Feasibility of Preoperative Video Head Impulse Test to Predict the Nerve of Origin in Patients with Vestibular Schwannomas

Abstract

Vestibular schwannoma (VS) originates from Schwann cells in the superior or inferior vestibular nerve. Identifying the precise origin will help in determining the optimal surgical approach. We retrospectively analyzed the preoperative vestibular function test according to VS origin to determine whether the test is a valuable indicator of tumor origin. Forty-seven patients with VS (male:female = 18:29, mean age: 54.06 ± 13.50 years) underwent the cochleovestibular function test (pure-tone audiometry, caloric test, video head impulse test (vHIT), cervical and ocular vestibular-evoked myogenic potential, and posturography). All patients then underwent surgical removal of VS, and the schwannoma origin was confirmed. The tumor originated from the superior vestibular nerve (SVN group) in 21 patients, the inferior vestibular nerve (IVN group) in 26 patients, and an undetermined site in eight patients. The only value that differed significantly among the groups was the gain of the vestibular-ocular reflex (VOR) in the ipsilesional posterior canal (iPC) during the vHIT. Our results indicate that VOR gain in the iPC may be used to predict the nerve origin in patients with VS. Other cochleovestibular function tests have limited value to discriminate nerve origins, especially in cases of medium to large VS.

Significance of Baseline Inferior Vestibular Function on the Prognosis of Patients with Labyrinthitis

“…Additionally, they reported that low posterior canal gain had a specificity of 94.4% for predicting the hearing prognosis. Also, attempts were made to discriminate the origin of the vestibular schwannoma based on the PC gain analysis (25), and another study report that the AC gain is relatively preserved compared with the PC and HC gain in the central acute vestibular syndrome (21). These results suggest that the function of the vertical canal often has various clinical implications although vertical canal vHIT required technical proficiency and has lower reliability compared with HC testing.…”