Huntingtons Disease

Motor Control and Disorders

Copyright 2004 Allyn and BaconBasal Ganglia DisordersParkinsons Disease

Huntingtons Disease

Tourettes Syndrome

Copyright 2004 Allyn and BaconParkinsons Diseasedamage to cells in the substantia nigra pars compacta (80% of dopamine producing cells are damaged therefore, dopamine deficiency results).

typically idiopathic (of unknown cause) but can result from encephalitis, toxins, trauma (e.g., boxers encephalopathy), designer drugs (MPTP).

Copyright 2004 Allyn and BaconParkinsons Disease

Copyright 2004 Allyn and BaconParkinsons Diseasehypokinesia (akinesia, bradykinesia)lack of movement or limited movement

resting tremors (pill rolling)

cogwheel rigidityintermittent in nature

posture and gait disturbances

Copyright 2004 Allyn and BaconPD - hypokinesiahypokinesia difficulty initiating movements.bradykinesia a slowness in control of movements (bradyphrenia slowness of thought).Parkinsonian mask frozen facial features.

Copyright 2004 Allyn and BaconPD - tremorsresting tremors can be used to determine the laterality of PD PD is most often unilateral but can be bilateral.

pill-rolling tremor refers to a stereotypical movement made at rest that resembles rolling a pill between your fingertips and thumb.

Copyright 2004 Allyn and BaconPD cogwheel rigidityincreased muscle tone in extensor and flexor muscles leads to resistance to movement.

cogwheel rigidity refers small rigid steps in a passive movement (i.e., when the examiner tries to move the patients arm she encounters resistance leading to brief rigid steps rather than smooth movement).

Copyright 2004 Allyn and BaconPD postural disturbancesbent posture, sometimes to point of falling.

head droops.

postural adjustments can be impaired may fall when bumped.

Copyright 2004 Allyn and BaconPD gait disturbancesshuffling gait very different from Ozzys wide based gait!

gradually diminishing distance between steps.

eventual freezing.

virtual lines as treatment.

Copyright 2004 Allyn and BaconTreatment of PDL-dopadopamine does not cross the blood-brain barrier.L-dopa is a precursor for dopamine.

anti-cholinergic drugs reduce the uptake of acetylcholine restoring the balance between dopamine and acetylcholine (a balance disrupted by the depletion of dopamine).

new combination medicines like Stalevo.

Copyright 2004 Allyn and Bacon

Treatment of PDpallidotomies Michael J Fox has two!the internal globus pallidus is lesioned during stereotaxic surgery.stimulated first to determine region responsible for excessive inhibition.

internal stimulators like a brain pacemaker. An electrode implanted in the thalamus stimulates the motor pathways (bypassing the connections from the basal ganglia).

Copyright 2004 Allyn and BaconPallidotomies and stimulators

Copyright 2004 Allyn and BaconHuntington's Disease

Copyright 2004 Allyn and BaconHuntington's Diseaseinherited, autosomal dominant, degenerative disease affecting the caudate.

St. Vitus dance 16th century Germany. Dance in front of statue for good health mistaken for chorea.

Huntingtons chorea

begins between 30 and 45 years of age.

death occurs 10 to 15 years after onset.

Healthy brainHD brainCopyright 2004 Allyn and BaconHuntingtons Disease

Copyright 2004 Allyn and BaconHuntingtons DiseaseHyperkinesiaschorea (Greek for dance).athetosis writhing contractions.contorted postures head, arms and legs in constant motion.

also demonstrate bradykinesia a slowness in control of movement.more closely associated with degeneration of the caudate.disease was brought to North America by Europeans fleeing persecution (burned as witches). European origin to HD in Asian cultures too.

Copyright 2004 Allyn and BaconHuntingtons Disease Nancy WexlerNancy Wexler is a scientist whose mother died of HD.

she and her colleagues isolated the gene responsible for HD in a small community in Venezuela with the highest incidence of HD in the world.

made a genetic test for the gene possible can determine whether you will develop HD.

Copyright 2004 Allyn and BaconParkinsons and Huntingtons Disease

Copyright 2004 Allyn and BaconTourettes syndromenamed after French neurologist Georges Gilles de la Tourette.

primary symptoms are vocal and motor tics.

involuntary, repetitive often compulsive movements.

begins in childhood ( 11 years old).

face and head are typically affected, although in more severe forms the limbs and whole body can be involved.

Copyright 2004 Allyn and BaconTourettes syndromecomplex movements (e.g., touching) can also be evident.

echolalia the repetition of what has just been heard.

coprolalia obscene utterances.

Copyright 2004 Allyn and BaconTourettes syndromeassociated with a gene on chromosome 18 possible sex-linked trait expressed higher in males.

also associated with OCD (25% manifest full symptoms of OCD) tics often have a compulsive element to them.

treatment involves dopamine antagonists (anti-dopamine).

not generally associated with major cognitive impairment.

tics may subside somewhat with age with severity of childhood tics not predictive of recovery.Copyright 2004 Allyn and BaconCortical movement disordershemiplegia paralysis arising from motor strip lesions.apraxia impaired sequential and gestural movement control arising from left inferior parietal lesions. optic ataxia poor control of movements in the periphery arising from bilateral superior parietal injury. alien hand syndrome anarchic control of contralateral hand.

Copyright 2004 Allyn and BaconAlien (anarchic) Handla main tranger.

patient feels their hand behaves in a foreign or uncooperative manner.

unco-operative movements are nevertheless purposeful.

related to intermanual conflict in which hands behave at cross purposes to one another.

arises from medial frontal cortex (SMA) and anterior corpus callosotomies.

Anarchic hand is almost always unilateralusually left hand in right handers and canoccur for feet as well!Copyright 2004 Allyn and BaconApraxiaa = without praxis = action

impairment of learned actions (e.g., gestures, tool use, skilled, purposeful movements) and sequencing of movements that can not be explained by a loss of muscle tone, weakness, somatosensation, comprehension.

like many neuropsychological disorders apraxia is diagnosed by exclusion.

term apraxia introduced by Hugo Karl Liepmann (1863 1925).Copyright 2004 Allyn and BaconApraxiatypically arises from left inferior parietal lesions.bilateral both hands are apraxic.often co-occurs with aphasia so comprehension must be distinguished from poor execution of motor commands.

Copyright 2004 Allyn and BaconApraxiaIdeomotor apraxia inability to carry out a simple motor activity in response to a verbal command (cant mime the use either).

Ideational apraxia inability to carry out a sequence of actions that are components of a behavioural script.

anatomy is very complex (most strokes cause some degree of apraxia.

may involve disconnection of motor cortical areas from the rest of cortex.Copyright 2004 Allyn and BaconBrain areas involved in motor control

Copyright 2004 Allyn and BaconReview Questions

1 ) A primary symptom of Huntington's disease isA) akinesia.B) dystonias.C) tremor at rest.D) difficulty initiating movement.E) uncontrollable movements.

2 ) Apraxia is characterized byA) the inability to perform properly a learned, skilled movementB) an impairment in learning a skilled movement C) muscle weaknessD) motor paralysisE) an impairment in motor coordination

3) The slowness of movement noted in Parkinsons disease reflectsA) damage to frontal cortex neurons that plan motor movementsB) damage to the primary motor cortexC) loss of inhibition to the motor cortexD) damage to dopamine neurons that normally facilitate motor movementsE) loss of inhibition of the ventromedial system from the GPi.

Copyright 2004 Allyn and BaconReview Questions

4 ) The aim of pallidotomy is to damage the ________ in order to ________ .A) external division of the globus pallidus; remove inhibition of the motor cortexB) nigrostriatal bundle; balance the inputs to the globus pallidusC) internal division of the globus pallidus; increase the inhibition of the motor cortexD) internal division of the globus pallidus; remove inhibition of the motor cortexE) external division of the globus pallidus; increase excitation of the motor cortex

5 ) An impairment of the ability to execute a learned movement is termed A) paralysis.B) Parkinsonism.C) apraxia.D) coordination deficit.E) a learning deficit.

Copyright 2004 Allyn and Bacon