Basal ganglia & cerebellar pathology Vivian Phan.
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Transcript of Basal ganglia & cerebellar pathology Vivian Phan.
Basal ganglia & cerebellar pathology
Vivian Phan
Cerebellum
MAJOR TRACTS THAT GO THROUGH CEREBELLUM:- Spinocerebellar (sensory/ascending): unconscious proprioception- Vestibulospinal (motor/ extrapyramidal): balance, posture (+ extensors)- Olivocerebellar
Cerebellar lesionsLesion Causes Symptoms
Posterior lobe= Neocerebellar lesions
- Vascular e.g. stroke- Tumours- Neurodegenerative
Dysmetria, DysdiadochokinesiaAtaxiaNystagmusIntention tremorSlurred speechHypotonia
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
Basal ganglia
Basal ganglia consists of 4 subcortical nuclei:1. Striatum (caudate nucleus, putamen, nucleus accumbens)2. Globus pallidus (Gp)3. Subthalamic nucleus4. Substantia nigra
BG movement disorders
• Bradykinesia / hypokinesia• Rigidity• Dystonia• Athetosis• Chorea• Ballismus• Tics• Myoclonus• Tremor (fast or slow depending on type)
FAST
SLOW
HYPERKINETICUnwanted or excessive
movements
BG movement disorders
Striatum Huntington’s chorea
GP Choreoathetosis e.g. Wilson’s
Subthalamic nucleus (Hemi)Ballismus
Substantia nigra Parkinson’s
BG disorder treatmentsDisorder 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
BG disorder treatmentDisorder 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)
Motor controlMotor 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