Diagnostic Value of Bedside Eye Movement Examination in Movement Disorders

The differential diagnosis of neurodegenerative disorders such as parkinsonism and progressive cerebellar ataxia remains (CA) a major clinical challenge due to overlapping clinical features and variable disease trajectories.1 In this context, the assessment of eye movements offers a simple, non-invasive, and underutilized diagnostic tool that can be performed rapidly at the bedside.2 Despite its potential, the diagnostic accuracy of bedside eye movement examination in movement disorders has not, to our knowledge, been formally evaluated. We retrospectively reviewed medical records of adult inpatients referred by the Movement Disorders team during their inpatient stay for specialist neuro-otological (eye movement) examination at the National Hospital for Neurology and Neurosurgery between January 2018 and June 2025, as part of the diagnostic assessment of movement disorders, including parkinsonism and ataxia. Demographic data, eye movement findings, the provisional diagnosis based on ocular motor assessment, and the final confirmed diagnosis were extracted. Diagnostic accuracy and predictive values were calculated using confusion matrices, Cohen's kappa, and sensitivity analyses. Of 123 reviewed patients, 69 met inclusion criteria (mean age 66 ± 13.3 years; 53.6% male). Final impression, established by senior movement disorder specialists based on comprehensive clinical and imaging data, included progressive supranuclear palsy (PSP, n = 17), CA (n = 17), idiopathic Parkinson's disease (iPD, n = 9), corticobasal syndrome (CBS, n = 7), multiple system atrophy (MSA, n = 5), dementia with Lewy bodies (DLB, n = 1), and unclassified parkinsonism (n = 13). No cases of parkinsonism or ataxia were secondary to structural brain lesions. Eye movement-based diagnoses were consistent with the final impression of the movement disorders specialist in 46 of 56 cases (82.1%) with definitive syndromic classification (kappa = 0.76, p < 0.001). Diagnostic concordance was highest for PSP (88.2%), iPD (88.8%), and CBS (85.7%). Table S1 summarizes the demographic and clinical characteristics of the patients. Table S2 presents the diagnostic information for patients with PCA. These findings highlight the substantial diagnostic utility of bedside eye movement examination in distinguishing parkinsonian syndromes. Unlike videonystagmography or other instrumented approaches -valuable for quantifying eye movement metrics3, 4 but largely inaccessible to most practicing neurologists- bedside assessment requires no equipment, is cost-free, and can be performed within minutes. Yet, despite this, training in ocular motor examination remains insufficient across neurology curricula, as recently emphasized in Neurology Education.5 This lack of training represents a missed opportunity, given that careful observation of eye movements can localize pathology to cortical, cerebellar, or basal ganglia circuits and may reveal early disease signatures before the onset of classic appendicular motor symptoms.1 Beyond their diagnostic value, eye movement abnormalities may also serve as clinical biomarkers of disease progression and treatment response. However, such potential can only be realized if future neurologists are equipped with the skills to recognize and interpret them at the bedside. Our results underscore the need to reinstate detailed ocularmotor examination as a core competency in neurological training. In conclusion, bedside eye movement examination demonstrates high diagnostic accuracy (~80%) for idiopathic Parkinson's disease and atypical parkinsonian syndromes, reinforcing its value as an essential clinical skill for all neurologists. (1) Research project: A. Conception, B. Organization, C. Execution; (2) Statistical Analysis: A. Design, B. Execution, C. Review and Critique; (3) Manuscript Preparation: A. Writing of the first draft, B. Review and Critique E.B.T.A.: 1B, 2C, 3A. P.M.R.: 1A, 1C. C.A.G.: 1A, 1C. H.N.O.: 2A, 2B, 3A. D.K.: 1A, 3B. The authors have no acknowledgments to declare. Ethical Compliance Statement: This study followed the guidelines of National Health Services Research Ethical Committee guidelines. Informed patient consent was not necessary for this work. We confirm that we have read the Journal's position on issues involved in ethical publication and affirm that this work is consistent with those guidelines. Funding Sources and Conflict of Interest: No specific funding was received for this work. The authors declare that there are no conflicts of interest relevant to this work. Financial Disclosures for the previous 12 months: HNÖ is supported by Turkish Neurological Society with an International Education Scholarship. DK is supported by the National Institute for Health Research University College London Hospitals Biomedical Research Centre. The data that support the findings of this study are available from the corresponding author upon reasonable request. TABLE S1. Summarizes the number of patients with definite diagnoses, sex distribution, mean age with standard deviation, eye movement findings, and diagnoses following the eye examination. TABLE S2. Diagnostic information for patients with ataxic disorders. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. 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