Cerebellar Dysfunction / Ataxia

Question 1

Cerebellum’s function is…

Answer 1

Sensory input into the cerebellum is thought to be the critical component in the cerebellum’s function in motor control

It compares internal feedback with external feedback and generates corrective signals for subsequent movements in order to reduce errors (feedforward mechanism)

Cerebellar outputs remain mostly UNCROSSED. Therefore, most damage to the cerebellum will lead to unilateral and ipsilateral motor impairments

Question 2

Cerebellar Lesions - Functional Region:
Midline

Structures involved & S/S

Answer 2

Structures:
- vermis
- palocerebellum

S/S:
- truncal ataxia
- titubation (oscillatory mvmt that occurs at head or trunk - involvuntary & very fast)
- orthostatic tremor (shaky leg syndrome - ONLY happens in standing)
- gait imbalances (postural problems)

Question 3

Cerebellar Lesions - Functional Region:
Hemispheres

Structures involved & S/S

Answer 3

Structures:
- neocerebellum

S/S:
- limb ataxia
- dysarthria
- hypotonia

Question 4

Cerebellar Lesions - Functional Region:
Posterior

Structures involved & S/S

Answer 4

Structures:
- fluocculonodular lobe (vestibulocerebellum)
- archicerebellum

S/S:
- eye movement disorders (ie nystagmus, VOR disruption)
- posture and gait imbalances

Question 5

Characteristics of an ATAXIC GAIT

(6)

Answer 5

• Wide BOS
• High guard position
• Stepping pattern irregular in direction & distance

Generally…
- Unsteady
- irregular
- staggering w/ deviations from line of progression

** High falls risk

Question 6

Rebound Phenomenon

Answer 6

The ability to stop forceful active movement when resistance is removed
- Synonymous with “check reflex”

TEST: Provide resistance/isometric contraction to a mm & then let go - should be able to stop the correction right away - coordination & control
(+) cerebellar lesion - limb shoots up after resistance is removed

Question 7

Sensory Ataxia: Causes of proprioceptive input losses….

Answer 7

Peripheral
- Peripheral nerve (peripheral neuropathy - DMII)
- Dorsal nerve root

Central
- Parietal cortex
- Thalamus
- Dorsal column of spinal cord (DCML - Dorsal Column Medial Lemniscal tract)

Conscious proprioception, vibration, & fine touch (tactile sensation)