Auditory Brain Stem Response Predictors of Hearing Outcomes after Middle Fossa Resection of Vestibular Schwannomas.

Objectives  To analyze the relationship between preoperative and intraoperative auditory brain stem response (ABR) characteristics and hearing outcomes in patients with vestibular schwannomas (VS) undergoing hearing preservation (HP) surgery via a middle cranial fossa (MCF) approach. Design  Prospective study. Setting  Academic tertiary skull base referral center. Methods  Pre- and postoperative pure-tone average (PTA) and word recognition score (WRS) were examined. Intraoperative ABR wave III latency, wave V latency, and amplitude were recorded. HP was defined as postoperative WRS ≥50%. Participants  Adult patients with VS and WRS ≥50% who underwent MCF tumor resection between November 2017 and September 2019. Main Outcome Measures  Postoperative hearing outcomes. Results  Sixty patients were included. Mean tumor size was 9.2 mm (range, 3-17). HP rates were 56.7% for the cohort and 69.7% for tumors <10 mm. A complete loss of wave V was associated with an 82.9% increase in postoperative PTA ( p  < 0.001) and 97.2% decrease in WRS ( p  < 0.001), whereas a diminished wave V was correlated with 62.7% increase in PTA ( p  < 0.001) and 55.7% decrease in WRS ( p  = 0.006). A diminished or absent wave V, but not increased wave III/V latency or decreased wave V amplitude, was correlated with a decline in postoperative hearing class ( r  = 0.735, p  < 0.001). Receiver-operating characteristic analysis demonstrated that a stable wave V has the highest accuracy in predicting HP (sensitivity of 82.6%, specificity of 84.8%). Conclusion  Of the examined preoperative and intraoperative ABR characteristics, a stable wave V intraoperatively was the strongest predictor of HP after MCF resection of VS. Level of Evidence  Level III.