Intraoperative Auditory Brainstem Response Results Predict Delayed Sensorineural Hearing Loss After Middle Cranial Fossa Resection of Vestibular Schwannoma.

OBJECTIVE: To identify intraoperative neurophysiologic measures predictive of delayed progressive sensorineural hearing loss in the operative ear after a middle fossa approach (MCF) for resection of vestibular schwannoma (VS). STUDY DESIGN: Retrospective review. SETTING: Academic, tertiary referral center. PATIENTS: Subjects with vestibular schwannoma who underwent a MCF microsurgical resection of VS were analyzed for individuals whose hearing was initially preserved but subsequently developed progressive sensorineural hearing loss in the operative ear. Thirty-seven patients were identified for whom audiologic and neurophysiologic data was available. INTERVENTION: Intraoperative neurophysiologic changes will correlate with delayed sensorineural hearing loss in the operative ear. MAIN OUTCOME MEASURES: Audiometric evaluations, intraoperative electrocochleography (ECoG), and auditory brainstem response (ABR) measures. RESULTS: Twenty-five subjects experienced stable hearing or hearing loss in the operative ear comparable to the contralateral ear. Twelve subjects suffered a significant increase in the hearing asymmetry between ears. Deterioration in the amplitude of wave V of the ABR persisting at the close of tumor resection correlated with delayed sensorineural hearing loss in the operative ear (p 0.02, 5% mean improvement in the stable hearing group, versus a 14% decline with progressive asymmetry), but changes in ECoG or other auditory brainstem response parameters (p > 0.05) were not predictive. CONCLUSIONS: Persisting amplitude reduction of wave V of the intraoperative ABR best correlates with delayed progressive sensorineural hearing loss in the operative ear. Neither persistent changes in ECoG, other ABR parameters, nor transient changes, correlated with delayed progressive sensorineural hearing loss in the operative ear.

Assessment of Intraoperative Nerve Monitoring Parameters Associated With Facial Nerve Outcome in Parotidectomy for Benign Disease.

Importance: Prior studies suggest that the use of facial nerve monitoring decreases the rate of immediate postoperative facial nerve weakness in parotid surgery, but published data are lacking on normative values for these parameters or cutoff values to prognosticate facial nerve outcomes. Objective: To identify intraoperative facial nerve monitoring parameters associated with postoperative weakness and to evaluate cutoff values for these parameters under which normal nerve function is more likely. Design, Setting, and Participants: This retrospective case series of 222 adult patients undergoing parotid surgery for benign disease performed with intraoperative nerve monitoring was conducted at an academic medical institution from September 13, 2004, to October 30, 2014. The data analysis was conducted from May 2018 to January 2019. Main Outcomes and Measures: The main outcome measure was facial nerve weakness. Receiver operating characteristic curves were generated to define optimal cut point to maximize the sensitivity and specificity of the stimulation threshold, mechanical events, and spasm events associated with facial nerve weakness. Results: Of 222 participants, 121 were women and 101 were men, with a mean (SD) age of 51 (16) years. The rate of temporary facial nerve paresis of any nerve branch was 45%, and the rate of permanent paralysis was 1.3%. The mean predissection threshold was 0.22 milliamperes (mA) (range, 0.1-0.6 mA) and the mean postdissection threshold was 0.24 mA (range, 0.08-1.0 mA). The average number of mechanical events was 9 (range, 0-66), and mean number of spontaneous spasm events was 1 (range, 0-12). Both the postdissection threshold (area under the curve [AUC], 0.69; 95% CI, 0.62-0.77) and the number of mechanical events (AUC, 0.58; 95% CI, 0.50-0.66) were associated with early postoperative facial nerve outcome. The number of spasm events was not associated with facial nerve outcome. The optimal cutoff value for the threshold was 0.25 mA, and the optimal cutoff for number of mechanical events was 8. If a threshold of greater than 0.25 mA was paired with more than 8 mechanical events, there was a 77% chance of postoperative nerve weakness. Conversely, if a threshold was 0.25 mA or less and there were 8 mechanical events or less, there was 69% chance of normal postoperative nerve function. No parameters were associated with permanent facial nerve injury. Conclusions and Relevance: Postdissection threshold and the number of mechanical events are associated with immediate postoperative facial nerve function. Accurate prediction of facial nerve function may provide anticipatory guidance to patients and may provide surgeons with intraoperative feedback allowing adjustment in operative techniques and perioperative management.

Comprehensive Hearing Aid Intervention at a Free Subspecialty Clinic.

Importance: Providing a model of a comprehensive free audiologic program may assist other health care professionals in developing their own similar program. Objective: To describe the structure, feasibility, and outcomes of a free subspecialty clinic providing hearing aids to develop a paradigm for other programs interested in implementing similar projects. Design, Setting, and Participants: A retrospective case series was conducted from September 1, 2013, through March 31, 2016. In a partnership between a free independent clinic for indigent patients and an academic medical center, 54 indigent patients were referred to the clinic for audiograms. A total of 50 of these patients had results of audiograms available for review and were therefore included in the study; 34 of these 50 patients were determined to be eligible for hearing aid fitting based on audiometric results. Exposures: Free audiometric testing, hearing aid fitting, and hearing aid donation. Main Outcomes and Measures: The number of hearing aids donated, number of eligible patients identified, number of patients fitted with hearing aids, and work effort (hours) and start-up costs associated with implementation of this program were quantified. Results: A total of 54 patients (31 women [57.4%] and 23 men [42.6%]; median age, 61 years; range, 33-85 years) had audiograms performed, and 84 hearing aids were donated to the program. The patients were provided with free audiograms, hearing aid molds, and hearing aid programming, as well as follow-up appointments to ensure continued proper functioning of their hearing aids. Since 2013, a total of 34 patients have been determined to be eligible for the free program and were offered hearing aid services. Of these, 20 patients (59%) have been fitted or are being fitted with free hearing aids. The value of services provided is estimated to be $2260 per patient. Conclusions and Relevance: It is feasible to provide free, comprehensive audiologic care, including hearing aids and fitting, in a well-established, free clinic model. The opportunity for indigent patients to use hearing aids at minimal personal cost is a major step forward in improving access to high-quality care.

Electrocochleography as a diagnostic and intraoperative adjunct in superior semicircular canal dehiscence syndrome.

OBJECTIVE: To determine the electrocochleographic characteristics of ears with superior semicircular canal dehiscence (SSCD) and to examine its use for intraoperative monitoring in canal occlusion procedures. STUDY DESIGN: Case series. SETTING: Academic medical center. PATIENTS: Thirty-three patients (45 ears) had clinical and computed tomographic evidence of SSCD; 8 patients underwent intraoperative electrocochleography (ECoG) during superior canal occlusion; 9 patients underwent postoperative ECoG after SSCD occlusion. INTERVENTIONS: Diagnostic, intraoperative, and postoperative extratympanic ECoG; middle fossa or transmastoid occlusion of the superior semicircular canal. MAIN OUTCOME MEASURE: Summating potential (SP) to action potential (AP) ratio, as measured by ECoG, and alterations in SP/AP during canal exposure and occlusion. RESULTS: Using computed tomography as the standard, elevation of SP/AP on ECoG demonstrated 89% sensitivity and 70% specificity for SSCD. The mean SP/AP ratio among ears with SSCD was significantly higher than that among unaffected ears (0.62 versus 0.29, p < 0.0001). During occlusion procedures, SP/AP increased on exposure of the canal lumen (mean change ± standard deviation, 0.48 ± 0.30). After occlusion, SP/AP dropped below the intraoperative baseline in most cases (mean change, -0.23 ± 0.52). All patients experienced symptomatic improvement. All patients who underwent postoperative ECoG 1 to 3 months after SSCD repair maintained SP/AP of 0.4 or lesser. CONCLUSION: These findings expand the differential diagnosis of abnormal ECoG. In conjunction with clinical findings, ECoG may support a clinical diagnosis of SSCD. Intraoperative ECoG facilitates dehiscence documentation and allows the surgeon to confirm satisfactory canal occlusion.