2 Cerebellum MAJOR TRACTS THAT GO THROUGH CEREBELLUM: Spinocerebellar (sensory/ascending): unconscious proprioceptionVestibulospinal (motor/ extrapyramidal): balance, posture (+ extensors)Olivocerebellar
3 Cerebellar lesions Lesion Causes Symptoms Posterior lobe = Neocerebellar lesionsVascular e.g. strokeTumoursNeurodegenerativeDysmetria, DysdiadochokinesiaAtaxiaNystagmusIntention tremorSlurred speechHypotoniaAnterior lobe= Gait/limbic ataxiaAlcoholMalnutrition-> improve symptoms if stop drinkingDrunken gait, can’t walk straightHead tremorMidline= Truncal ataxiaMedulloblastoma in 4th ventricle – young children-> Affect Vestibular n.Fall towards most affected sideMay involve eye movementsIf you want to learn any more about cerebellum, learn some key points on Freidrich’s ataxia (recessive, most common inherited cerebellar disorder)
5 Unwanted or excessive movements BG movement disordersBradykinesia / hypokinesiaRigidityDystoniaAthetosisChoreaBallismusTicsMyoclonusTremor (fast or slow depending on type)SLOWHYPERKINETICUnwanted or excessive movementsFAST
6 BG movement disordersStriatum Huntington’s chorea GP Choreoathetosis e.g. Wilson’s Subthalamic nucleus (Hemi)Ballismus Substantia nigra Parkinson’s
7 BG disorder treatments PathologyDrugsHuntington’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, TCAsWilson’s (AR)- copper metabolism -> deposits in liver & BGChoreathetosis, dementiaLiver cirrhosisKayser-Fleischer ringCopper chelators (pick up excess copper): Penicillamine, TrientineBallismusDegeneration of subthalamic nucleusUnilat, involuntary flinging mvmts of prox limbsDopamine antagonistsDopamine depleting drugsGABAergics e.g. antiepileptic, gabapentin, benzodiazepineTreatment 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 inhibitorAnticholinergicsEssential tremor- Progressive, intention tremor (not at rest)- Start in arms -> other parts of bodyBeta blockers - PropanololGeneral rule:Hypokinesia (e.g. Parkinson’s): Dopamine levels – precursor, prevent breakdownHyperkinesia (the rest!): Dopamine levels – antagonists, depletors, then relaxants (to calm them down)
9 Fine control/adjustment of movement by facilitation &/or suppression Motor controlMotor SystemNormal roleDysfunctionDescending tractsPurposeful, rapid, skilled, intricate movements; influence over motor tone & reflexesLoss of skilled voluntary movements; characteristic changes in tone & reflexesBasal gangliaFine control/adjustment of movement by facilitation &/or suppressionMovement disorders - affecting the speed of movement &/or unwanted movementsCerebellumCoordination of movements, posture, balance, eye movement, planning of movement, procedural memoryAtaxia = Unsteady & jerky movements = loss of coordination & accuracy of limb/trunk movement