Tzu-Pu Chang, Hong-Hua Lin, Anand K Bery
Background: Skew deviation, a vertical ocular misalignment caused by brainstem or cerebellar dysfunction, is strongly associated with central lesions in acute vestibular syndrome but has not been systematically studied in outpatient settings. This clinic-based study evaluated the prevalence of video-oculography (VOG)-guided skew deviation, its diagnostic value for posterior fossa lesions, and the accuracy of an automated VOG algorithm for skew detection. Methods: Consecutive dizzy patients attending a neurology clinic over 18 months underwent a VOG-guided alternate cover test. Vertical eye deviation was automatically quantified by the VOG software and validated by expert review of VOG traces and/or videos (expert review constituted the gold standard in this study). We analyzed the prevalence and diagnostic performance of skew deviation for posterior fossa lesions. Receiver operating characteristic analysis and area under the curve (AUC) were used to evaluate the automated algorithm. Results: Among 226 dizzy patients, skew deviation was identified in 5.3% (95% CI 3.1-9.1%). For predicting posterior fossa lesions, skew deviation showed a sensitivity of 23.7% (95% CI 13.0-39.2%), specificity of 98.4% (95% CI 95.4-99.5%), positive predictive value of 75.0% (95% CI 46.8-91.1%), and negative predictive value of 86.4% (95% CI 81.2-90.4%). The automated VOG algorithm demonstrated promising performance for detecting skew deviation, with AUCs of 0.88 for the right eye (95% CI 0.77-0.99) and 0.94 for the left eye (95% CI 0.91-0.97). Conclusions: Skew deviation is uncommon in outpatient dizzy patients, but its high positive predictive value supports its utility as an adjunctive predictor of posterior fossa lesions. Although the automated VOG algorithm showed promising performance, expert review of traces and/or video remains necessary because false-positive results may occur.