Lohse, Christine M.

Objective To examine comfort (C) and threshold (T) levels in adult cochlear implant (CI) recipients over the first 18 months postactivation. Study Design Retrospective review of longitudinal CI programming data. Setting Tertiary academic center. Patients A total of 480 CIs among 428 adult CI recipients. Interventions Cochlear implantation with Cochlear Ltd. devices with subsequent programming to behavioral standards using Custom Sound® fitting software. Main Outcome Measures Charge levels needed to achieve C and T levels were measured longitudinally using Custom Sound®, from time of activation to a minimum of 6 and a maximum of 18 months postactivation. Charge (nC) levels were calculated as the product of pulse width (μs) and current amplitude (μA) to standardize among implant models. Changes in C and T charge levels over time were evaluated using repeated-measures analysis of variance. Results When considering the entire electrode, the largest increases were seen at 1 month postactivation, and C and T charge levels did not increase significantly after 6 and 12 months, respectively. These findings were consistent across patient age at implantation and sex. When considering proximal electrodes only, C and T levels did not increase significantly after 6 months. In distal electrodes only, C levels did not increase significantly after 6 months, but T levels continued to demonstrate small, but statistically significant increases up to 18 months postactivation. Conclusions Across the entire electrode, we observed the largest changes in C and T charge levels at 1 month postactivation. Small increases in C and T levels continued out to 6 and 12 months, respectively, but may be of limited clinical significance. The stability of programming levels over time may support selective de-escalation of CI follow-up after the initial postactivation period, but, given small yet persistent increases with time, most notably in the distal electrodes, alternatives for follow-up or remote programming may still be encouraged.

AbstractObjectiveLimited evidence guides the optimal timing of treatment after the detection of tumor growth during the observation of sporadic vestibular schwannoma (VS). The current work aimed to inform the timing of radiosurgical intervention based on an analysis of patient outcomes among those who ultimately failed stereotactic radiosurgery (SRS) and underwent salvage microsurgery.Study DesignA historical cohort study.SettingSeven centers across the United States and Norway.MethodsAdults with sporadic VS who underwent salvage microsurgery following failed primary SRS were included. The primary outcome of interest was the association between tumor size at the time of primary SRS and the ability to achieve gross total resection (GTR) and maintain postoperative House–Brackmann (HB) facial nerve grade I at the last follow‐up after salvage microsurgery.ResultsAmong 96 patients, the median (interquartile range [IQR]) cerebellopontine angle (CPA) tumor size at primary SRS was 14.5 mm (10.0‐19.0). Each 1‐mm increase in CPA tumor size at the time of primary SRS was associated with a 13% increased likelihood of near‐total/subtotal resection or most recent postoperative HB grade >I (odds ratio [OR] 1.13, 95% confidence interval [CI] 1.05‐1.21, P = .001), with an optimal tumor size threshold to distinguish this outcome of 12 mm of CPA extension (c‐index 0.73). Similarly, for each 1‐mm increase in CPA tumor size at the time of primary SRS, a 9% increase in any postoperative complication with salvage microsurgery was observed (OR 1.09, 95% CI 1.02‐1.15, P = .009).ConclusionCorroborated by size threshold surveillance data informing the timing of primary microsurgical resection, the current study suggests that VS outcomes are optimized when primary radiosurgical intervention is undertaken on growing tumors when they harbor 10–15 mm of cerebellopontine angle extension or less.

Objective To evaluate cochlear implant speech perception among patients with sporadic inner ear schwannoma who underwent ipsilateral implantation. Study Design Retrospective multi-institutional cohort study. Setting Eleven tertiary academic medical centers across Germany, Denmark, and the United States. Patients One hundred six patients with sporadic inner ear schwannoma who received an ipsilateral cochlear implant from 2011 to 2022. Interventions Ipsilateral cochlear implantation with observation, stereotactic radiosurgery, or microsurgery for tumor management. Main Outcome Measures Monosyllabic speech perception testing scores and rates of open-set speech perception. Results Among 106 patients studied, 101 (95%) achieved open-set speech perception with a median of 24 months (interquartile range [IQR] 12–42 mo) of audiometric follow-up. Median ipsilateral monosyllabic speech perception testing achieved was 72% (IQR 54–85%), and median ipsilateral AzBio in quiet was 75% (IQR 46–90%). Most (91 of 106 [86%]) underwent microsurgery for tumor control, with cochlear implantation performed simultaneously in 98% (89 of 91) of these patients. The ability to achieve gross total resection significantly differed by tumor complexity, with 97% of low-complexity tumors, 100% of intermediate complexity, and 0% of high-complexity tumors undergoing gross total resection (p < 0.001). However, among patients managed with microsurgery, there was not a statistically significant difference in post-cochlear implantation monosyllabic speech perception scores across complexity groupings, with median scores of 75 and 70% for patients with tumors of low or intermediate complexity and those with tumors of high complexity, respectively (p = 0.5). Eight of 102 patients (8%) assessed experienced deterioration in cochlear implant performance over time. Among the subset of 39 patients with available MRI to review, the region of surveillance interest could be visualized postoperatively on MRI in all cases. Conclusions Open-set speech perception is achieved in most patients with inner ear schwannoma undergoing ipsilateral cochlear implantation. Although cochlear implantation in high-complexity inner ear schwannomas is only possible with incomplete tumor resection, long-term open-set speech perception outcomes are similar to lower-complexity tumors.

Objective To analyze cases of medial migration of vestibular schwannomas to propose an underlying mechanism. Study Design Retrospective chart review. Patients Ten patients from one institution with sporadic vestibular schwannomas that demonstrated medial migration toward the cerebellopontine angle on serial imaging were reviewed. Interventions Among the 10 patients studied, 8 patients underwent stereotactic radiosurgery and 2 were managed with wait-and-scan. All serial imaging was analyzed throughout follow-up. Main Outcome Measures Volumetric and linear measurements were used to assess vestibular schwannoma growth. The fundal fluid cap length was measured from the most lateral end of the neoplasm within the internal auditory canal to the medial end of the cochlea. Pure tone averages of 0.5, 1, 2, and 3 kHz, word recognition scores, and AAO-HNS hearing class were used to assess levels of hearing loss per patient. Results Tumor growth exhibited a positive correlation with medial migration. Of the 10 patients studied, 9 exhibited tumor volume growth from initial to most recent imaging. Median changes in tumor volumes and fundal fluid cap lengths from initial diagnosis to the most recent imaging regardless of intervention were 130 mm3 (range 1,400–2,970) and 2.8 mm (range 1.8–6.0), respectively. Migration was noted in 4 patients prior to any intervention, in 4 patients postradiosurgery, and in 2 patients before and after radiosurgery. Therefore, half of the tumors studied migrated before an intervention and half migrated postradiosurgery. No correlation of migration and hearing decline was observed. Conclusion Medial migration of vestibular schwannoma is associated with an increase in tumor volume, supporting a “tumor squeeze” mechanism within a conical internal auditory canal toward the wider porus acusticus and cerebellopontine angle.

Objective To compare the utility of intraoperative electrically evoked auditory brainstem response (eABR) and electrically evoked stapedial reflex testing (eSRT) for cochlear nerve integrity monitoring during simultaneous translabyrinthine resection of vestibular schwannoma (VS) and cochlear implantation. Study design Historical cohort study. Setting Tertiary academic referral center. Patients Eleven patients (12 cases) who underwent translabyrinthine tumor resection with simultaneous placement of a standard, unmodified cochlear implant (CI). Intervention A CI placed at the beginning of the operation before tumor resection to facilitate intraoperative cochlear nerve monitoring through a CI-delivered electrical stimulus. Main outcome measure Correlation of intraoperative monitoring outcomes with postoperative CI performance. Results Among the 12 cases (median age, 47 years), eABR waveforms were present at the conclusion of tumor resection in 10, including 6 that achieved open set speech perception. Of the 2 cases with negative eABR, 1 achieved open set speech perception. By contrast, of the 8 cases with a positive eSRT response, 7 achieved open set speech perception. Of the 4 cases with a negative eSRT response, none achieved open set speech perception. The 3 cases that did not receive auditory stimulation included 2 with positive and 1 with negative eABR; all 3 had a negative eSRT response. Conclusions Intraoperative eSRT using an unmodified CI is a promising new method for monitoring the integrity of the cochlear nerve during simultaneous VS resection. eSRT response at the conclusion of tumor resection strongly correlated with CI open set speech capacity. Although still useful, eABR was less reliable at predicting postoperative hearing outcomes in this series.

OBJECTIVE It is uncertain which cochlear dose parameters significantly impact hearing after stereotactic radiosurgery (SRS) for sporadic vestibular schwannoma (VS). The objective of this study was to determine the impact of cochlear dose parameters on hearing outcomes for patients with serviceable hearing (SH). METHODS This was a historical cohort study performed at a single tertiary center that included patients with sporadic VS and SH who underwent single-session Gamma Knife radiosurgery treatment from 2007 to 2022. Associations of cochlear dose parameters with time to non-SH and rates of change in pure-tone average (PTA) and word recognition score (WRS) following SRS were assessed. RESULTS A total of 205 patients with SH underwent SRS for a sporadic VS. At SRS, 54 (26%) tumors were confined to the internal auditory canal and 151 (74%) extended into the cerebellopontine angle. At 2, 5, and 10 years following SRS, 62%, 37%, and 15% of patients maintained SH, respectively. The median time to non-SH was 1.8 years. The median rates of change in PTA and WRS were 6.0 dB of hearing loss per year and −6.5% per year, respectively. In a multivariable analysis, each 1-Gy increase in minimum cochlear dose was significantly associated with time to non-SH (HR 1.5, 95% CI 1.2–1.9), rate of change in PTA decibel hearing loss per year (parameter estimate [PE] 3.4, 95% CI 0.6–6.2), and rate of change in WRS percentage per year (PE −6.4, 95% CI −11.2 to −1.5). The associations of each 1-Gy increase in mean cochlear dose with hearing outcomes were only significant among patients with class B hearing (time to non-SH HR 1.3, 95% CI 1.1–1.6; rate of change in PTA PE 3.6, 95% CI 1.2–5.9; and rate of change in WRS PE −5.7, 95% CI −9.7 to −1.7). CONCLUSIONS The minimum cochlear dose impacts hearing outcomes after SRS for VS and should be considered in radiosurgical treatment planning. In this cohort, the mean cochlear dose was only associated with hearing outcomes in the subgroup of patients with class B hearing at SRS.

Objective To compare cochlear implant (CI) speech perception outcomes in patients with sporadic vestibular schwannoma (VS) managed with observation, radiosurgery, or microsurgery. Study Design Retrospective review. Setting Eleven tertiary academic medical centers. Patients One hundred patients with sporadic VS who received an ipsilateral CI. Interventions Ipsilateral cochlear implantation. Main Outcome Measures Pure-tone thresholds, monosyllabic speech perception testing scores, and rates of open-set speech acquisition. Results Of the 100 patients studied, 54 underwent microsurgery, 26 underwent radiosurgery, 19 continued observation, and 1 underwent multimodal therapy. Among all patients, the median post-implantation pure-tone average was 31 dB (interquartile range [IQR] 25–39 dB) and the median monosyllabic speech perception score was 30% (IQR 0–60%) at a median of 12 months (IQR 5–25 months) post-implantation. Patients who were managed with microsurgery (median speech perception score 11%, IQR 0–52%) exhibited poorer implant outcomes overall compared with those managed with observation (median speech perception score 52%, IQR 40–72%) or radiosurgery (median speech perception score 30%, IQR 16–60%). Open-set speech perception was achieved in 61% of patients managed with microsurgery, 100% with observation, and 80% with radiosurgery. In a multivariable setting, those managed with observation (p = 0.02) or who underwent radiosurgery (p = 0.04) were significantly more likely to achieve open-set speech perception compared with patients who underwent microsurgery. Conclusions Cochlear implants offer benefit in selected patients with sporadic VS. Although achieved in over half of people after microsurgery, open-set speech perception is more reliably attained in patients who are treated with observation or radiosurgery compared with microsurgical resection. These data may inform patient counseling and VS tumor management in people who may benefit from implantation.

Objective To report the feasibility and potential utility of monitoring acoustic hearing on awake patients using intraoperative behavioral responses to threshold and suprathreshold stimuli while undergoing cochlear implantation (CI) under local anesthesia, without any form of sedation. Study Design Retrospective review of the first five cases performed by one surgeon. Setting Tertiary care academic medical center. Patients Adult patients with residual acoustic hearing undergoing CI. Interventions CI under local anesthesia, without any form of sedation. Main Outcome Measures Procedural tolerance, reliability of intraoperative pure tone threshold and suprathreshold audiometry, and correlation of intraoperative findings with early postoperative residual hearing. Results Five ears in four patients underwent CI, including three males and one female, with a median age of 61 years. Intraoperatively, patients reported reliable behavioral responses to pure tone threshold and suprathreshold stimuli and provided real-time feedback on perceived stimulus change to the surgeon just prior to, during, and immediately following electrode insertion. All patients were able to complete the operation under local anesthesia. During electrode insertion, three cases reported no change and two cases reported diminished stimulus perception that reversed with limited electrode pull back near terminal insertion. Immediate postoperative audiograms demonstrated preservation of bone conduction thresholds within 10 dB of their preoperative baseline for all cases, suggesting hearing preservation. Three-month postoperative AzBio in quiet scores were available for two patients, measuring 45% and 94%, respectively. Conclusions This report describes the feasibility of intraoperative behavioral audiometry during CI under local anesthesia, using patient feedback during electrode insertion to optimize hearing preservation surgery. Akin to other surgical subspecialties that use real-time patient feedback where objective intraoperative measures of neurofunction are imperfect, we demonstrate feasibility and potential utility of live acoustic monitoring during CI.

AbstractObjectiveStereotactic radiosurgery (SRS) is increasingly used for small‐to‐medium‐sized sporadic vestibular schwannoma (VS) and is associated with good tumor control and low‐risk of adverse radiation‐associated events. The exact mechanism of VS tumor control is unknown but may relate to microvascular hyalinization and resultant tumoral ischemia. This study examined associations of microvascular risk factors with outcomes following SRS.DesignHistorical cohort of patients who underwent SRS for sporadic VS from 2000 to 2022.SettingTertiary academic center.MethodsAssociations of microvascular risk factors with tumor control and complications were evaluated using Cox proportional hazards regression.ResultsIn total 749 patients were studied, 31% with a history of smoking, 38% obesity, 19% hypertension, 8% diabetes, 3% peripheral vascular disease, and 2% history of coronary bypass. Regarding tumor control, no factor was associated with salvage treatment following SRS (n = 42). Hypertension (hazard ratio [HR] 2.81; P = .02) and coronary bypass (HR 6.91; P = .002) were significantly associated with developing facial nerve paresis (n = 22). No significant associations with new facial spasms (n = 53) were identified. Lastly, 191 of 294 patients with serviceable hearing at SRS progressed to nonserviceable hearing at a median 2.0 years (interquartile range: 1.0‐5.0). After multivariable adjustment for age and ipsilateral hearing status, the HR for the association of smoking history with time to nonserviceable hearing was 1.46 (95% confidence interval 1.04‐2.04; P = .03).ConclusionWe demonstrate that hypertension and history of coronary bypass may be associated with development of facial nerve weakness, while smoking may be associated with accelerated hearing loss in patients undergoing SRS for sporadic VS. These data may help guide patient counseling and inform decision‐making regarding treatment.

ABSTRACT Over the past two decades, there has been increasing interest in the diagnosis and management of schwannomas of the inner ear including hearing rehabilitation with cochlear implants. However, tumor nomenclature and classification within the literature have been variable and oftentimes cumbersome. The term “intralabyrinthine schwannoma” is in common use when describing these tumors but is a potential source of confusion given that people often use the term “labyrinth” or “labyrinthine” to refer to the vestibular component of the inner ear only (i.e., labyrinthectomy or the translabyrinthine approach). During the Ninth Quadrennial Conference on Vestibular Schwannoma and Other Cerebellopontine Angle Lesions in Bergen, Norway, in May 2023, a multidisciplinary group of conference participants met and discussed issues pertaining to current terminology and classifications to enhance clarity and to reflect recent advances in tumor management and hearing rehabilitation. Although a variety of terms have been previously used to describe inner ear schwannomas, consensus was achieved on the term “inner ear schwannoma (IES)” to describe eighth nerve schwannomas of the cochlea, vestibule, or semicircular canals. Subgroups under this term comprise intravestibular, intracochlear, or intravestibulocochlear inner ear schwannomas (low complexity tumors), inner ear schwannomas with transfundal extension into the internal auditory canal but without modiolar involvement (intermediate complexity tumors), and inner ear schwannomas with transfundal extension with modiolar involvement (high complexity tumors). The details of the recommendations for an updated and simplified tumor nomenclature centered around tumor control and hearing rehabilitation with cochlear implantation are presented.