Lecture 13 - Motor Control & Disorders

Question 1

Basal Ganglia Disorders

Answer 1

Parkinson’s Disease

Huntington’s Disease

Tourette’s Syndrome

Question 2

Parkinson’s Disease definition

Answer 2

• difficult times making movements, slouched over, make small shuffling steps
• lack of movement

Question 3

Huntington’s Disease definition

Answer 3

• too much movement

Question 4

Tourette’s Syndrome definition

Answer 4

• repetition, ticks, OCD, swearing

Question 5

Parkinson’s Disease

Answer 5

damage to cells in the substantia nigra pars compacta (80% of dopamine producing cells are damaged – therefore, DOPAMINE DEFICIENCY results).
- less/no smooth movements

typically IDIOPATHIC (of unknown cause) but can result from encephalitis, toxins, trauma (e.g., boxer’s encephalopathy), designer drugs (MPTP).

SLIDE 4 PATHWAY - stimulates cortex too little

Question 6

Parkinson’s Disease

Symptoms

Answer 6

hypokinesia (akinesia, bradykinesia)
- lack of movement or limited movement
(shuffling steps)

RESTING tremors (pill rolling)

• when at rest (ex: hands on knees, rising up - no tremor, at higher area - tremor again)
• almost any part of body can have a tremor

cogwheel rigidity (click clack effect)
- intermittent in nature

posture and gait disturbances

• hunched over
• arms don’t swing

Question 7

PD - hypokinesia

Answer 7

hypokinesia – difficulty initiating movements.

bradykinesia – a slowness in control of movements (bradyphrenia – slowness of thought).

Parkinsonian mask – frozen facial features.

(reptilian stare - droopy face)

Question 8

Hypokinesia

Answer 8

difficulty initiating movements.

Question 9

Bradykinesia

Answer 9

a slowness in control of movements (bradyphrenia – slowness of thought).

Question 10

Parkinsonian mask

Answer 10

frozen facial features.

Question 11

PD - tremors

Answer 11

resting 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.

Question 12

Resting tremors

Answer 12

can be used to determine the laterality of PD – PD is most often UNIlateral but can be BIlateral.

Question 13

Pill-rolling tremor

Answer 13

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

Question 14

PD – cogwheel rigidity

Answer 14

increased 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 patient’s arm she encounters resistance leading to brief rigid steps rather than smooth movement).

Question 15

PD – postural disturbances

Answer 15

bent posture, sometimes to point of falling.

head droops.

postural adjustments can be impaired – may fall when bumped. (shuffling back instead of quickly moving back)

(or on uneven ground b/c you can’t stabilize self quickly/move hands quickly)

Question 16

PD – gait disturbances

Answer 16

SHUFFLING gait – very different from Ozzy’s wide based gait!

gradually DIMINISHING DISTANCE between steps.

eventual FREEZING.

virtual lines as treatment. - lazer light on cane - used as a goal (goal-directed movement), step over line each time

Question 17

Treatment of PD (drugs)

Answer 17

L-dopa

• dopamine 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. (help with some symptoms)

Question 18

Treatment of PD (treatments)

Answer 18

PALLIDOTOMIES – 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).

SLIDE 13 - inhibit GPi/SNr & stimulate thalamus

Question 19

Pallidotomies

Answer 19

Michael J Fox has two!

• the internal globus pallidus is lesioned during stereotaxic surgery.
• stimulated first to determine region responsible for excessive inhibition.

tend to be done in younger patients who don’t have as much but have TREMORS as a main issue (help with tremors in younger patients)

Question 20

Internal stimulators

Answer 20

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

Question 21

Huntington’s Disease

Answer 21

inherited, autosomal dominant, degenerative disease affecting the caudate.

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

Huntington’s chorea

begins between 30 and 45 years of age. (kids see parent have it & they don’t want (genetic) so suicide rates were high - but now have tests to determine))

death occurs 10 to 15 years after onset.

SLIDE 16 - excites cortex too much

Question 22

Huntington’s Disease background

Answer 22

Hyperkinesias

• chorea (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.

Question 23

Huntington’s Disease – Nancy Wexler

Answer 23

Nancy 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.
- lot of intermarrying

made a genetic test for the gene possible – can determine whether you will develop HD.
- becomes ethical - but should be if you want

Question 24

Tourette’s syndrome

Answer 24

named 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.

Question 25

Tourette’s syndrome (symptoms)

Answer 25

(like a fizzing can that wants to explode)

complex movements (e.g., touching) can also be evident.

echolalia – the repetition of what has just been heard.

coprolalia – obscene utterances.

Question 26

Echolalia

Answer 26

the repetition of what has just been heard.

Question 27

Coprolalia

Answer 27

obscene utterances.

Question 28

Tourette’s syndrome (background)

Answer 28

associated 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.
- overwhelming urge to do certain activities or do certain things

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.

Question 29

Cortical movement disorders

Answer 29

hemiplegia

apraxia

optic ataxia

alien hand syndrome

Question 30

Hemiplegia

Answer 30

paralysis arising from motor strip lesions.

Question 31

Apraxia

Answer 31

impaired sequential and gestural movement control arising from left inferior parietal lesions.

Question 32

Optic ataxia

Answer 32

poor control of movements in the periphery arising from BILATERAL SUPERIOR PARIETAL INJURY.

Question 33

Alien hand syndrome

Answer 33

anarchic control of contralateral hand.

Question 34

Alien (anarchic) Hand

Answer 34

“la main étrangère”.

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 unilateral
usually left hand in right handers and can
occur for feet as well!

Question 35

Apraxia (dets)

Answer 35

a = 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).

Question 36

Apraxia (arises)

Answer 36

typically 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.

Question 37

Ideomotor apraxia

Answer 37

inability to carry out a simple motor activity in response to a verbal command (can’t mime the use either).

Question 38

Ideational apraxia

Answer 38

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

Question 39

Apraxia (Ideomotor apraxia, Ideational apraxia)

Answer 39

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

may involve disconnection of motor cortical areas from the rest of cortex.

Question 40

Brain areas involved in motor control

Answer 40

• Premotor & supplementary motor cortical regions
• Cerebellum
• Basal Ganglia
• Motor Cortex
• Brainstem
• Spinal Cord
• Output signals (to muscles)

Question 41

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

Answer 41

E) uncontrollable movements.

Question 42

Apraxia is characterized by
A) the inability to perform properly a learned, skilled movement
B) an impairment in learning a skilled movement
C) muscle weakness
D) motor paralysis
E) an impairment in motor coordination

Answer 42

A) the inability to perform properly a learned, skilled movement

Question 43

The slowness of movement noted in Parkinson’s disease reflects
A) damage to frontal cortex neurons that plan motor movements
B) damage to the primary motor cortex
C) loss of inhibition to the motor cortex
D) damage to dopamine neurons that normally facilitate motor movements
E) loss of inhibition of the ventromedial system from the GPi.

Answer 43

D) damage to dopamine neurons that normally facilitate motor movements

Question 44

The aim of pallidotomy is to damage the ________ in order to ________ .
A) external division of the globus pallidus; remove inhibition of the motor cortex
B) nigrostriatal bundle; balance the inputs to the globus pallidus
C) internal division of the globus pallidus; increase the inhibition of the motor cortex
D) internal division of the globus pallidus; remove inhibition of the motor cortex
E) external division of the globus pallidus; increase excitation of the motor cortex

Answer 44

D) internal division of the globus pallidus; remove inhibition of the motor cortex

Question 45

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.

Answer 45

C) apraxia.