Supersaccades and Vestibulo-Ocular Reflex Inconsistency Score as Predictors of Gain Recovery After Acute Unilateral Vestibular Loss

Objectives: To evaluate the predictive value of two novel video head impulse test-derived biomarkers—supersaccades (single covert saccades) and the VOR Inconsistency Score (VIS)—in forecasting early vestibulo-ocular reflex (VOR) gain recovery in patients with unilateral peripheral vestibular dysfunction (UPVD). Design: Retrospective cohort study including 90 patients with UPVD assessed within 48 hours of symptom onset and followed up at 1 month. Examinations were performed at two neurotology units between July 2014 and December 2023. Results: Early VOR gain recovery was achieved by 32 patients (36%): binary logistic regression identified age, supersaccades, and VIS as independent predictors of recovery. A significant interaction was found between age and VIS, indicating that the detrimental effect of reflex inconsistency on VOR recovery is significantly amplified by older age. Receiver operating characteristic analysis of the logistic regression model yielded an area under the curve of 0.881. Using the Youden Index to determine the optimal cut-off probability provided a sensitivity of 81.3% and a specificity of 87.9%. Restricted cubic splines and segmented regression identified a critical structural breakpoint at a VOR gain of 0.448. This threshold defined two physiological states: when gain <0.448, supersaccades were rarely observed, and VIS served as the dominant predictor. When gain ≥0.448, VIS was more stable and less discriminant, whereas supersaccades were more frequent and served as the main recovery marker. Conclusions: Supersaccades and VIS independently predict early VOR gain recovery, offering a more nuanced prognostic assessment than gain values alone. Incorporating dynamic VOR response features may improve early patient stratification and guide rehabilitation strategies in UPVD.