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

Abstract

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.

Brazilian Society of Otology task force – Vestibular Schwannoma ‒ evaluation and treatment

“…For intracanalicular tumors, the preservation rate was 100%, whereas only 5.3% of patients with tumors >25 mm had preserved hearing. Ren et al 183 found a hearing preservation rate of 41.7% (63 out of 151 patients). This rate was higher for intracanalicular tumors than for tumors with an APC component (57.6% vs. 29.4%, p = 0.03).…”

“…The MF approach is chosen based on the surgeon’s preference, tumor size, and degree of lateral IAC involvement. 162 , 179 , 180 , 181 , 182 , 183 …”

“…Ren et al 183 conducted a prospective study evaluating pre and postoperative ABR prediction of hearing preservation. They found a hearing preservation rate of 56.7%.…”

“…The RS approach has similar hearing preservation rates to the MF approach, especially when performed in small or intracanalicular tumors. 89 , 183 , 186 Bozhkov et al 89 retrospectively evaluated 138 patients undergoing RS resection of VS. The overall hearing preservation rate was 32%.…”

A Retrospective Analysis of Temporal Lobe Gliosis after Middle Fossa Resection of Small Vestibular Schwannomas

“…In addition to the neurosurgical retrosigmoid (RS) access and destructive translabyrinthine (TL) approaches, the MCF approach is mainly used by otosurgeons for hearing-preserving microsurgery of small vestibular schwannomas (VS). The functional outcomes are good [ 5 , 6 , 7 ] and complication rates are low [ 8 ]. Other indications include vestibular neurectomy, petrous apex biopsy, cholesterol granuloma, or decompression of the internal auditory canal in patients with neurofibromatosis type II.…”