Anatomy
The cerebellum is an important structure responsible for motor planning, timing, and execution. It is composed of 3 broad structures with different roles:
- The cerebrocerebellum: complex motor planning
- The spinocerebellum: maintenance of posture and gait
- The vestibulocerebellum: processing vestibular inputs to compute head position in space
Lesions to different parts of the cerebellum present differently:
- Cerebrocerebellum >> ipsilateral limb ataxia
- Spinocerebellum >> gait & truncal ataxia
- Vestibulocerebellum >> vertigo & nystagmus
However there is significant overlap in these presentations and lesions often affect multiple parts of the cerebellum, producing a complex picture.
Clinical approach
The signs of cerebellar disease:
- Ataxia
- Gait
- Truncal
- Limb: dysmetria, dysdiadochokinesis
- Eyes
- Saccadic intrusions
- Nystagmus: can be in any direction
- Speech: stuttering dysarthria
Other things to look for on examination:
- Localising signs:
- Cranial nerve signs
- Horner’s syndrome
- Long tract signs
- Evidence of a cause
Causes
- Infective: any cause of meningo-encephalitis, esp VZV, listeria
- Neoplastic: compressive, paraneoplastic
- Vascular: infarction or haemorrhage
- Inflammatory: MS
- Toxins: alcohol, drugs (antiepileptics, chemotherapy)
- Endo/metabolic: B1, B12, vit E, copper, hypothyroid, hypocalcaemia
- Degenerative: Friedrich’s ataxia, SCAs…