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N34 Neurology
Cerebellar Disorders Toronto Notes 2019
• provisionalticdisorder:singleormultiplemotorand/orvocalticspresentfor<1yrsincefirstticonset
• otherspecifiedorunspecifiedticdisorder:symptomscharacteristicofaticdisorderbutdonotmeet
full criteria
• secondaryticdisorders:encephalitis,CJD,Sydenham’schorea,headtrauma,drugs,mental
retardation syndromes
Tic Types
• simpletics:shortduration(milliseconds)
• complextics:longer(seconds),morepurposefulandoftenincludeacombinationofsimpletics • motortics
■ simple: blinking, head jerking, shoulder shrugging, extension of the extremities
■ dystonic: bruxism (grinding teeth), abdominal tension, sustained mouth opening
■ complex: copropraxia (obscene gestures), echopraxia (imitate gestures), throwing, touching
• vocaltics
■ simple: blowing, coughing, grunting, throat clearing
■ complex: coprolalia (shout obscenities), echolalia (repeat others’ phrases), palilalia (repeat own
phrases)
Treatment
• dopamineblockers,dopaminedepletors(tetrabenazine),clonidine,clonazepam,orDBS
Tourette’s Syndrome (Gilles de la Tourette Syndrome)
Definition According to DSM V
1. Presence of both multiple motor and one or more vocal tics at some point during the illness, although not necessarily concurrently
2. Tics may wax and wane in frequency but have persisted for more than 1 yr since first tic onset (with no tic-free periods gr>3 mo)
3. Onset is <18 yr
4. Not due to effect of a substance or another medical condition
Epidemiology
• estimatedprevalenceamongadolescents3-8per1,000school-agechildren;M:F=2:1-4:1
Signs and Symptoms
• tics:widevarietythatwaxandwaneintypeandseverity;canbevoluntarilysuppressedforsometime but are preceded by unpleasant sensation that is relieved once tic is carried out
■ can be worsened by anxiety, excitement, and exhaustion; better during calm, focused activities
• psychiatric:compulsivebehaviour(associatedwithOCDandADHD),hyperactivebehaviour,‘rages’,
sleep-wake disturbances, or learning disabilities
Treatment
• sameastics(dopamineblockers,dopaminedepletors,clonidine,clonazepam,DBS)
Prognosis
• typicallybeginsbetweenages4-6
• peakseverityoccursbetweenages10-12,withadeclineinseverityduringadolescence(50%aretic-free
by age 18)
• ticsymptoms,however,canmanifestsimilarlyinallagegroupsandacrossthelifespan
Cerebellar Disorders
Clinico-Anatomic Correlations
• vermis:trunk/gaitataxia
• cerebellarlobe(i.e.lateral):reboundphenomenon,scanningdysarthria,dysdiadochokinesia,
dysmetria, nystagmus
Symptoms and Signs of Cerebellar Dysfunction
• nystagmus:observeduringextraocularmovementtesting(mostcommonisgaze-evokednystagmus)
• dysarthria(ataxic):abnormalmodulationofspeechvelocityandvolume–elicitscanning/telegraphic/
slurred speech on spontaneous speech
• ataxia:broad-based,uncoordinated,lurchinggait
• dysmetria:irregularplacementduringvoluntarymovementoflimboreye
• dysdiadochokinesia:impairmentofrapidalternatingmovements(e.g.pronation-supinationtask)
• posturalinstability:truncalataxiaonsitting,titubation(rhythmicrockingoftrunkandhead),difficulty
with tandem and broad-based gait
• intentiontremor:typicallyorthogonaltointendedmovement,andincreasesastargetisapproached
• hypotonia:decreasedresistancetopassivemuscularextension(occursshortlyafterinjurytolateral
cerebellum)
• pendularpatellarreflex:kneereflexcausespendularmotionofleg(occursafterinjurytocerebellar
hemispheres), pendular reflexes at triceps
• reboundphenomenon:overcorrectionafterdisplacementofalimb
• hypometricandhypermetricsaccades