Oculomotor Phenomenology in Cerebellar Ataxias: A Video‐Illustrated Practical Diagnostic Approach
Pedro Fraiman, Flávio Moura Rezende‐Filho, Malco Rossi, Rodrigo Alencar e Silva, José Luiz Pedroso, Orlando G.P. Barsottini, Clécio GodeiroAbstract
Background
Cerebellar ataxias are a heterogeneous group of neurological disorders with overlapping clinical, genetic, and epidemiological features, arising from the dysfunction of cerebellar and extracerebellar structures, including brainstem pathways. Etiologies include autosomal dominant, autosomal recessive, mitochondrial, X‐linked, congenital, and acquired causes. Oculomotor abnormalities are common and vary across ataxia subtypes, making their recognition relevant to diagnosis.
Objective
The aim of the study was to review key oculomotor abnormalities in cerebellar ataxias, illustrate their neuroanatomical basis through video‐based teaching material, and propose a structured clinical workflow for diagnostic decision‐making.
Methods
A narrative literature search was conducted in PubMed (2015–2025), complemented by earlier landmark references, focusing on oculomotor phenomenology in genetic and acquired ataxias. Disorders were organized based on predominant ocular motor patterns. Six major eye movement systems—vestibulo‐ocular reflex (VOR), smooth pursuit, optokinetic reflex, saccades, gaze holding, and vergence—were reviewed, followed by characteristic abnormalities, representative video findings, and a stepwise bedside workflow.
Results
Oculomotor patterns, including saccadic intrusions, gaze‐evoked and vertical nystagmus, supranuclear gaze palsies, saccadic dysmetria, slow saccades, ocular motor apraxia, impaired optokinetic responses, and VOR deficits, reflect the dysfunction of specific cerebellar and brainstem pathways. Some patterns suggest particular etiologies, including spinocerebellar ataxia type 2 (SCA2) (slow saccades), Niemann–Pick type C (vertical supranuclear gaze palsy), SCA3 (pseudoproptosis), and cerebellar ataxia, neuropathy, and vestibular areflexia syndrome (CANVAS) or Friedreich ataxia (VOR deficits).
Conclusions
Oculomotor abnormalities provide valuable diagnostic clues in cerebellar ataxias. Structured assessment of spontaneous eye movements, saccades, smooth pursuit, and VOR function may improve bedside phenotyping and diagnostic accuracy.