Diagnostic Accuracy of Intraoperative Neurophysiologic Auditory Monitoring in Predicting Hearing Outcome in Acoustic Neuroma Surgery: A Systematic Review

Background Refinements in magnetic resonance imaging technology have allowed for earlier detection of acoustic tumors, thus increasing the likelihood of serviceable hearing being present at the time of diagnosis. A variety of intraoperative auditory monitoring techniques are available to optimize hearing outcomes in hearing preservation acoustic tumor surgery. We sought to systematically review the literature to investigate the diagnostic accuracy of the three most commonly utilized intraoperative neurophysiologic auditory monitoring techniques in predicting serviceable hearing following acoustic neuroma removal.

Methods The PubMed, Embase, Web of Science, Cochrane Central Resister of Controlled Trials, World Health Organization (WHO) Database, Clinicaltrials.gov, and bioPreprint databases were queried. A systematic review of the literature was performed on November 16, 2016, using the 2009 PRISMA guidelines. Search terms used to discover articles were separated into three main categories using keywords or subject headings that described: “Intraoperative Monitoring” or “Brainstem Auditory Evoked Potentials,” “Hearing Loss” or “Hearing Preservation,” and “Vestibular Schwannomas” or “Acoustic Neuroma,” yielding more than 2,000 hits. Studies with both pre- and postoperative audiologic data, and intra- and postoperative neurophysiologic monitoring data from auditory brainstem response (ABR), electrocochleography (ECoG), or direct eighth nerve monitoring (DENM) were considered appropriate for inclusion. For inclusion in this study, publications had to be written in English, include patients aged 19 years or older, and have a minimum follow-up of 6 months. Sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic odds ratios were calculated using standard statistical methods.

Results Nineteen sources were selected for use in this review, totaling 1,207 acoustic neuroma surgeries. The primary outcome was the diagnostic accuracy of ABR, ECoG, and DENM in predicting the presence of postoperative serviceable hearing following acoustic neuroma removal. Sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic odds ratios were calculated to quantify diagnostic accuracy. The weighted mean specificity of predicting postoperative serviceable hearing was 58.3% for ABR (range: 26.4–100%), 63% (range: 45.5–82.4%) for ECoG, and 60.7% (range: 27.3–72.2%) for DENM. Most studies demonstrated reasonable diagnostic accuracy for all neurophysiologic monitoring techniques, with a trend toward increased predictive value of DENM.

Conclusion ECoG and DENM had slightly greater prognostic significance in predicting postoperative serviceable hearing than ABR. For all modalities of intraoperative auditory monitoring, loss of intraoperative response had moderate prognostic value in predicting postoperative hearing loss.