Saturday, July 3, 2010

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)

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