10) Motor Disorders

Question 1

What are the major motor pathways?

Answer 1

Corticospinal, corticobulbar and extrapyramidal tracts

Question 2

What is the function of the cerebellum?

Answer 2

Motor control and coordination

Question 3

How is the cerebellum separated from the occipital and parietal lobes?

Answer 3

Tentorium cerebelli

Question 4

How is the cerebellum separated from the pons?

Answer 4

4th ventricle

Question 5

Describe the structure of the cerebellum?

Answer 5

Consists of vermis (midline) and two lateral hemispheres

Question 6

How does the cerebellum communicate with brainstem?

Answer 6

Cerebellar puduncles:
Superior to midbrain
Middle to pons
Inferior to medulla

Question 7

What would be the effect of a midline lesion in the cerebellum?

Answer 7

Truncal ataxia and abnormal gait

Question 8

A 45 year old man has a left cerebellar hemisphere lesion, list the effects:

Answer 8

Ipsilateral signs

DANISH - dysdiadochokinesia, ataxia, nystagmus, intention tremor, scanning dysarthria, heel shin test positive/hypotonia

Question 9

What is the function of the basal ganglia?

Answer 9

Stimulates motor activity in cerebral cortex

Question 10

What are some structures in the basal ganglia?

Answer 10

Caudate, lentiform nucleus, substantia nigra

Question 11

What neurotransmitter do the majority of neurones in the striatum use?

Answer 11

GABA

Question 12

Describe the structure of the substantia nigra and the neurotransmitters used:

Answer 12

Made up of pigmented neurones with pars compacta dorsally and pars reticularis ventrally
Dopamine

Question 13

What is the overall net effect of the basal ganglia direct and indirect pathways on the thalamus?

Answer 13

Thalamic stimulation of motor cortex

Question 14

Describe the direct pathway in the basal ganglia:

Answer 14

PC of SN sends excitatory dopaminergic connections to putamen which inhibits the globus pallidus interna which would normally inhibit the thalamus

Question 15

Describe the indirect pathway in the basal ganglia:

Answer 15

PC of SN sends inhibitory dopaminergic connections to putamen which inhibits inhibitory connections to globus pallidus externa which in turn inhibits connections to subthalamic nucleus. STN doesn’t activate PR of SN and GPI so less inhibition of thalamus

Question 16

How do disorders of the basal ganglia present?

Answer 16

Abnormal motor control, altered posture, muscle tone affected, dyskinesia

Question 17

What is Parkinson’s disease?

Answer 17

Chronic, progressive, movement disorder due to degeneration of substantia nigra causes deficiency in dopamine

Question 18

What is the triad of symptoms in Parkinson’s disease?

Answer 18

Bradykinesia, tremor and rigidity

Question 19

What are some other symptoms of Parkinson’s disease?

Answer 19

Hypophonia, reduced facial expression, micrographia, LB dementia, depression, shuffling gait, visual hallucination

Question 20

Describe the features of Huntingdon’s disease:

Answer 20

Autosomal dominant, progressive neurodegenerative disorder

Cell loss in basal ganglia and cortex

Question 21

What are some symptoms of Huntingdon’s disease?

Answer 21

Dystonia, in-coordination, cognitive decline, behavioural difficulty, chorea

Question 22

What is the function of the vermis and lateral hemispheres of the cerebellum?

Answer 22

Vermis regulates trunk musculature

Lateral hemispheres regulate distal structures

Question 23

What is dysdiadochokinesia?

Answer 23

Inability to perform and sustain a series of rapidly alternating muscle movements (typically flipping one hand rapidly in the palm of the other)

Question 24

What is ataxia?

Answer 24

Gross incoordination of muscle movements. May be very unsteady on their feet towards the side of the lesion

Question 25

What is nystagmus?

Answer 25

Repetitive, involuntary oscillation of the eyes