Preoperative Assessment of Cervical Vestibular Evoked Myogenic Potentials (cVEMPs) Help in Predicting Hearing Preservation After Removal of Vestibular Schwannomas Through a Middle Fossa Craniotomy

Abstract

To determine whether cervical vestibular evoked myogenic potentials (cVEMPs) are predictive of hearing preservation in patients undergoing vestibular schwannoma removal through middle fossa craniotomy approach. Retrospective case study. Tertiary referral center. Eighteen patients who underwent a middle fossa craniotomy for vestibular schwannoma (stage I or II of Koos classification) with attempted hearing preservation from January 2008 to February 2016 were retrospectively reviewed. Pre-surgical cVEMPs test, videonystagmography (caloric test), and magnetic resonance imaging (MRI) as well as a pre- and post-surgical audiometry test. cVEMPs parameters including amplitude asymmetry ratio (AR), P13, and N23 latencies and peak-to-peak amplitude between P13 and N23 waves were calculated. Hearing data were classified according to the AAO-HNS hearing classes. The nerve of origin of the tumor was specified during surgery and the largest tumor diameter was measure on MRI axial plane on T2-CISS weighed images. Preoperative amplitude asymmetry ratio was lower (n = 15, Mann-Whitney U test, p < 0.001) in the group with postoperative hearing preservation (n = 11) compared with the group with postoperative hearing preservation failure (n = 4). The positive predictive value of an AR less than 24% to assess postoperative hearing preservation is 91.6%. Tumor size and localization were not correlated with cVEMPs, nor with caloric testing in this group of small-sized intracanalicular vestibular schwannomas. Our data suggest that cVEMPs may help predict hearing preservation outcome in vestibular schwannoma surgery via the middle fossa craniotomy approach.