Week 10: Cerebellar Disorders

Question 1

The cerebellum is responsible for?

The cerebellum can be divided into 3 functional units. what are they/ function?

Answer 1

for the coordination of skilled voluntary movement, posture and gait.
1. Flocculonodular lobe (vestibulocerebellum) and inferior vermis
• Mainly involved in controlling information from the vestibular system 2. Anterior lobe and anterior superior vermis
• Mainly involved in receiving proprioceptive information from the limbs. 3. Large posterior lobe and middle part of the vermis
• Mainly involved in receiving inputs from the contralateral cerebral cortex

Question 2

What happens when there is cerebellar dysfunction?

Answer 2

• Cerebellar dysfunction causes impairment of the process of controlling movements once they have been initiated. This gives rise to ataxia.
• Ataxia
o is a neurological sign consisting of lack of voluntary coordination of muscle movements. Ataxia is a non-specific clinical manifestation implying dysfunction of the parts of the nervous system that coordinate movement, such as the cerebellum.
o Is manifested by
• Intention tremor
o No tremor at rest. A tremor appears once movement is initiated • Dysdiadochokinesia
o The inability to perform rapid alternating movements with regularity.
• Dysmetria
o The inability to control smooth and accurate targeted movement o Movements are jerky and overshoot the target.

Question 3

What are some cerebellar disorders?

4

Answer 3

Ataxic gait
o Patient walks with a staggering gait.
o Later they will develop a wide-based gait to improve stability
o In a unilateral cerebellar lesion there is unsteadiness towards the side of the
lesion.

Ataxic dysarthric speech
o Speech can be slow, slurred and scanning (unclear) in quality o There is a loss of variation of intonation
o Words may be broken up into syllables

Abnormal eye movements o Jerky pursuits
• Pursuit movements are slow
• Catch up saccadic movements
o Dysmetria of saccades
• When trying to fixate on a target, the eyes overshoot and oscillate several times before fixation is achieved.
o Nystagmus
• Towards the side of lesion

Question 4

Localisation of lesion?

Answer 4

• Localisation of lesion o Cerebellar hemisphere
• Ataxia in limbs ipsilateral to the lesion
• Gait is ataxic
• Tendency to fall towards the side of the lesion

o Cerebellar vermis
• Truncal ataxia – imbalance of gait and stance
• Usually limb ataxia, dysarthria and nystagmus are not present