What are cerebellar signs?

Cerebellar Signs

Cerebellar signs are a constellation of motor, oculomotor, and speech abnormalities that persist regardless of visual input, including ataxia (widened-based gait, dysmetria, truncal instability), dysarthria, dysdiadochokinesia, nystagmus, and ocular dysmetria. 1

Core Motor Signs

• Ataxia is the hallmark feature, characterized by impaired coordination of voluntary movements affecting gait, limbs, and trunk 2

  • Widened-based gait with unsteadiness that does NOT worsen with eye closure (distinguishing it from sensory ataxia) 1
  • Truncal ataxia (difficulty maintaining posture) is particularly prominent with cerebellar vermian pathology 3, 1

• Dysmetria manifests as overshooting or undershooting during finger-to-nose and heel-to-shin testing 1

• Dysdiadochokinesia (impaired rapid alternating movements) is evident on examination 1

• Dyssynergia (loss of coordinated multi-joint movements) occurs with cerebellar dysfunction 1

• Hypotonia may be present in affected limbs 4

• Intention tremor can develop during goal-directed movements 5, 4

Oculomotor Signs

• Ocular dysmetria involves overshooting or undershooting of eye movements (saccadic overshooting) 2, 1

• Nystagmus is a common finding in cerebellar disorders 1, 5

• Impaired smooth pursuit and vestibulo-ocular reflex abnormalities may be present 4

• Saccadic intrusions and ocular misalignment can occur 4

Speech and Language Signs

• Dysarthria with scanning or ataxic speech pattern is characteristic 2, 1, 5
  • This represents a motor speech disorder highly suggestive of cerebellar pathology 1

Critical Distinguishing Feature

• The key distinguishing feature is that unsteadiness does NOT significantly worsen with eye closure, unlike sensory ataxia where a positive Romberg test (worsening with eyes closed) indicates dorsal column pathology rather than cerebellar dysfunction 1

Associated Non-Motor Signs (Often Overlooked)

• Cognitive deficits including impaired executive functions, planning, working memory, and visuospatial skills 6, 4

• Affective dysregulation and inappropriate behavior (cerebellar cognitive affective syndrome) 6, 4

• Linguistic deficiencies including agrammatism, verbal fluency deficits, and impaired phonological/semantic word retrieval 4

Common Pitfalls to Avoid

• Do not mistake weakness or hypotonia for ataxia in children—careful examination is required 1

• Do not overlook "pseudoataxia" from functional disorders which can mimic organic cerebellar disease 1

• Do not confuse vestibular dysfunction (lurching gait triggered by head rotation) with cerebellar ataxia 1

• Do not miss associated spinal cord signs (motor spasticity, sensory ataxia) that would indicate combined cerebellar and spinal pathology 1

• Do not assume the Romberg test can be properly performed in cerebellar ataxia, as unsteadiness is present regardless of visual input 1