Cerebellar Function and Lesion Signs

Key points

• • Three functional divisions: the vestibulocerebellum for balance and eye movement, the spinocerebellum for posture, gait and ongoing limb correction, and the cerebrocerebellum for planning and timing skilled movement.
• • Its major output pathways ultimately cross twice, which is why cerebellar signs appear on the same (ipsilateral) side as the lesion.
• • The classic signs are dysdiadochokinesia, ataxia, nystagmus, intention tremor, scanning speech and hypotonia.
• • Intention tremor worsens as the hand approaches the target, which distinguishes it from a resting tremor.
• • Midline vermis lesions give truncal ataxia and a broad-based unsteady gait; hemisphere lesions give incoordination of the limbs on that side.
• • Cerebellar ataxia is not corrected by looking at the feet, whereas sensory ataxia improves with vision and worsens when the eyes close.