Clinical meaning
The cerebellum coordinates voluntary movement, maintains balance and posture, and modulates motor learning. It processes proprioceptive, visual, and vestibular inputs to produce smooth, accurate, coordinated movements. Three functional divisions: vestibulocerebellum (flocculonodular lobe — balance, eye movements; lesion causes truncal ataxia, nystagmus), spinocerebellum (vermis and intermediate zone — limb coordination, gait; lesion causes appendicular ataxia, dysmetria), and cerebrocerebellum (lateral hemispheres — motor planning, timing; lesion causes intention tremor, dysarthria). Cerebellar signs are IPSILATERAL to the lesion (uncrossed — unlike cortical motor signs which are contralateral). Key cerebellar findings: ataxia (limb and gait), dysmetria (overshooting/undershooting targets), dysdiadochokinesia (impaired rapid alternating movements), intention tremor (worsens approaching target), dysarthria (scanning/staccato speech), nystagmus, and hypotonia.
Diagnosis & workup
Diagnostics & workup: - Finger-nose-finger test: patient touches their nose then examiner's finger repeatedly — assesses dysmetria and intention tremor (tremor worsens as finger approaches target) - Heel-shin test: patient slides heel down opposite shin — tests lower extremity coordination (dysmetria = heel overshoots/wavers) - Rapid alternating movements (RAM): hand pronation/supination on thigh, finger tapping — impaired = dysdiadochokinesia - Romberg test: standing with feet together, eyes open then closed — cerebellar ataxia present with eyes OPEN (unlike sensory ataxia which requires eye closure to manifest) - Gait assessment: wide-based, lurching, ataxic gait; tandem gait (heel-to-toe) is most sensitive - Speech assessment: scanning/staccato dysarthria (irregular rhythm and volume) - Rebound test: patient pushes against examiner's hand, then hand is released — inability to check movement = impaired cerebellar checking - Nystagmus: gaze-evoked, direction-changing, or positional