Early Adaptation and Compensation of Clinical Vestibular Responses After Unilateral Vestibular Deafferentation Surgery

Objective To describe vestibulo-ocular function in the immediate postoperative period after unilateral vestibular deafferentation from vestibular schwannoma resection. Study Design Prospective longitudinal study. Setting Tertiary medical center. Patients Five patients who underwent vestibular schwannoma resection via retrosigmoid approach. Interventions Bedside video-oculography and video head impulse testing (HIT). Main Outcome Measures Static and dynamic measures of vestibulo-ocular reflex (VOR) function including spontaneous nystagmus, skew deviation, VOR gain during HIT, and presence of saccades related to HIT. Results Mean ipsilesional horizontal VOR gain decreased from 0.88 ± 0.09 preoperatively to 0.27 ± 0.20 on POD 2 (p = 0.004). Mean contralesional VOR gain declined from 0.95 ± 0.1 preoperatively to 0.79 ± 0.17 on POD 2 (p = 0.032). By POD 4, ipsilesional VOR gain remained low, whereas contralesional VOR gain returned to baseline. Initially on POD 1 to 3, compensatory saccades occurred exclusively after the head stopped moving (overt) with latency of 192.8 ± 36.1 ms; by POD 5, saccade latency decreased to 134.5 ± 23.5 ms (p = 0.026), and saccades were occurring during the head rotation. Skew deviation was present and remained abnormal through POD 5 in 3 of the 5 patients. Conclusion In the postoperative period, gaze stability seems to improve from contralesional VOR gain restoration and reduced latency of compensatory saccades.