucose, which is extracted from blood as needed (brain can NOT store glucose); mitochondria takes up glucose and breaks it down for energy

Dendrites

  • Extensions of cell body that increase surface area and specialized to receive info from other cells
  • Number of dendrites varies by neuron, although usually thousands
  • Total possible connections among neurons in human brain approximately 10,000,000,000,000,000 -more numerous than stars in universe
  • Striking feature is ability to grow and change; one substrate for learning
    • some dendrites in elderly may be very long
    • some diseases that produce MR or dementia may be ass’d w/ reduced dendritic length or spine #
  • Shapes of dendritic ‘trees’ and spines are often among most characteristic morphologic features of neuron (eg, purkinje cells [found in cerebellar cortex] spread out in one plane and thousands of dendritic spines; pyramidal cells [found in all areas of cerebral cortex] have bodies that are pyramidal or conical

Axons

  • Originate in cell body at transition called axon hillock
  • Each cell has only one, so cell can only send one message
  • Can vary in size from a few microns to more than a meter
  • Most axons have branches called collaterals
  • At end of axon and collaterals are fine terminations called teleodendria, which end in little knobs called terminals that juncture w/ other cells
  • Can grow new teleodendria and new terminals so, along w/ dendrites, mediate learning
  • Many axons surrounded w/ myelin sheath (which is lipoprotein), giving whitish appearance
    • Speed/efficiency of action potential propagation significantly influenced by degree and integrity of myelination of axons
    • Increase of neuronal conduction conferred by saltatory conduction (from saltare, meaning “to leap”): myelin sheath interrupted every 1-2 mm by unmyelinated segment called Node of Ranvier, which permits the action potential to jump from one node to next

Terminal Synaptic Buttons

  • Near end of axon are branches w/ slightly enlarged ends called axon terminals or terminal buttons, the presynaptic portion of the synapse where electrical nerve impulses cause release of neurotransmitters
  • Synapse: site of interneuronal communication
  • Main fx of axons is to transmit electrochemical info; info travels along axon electrically, then transfers across synapses chemically; so can study brain electrically (EEG, EP, etc.) or biochemically or metabolically (PET, etc.)

THE NEURON’S ELECTRICAL COMMUNICATION (Communication w/in a neuron)

Resting Membrane Potential

  • Neurons show a resting potential when inactive: slight electrical imbalance between inner and outer surfaces of membrane caused by separation of electrically charged ions
  • Ions: atoms or molecules that have acquired electrical charge by gaining or losing one or more electrons
  • Ions pass through tiny channels in axon wall to communicate
  • Four ions important: organic ions (symbolized by A-), sodium (Na+), potassium (K+), and chloride (Cl-)
  • Inside of axon is electrically negative: electrical potential difference between interior and exterior is synonymous w/ membrane potential (in range of -70 millivolts)
  • Electrical imbalance can occur b/c axon membrane is semipermeable
    • Some molecules (oxygen, water) pass thru membrane constantly
    • Other chemicals (K+, Cl-, NA+) can’t cross, so pass through gates
  • Membrane Potential is property of two opposing forces:
  1. Force of Diffusion: molecules distribute themselves equally throughout medium in which they’re dissolved
  2. Force of Electrostatic Pressure: particles w/ same kind of charge repel; different charge attract

At rest, outside of cell charged positively w/ respect to inside (out = +, in = – charge)

  • Organic anions (negatively charged)
    • Found only inside cell
    • Can’t go anywhere b/c cell membrane is impermeable to them
  • K+ is found predominantly in the intracellular fluid
    • Diffusion force pushes out
    • Electrostatic pressure pushes in
    • Two opposing forces balance
  • Cl- found predominantly in the extracellular fluid
    • Diffusion pressure pushes in
    • Electrostatic pressure pushes out
    • Two opposing forces balance
  • Na+ found predominantly in the extracellular fluid
    • Diffusion pressure pushes in
    • Electrostatic pressure does NOT prevent Na+ from entering cell
    • Thus, need sodium-potassium pump to continuously push Na+ out of cell (pump exchanges 3 sodium ions for every 2 potassium ions; pump uses up to 40% of neuron’s metabolic resources)

The Action Potential

  • To generate a nerve impulse, cell membrane must first depolarize
  • Depolarization begins when sodium channel across membrane opens and sodium ions pass through into cell, reducing voltage
  • Cause of action potential: brief drop in membrane resistance to Na+ (ions rush into cell), immediately followed by drop in membrane resistance to K+ (ions rush out of cell)
  • Depolarization occurs when membrane potential reaches about –55 mV
    • at this time, sodium gates fly open, permitting a rapid, massive, explosive flow of ions
    • in few milliseconds, see change in membrane potential from about –70 mV to about +35 mV
  • Neurons fire in All-or-None fashion
    • Subthreshold stimulation does NOT result in an action potential
    • Neuron cannot send stronger action potentials down its axon
    • Force of action potential does not depend on intensity of stimulus initiating it; in other words, strength of a signal does not matter (although neurons can be in different states of preparedness for firing)
  • Thus, only two features of the conducting signal convey information (again, intensity of stimulus doesn’t):
  1. the number of action potentials
  2. the time interval between action potentials
  • After neuron has fired, there’s an absolute refractory period that lasts one or more milliseconds when neuron incapable of firing; Absolute refractory period followed by relative refractory period, when neuron can fire but needs higher than normal levels of stimulation to do so

THE NEURON’S BIOCHEMICAL COMMUNICATION

Communication Between Neurons

  • Transmission of info between cells dependent on chemicals including neurotransmitters, neuromodulators, and hormones
    • Neurotransmitters: released by terminal buttons of neurons and detected by receptors in membrane of another cell located short distance away
    • Neuromodulators: also released by terminal buttons, but secreted in larger amounts and diffuse for longer distances, modulating activity of many neurons in particular area (most composed of peptides)
      • Not all communication is mediated at synaptic juncture; Other parts of membrane sensitive to neuromodulators and hormones
    • Hormones: most produced in endocrine glands; cells that secrete hormones release into extracellular fluid and then distributed to rest of body thru bloodstream; only cells that have target cells for particular hormone respond to its presence
      • Two classses of hormones:
  1. Peptides – chains of amino acids linked by peptide bonds (ex include insulin and pituitary gland hormones)
  2. Steroids – very small fat-soluble molecules (ex include sex hormones and hormones secreted by adrenal cortex)
  • Synapses can occur on dendrite, cell body, or axon
  • Synapse includes: presynaptic membrane, postsynaptic membrane, and in between area called synaptic cleft
    • When action potential conducted down axon, a number of small synaptic vesicles located just inside membrane fuse w/ membrane and then break open, spilling contents into synaptic cleft
    • Then, transmitter substances attach to postsynaptic membrane at postsynaptic receptors
    • The presence of substance in cleft allows particular ions to pass through membrane, changing local membrane potential
  • Postsynaptic potentials are either brief depolarizations or hyperpolarizations of postsynaptic membrane
    • kept brief by reuptake (rapid removal of transmitter substance by terminal button) and enzymatic deactivation (enzyme destroys transmitter – occurs for acetyclcholine by way of acetylcholinesterase)
  • Nature of postsynaptic potential depends on type of ion channel opened by postsynaptic receptors at particular synapse
    • Excitatory potentials (EPSP)occur when Na+ enters cell
    • Inhibitory potentials (IPSP) produced by opening of K+ or Cl- channels
  • Temporal Summation – occurs when a burst of action potentials reaches a nerve fiber terminal; the series of impulses in one excitatory fiber can sum over time to fire a target neuron, even though each individual EPSP wouldn’t do it
  • Spatial Summation – impulses in two excitatory fibers cause two synaptic depolarizations at about the same time that together reach firing threshold; they sum over space to fire a target neuron, even though each individual EPSP wouldn’t do it
  • Rate of firing of axon of postsynaptic cell is determined by relative activity of both excitatory and inhibitory synapses on membrane of dendrites and soma – phenomenon called neural integration
  • Once receptors are activated they can produce two effects:
  1. if voltage change large enough, adjacent Na+ channels are excited and cause action potential
  2. can also initiate chemical changes within the cell, which can lead to permanent changes in number of receptors or may change other structures w/in the cell – the chemicals involved in this postsynaptic activity are called second messengers (eg, cAMP; first messenger is neurotransmitter); play role in learning

Neurotransmitters

  • More than 50 different chemicals known to fx as transmitters
  • In brain, most synaptic communication is accomplished by two transmitter substances: one w/ excitatory effects (glutamate) and one with inhibitory effects (GABA)
    • in general, all other substances have modulating effects rather than info-transmitting effects; that is, release of other substances activates or inhibits entire circuits of neurons that are involved in particular brain functions
    • eg, Ach activates cortex and facilitates learning, but info that is actually learned is transmitted by neurons that secrete glutamate or GABA
  • Classification of neurotransmitters
    • Acetylcholine
  • Monoamines
    • Catecholamines (Dopamine, Norepinephrine, Epinephrine)
    • Indolamines (Serotonin)
  • Amino Acids
    • GABA, Glutamate, Glycine, Aspartate
  • Peptides (examples)
    • Opiods: enkephalins
    • Neurohypophyseals: vasopressin, oxytocin
    • Secretins: corticotropin-releasing factor
    • Insulins: insulin, insulin growth factors
    • substance P

Classic Neurotransmitters

Acetylcholine (ACh)

General Information

First transmitter discovered

Stimulates parasympathetic nervous system

Prominent role in PNS, influencing motor control; Primary transmitter found at neuromuscular juncture (all muscular movement accomplished by release of Ach)

In CNS and brain, influences alertness, attention, and memory

In Alz, have found decreased Ach fx

Mysthenia Gravis characterized by defect in Ach transmission

Location of important cell bodies and projection

In PNS: Spinal cord anterior horn → skeletal muscles

In CNS: Basal forebrain (nucleus basalis, medial septal nucleus, and nucleus of diagonal band) → cerebral cortex

Synthesis

formed by combination of acetyl CoA + choline; in presence of enzyme choline acetyltransferase

does not undergo reuptake; action is terminated by cholinesterase

Drug Info

Two receptor types: Nicotonic (movement) Muscarinic (both found in CNS but muscarinic predominates there)

Tacrine (Cognex): reversible anticholinestrase used to enhance cog functioning

Botulinum toxin prevents release of Ach; Black widow spider venom stimulates release; Curare blocks Ach nicotine receptors

Serotonin (5-HT, or 5-hydroxytryptamine)

General info

Behavioral effects are complex

Plays a role in regulation of mood; control of eating, sleep, and arousal; and pain

Location of important cell bodies and projection

Raphe Nuclei (in brainstem) → entire CNS

Drug info

Prozac, Paxil, Zoloft, LSD, etc. have effects on 5HT

Tricyclic antidepressants (eg, imipramine, clomipramine) block both Serotonin and NE uptake

Dopamine (DA)

General info

Generally associated w/ motor disorders and neuropsychiatric problems (schiz, ADHD, tics), as well as modulation of reward

Conditions due to defects in dopamine synthesis include PKU, Parkinson’s

Excessive dopamine produced by coke, amphetamine, L-dopa; can lead to visual hallucinations, hyperkinetic movement disorders

Location of important cell bodies and projection

Midbrain (substantia nigra, pars compacta, and ventral tegmental) → striatum, prefrontal, limbic, amygdala

3 well-known pathways:

  1. Nigrostriatal – major component of extrapyramidal motor system; decreased DA here causes rigidity, tremor, and akinesia; excess causes dyskinesia
  2. Mesolimbic – probably propagates positive sxs of psychosis; rewarding effects of certain stimuli including drugs; ventral tegmental areas (midbrain) to amygdala/limbic
  3. Mesocortical – probably propagates some neg sxs of psychosis; planning, strategy preparation; ventral tegmental to frontal cortex

Synthesis

Phenyalanine → tyrosine → DOPA → Dopamine (tyrosine hydroxylase rate-limiting)

Terminate process: reuptake, monoamine oxidase (MAO), etc.

Drug Info

Most antipsychotics work primarily on dopamine (eg, Haldol, Thorazine, Clozaril, Risperdal), as does L-dopa

Norepinephrine (NE) (noradrenalin)

General info

Functions complex, but probably helps regulate mood, memory, hormones, blood flow, and motor behavior

Also thought to increase vigilance; role in sexual behavior and control of appetite

Location of important cell bodies and projection

Locus Ceruleus (pons) → entire CNS

Drug Info

Tricyclic antidepressants (eg, imipramine, clomipramine) block both Serotonin and NE uptake

Epinephrine (adrenalin)

General info

Hormone produced by adrenal medulla

Also produced in brain, but minor importance compared with NE

Stimulates sympathetic division of ANS to produce “flight or fight”

AMINO ACIDS

GABA

  • Cell bodies in entire CNS project to entire CNS
  • Principal inhibitory transmitter substance in brain and cord
  • Enhanced activity produces sedative, anxiolytic, and anticonvulsant effects
  • Benzodiazepines (eg, diazepam/valium, xanax, ativan) thought to work by stimulating GABA
  • (markedly decreased in Huntington’s)

Glutamate

  • Cell bodies in entire CNS project to entire CNS
  • Principal excitatory transmitter substance in brain and cord
  • Implicated in neural plasticity, learning, and memory
  • Excessive activity associated w/ excitotoxicity
  • Four types of glutamate receptors, one being the NMDA receptor

Glycine

  • Inhibitory neurotransmitter in spinal cord and lower brain
  • May play a modulatory role at interneurons in cord
  • Blocked by strychnine

PEPTIDES

  • project to entire CNS; no mechanism for reuptake once released; deactivated by enzymes
    • Enkephalin- physiological roles include pain perception, stress, respiratory regulation, temperature control, tolerance development
    • Substance P – mediator of inflammation, as well as a neurotransmitter in primary afferent fibers carrying pain signals
    • Vasopressin (aka antidiuretic hormone); acts peripherally to facilitate water reabsorption by kidneys; may play a role in memory consolidation
    • Somatostatin – modulation of heat, pain, sleep; also reduced in cortex of Alz pts
    • Angiotensin II- potent vasconstrictor activity in periphery; central actions include stimulation of pressor responses and drinking

Childhood Disorders

CHILDHOOD DISORDERS

CEREBRAL PALSY

  • Nonscientific term describing permanent, nonprogressive neurologic motor system impairment resulting from CNS injuries of the immature brain (occur pre- or peri-natally, infancy, or early childhood); .2% incidence
    • Can be associated with prematurity (especially as smaller premature infants continue to survive) and low birth weight; however, specific causes have not yet been identified
    • Less than 15% result from a preventable obstetric injury
    • CP is not a single entity and the etiology of its various presentations is not the same
    • It is a general term which doesn’t tell the severity/nature of the disorder (same as “learning disability”)
  • Nonprogressive but not unchanging disorder of movement and posture; changes occur as the nervous system matures (e.g., a baby may be hypotonic but later b/c spastic or rigid; all CP has an early hypotonic phase) – in some instances there is a gradual improvement, but others reach a plateau; many require bracing and surgery
  • Two most common varieties:
    • Spastic paresis (70%)
      • Combination of spasticity (causes slow clumsy movements; usually accompanied by hyperactive deep tendon reflexes, clonus, and Babinski signs) and paresis
      • Affected limbs have growth arrest
      • Results from necrotic areas in the white matter around the ventricles (periventricular leukomalacia) – most closely related to prematurity
    • Extrapyramidal (“dyskinetic”) CP (choreoathetosis) (15%)
      • Characterized by choreoathetosis (involuntary writhing of face, tongue, hands, and feet sometimes overridden by jerking movements of trunk, arms, and legs)
      • Involvement of larynx, pharynx, and diaphragm may lead to severe dysarthria
      • Usually produced by combo of low birth weight, anoxia, and kernicterus that damages basal ganglia and auditory pathways
      • Lowest incidence of epilepsy and MR
  • 15% of the cases are “mixed”
  • Associated complications/disabilities:
    • MR; cognitive dysfxn
    • Epilepsy (generally associated with more global impairment)
    • Vision/hearing impairments
    • LD
    • Language disorders
    • Psychological problems
    • Pseudobulbar palsy
    • Hyperactivity
  • Sometimes the child’s most disabling problems are associated cognitive difficulties (though 50% have normal intelligence); visual-perceptual problems, speech and hearing impairments may influence learning

ABNORMALITIES OF THE NEURAL TUBE AND FUSION DEFECTS

Result from defective embryologic development of CNS during 3rd and 4th weeks gestation

UPPER NEURAL TUBE CLOSURE DEFECTS

ANENCEPHALY

  • Vault of skull absent; brain usually represented by a vascular mass; face grossly abnormal
  • May be due to severe trauma, radiation, infection; abnormal embryonic development between day 18 and week 4 gestation
  • Incompatible with life (die within minutes/hours of birth); interestingly, organs are ideal for transplants

CRANIUM BIFIDUM and ENCEPHALOCELE

  • Skin-covered brain, meninges, or CSF protrudes through skull defect
  • Results from incomplete closure of mesodermal layers over the upper neural tube
  • Cranium bifida = fusion defects of the skull
  • Encephalocele = myelomeningoceles or meningoceles that occur on the skull
  • Many possible behavioral complications arising from associated hydrocephalus – e.g., MR, ataxia, CP, and epilepsy

DANDY-WALKER MALFORMATION

  • Posterior portion of upper neural tube fails to develop; born with rudimentary posterior brain structures
  • Cerebellum/medulla fail to develop past early embryonic stage; fourth ventricle grows into a large cyst
  • Associated with hydrocephalus, agenesis of CC, craniofacial deformities, Klippel-Feil syndrome, DeLange syndrome, macrocephaly, MR
  • Frequent severe psychomotor retardation

ARNOLD-CHIARI MALFORMATION

  • Congenital deformation of the brain stem and cerebellum
  • Some combination of medulla and cerebellum are displaced downward through foramen magnum; aqueductal stenosis; overlying skull and cervical spine defects
  • May be due to traction caused by myelomeningocele or hydrocephalus; may be a dysgenesis of the brainstem
  • Associated with congenital hydrocephalus, spina bifida, myelomeningocele, severe psychomotor retardation; in “asymptomatic” cases, adults may present with headache, bulbar palsy, and neck pain

LOWER NEURAL TUBE CLOSURE DEFECTS

SPINA BIFIDA OCCULTA

  • Asymptomatic spinal lesion discovered incidentally; possibly 20% of population
  • Abnormal fusion of spinal lumbar vertebra
  • Often asymptomatic; may be associated with lipoma, congenital dermal sinuses, dimples
  • No documented cognitive deficits

SPINA BIFIDA CYSTICA

  • Spinal defect that includes a cystic-like sac (meningomyelocele), which may or may not contain the spinal cord; 1-2: 1,000 live birth incidence
  • Meningocele – meninges & skin protrude through lumbosacral spine defect to form CSF-filled bulge (no spinal cord) = good prognosis, though may cause gait impairment, kidney and bladder problems, loss of tissue barriers that protect CNS
  • Myelomeningocele or meningomyelocele (much more common) – tangle of rudimentary spinal cord, lumbar and sacral nerve roots, meninges protruding into sac = 80-90% chance of developing hydrocephalus and have many other problems (incl. meningitis, Arnold-Chiari)
    • Clinical deficits worsen during childhood and during growth spurts despite early surgical intervention
    • Most all are MR and paraplegic
    • May be due to autosomal recessive genetic abnormality; radiation, folic acid deficiency, toxins, and AEDs also implicated

OTHER DEFECTS

HYDRANENCEPHALY

  • Cerebral hemispheres replaced by cystic sacs containing CSF
  • May be due to vascular occlusion causing necrosis
  • May initially look like hydrocephalus; eye movement disturbances, feeding problems, hyponatremia
  • Incompatible with life

PORENCEPHALY

  • Large cystic lesion develops, usually bilateral
  • Disturbed cortical development between month 5-7 gestation; may be due to severe trauma, vascular occlusion, infection
  • May be asymptomatic; often associated with MR, epilepsy, other malformations (e.g., polymicrogyria)
  • Gyri often form radial patterns around cyst

STENOSIS OF THE AQUEDUCT OF SYLVIUS

  • Obstruction of the aqueduct and CSF circulation
  • Evidence for familial transmission
  • Often insidious onset of symptoms associated with hydrocephalus
  • Shunted children may have learning/behavioral problems; nonverbal IQ worse than VIQ

NEUROMIGRATIONAL DISORDERS (NMD’S) (malformations of the cerebral cortex et al.)

Disorders due to errors in the development of the brain (cells migrating incorrectly)

LISSENCEPHALY (AGYRIA – absent gyri, smooth cortical surface/PACHYGYRIA – few, course gyri)

  • Disorders of cell migration; arrest of migration of neuroblasts from periventricular matrix to cortex
  • Characteristic facial appearance: prominent forehead, short nose, protuberant upper lip, and small jaw
  • Associated with agenesis of CC, micrencephaly, epilepsy, severe growth and developmental retardation, decreased spontaneous activity; early death due to intercurrent disease common
  • May have difficulty swallowing or eating; may respond minimally to visual or auditory stimuli
  • Seizures

POLYMICROGYRIA

  • Development of many small gyri
  • Possibly due to focal necrosis during neuroblast migration between 5-6 months gestation
  • Associated with LD (dyslexia), severe MR, epilepsy; may be asymptomatic

FOCAL DYSPLASIA (heterotopias)

  • Focal abnormalities of the cortical cytoarchitecture; areas of disordered layering and displaced cells
  • Disruption of neuroblast migration
  • Reported in pts with epilepsy and LD

MEGALENCEPHALY

  • Refers to a large head (circumference > 2 SD’s above the mean)
  • Involves increased numbers of neurons and glia.
  • Typically mentally retarded, but may be mild

SCHIZENCEPHALY

  • Characterized by clefts in parasylvian region and in precentral/postcentral gyri of one or both hemispheres
  • Often accompanied by hydrocephalus, mental retardation and significant motor handicap

AGENESIS OF THE CORPUS CALLOSUM

  • Failure (complete or partial) of CC to develop; <.7% incidence
  • Evidence for familial transmission
  • Interruption of normal embryogenesis at 12-22 weeks gestation
  • Increased incidence in schizophrenics; and is seen in association with spina bifida, facial and ocular deformities, micrencephaly, megalencephaly, hydrocephalus, Dandy-walker Syndrome and Leigh’s syndrome; epilepsy and MR may occur; may see EEG abnormalities
  • Can follow intrauterine exposure to toxins (e.g., FAS)
  • Associated with specific, but different patterns of neuropsychological deficits including:
    • Visual spatial deficits
    • Impaired syntactic ability (comprehending, producing or repeating complex sentences)

NEUROCUTANEOUS DISORDERS

  • Embryologic defects in the ectoderm
  • Often include abnormalities of other ectoderm and nonectoderm organs
  • Most are inherited in an autosomal dominant pattern
  • Usually stable through adulthood, though cerebral lesions may undergo malignant transformation

TUBEROUS SCLEROSIS

  • Smooth and firm nodules on malar surface of face (adenoma sebaceum or facial angiofibromas) don’t appear until adolescence
  • Infancy and childhood – subtle hypopigmented areas on skin, scaly lesions on trunk (shagreen patches), and periungual fibromas of the fingers
  • Classic Triad (occurs in minority): epilepsy (usually intractable), MR, hypopigmented areas or adenoma sebaceum; includes speech and language delays
  • Some eventually decline to the point of dementia; some have autistic features – overall, highly variable (partly attributable to location of abnormal gene – chromosome 9 or 16)
  • CNS correlate of skin lesions are cerebral tubers (“potato-like brain nodules”) – cause epilepsy and cognitive impairment; may become malignant; may develop retinal, renal, cardiac tumors

NEUROFIBROMATOSIS

  • NF Type I (aka von Recklinghausen’s disease, or “peripheral type” NF)
    • Inherited on chromosome 17 in autosomal dominant pattern; though often (upto 50%) arises spontaneously
    • Classic Triad: café au lait spots, neurofibromas (emerge along peripheral nerves; may reach grotesque proportions), Lisch nodules (multiple, asymptomatic, macroscopic, melanocytic hamartomas on the iris – pathognomonic) (brain hamaratomas often observed on imaging)
    • Also involves intracerebral tumors (e.g., astrocytomas, optic nerve gliomas)
    • High association with ADHD and LD (1/3-2/3 of affected children); lower IQ
  • NF Type II (aka familial acoustic neuroma, or “central type” NF)
    • Bilateral acoustic neuromas (hallmark) that impair hearing until deaf
    • Inherited on chromosome 22 in autosomal dominant pattern
    • May manifest meningiomas; mental impairment only if they compress critical brain region

STURGE-WEBER SYNDROME (aka encephalo-trigeminal angiomatosis)

  • Facial (port wine stain in region of trigeminal nerve) and cerebrovascular malformations
  • NO known genetic basis
  • Cerebral component – calcified vascular region accompanied by atrophy in one hemisphere
  • Tend to have MR, LD, behavioral disturbances, refractory epilepsy; may also have focal physical deficits depending on site of lesion
  • Presence of seizures associated with much poorer prognosis

ATAXIA-TELANGIECTASIA

  • Inherited in a recessive pattern; abnormality on chromosome 11 – interferes with DNA repair
  • Consistently associated with immunodeficiency (little or no IgA or IgE)
  • First manifestations – chronic sinus and respiratory tract infections; later, lymphomas and neoplasms
  • Neurologic manifestations at age 3-5: progressive ataxic gait (due to degeneration of cerebellar vermis)
  • Develop cognitive impairments
  • Cutaneous component – small dilated vessels (telangiectasia) on conjunctiva, nose bridge, and cheeks

DISORDERS DUE TO GENETIC AND CHROMOSOMAL ANOMALIES

Remain stable post-puberty; do not cause signs of white matter disease (leukodystrophies), do not cause metabolic storage disease

Genetic imprinting – when the same autosomal dominant abnormality produces different syndromes depending on whether it is transmitted from mom or dad (as in Prader-Willi and Angelman syndromes)

AUTOSOMAL CHROMOSOMAL DISORDERS

DOWNS SYNDROME

  • 1:600 births
  • Trisomy 21 (3 chromosomes or parts of chromosomes instead of two – the entire chromosome 21 is not required; it is possible that the variation in the amount of chromosome is related to the variability of the cognitive deficits)
  • Risk increases with maternal age
  • Affects organ systems (e.g., may have increased risk for congenital heart defect); alters antibody rxn to vaccine; increased risk for otitis media; increased risk of leukemia and seizures
  • Alzheimer’s is invariably found over the age of 40 (increased risk from age 10 on! 15% of those from 10 – 20; 36% in those 21 – 30 yrs; 100% if over 30)
  • Mean IQ is approximately 44.3; range from mild to moderate MR
  • Visuospatial abilities are generally preserved and language is impaired; motor delays; intact social skills
  • Difficulty processing sequential information

PRADER-WILLI SYNDROME (chromosome 15 – get this disorder if passed from father “Prader-Willi is passed in a paternal pattern”) ~ although some cases are sporadic

  • Due to a deletion in a chromosome
  • Obese, voracious appetites (hyperphagia); poorly controlled food-seeking behavior (will steal food from classmates, rummage through garbage, etc.) and they gain wait at an accelerated rate (doesn’t appear until the preschool years; prior to this they are pleasant and not obese); short stature, hypogonadism
  • Outbursts of aggressive, angry behaviors; some repetitive, compulsive skin picking
  • Mental retardation, obsessive-compulsive personality, decreased sensitivity to pain
  • Major language production deficits (affect articulation)

ANGELMAN SYNDROME (“Happy Puppet”) (chromosome 15 – get this disorder if passed from mother)

  • Rare (also due to a deletion in chromosome)
  • Associated with motor and severe mental retardation, microcephaly, epilepsy
  • Stereotyped involuntary and jerky-ataxic voluntary movements, smiling face, paroxysms of unprovoked laughter
  • Appear to be normal at birth but rapidly drift off developmental course
  • Speech is limited to a few words at best but can communicate with gesture
  • Hyperactive
  • Girls are sometimes misdiagnosed as Rett’s syndrome (MR, microcephaly, involuntary movements); others may be diagnosed as autistic

WILLIAMS SYNDROME (chromosome 7)

  • Minute deletion on 7 which disrupts elastic properties of arteries, root of aorta, skin, and other organs
  • Characteristic elfin face; facial features become more prominent with age
  • No gross neurological abnormalities, though motor delays and fine and gross motor clumsiness
  • Mild to moderate MR; impaired reading and writing; visuospatial deficits; difficulty w/nonverbal tasks
  • Inexplicably, extraordinary talents in music (gifted) and verbal fluency (though devoid of substance)

PKU (chromosome 12)

  • Amino acid metabolism disorder; autosomal recessive
  • Aminoacidurias (another aminoacidurias is maple syrup urine disorder which can also be treated with diet)
  • Prevents normal metabolism of phenylalanine to tyrosine; prevents normal synthesis of dopamine, subsequent neurotransmitters, and melanin; phenylketones are excreted in urine
  • Untreated leads to severe MR, decreased attention, lack of responsiveness to environmental stimuli, seizures, spasticity, hyperactive reflexes, tremors, “psychiatric illness”
  • Treatment diet (no phenylalanine) leads to short stature and weight, anemia, and hypoglycemia
  • Even when treated, tend to show executive deficits, ADHD symptoms and below average IQ

SEX-LINKED CHROMOSOMAL DISORDERS

x-linked disorders – may be rare in females if it is a recessive trait unless there is a mutation in the other X (or if they both contain the disorder); if it is dominant it will be expressed in both genders

FRAGILE-X SYNDROME

  • 2nd most common form of mental retardation (second to Down Syndrome); most common inherited form (responsible for as much as 10% of all MR cases)
  • Trinucleotide (CGG) repeat in defective gene; people with >200 repeats are invariably affected; size of repeat increases with successive generations which results in earlier onset (“anticipation”) and more pronounced symptoms
  • Fragile-x males (1:1500)
    • Head circumference and weight > peers; by adulthood only the head remains large; elongated face; enlarged testicles
    • IQ ranges from normal to profoundly mentally retarded (70% moderate to severe MR; 20% seemingly normal); studies suggest IQ declines b/t childhood and adulthood
    • Tend to plateau with regard to their ability to learn more complex and abstract information, typically during early puberty
    • Dysfluent, apraxic speech, echolalia, palilalia and cluttering are characteristic; receptive language relatively preserved
    • Frequent behavioral abnormalities, including ADHD; also, LD, mood disorder, repetitive purposeless involuntary movements, autism, PDD (15%)
  • Fragile-x females (1:3000)
    • In contrast to other sex-linked disorders, 1/3 of female carriers express some of its characteristics
    • Often lack dysmorphic features seen in males
    • Specific frontal lobe deficits have been seen
    • No evidence of right hemispheric impairment, dyslexia or short-term verbal memory deficit; but another book states there is!! (e.g., problems with spatial skills and math)
    • Attention deficits, distractibility, shyness, impaired organizational skills and difficulty with transitions
    • IQ – 80’s to 100; often below 85
    • Behavioral abnormalities (see above) less common than in boys

RETT’S SYNDROME

  • Females only; abnormality assumed lethal in males
  • Onset begins after about 6 months of normal development, then regress in all areas of psychomotor development over several years until no language, walking, cognitive capacity, etc.
    • profound MR
  • Two virtually unique physical characteristics: stereotypies (often incessant hand clapping and wringing) and acquired microcephaly (after 6 months of normal growth)
  • 50% have seizures
  • Shares features with autism, but also have progressive loss of motor ability and develop microcephaly
  • Of note: Rett’s, Angelman’s and Fragile X should all be differentials for autism

KLINEFELTER’S SYNDROME (XXY)

  • Seen in males
  • Tall stature, but “eunuchoid” after puberty (often diagnosed after puberty, sometimes in context of fertility workup – sterile, testicular dysgenesis)
  • In general, IQ below average (80-90); 25% have some degree of MR (usually mild)
  • Tend to have dyslexia and LD
  • Some describe as “passive” or with decreased libido

TURNER’S SYNDROME (XO)

  • Seen in females (often associated with miscarriage; only 1% of affected fetuses are born)
  • Due to various genetic defects; missing X chromosome (XO), some are XO/XX mosaics
  • Dysmorphic features – small stature, poorly developed secondary sex characteristics, sexual dysfxn in puberty/adulthood, webbed neck, broad chest, deformed bend in forearm, low set hairlines, low set ears and atypical facies; usually no neurological abnormalities
  • Do not have a consistent npsych profile; considerable heterogeneity in the profile and severity; MR is rare or mild (20% have mild)
  • Verbal strengths contrast with nonverbal; visuospatial deficits are common (PIQ<VIQ is usual; but 10 – 20% show the opposite); typically show a pattern consistent with NVLD
  • Math difficulty is common; social deficits and impaired facial recognition; at risk for NVLD; some say striking deficits in perception of form and space; may see LD and ADD
  • May have anxiety/depression

XYY SYNDROME

  • Extremely tall; severe acne persists beyond adolescence
  • Cerebral development may include migrational abnormalities and maturational delays
  • Tendency toward higher activity levels, more negative mood and temper tantrums have been noted
  • Historically, research on “supermales” conducted in prisons, and indicated deviant, violent, aggressive behavior, but, obviously, ascertainment bias
  • Modern studies: delayed speech acquisition and other neurodevelopmental milestones, characterologic problems, psychiatric difficulties, average to below normal IQ; legal/medical now reject relationship between XYY and violent criminal behavior

LESCH-NYHAN SYNDROME

  • X-linked disorder
  • Self-injurous behavior
  • Extrapyramidal involvement
  • Behavioral disturbances
  • Neuropsych presentation is variable

DEGENERATIVE DISORDERS

LEUKODYSTROPHIES (LD)

  • Rare group of genetic disorders which involve the destruction of CNS white mater (may also affect PNS)
  • Like MS, can also cause optic nerve, cerebellum, and spinal cord demyelination
  • Usually manifest as infants, but sometimes not until teens or young adults
  • Unremitting physical and mental deterioration

ADRENAL LEUKODYSTROPHY

  • X-linked, recessive
  • Typically first produces neurologic symptoms and adrenal insufficiency in boys between 5 and 15 years
  • Occasionally develops in men aged 20-30 yrs, then associated by mania, gait impairment, and eventual dementia
  • “Lorenzo’s Oil” – reduces the accumulation of VLCFA’s, but DOES NOT alter the disease course
  • similarly, treatment by adrenal hormone replacement does not arrest the demyelination

DISORDERS DUE TO INFECTION/INTOXICATION

  • Prenatal infections can lead to severe MR, convulsions, micro- or hydrocephalus
  • Maternal infections with psychological consequences: syphilis, toxoplasmosis, rubella, cytomegalovirus, herpes simplex, mumps, hepatitis, chicken pox (“STORCH”)

RUBELLA

  • Low birth weight, meningoencephalitis, psychomotor and MR, cataracts/retinopathy, abnormalities of heart and major blood vessels

CYTOMEGALOVIRUS

  • One of most common intrauterine infections
  • Enlargement of spleen and liver, intrauterine growth retardation, various congenital malformations, damage to visual and auditory systems, microcephaly, MR

INTOXICATION

  • Kernicterus, bilirubinemia (secondary to blood-type incompatibilities between mother and fetus), FAS

NUTRITIONAL DISORDERS

  • Protein-calorie malnutrition is a major problem worldwide
  • Protein/lipid deficiencies are developmental disorders with problems of myelination
  • Following two disorders are commonly combined rather than presenting separately

KWASHIORKOR

  • Protein deficient diet

MARASMUS

  • Calorie deficient diet

ANOXIC EPISODES

  • Period around time of birth is time of greatest risk
  • Premature infant at particularly high risk because it is essentially unprepared for birth
  • May lead to MR, motor deficits, seizures, CP
  • Neurobehavioral sequelae vary depending on type of damage; in some cases, there is no sequelae

BRAIN INJURY AND NEOPLASM

  • Perinatal mechanical damage can lead to intracranial hemorrhage and CNS tissue damage
  • Head injury from falls, MVA, abuse
  • >60% of all childhood cerebral neoplasms and >75% of all intracranial tumors are gliomas (i.e., glial cell tumors – e.g., astrocytoma, medulloblastoma, ependymoma)

CONVULSIVE DISORDERS

NEONATAL SEIZURES

  • First week of life
  • Most frequent neonatal neurological emergency
  • Usually result of serious perinatal conditions (e.g., anoxic episodes, hemorrhage)

INFANTILE SPASMS

  • Peak between 4-6 months
  • Characterized by spasms, severe MR, markedly abnormal EEG
  • Poor prognosis
  • Important to differentiate from reflux (as may look similar at first glance)

FEBRILE SEIZURES

  • Typically occur 6 months-5 years
  • Little lasting effects with single seizure

EPILEPSY

  • Etiology may be trauma plus all pre-, peri-, and post-natal disorders (e.g., metabolic d/o, infection, anoxic episode)

Miscellaneous Info

  • Insulin-Dependent Diabetes – onset < 7years old and chronic course (>5 years) more likely to show reading and memory difficulties and slow response times
  • Brain dysfunction in children is associated with increased risk of psychiatric disorder, and vice versa; specifically, perinatal cerebral injuries constitute at least a weak risk factor for schizophrenia

Chemical Senses

GUSTATION

Stimuli

  • Only 4 qualities of taste: bitterness, sourness, sweetness, and saltiness
  • Flavor (not taste) is composite of olfaction and gustation
    • (aside: most vertebrates taste all four; exception: cats, who don’t detect sweetness)

Anatomy of Taste Buds and Gustatory Cells

  • Tongue, palate, pharynx, and larynx contain approximately 10,000 taste buds
  • Most receptors are around papillae, small protuberances of the tongue
  • Tip of tongue: sweet and salty
  • Sides: sourness
  • Back: bitter

Gustatory Pathway

  • Gustatory info transmitted thru Cranial Nerves 7, 9, and 10
    • info from anterior part of tongue travels thru chorda tympani (branch of CN 7 – Facial)
    • info from posterior part of tongue send info through CN 9 (Glossopharyngeal)
    • info from palate and epiglottis carried by CN 10 (Vagus)
  • First relay station is the nucleus of the solitary tract (in medulla)
  • Then send axons to the thalamus – ventral posteromedial nucleus
  • Thalamic neurons send axons to primary gustatory cortex, which is located in anterior insula-frontal operculum
  • Info then sent to the secondary gustatory cortex in orbitofrontal cortex

OLFACTION

Anatomy and Pathways of Olfaction

  • Bipolar olfactory receptor neurons in olfactory mucosa activated by odorants
  • Constant turnover of olfactory cells (every 60 days); same for gustatory cells
  • Odorous molecules dissolve in mucus and stimulate receptor cells on the olfactory cilia
  • Axons of olfactory receptor cells enter skull through small holes in cribriform plate
    • mucosa also contain some free nerve endings of trigeminal, which mediate sensations of pain that can be produced by some irritating chemicals like ammonia
  • Olfactory bulbs are at base of brain on ends of stalklike olfactory tracts
  • Each olfactory cell sends single axon into olfactory bulb, where synapses w/ dendrites of mitral cells
  • Axons of mitral cells travel to rest of brain thru olfactory tract
    • some axons terminate in ipsilateral areas; others cross and enter the olfactory nerve and terminate in contralateral olfactory bulb
    • primary olfactory cortex is unique among sensory systems since receives diret input from secondary sensory neurons w/out intervening thalamic relay
  • Olfactory tract axons project directly to: piriform cortex, amygdala, and entorhinal cortex
  • Primary olfactory cortex projects to several secondary olfactory areas including:
    • Hypothalamus
    • Hippocampus
    • Orbitofrontal cortex
    • Dorsomedial nucleus of thalamus

Disorders of Smell

Olfactory disturbances can be subdivided into 4 groups:

1. Quantitative abnormalities

  • Loss or reduction of sense of smell (anosmia or hyposmia)
    • Can be from pxs at the nasal, neuroepithelial, or central level
    • if bilateral, pt usually complains of ageusia (loss of taste)
  • Increased olfactory acuity (hyperosmia)
    • very rare, if exists

2. Qualitative abnormalities

  • Distortions or illusions of smell (dysosmia or parosmia)
    • May be ass’d w/ depressive illness

3. Olfactory hallucinations/delusions

  • Always of central origin
  • Most often due to temporal lobe seizures (uncinate fits)

4. Higher-order loss of discrimination (Olfactory agnosia)

  • Perceptual aspects intact, but can’t recognize

Cerebral Hemispheres and Vascular Supply

Review of Main Functional Areas of Cerebral Cortex

  • Sensory areas for face and hand are on the lateral convexities while the leg areas are in the interhemispheric fissure
  • Broca’s area in inferior frontal gyrus, just anterior to the articulatory areas of the primary motor cortex
  • Wernicke’s area lies in the superior temporal gyrus, adjacent to the primary auditory cortex
  • Optic radiations pass under the parietal and temporal cortex; thus infarcts in these lobes can cause contralateral visual field deficits

General Information Regarding CVAs

  • CVAs can cause seizures due to scar tissue
  • Depression occurs in approximately 30% of CVA patients – such patients have greater functional disability and subsequent mortality.
    • Left-sided CVAs are most closely associated with depression
  • Although function usually improves over time, patients may continue to show worsening deficits or decreased consciousness over the next few days because of cerebral edema (or less often, from extension of the infarct)
    • Severe cerebral edema can cause potentially fatal shift in intracranial structures
  • Locked-in Syndrome Mute and quadriplegic – but intact cognitive capacity
    • Usually result from infarct of inferior portion of the pons or medulla
    • Can respond by opening and closing eyes
    • Alert with normal cognition and affect
  • Anastomes Connections between different cerebral arteries on the cortical surface. Allows perfusion between arterial systems to limit extent of cortical damage in stroke. While this can protect gray matter, it also creates greater vulnerability in the “border zones” or watershed areas between arteries, as they are the most distal portions of the blood supply. There is little collateral circulation in the white matter

Circle of Willis: Anterior and Posterior Circulations

Circle of Willis

  • An anastomotic ring, from which all major cerebral vessels arise
  • Provides abundant opportunities for collateral flow; however a complete ring is present in only approximately 25% of individuals

Main Arteries of the Circle of Willis

  • Cerebral blood supply provided to circle of Willis by the:
    • Internal Carotid Arteries (paired; see text p. 370 for names of artery sections prior to entering Circle of Willis)
      • Supplies most of the diencephalon and cerebral hemispheres
    • Vertebral Arteries (paired) which fuse into the Basilar Artery
  • Cortex and subcortical structures receive blood through three main artery supplies:
    • Anterior Cerebral Artery Arise from internal carotid arteries
    • Middle Cerebral Artery Arise from internal carotid arteries
    • Posterior Cerebral Artery Arise from top of basilar artery
  • Two anastomes in the Circle of Willis
    • Anterior Communicating Artery (anastomes of the anterior cerebral artery)
    • Posterior Communicating Artery (connect internal carotids to the posterior cerebral arteries)

Anatomy and Vascular Territories of the Three Main Cerebral Arteries

  • The 3 main arteries give rise to numerous branches that travel in the subarachnoid space of the surface of the brain
  • Subcortical areas are supplied by penetrating branches that arise from initial segments of the arteries near the Circle of Willis at the base of the brain

Vascular Supplies of the Superficial Cerebral Structures

(see figure 10.5 for visual depiction of information provided below; ACA and MCA are both involved in the ”anterior circulation”)

Anterior Cerebral Artery

  • Supplies most of cortex on the anterior medial surface of the brain, from the frontal to the anterior parietal lobes, usually including the medial sensorimotor cortex (i.e., the sensory cortex for the lower extremity).
  • Travels in the interhemispheric fissure as it sweeps back over the corpus callosum
  • Two branches: Pericallosal Artery and the Callosomarginal Artery

Middle Cerebral Artery

  • Supplies most of the cortex on the dorsolateral convexity of the brain (involving frontal, parietal and temporal lobes).
  • Passes over the insula, around the operculum and then exits the Sylvian fissure onto the lateral convexity
  • Superior Division Supplies cortex above Sylvian fissure and inferior division supplies the region below the Sylvian fissure.

Posterior Cerebral Artery

  • Supplies inferior and medial temporal and occipital cortex (including the visual cortex).

Vascular Supplies of the Deep Cerebral Structures

(see figures 10.8 and 10.9 pp 374-375 for visual depiction of information provided below)

Middle Cerebral Artery

  • Lenticulostriate Arteries
  • They arise from the initial portions of the MCA, before it enters the Sylvian Fissure and supply:
    • basal ganglia
    • internal capsule
  • In hypertension, these arteries are prone to narrowing, leads to lacunar infarcts or rupture (hemorrhage).

Anterior Cerebral Artery

  • current Artery of Heubner
  • They supply:
    • head of the caudate
    • anterior putamen
    • globus pallidus
    • internal capsule

Posterior Cerebral Artery

  • Thalamoperforator Arteries
  • Thalamus and sometimes posterior limb of the internal capsule

Vertebral/Basilar System

  • Midbrain, cerebellum, and portions of the temporal and occipital lobes
    • CVAs with total occlusion lead to coma or locked-in syndrome
    • Occlusion of a branch can lead to cranial nerve palsy or contralateral hemiparesis

Internal Carotid Artery

  • Anterior Choroidal Artery
  • They supply:
    • globus pallidus
    • putamen
    • thalamus
    • posterior limb of internal capsule

Clinical Syndromes of the Three Main Cerebral Arteries

(see Table 10.1 pp 376 and 377)

Middle Cerebral Artery (MCA)

  • Occlusion of the proximal part of the artery generally results in contralateral hemiparesis, hemi-sensory loss, homonymous hemianopsia, aphasia (w/left hemisphere lesions) and hemi-inattention, anosognosia, apraxia, neglect, dysprosody, etc. (w/right hemisphere lesions)
    • if anterior – Broca’s aphasia
    • if posterior – fluent aphasia
    • may also see transcortical aphasia or global aphasia (if entire MCA watershed area affected)
    • posterior MCA infarcts may also lead to Angular Gyrus syndrome (fluent aphasia, alexia with agraphia, Gerstmann’s syndrome, constructional problems)
  • Infarcts and ischemic events are more common in the MCA than in the ACA or PCA, partly because of their relatively larger territory. Infarcts occur in 3 general areas:
    • Superior Division Supplies cortex above the Sylvian fissure
    • Inferior Division Supplies cortex of lateral temporal and occipital lobes below Sylvian fissure, and part of lateral parietal cortex
    • Deep Territory Includes internal capsule and much of the basal ganglia
    • Proximal MCA occlusions affecting all 3 regions are called: MCA stem infarcts
  • Large MCA infarcts often have a gaze preference towards side of lesion, especially during acute period
  • Lacunes Small deep infarcts involving penetrating branches of the MCA or other vessels

Anterior Cerebral Artery (ACA)

  • Infarcts are uncommon, but typically produce contralateral lower extremity cortical sensory loss and weakness of the upper motor neuron type
  • Damage to supplementary area can lead to “alien hand syndrome” (semiautomatic movements of contralateral arm that aren’t under voluntary control)
  • Can cause frontal lobe dysfunction typically characterized by:
    • impaired judgment
    • flat affect
    • grasp reflex
    • apraxia
    • abulia
    • incontinence
    • pseudobulbar palsy
  • Bilateral occlusion can cause emotional disturbance with apathy, confusion, and occasional mutism, plus spastic paraparesis

Posterior Cerebral Artery (PCA)

  • Typically cause contralateral homonymous hemianopia
  • If smaller penetrating vessels are involved may lead to infarcts in the thalamus or posterior limb of the internal capsule leading to:
    • Contralateral sensory loss
    • Contralateral homonymous hemianopsia
    • Contralateral hemiparesis
    • Thalamic aphasia (if in dominant hemisphere) – so can mimic MCA infarcts
    • If involve left occipital cortex and splenium of corpus callosum  alexia without agraphia

Internal Carotid Artery

  • Occlusion leads to infarction in the central-lateral portion of the cerebral hemisphere
  • Symptoms are identical to those of the middle cerebral artery occlusion except for occasional ocular symptoms ipsilateral to the affected artery

Hemorrhages

  • Most often result from hypertension
  • Tend to affect basal ganglia, thalamus, pons, and cerebellum
  • Typically occur abruptly and, because of increased ICP produce headache, nausea and vomiting
  • Patients usually lose consciousness and have profound neurologic deficits

Subarachnoid Hemorrhage

  • Nontraumatic cause is usually from a ruptured berry aneurysm; may mimic a migraine or a muscle tension headache (often referred to as “the worst headache in my life”)
  • Also can present with vomiting, diplopia, altered state of consciousness (signs of increased ICP)
  • Since bleeding is around brain rather than into a particular region, typically no sensory, motor or visual signs

Cerebellar Hemorrhage

  • Can be readily evacuated and is diagnosed by occipital headaches, gait ataxia, dysarthria and lethargy

Watershed Infarcts

  • Watershed Zones Regions who lie between adjacent cerebral arteries
  • Bilateral watershed infarcts in the ACA-MCA and in the MCA-PCA zones can occur with severe drops in blood pressure and in patients with carotid stenosis
  • Watershed infarcts produce proximal arm and leg weakness (“man in the barrel syndrome)
  • Can also cause transcortical aphasia syndromes in the dominant hemisphere

Transient Ischemic Attack and Other Transient Neurologic Episodes

  • The most common causes include:
    • TIA
    • Migraine
    • Seizures
    • Other non-neurologic conditions such as cardiac arrhythmia or hypoglycemia

Transient Ischemic Attack

  • Neurologic deficit lasting less than 24 hours, caused by temporary brain ischemia
  • Recent research suggests that typical TIA duration is 10 minutes and that those lasting more than 1 hour are usually small infarcts.
  • BUT, despite the appearance of a small infarct on MRI scan, complete functional recovery can sometimes occur within 1 day.
  • Mechanisms can include an embolism which dissolves, in situ thrombus formation or vasospasm leading to temporary narrowing of the vessel.
  • Are typically indicative of underlying atherosclerotic cerebrovascular disease and increased risk of sustaining stroke.
  • May mimic partial seizures, postictal confusion, migraine and metabolic aberrations.
  • Are slightly more common in the vertebral basilar system (w/c includes the posterior cerebral arteries) than in the carotid system (which includes the middle and anterior cerebral arteries).

Transient Loss of Consciousness Without other Focal Features

  • Cardiogenic syncope most common cause
  • Neurologic causes are responsible for less than 10% of cases

Differential Diagnosis of Transient Neurologic Episodes

  • Vascular (TIA, Migraine, AVM)
  • Seizures
  • CSF flow-related (cyst of 3rd ventricle)
  • Genetic
  • Toxic/metabolic (e.g., medication/toxin related; hypoglycemia)
  • Infectious/inflammatory (encephalitis, MS)
  • Movement disorders (chorea, dystonia, tic disorders)
  • Psychogenic

Stroke: Mechanisms and Treatment

  • Stroke refers to both hemorrhagic events and to ischemic infarcts
  • Stroke is typically produced by one of 3 ways:
    • Sudden reduction in blood pressure and blood perfusion
    • Impaired blood supply as a result of occlusion or stenosis
    • Obstruction of a vessel by embolus
  • In addition to focal neurologic deficits, strokes can be associated with headaches or seizures
    • Headaches
      • Most often unilateral (ipsilateral to infarct)
      • More common for posterior than anterior circulation infarcts (often in carotid or vertebral arteries)
    • Hemorrhagic Conversion When ischemic strokes cause blood vessels to become fragile and rupture

Risk Factors

  • Age (incidence rises exponentially over 65 year)
  • Hypertension
  • Cardiac conditions
  • Diabetes
  • Smoking
  • Possibly oral contraceptives
  • Lack of exercise, type A personality, heavy alcohol use and cholesterol high diets are risk factors for coronary artery disease, but not directly for CVAs

Etiologies of Stroke

Most common cause is thrombosis; second causes is emboli originating in a carotid artery and lodging in a cerebral artery

  • Intracerebral hematoma (nontraumatic) – bleeding with blood collection
  • Hypertension – spontaneous bleed secondary to hypertension
  • Arterial Vascular Malformation (AVM) – congenital malformation leading to poor perfusion, weak areas in the vessels that may bleed, or secondary aneurysm at vessel bifurcations or junctures
  • Aneurysm
    • Berry aneurysm, congenital weakness, typically at a bifurcation of blood vessels that balloons over time and can burst resulting in hemorrhagic stroke
    • Ruptured aneurysm can result in severe headache, focal symptoms, possible coma – typically requires emergency surgical clipping of the aneurysm
  • Prematurity can lead to intraventricular hemorrhage (IVH)
  • Neoplasm – tumor growth can disrupt or burst blood vessels

Mechanisms of Ischemic Stroke

Ischemic stroke occurs when there is inadequate blood supply to a region of the brain for enough time to cause infarction (death) of brain tissue

Embolic Infarct

  • A piece of material (usually a blood clot) is formed in one place and then travels through the bloodstream to lodge in and occlude a blood vessel supplying the brain
  • Typically occur more suddenly, with maximal deficits at onset (and are also painful)
  • Treatment involves finding the source so future strokes may be avoided (e.g., heart related disorders or atherosclerotic disease); often involves prescribing anticoagulants (aspirin)
  • Other sources of emboli include (1) air emboli in deep sea divers; (2) septic emboli in bacteria endocartis; (3) fat emboli in trauma to long bones, etc…

Thrombotic Infarcts

  • A blood clot forms locally on the blood vessel wall, usually at the site of an underlying atherosclerotic plaque, causing the vessel to occlude
  • May have more of a stuttering or slow course; also relatively painless
  • Can also lead to the development of emboli
  • May be the result of carotid stenosis (70-99%)

Hypoperfusion with Resultant Ischemia and Hypoxia

  • Leads to borderzone infarcts
  • Certain brain regions are particularly vulnerable to ischemic-anoxic insults including the hippocampus, cerebellum and cerebral cortex
  • The brain regions with the most marginal vascular supply, the border zones are most often affected
  • In large vessel infarcts (involve the surface of the brain) – infarcts most often due to emboli, although thrombosis can occur occasionally, especially in large proximal vessels such as the vertebral, basilar, and carotid arteries

Small Vessel Infarcts

  • Involve vessels that feed the deep structures/subcortical structures and brainstem).
  • Also called lacunar infarcts because they resemble small lakes when brain is examined on pathologic sections.
  • Often associated with small-vessel disease caused by chronic hypertension, and generally affect the deep white matter and nuclei of the cerebral hemispheres and brainstem
  • Common lacunar syndromes for your notes (see page 382, Table 10.3)

Cortical Versus Subcortical Lesions

  • Can sometimes be differentiated based on the presence or absence of cortical signs, such as:
    • Aphasia
    • Neglect
    • Homonymous visual field deficits
    • Cortical sensory loss
  • BUT, each of these can be seen in some cases of subcortical lesions as well

Stroke Risk Factors

  • Hypertension, diabetes, high cholesterol, cigarette smoking, family history and prior history of stroke or other vascular disease.
  • Migraines can also be a risk factor for stroke in young adults, as is sickle-cell disease, cardiac disease and vasculitis

Treatment and Diagnostic Workup of Ischemic Stroke and TIA

  • CT Scans Remember that an infarct will often not be visible on the initial scan, especially if it is done within a few hours – BUT a hemorrhage will almost always be visible
  • Once a hemorrhage has been ruled out by CT, many physicians treat with thrombolytic agents or heparin
  • See page 384 for a more extensive treatment plan

Carotid Stenosis

  • Atherosclerotic disease commonly leads to stenosis of the internal carotid artery just beyond the carotid bifurcation.
  • Thrombi formed can embolize distally giving rise to TIAs or infarcts – most often affecting the MCA, ACA, and ophthalmic artery
  • Thus, is often associated with MCA symptoms such as contralateral face/arm or face/arm/leg weakness, contralateral sensory changes, contralateral visual field defects, aphasia or neglect.
  • ACA territory symptoms include contralateral weakness
  • Carotid occlusions can be asymptomatic if there is adequate collateral flow via the anterior or posterior communicating arteries However emboli may become dislodged and cause TIAs or strokes

“Dissection” of the Carotid or Vertebral Arteries

  • Head or neck trauma, and sometimes even minor events (e.g., sneeze) can cause a small tear to form on the surface of the carotid or vertebrate arteries. This allows blood to burrow in the vessel wall, producing a dissection.
  • Can lead to development of a thrombosis/embolism
  • Some patients report hearing a pop at the onset

Venous Drainage of the Cerebral Hemispheres

(Venous sinuses lie enclosed within folds of the 2 layers of dura; see pp. 386 & 387 for diagrams of venous drainage system and for more specific details regarding the smaller vessels)

Drainage Occurs Two Ways

  • Through Dural Sinuses These are large channels between layers of the dura (between the dura and the arachnoid). They are also where the CSF is reabsorbed into the ventricular system before blood passes out of the brain.
  • Direct Venous Return Only the spinal cord and medulla supply drain directly to the system (the remainder of the brain supply is drained via veins that empty into the dural sinuses).
    • Like the arterial system, venous drainage has superficial and deep territories:
      • Superficial Veins Drain mainly into the Superior Sagittal Sinus and the Cavernous sinus
      • Deep Veins Drain into the Great Vein of Galen
    • Nearly all venous drainage systems merge into the Internal Jugular Veins

Sagittal Sinus Thrombosis

  • Often associated with same syndromes which affect arteries
  • Increased frequency in pregnant women and within the first few weeks postpartum
  • Obstruction of venous drainage usually causes elevated intracranial pressure which can cause:
    • parasagittal hemorrhages
    • also, increased venous pressure can decrease cerebral perfusion leading to infarcts
    • seizures are common
    • headaches and papilledema
    • depressed level of consciousness
  • Thrombosis can also occur less commonly in the deep cerebral veins or in other cortical veins, leading to infarcts or hemorrhage in their territories
  • Empty Delta Sign Defect observed on imaging; the sinus normally fills uniformly with contrast, so a dark region in the middle suggests a filling defect (possibly due to a blood clot).

Notes from the Clinical Cases

  • Sudden onset of severe headache, worse than any experienced should be considered a subarachnoid hemorrhage until prove otherwise.
  • In about 80% of the cases, spontaneous subarachnoid hemorrhage is caused by rupture of an arterial aneurysm in the subarachnoid space.
  • The most common locations for aneurysms are the origin of the ACA, PCA or bifurcation points of the MCA.
  • Subarachnoid hemorrhage can lead to hydrocephalus due to impaired CSF flow in the subarachnoid space. However, in these cases, a lumbar puncture should not be performed as it can occasionally cause aneurysmal rupture by increasing the pressure across the wall of an aneurysm.
  • Pure motor hemiplegia, without sensory abnormalities or cortical signs (e.g., aphasia or neglect) can be localized to the contralateral corticobulbar and corticospinal tracts in the internal capsule or ventral pons. Dysarthria is commonly present, giving rise to the name dysarthria hemiparesis
  • Facial weakness associated with sparing of the forehead is indicative of an upper motor neuron injury
  • Large cortical lesions can be associated with an ipsilateral gaze preference; there is a loss of the ability to drive the eyes toward the side opposite the lesion
  • Balint’s Syndrome Disruption of the “where” system rather than the “what” system. Patients have trouble focusing on an object, but recognize it once they can focus.

Cerebellum

Anatomical and Clinical Review

The Cerebellum

The cerebellum is the largest structure in the posterior fossa (see figures 15.1, 15.2, & 15.3). It is attached to the dorsal aspect of the pons and rostral medulla by three white matter peduncles and forms the roof of the fourth ventricle. It consists of:

  • Vermis – the midline structure, named for its “wormlike” appearance
  • Cerebellar Hemispheres

Cerebellar Tonsils

  • Important landmark on the inferior surface, which may be herniated secondary to mass lesions of the cerebrum or cerebellum, or brain swelling and associated severely elevated intracranial pressure
  • With severe herniation, the tonsils may herniate through the foramen magnum, compress the medulla, and cause death through impingement on the medullary respiratory centers

Cerebellar Peduncles

  • Superior Cerebellar Peduncle Carries mainly output from the cerebellum
  • Middle and Inferior Cerebellar Peduncles Carry mainly input to the cerebellum

 

Cerebellar Functions

 

(see Table 15.1)

  • Serves to integrate sensory and other inputs from many regions of the brain and spinal cord (SC)
  • Coordinates and “smoothes” ongoing movements and participates in motor planning
  • Has no direct connections to lower motor neurons, but exerts its influence through connections to motor systems of the cortex and brainstem

Different regions of the cerebellum have specialized functions

  • Inferior Vermis and Flocculonodular Lobes Regulate balance and eye movement through interactions with the vestibular circuitry
    • Act with other parts of the vermis to control medial motor systems (i.e., proximal trunk and limb muscles)
  • Intermediate Hemispheres Control lateral motor systems (i.e., distal appendicular muscles)
  • Lateral Cerebellar Regions (i.e., far lateral) Function in motor planning

Additional Functions of the Cerebellar Pathways

  • Articulation of speech
  • Respiratory movements
  • Motor learning
  • Higher-order cognitive functions

 

Functional Regions of the Cerebellum – Table

Region Functions Motor Pathways Influenced
Lateral Hemispheres (largest part of the cerebellum) Motor planning for extremities Lateral Corticospinal tract
Intermediate Hemispheres Distal limb coordination (especially the appendicular muscles in the legs and arms) Lateral Corticospinal tract and Rubrospinal tract
Vermis Proximal limb and trunk coordination Anterior Corticospinal tract, Retibulospinal tract, Vestibulospinal tract and Tectospinal tract
Flocculonodular Lobe Balance and vestibulo-ocular reflexes Medial Longitudinal fasciculus

Of Interest: Cerebellar lesions typically result in a characteristic type of irregular uncoordinated movement – Ataxia.

 

Cerebellar Output Pathways

Output pathways are organized around the three functional regions of the cerebellum:

  • Lateral Hemispheres
  • Intermediate Hemispheres
  • Vermis plus Flocculonodular Lobe

Pathways from the cerebellum to the lateral motor systems and then to the periphery are “double crossed”

  • 1st crossing occurs as the cerebellar output pathways exit in the decussation of the superior cerebellar peduncle
  • 2nd crossing occurs as the corticospinal and rubrospinal tracts descend to the spinal cord. Inputs also follow this pattern, so each cerebellar hemisphere receives information about the ipsilateral limbs

 

Cerebellar Input Pathways

Input to the Cerebellum Arises From

  • All areas within the CNS
  • Multiple sensory modalities (e.g., vestibular, visual, auditory & somatosensory systems)
  • Brainstem nuclei
  • Spinal cord

Input is somatotopically organized, with the ipsilateral body represented in both the anterior and posterior lobes Major source of input consists of corticopontine fibers (i.e., from frontal, temporal, parietal & occipital lobes) that travel in the internal capsule and cerebral peduncles

  • Derive from primary sensory and motor cortices and part of the visual cortex
  • Travel to the ipsilateral pons and synapse in the pontine nuclei
  • Pontocerebellar fibers cross the midline to enter the contralateral middle cerebellar peduncle and give rise to mossy fibers that innervate much of the cerebellar cortex

Spinocerebellar fibers comprise another major source of cerebellar input and provide afferent information to the cerebellum

  • Information about limb movements conveyed by the dorsal spinocerebellar tract and the cuneocerebellar tract
  • Of Interest: Spinocerebellar input is either ipsilateral or “double-crossed” —> ipsilateral limb ataxia when lesioned

 

Vascular Supply to the Cerebellum

(see Figures 15.12 & 15.13)

Blood Supply to the Cerebellum

 

Provided by three branches of the vertebral and basilar arteries:

Posterior Inferior Cerebellar Artery (PICA)

  • Arises from the vertebral artery

Anterior Inferior Cerebellar Artery (AICA)

  • Arises from the lower basilar artery

Superior Cerebellar Artery (SCA)

  • Arises from the top of the basilar artery

In addition to supplying the cerebellum, these arteries course through the brainstem, providing blood to portions of the lateral medulla and pons.

Of Interest: Infarcts are more common in the PICA and SCA than in the AICA territory.

 

Principles for Localizing Cerebellar Lesions

  • Ataxia is ipsilateral to the side of the cerebellar lesion
  • Midline lesions of the cerebellar vermis or flocculonodular lobes mainly cause unsteady gait (i.e., truncal ataxia) and eye movement abnormalities, which often are accompanied by intense vertigo, nausea and vomiting
    • Affect the medial motor systems
    • Do not typically cause unilateral deficits because the medial motor systems influence the proximal trunk muscles bilaterally
  • Lesions lateral to the cerebellar vermis mainly cause ataxia of the limbs (i.e., appendicular ataxia)

Of Interest: The cerebellum has multiple reciprocal connections with the brainstem and other regions therefore ataxia may be seen with lesions in those areas as well

Lesion Location Functional Impact
Lateral cerebellum Distal limb coordination
Medial cerebellum Trunk control, posture, balance and gait

 

Of Interest: Deficits in coordination occur ipsilateral to the lesion

 

Cerebellar Infarcts – Key Clinical Concepts

 

Characteristic Symptom Presentation

  • Vertigo
  • Nausea and vomiting
  • Horizontal nystagmus
  • Limb ataxia
  • Unsteady gait
  • Headache (localized to occipital, frontal, or upper cervical regions)

Of Interest: Many of the signs and symptoms of cerebellar artery infarct result from infarction of the lateral medulla or pons, rather than the cerebellum – Infarcts of these areas may cause trigeminal and spinothalamic sensory loss, and Horner’s syndrome.

*Conversely, infarcts of the lateral medulla or pons can cause ataxia because of involvement with cerebellar peduncles, even if the cerebellum is spared.

Infarct Patterns

  • Infarcts that spare the brainstem and involve predominantly the cerebellum are more common with SCA infarcts than with PICA or AICA, therefore infarcts causing unilateral ataxia with little or no brainstem signs are most commonly in the SCA territory
  • Infarcts of the PICA and AICA more often involve both the lateral brainstem and cerebellum
  • Infarcts of the lateral pons or medulla that spare the cerebellum typically occur with PICA or AICA rather than SCA
  • Large cerebellar infarcts that involve the territories of the PICA or SCA can cause swelling of the cerebellum
    • Subsequent compression of the fourth ventricle can cause hydrocephalus
    • Compression in the posterior fossa may be life threatening because the respiratory centers and other vital brainstem structures may be affected

Treatment

  • Surgical decompression and resection of portions of the infracted cerebellum
  • Hemorrhage into the cerebellar white matter also can cause brainstem compression

 

Cerebellar Hemorrhage – Key Clinical Concepts

 

Characteristics Symptom Presentation

  • Headache
  • Nausea
  • Vomiting
  • Ataxia
  • Nystagmus

Large Cerebellar Hemorrhages May Cause

  • Hydrocephalus [treated with ventriculostomy]
  • 6th nerve palsies
  • Impaired consciousness
  • Brainstem compression
  • Death

Can Occur Secondary To

  • Chronic hypertension
  • Arteriovenous malformation
  • Hemorrhagic conversion of an ischemic infarct
  • Metastases

Treatment

  • May include surgical evacuation of the hemorrhage and decompression of the posterior fossa.
  • Hydrocephalus treated by ventriculostomy carries with it the risk of upward transtentorial herniation.

 

Signs and Symptoms of Cerebellar Disorders

  • Nausea
  • Vomiting
  • Vertigo
  • Slurred speech
  • Unsteadiness
  • Uncoordinated limb movements
  • Headache Occurs in the frontal, occipital, or upper cervical regions, and usually occurs on the side of the lesion

 

Most Abnormalities a Combination Of

 

Dysmetria

  • Abnormal undershoot or overshoot (i.e., past pointing) during movements toward a target

Dysrhythmia

  • Abnormal rhythm and timing of movements

 

Incipient Tonsilar Herniation Lesions May Cause

 

  • Depressed consciousness
  • Brainstem findings
  • Hydrocephalus
  • Head tilt [also seen with lesions to the anterior medullary velum]

 

Additional Cerebellar Disorders

 

Dysdiadochokinesia

  • (aka adiadochokinesia) Abnormalities of rapid alternating movements, such as tapping one hand with the palm and dorsum of the other hand

Eye Movement Abnormalities

  • Ocular Dysmetria Saccades overshoot or undershoot their target
  • Slow Saccades Present in some degenerative disorders involving the cerebellum
  • Nystagmus Typically of the gaze paretic type in which the patient looking toward a target in the periphery exhibits slow phases toward the primary position and fast phases occur back toward the target. May change directions depending upon the direction of gaze (unlike peripheral vertigo).
  • Vertical Nystagmus may occur.

Speech Abnormalities

  • Scanning or Explosive Speech Individual’s speech may have an ataxic quality in cerebellar disorders with irregular fluctuations in both rate and volume
  • Cerebellar dysfunction also may cause slurring or articulatory problems

Cerebellar Disease

  • Decreased muscle tone
  • “Pendular” reflexes
  • Cognitive disturbance

 

Abnormalities That Can Confound the Cerebellar Exam

 

Upper Motor Neuron Signs

  • Both corticospinal and cerebellar lesions can cause slow, clumsy, movements of the extremities

Lower Motor Neuron Signs

  • With severe upper or lower motor weakness, cerebellar testing may not be possible
  • Precision finger tapping may be helpful, as cerebellar involvement typically causes the tip of the finger to hit a different spot on the thumb each time [See neuroexam.com Video 63]

Sensory Loss

  • Loss of joint position sense can cause sensory ataxia
  • Loss of position sense must be severe and sensory ataxia usually improves with visual feedback

Basal Ganglia Dysfunction

  • Movement disorders (e.g., parkinsonism) associated with basal ganglia involvement can cause slow, clumsy movements or gait unsteadiness
  • Tremor and dyskinesia also may confound the cerebellar examination

 

Clinical Findings and Localization of Cerebellar Ataxia

Ataxia

 

  • Means literally “lack of order”
  • Refers to the disordered contractions of the agonist and antagonist muscles and lack of normal coordination between movements at different joints
  • Characterized by movements that have an irregular, wavering course that seems to consist of continuous overshooting, overcorrecting and then overshooting again around the intended trajectory

Characteristics of Ataxic Movements

  • Dysrhythmia or abnormal timing
  • Dysmetria or abnormal trajectories through space

Ipsilateral Localization of Ataxia

  • Cerebellar connections involved in the lateral motor system are either ipsilateral or cross twice (i.e., “double crossed’) between the cerebellum and spinal cord
  • Lesions of the cerebellar hemispheres cause ataxia in the extremities ipsilateral to the side of the lesion
  • Lesions of the cerebellar peduncles lead to ipsilateral ataxia

In contrast: cerebellar lesions affecting the medial motor system cause truncal ataxia, which is a bilateral disorder, but patients with truncal ataxia often fall or sway toward side of lesion

False Localization of Ataxia

  • Ataxia may be caused by lesions to the cerebellar input or output pathways located outside the cerebellum
  • Lesions in the cerebellar peduncles or pons (without damage to the cerebellar hemisphere) —> severe ataxia
  • Hydrocephalus [which may damage frontopontine pathways] and lesions within the prefrontal cortex —> gait abnormalities similar to truncal ataxia
  • Disorders of the spinal cord —> gait abnormalities

 

Truncal Ataxia versus Appendicular Ataxia

 

Truncal Ataxia

  • Caused by lesions confined to the cerebellar vermis
  • Affect primarily the medial motor systems
  • Lead to wide-based, unsteady, or “drunk like” gait or truncal ataxia
  • In severe cases, patients may even have difficulties sitting up without support

Appendicular Ataxia

  • Caused by lesions of the intermediate and lateral portions of the cerebellum
  • Affect the lateral motor systems
  • Cause ataxia on movement of the extremities

Of Interest: Lesions often extend to include both the vermis & cerebellar hemispheres and truncal and appendicular symptoms may coexist. More severe and longer-lasting deficits may occur with lesions of the intermediate hemisphere, vermis, deep nuclei, and cerebellar peduncles.

  • Unilateral lesions in the medial portion of the cerebellar hemisphere may produce no appreciable deficit.

 

Ataxia-Hemiparesis

 

  • Syndrome caused by lacunar infarcts
  • Presentation includes a combination of unilateral motor neuron signs and ataxia, usually affecting the same side
  • Both the ataxia and hemiparesis are contralateral to the lesion side
  • Most often caused by lesions in the:
    • Corona radiata
    • Internal capsule
    • Pons that involve both corticospinal and corticopontine fibers
  • May also follow lesions in the:
    • Frontal lobes
    • Parietal lobes
    • Sensorimotor cortex
    • Midbrain lesions that involve fibers of the superior cerebellar peduncle or red nucleus

 

Sensory Ataxia

 

  • Occurs when the posterior column – medial lemniscal pathway is disrupted
  • Causes impaired or loss of joint position sense [not typically observed in cerebellar patients]
  • Characterized by ataxic-appearing overshooting movements of the limbs and a wide-based, unsteady gait [similar to cerebellar involvement]
  • May improve significantly with visual feedback
  • Worsens with eyes closed or in the dark
  • Typically involves lesions of the peripheral nerves or posterior columns —> ipsilateral ataxia
  • May occur secondary to lesions in the thalamus, thalamic radiations or somatosensory cortex —> contralateral ataxia

 

Tests for Ataxia

Finger-Nose-Finger Test

 

(see Figure 15.14 and neuroexam.com Video 64)

  • Patient alternately touches her nose and then the examiner’s finger
  • Sensitivity of the test may be increased by holding the target finger at the limit of the patient’s reach or by moving the target finger to a different position each time the patient touches her nose

Heel-Shin Test

 

(see neuroexam.com Video 65)

  • Patient rubs his heel up and down the length of his shin in as straight a line as possible
  • Performed in the supine position to decrease contribution of gravity
  • Variations include tapping the heel repeatedly on the same spot just below the knee or having the patient alternately touch his knee and the examiner’s finger

Of Interest: Rapid tapping of the fingers together, hand on the thigh, or foot on the floor are good tests for dysrhythmia (see neuroexam.com Videos 52 & 53).

 

Testing for Overshoot or Loss of Check

 

  • Have patient raise both arms suddenly from their lap or lower them suddenly to the level of the examiner’s hand [see neuroexam.com Video 66] or
  • Apply pressure to the patient’s outstretched arms and suddenly release it

 

Testing for Truncal Ataxia

 

Wide-based, unsteady gait that resembles the drunk or a toddler may be observed with cerebellar involvement. Alcohol impairs cerebellar function and the cerebellar pathways of toddlers is not fully myelinated.

Tandem Gait Testing

  • The patient is instructed to touch the heel with the toe of the other foot on each step, which forces the patient to assume a narrow stance
  • Patients will fall or deviate toward the side of the lesion (see neuroexam.com Video 68)

Romberg or Romberg’s Test

  • Patient is asked to stand with feet together for half a minute, then asked to close eyes
  • A positive Romberg’s test occurs if the patient can stand with eyes open, but falls when they are closed.
  • The Romberg test indicates a proprioceptive lesion and is NOT a test of cerebellar function
  • With midline cerebellar lesions, the patient has difficulty standing with eyes open as well as closed [with these lesions, a peculiar tremor of the trunk or head, titubation, also can occur]
  • May help differentiate cerebellar lesions from lesions of the vestibular or proprioceptive systems

(see neuroexam.com Video 67)

 

Differential Diagnosis and Common Causes of Ataxia

Differential Diagnosis (depends on)

 

  • Age of the patient
  • Time course of evolution of the ataxia

 

Common Causes

 

Acute Ataxia in Adults

  • Toxin ingestion
  • Ischemic or hemorrhagic stroke

Chronic Ataxia in Adults

  • Brain metastases
  • Chronic toxin exposure (especially to alcohol)
  • Multiple sclerosis
  • Degenerative disorders of the cerebellum or cerebellar pathways

Acute Ataxia in Pediatric Patients

  • Accidental drug ingestion
  • Varicella-associated cerebellitis
  • Migraine

Chronic or Progressive Ataxia in Pediatric Patients

  • Cerebellar astrocytoma
  • Medulloblastoma
  • Friedreich’s ataxia
  • Ataxia-telangiectasia

 

Brief Anatomical Study Guide

Cerebellum

 

  • Located in the posterior fossa
  • Consists of:
    • midline vermis
    • intermediate part of the cerebellar hemisphere
    • lateral part of the cerebellar hemisphere
  • Attached to the brainstem by the:
    • superior cerebellar peduncle
    • middle cerebellar peduncle
    • inferior cerebellar peduncle

 

Outputs of the Cerebellum

 

All are carried by the deep cerebellar nuclei and the vestibular nuclei. The cerebellar cortex and the deep nuclei can be divided into three functional zones:

  • Vermis (via fastigial nuclei) and flocculonodular lobes (via vestibular nuclei)
    • Function in the control of proximal and trunk muscles and vestibulo-ocular control, respectively
  • Intermediate part of the Cerebellar Hemisphere (via interposed nuclei)
    • Functions in the control of more distal appendicular muscles mainly in the arms and legs
  • Lateral part of the Cerebellar Hemisphere (via the dentate nuclei)
    • Largest part of the cerebellum
    • Involved in planning the motor program for the extremities

Cerebellar input and output pathways

  • Form a complex system
  • Follow a medial-lateral organization and all pathways to the lateral motor systems are either ipsilateral or double crossed so that cerebellar lesions cause ipsilateral deficits

 

Local Cerebellar Neurons

 

  • Granule cells
  • Inhibitory cells
  • Golgi cells
  • Basket cells
  • Stellate cells

 

Principles of Localizing Cerebellar Lesions

 

(based on anatomical organization of the cerebellar pathways)

  • Ataxia is ipsilateral to the side of the cerebellar lesion
  • Midline lesions of the cerebellar vermis or flocculonodular lobes cause mainly unsteady gait (i.e., truncal ataxia) and eye movement abnormalities
  • Lesions of the intermediate part of the cerebellar hemisphere cause mainly ataxia of the limbs (i.e., appendicular ataxia)
  • Ataxia is often caused by lesions of the cerebellar circuitry in the brainstem or other locations rather than in the cerebellum itself, which can lead to false localization
  • Because of the strong reciprocal connection between the cerebellum and vestibular system, cerebellar lesions often are associated with:
    • Vertigo
    • Nausea
    • Vomiting
    • Nystagmus

 

Ataxia

 

Characteristic irregular movement abnormalities seen in cerebellar disorders