Acute-onset binocular diplopia in neurological unit: aetiological factors and diagnostic assessment

Objectives: To investigate the aetiology of acute-onset binocular diplopia (AOBD) in neurological units and identify the key diagnostic procedures in this setting. Materials and methods: Clinico-demographic data from patients hospitalized for AOBD from 2008 to 2019 were retrospectively reviewed. AOBD due to an underlying neurological disorder known to cause diplopia was addressed as secondary diplopia. Ophthalmoparesis plus was defined when subtle neurological signs/symptoms other than ophthalmoparesis were detected during neurological examination. Results: A total of 171 patients (mean age 57.6 years) were included in the study. A total of 89 subjects (52%) had an oculomotor disturbance consistent with sixth nerve palsy, and 42 (24.6%) showed multiple oculomotor nerve involvement. The most common cause of AOBD was presumed to be microvascular in 56 patients (32.7%), while a secondary aetiology was identified in 102 (59.6%). Ophthalmoparesis plus and multiple oculomotor nerve involvement significantly predicted a secondary aetiology in multivariable logistic regression analysis. Brain CT was never diagnostic in isolated ophthalmoparesis. A combination of neuroimaging examinations established AOBD diagnosis in 54.9% of subjects, whereas rachicentesis and neurophysiological examinations were found to be performant in the remaining cases. Conclusions: AOBD may herald insidious neurological disease, and an extensive diagnostic workup is often needed to establish a diagnosis. Neurological examination was pivotal in identifying patients at higher risk of secondary aetiology. Even in cases of apparently benign presentation, a serious underlying disease cannot be excluded. Brain MRI was found to perform well in all clinical scenarios, and it should be always considered when managing AOBD.