Diplopia due to skew deviation following neurotologic procedures.

OBJECTIVE To describe and characterize diplopia resulting from skew deviation after cerebellopontine angle (CPA) surgery and labyrinthectomy. PATIENTS AND INTERVENTIONS Retrospective case series of 4 patients who developed vertical diplopia from skew deviation after resection of tumors in the CPA or labyrinthectomy MAIN OUTCOME MEASURE Complete neuro-opthalmologic examination including opticokinetic testing, confrontational visual field assessment, color plate, pupillary reflex, slit lamp examination, and head tilt test. RESULTS Four patients with residual hearing preoperatively developed skew deviation immediately after surgical intervention, including translabyrinthine (n = 1) and retrosigmoid (n = 2) approaches to the CPA and labyrinthectomy (n = 1). Neuro-ophthalmologic examination demonstrated intact extraocular movements, and 2- to 14-mm prism diopter hypertropia on both primary gaze and head tilt testing. In all cases, skew deviation resolved spontaneously with normalization of the neuro-ophthalmologic examination within 10 weeks. CONCLUSION Patients undergoing CPA surgery or labyrinthectomy can develop postoperative diplopia due to skew deviation as a consequence of acute vestibular deafferentation. Patients with significant hearing preoperatively, a probable marker for residual vestibular function, may be especially at risk for developing skew deviation postoperatively.