Basal Ganglia Lesions

About the Basal Ganglia

  • The Basal Ganglia give rise to the extrapyramidal tract, which modulates the corticospinal (pyramidal) tract.
    • This tract controls muscle tone, regulates motor activity, and generates postural reflexes
    • However, the extrapyramidal tract’s efferent fibers communicate via the cerebral cortex and thalamus – they do NOT communicate directly with the spinal cord


Lesions to the Basal Ganglia

  • When damage is restricted to extrapyramidal tract, patients have NO paresis or neuropsychological impairments
  • Characteristic features of basal ganglia (i.e., extrapyramidal) injury involve the following involuntary movement disorders:
    • Parkinsonism – combination of resting tremor, rigidity, bradykinesia/akinesia, and postural abnormalities
    • Athetosis – slow continuous, writhing movements of the fingers, hands, face, and throat
    • Chorea – intermittent jerking of limbs and trunk
    • Hemiballismus – intermittent flinging of the arm and leg on one side of the body


Lewy Body Disease

  • Possibly accounts for up to 30% of cases diagnosed as Alzheimer’s Disease
  • May be a variant of Alzheimer’s rather than a distinct illness
  • Unlike Alzheimer’s, it has a relatively rapid development of dementia
  • It is accompanied by mild extrapyramidal features such as:
    • Masked face
    • Bradykinesia
    • Resting tremor
    • Gait impairment pronounced enough to lead to falls
    • Can also present with depression, delusions, and visual hallucinations

Definitive diagnosis confirmed with an abundant presence and unusual location of Lewy Bodies distributed diffusely throughout the cerebral cortex