1. Basal ganglia & cerebellar pathology
Vivian Phan

2. Cerebellum MAJOR TRACTS THAT GO THROUGH CEREBELLUM:
Spinocerebellar (sensory/ascending): unconscious proprioception
Vestibulospinal (motor/ extrapyramidal): balance, posture (+ extensors)
Olivocerebellar

3. Cerebellar lesions Lesion Causes Symptoms Posterior lobe
= Neocerebellar lesions
Vascular e.g. stroke
Tumours
Neurodegenerative
Dysmetria, Dysdiadochokinesia
Ataxia
Nystagmus
Intention tremor
Slurred speech
Hypotonia
Anterior lobe
= Gait/limbic ataxia
Alcohol
Malnutrition
-> improve symptoms if stop drinking
Drunken gait, can’t walk straight
Head tremor
Midline
= Truncal ataxia
Medulloblastoma in 4th ventricle – young children
-> Affect Vestibular n.
Fall towards most affected side
May involve eye movements
If you want to learn any more about cerebellum, learn some key points on Freidrich’s ataxia (recessive, most common inherited cerebellar disorder)

4. Basal ganglia Basal ganglia consists of 4 subcortical nuclei:
1. Striatum (caudate nucleus, putamen, nucleus accumbens)
2. Globus pallidus (Gp)
3. Subthalamic nucleus
4. Substantia nigra

5. Unwanted or excessive movements
BG movement disorders
Bradykinesia / hypokinesia
Rigidity
Dystonia
Athetosis
Chorea
Ballismus
Tics
Myoclonus
Tremor (fast or slow depending on type)
SLOW
HYPERKINETIC
Unwanted or excessive movements
FAST

6. BG movement disorders
Striatum  Huntington’s chorea GP  Choreoathetosis e.g. Wilson’s Subthalamic nucleus  (Hemi)Ballismus Substantia nigra  Parkinson’s

7. BG disorder treatments
Pathology
Drugs
Huntington’s (AD)
- Degeneration of cholinergic neurons in striatum
- Extended CAG repeat
- Movements + dementia
- Dopamine depleting drugs (release = involuntary mvmts): Tetrabenazine
- Antipsychotics (chorea, hallucinations, violence): Risperidone, Quetiapine
- Benzodiazepines - relax
- Treat moods: SSRIs, TCAs
Wilson’s (AR)
-  copper metabolism -> deposits in liver & BG
Choreathetosis, dementia
Liver cirrhosis
Kayser-Fleischer ring
Copper chelators (pick up excess copper): Penicillamine, Trientine
Ballismus
Degeneration of subthalamic nucleus
Unilat, involuntary flinging mvmts of prox limbs
Dopamine antagonists
Dopamine depleting drugs
GABAergics e.g. antiepileptic, gabapentin, benzodiazepine
Treatment for ballismus, chorea, athetosis is the same.

8. BG disorder treatment Disorder Pathology Treatment Parkinson’s
- Loss of dopamine in SN and striatum
- Degeneration of SN (and other basal ganglia nuclei)
- Lewy bodies (plaques)
- Levodopa = Dopamine precursor
- Drugs to  dopamine breakdown: DDC inhibitor, COMT inhibitor, MAO-B inhibitor
Anticholinergics
Essential tremor
- Progressive, intention tremor (not at rest)
- Start in arms -> other parts of body
Beta blockers - Propanolol
General rule:
Hypokinesia (e.g. Parkinson’s): Dopamine levels – precursor, prevent breakdown
Hyperkinesia (the rest!): Dopamine levels – antagonists, depletors, then relaxants (to calm them down)

9. Fine control/adjustment of movement by facilitation &/or suppression
Motor control
Motor System
Normal role
Dysfunction
Descending tracts
Purposeful, rapid, skilled, intricate movements; influence over motor tone & reflexes
Loss of skilled voluntary movements; characteristic changes in tone & reflexes
Basal ganglia
Fine control/adjustment of movement by facilitation &/or suppression
Movement disorders - affecting the speed of movement &/or unwanted movements
Cerebellum
Coordination of movements, posture, balance, eye movement, planning of movement, procedural memory
Ataxia = Unsteady & jerky movements = loss of coordination & accuracy of limb/trunk movement