Cerebellar Function

Expansion

DANISH:

• D - Dysdiadochokinesia and dysmetria
• A - Ataxia (gait and limb)
• N - Nystagmus, fast phase towards the lesion
• I - Intention tremor
• S - Slurred, staccato or scanning speech
• H - Hypotonia and pendular reflexes

Localisation

• Vermis and flocculonodular lobe (midline): truncal ataxia, gait ataxia, nystagmus. Classic in alcohol-related degeneration and medulloblastoma
• Cerebellar hemispheres (lateral): limb ataxia, intention tremor, dysmetria, ipsilateral to the lesion

The ipsilateral rule is worth understanding: cerebellar output crosses to the contralateral thalamus and cortex, and the corticospinal tract then crosses back, so the net effect returns to the same side.

The cerebellum does not initiate movement; it coordinates, times and calibrates it by comparing intended with actual movement, which is why lesions cause inaccuracy and decomposition rather than weakness.