6.1 movement disorders

Question 1

name 5 basal ganglia

Answer 1

• substantia nigra pars compacta
• striatum
• globus pallidus, internal and external
• lentiform nucleus
• subthalamic nucleus

Question 2

what does the striatum consist of?

Answer 2

the caudate nucleus and the putamen

caudate nucleus is C shaped and found in the walls of lateral ventricles.

they are joined by thin strands of grey matter collectively known as the striatum

Question 3

what does the lentiform nucleus consist of?

Answer 3

the putamen and globes pallidus

Question 4

what is the importance of the substantia nigra?

Answer 4

source of dopamine in the midbrain

Question 5

how do basal ganglia communicate with the motor cortex?

Answer 5

via the thalamus

Question 6

what is the normal function of basal ganglia?

Answer 6

• direct pathway reinforces appropriate movements
• indirect pathway edits out inappropriate movements
• dopamine from the substantia nigra pars compact facilitates movement by exciting the motor cortex
• regulate ipsilateral motor control e.g if substantia nigra is affected unilaterally, there would be contralateral signs due to the decussation of the corticospinal tract

Question 7

what is parksinsons disease caused by?

Answer 7

degeneration of dopaminergic neurones in the substantia nigra pars compact

therefore, have lost the dopamine driven facilitation of movement via both pathways

Question 8

what are the signs and symptoms of Parkinson’s?

Answer 8

• tremor (pill rolling)
• rigidity
• bradykinesia due to loss of cortical excitation
• hypophonia (quiet speech = bradykinesia of larynx and tongue)
• decreased facial movement (bradykinesia of the face)
• micrographia (bradykinesia of hands)
• dementia
• depression (as basal ganglia have role in cognition and mood)

Question 9

what causes Huntington’s chorea?

Answer 9

autosomal dominant progressive disorder
early onset around 30-50yrs
associated with loss of inhibitory projections from striatum to GPe
= hyperkinetic features

Question 10

what are the features of Huntington’s chorea?

Answer 10

chorea - due to increased motor cortex activation
dystonia - contractions leading to odd postures
loss of co ordination
cognitive decline and behavioural disturbances

Question 11

what is hemiballismus and what does it cause?

Answer 11

a rare disorder
can be caused by
- damage to subthalamic nucleus which usually inhibits thalamus via GPi
- can be caused by sub- cortical stroke

causes unilateral explosive/ballistic movements

Question 12

what is the structure of the cerebellum?

Answer 12

midline vermis and two laterally placed hemispheres

vermis deals with true, hemispheres with ipsilateral side of body (limbs)

communicates with rest of CNS via cerebral peduncles

sits above fourth ventricle
NB: cerebellar lesions e.g tumours can cause hydrocephalus

Question 13

what do the cerebral peduncles communicate with?

Answer 13

superior connects to midbrain
middle connects to pons
inferior connects to medulla

Question 14

what are the normal functions of the cerebellum?

Answer 14

sequencing and co-ordiantion of movements

work with basal ganglia to decide on the most appropriate movements and the cerebellum will then sequence these movements

hence, it has profuse sensory inputs from proprioceptive neurones

Question 15

what are the signs of cerebellar disease?

Answer 15

DANISH

D - dysdiadchokinesia 
A - ataxia 
N - Nystagmus (flickering eye)
I - intention tremor
S - slurred speech (dysarthria)
H - hypotonia