Cerebellum: Knowing their functions then knowing their dysfunctions

Functions of cerebellum

3 parts:

1) vestibulocerebellum

-maintain balance

-controls eye movement

2) spinocerebellum

- enhance muscle tone

-coordinate skilled voluntary movement

3) cerebrocerebellum

-plan and initiate voluntary activity

-provide input cortical motor area

Cerebellar dysfunction

· Ataxia (unsteady widebased, limp on side of lesion, cannot walk in straight line)

· Scanning speech (dysarthria- cannot coordinate skilled voluntary movement)

· Dysmetria/ past pointing (unable to plan and initiate voluntary activity. Usually had problem to past his/her finger initially but still can reach at the end of process)

· Intentional tremor

· Unable to stop movement promptly- rebound phenomenon

· Dysdiadochokinesia

· Ipsilateral hypotonia

· Cerebellar nystagmus

· Pendular jerk

· Romberg’s test usually negative, positive when lesion at dorsal column tract

Function of basal nuclei:

5 components:

1. Caudate nuclei

2. Putamen

3. Globus pallidus

4. Subthalamic nucleus

5. Substantia nigra

Roles:

1. Inhibit muscle tone throughout body

2. Select and maintain purposeful motor activity

3. Suppress useless/unwanted pattern of movement

4. Coordinate slow, sustained movement

Dysfunction causes:

1. Hyperkinesia

· Chorea- rapid involuntary movement

· Athetosis- continous slow writhing movement(dance-like)

· Ballism/hemiballism- involuntary movement that are flailing, intense, violent

2. Hypokinesia

· Akinesia - difficult initiate movement

- Reduce spontaneous movement

· Bradykinesia - slowness of movement

Disease due to basal ganglia dysfunction:

1. Huntington’s disease

· Hyperkinetic due to loss of GABAergic pathway

· Autosomal dominat (chr 4)

· Early: jerk trajectory of hand when reaching to touch spot

· Later: hyperkinetic choreiform

· Slurred speech

· Progressive dementia

· Death 10-25 years after onset

2. Parkinson disease

· Both hyperkinetic (rigidity and tremor) and hypokinetic (akinesia and bradykinesia)

· Sporadic idiopathic/ familial

· Loss of dopaminergic neuron and dopamine receptors in basal ganglia

source: lecture note second year by Prof Ruszymah

*alert: this info can be ask during short or long cases (in case dpt parkinson and cerebellar disorder)

~emmzesyra~