Age, preoperative tumor volume and widening of the internal acoustic meatus are independent factors associated with poor preoperative hearing in vestibular schwannoma patients - results of a single-center retrospective analysis.

Preoperative hearing function shows wide variations among patients diagnosed with vestibular schwannoma. Besides the preoperative tumor size there are other factors that influence the preoperative hearing function that are frequently discussed. A comprehensive analysis of a large cohort of vestibular schwannomas has the potential to describe new insights and influence the preoperative management. We analyzed clinical factors, imaging data and the expression of the proliferation marker MIB1 as potential influencing factors on the preoperative hearing function in a retrospective cohort of 523 primary sporadic vestibular schwannomas. The results of the preoperative audiometry were quantified using the Gardner-Robertson Score. Uni- and multivariate analyses were performed. Serviceable hearing (Gardner-Robertson class 1 or 2) was documented in 391 patients (74.8%). Factors associated with non-serviceable hearing (Gardner-Robertson class 3-5) were patients of older age (p < 0.0001), larger preoperative tumor volume (p = 0.0013) and widening of the internal acoustic meatus compared to the healthy side (p = 0.0353). Gender and differences in the expression of the proliferation marker MIB1 had no influence on preoperative hearing. In the multivariate nominal logistic regression older age (OR 27.60 (CI 9.17-87.18), p < 0.0001), larger preoperative tumor volume (OR 20.20 (CI 3.43-128.58), p = 0.0011) and widening of the internal acoustic canal (OR 7.86 (CI 1.77-35.46), p = 0.0079) remained independent factors associated with non-serviceable hearing. Widening of the internal acoustic canal is an independent factor for non-serviceable preoperative hearing in vestibular schwannoma patients together with older age and larger preoperative tumor volume.

Hearing Preservation Microsurgery in Vestibular Schwannomas: Worth Attempting in "Larger" Tumors?

OBJECTIVES/HYPOTHESIS: To review hearing preservation after microsurgical resection of sporadic vestibular schwannomas according to tumor size. STUDY DESIGN: Retrospective cohort. METHODS: Baseline, intraoperative, and postoperative patient and tumor characteristics were retrospectively collected for a cohort who underwent hearing preservation microsurgery. Serviceable hearing was defined by a pure tone average ≤50 dB and word recognition score ≥50%. RESULTS: A total of 243 patients had serviceable hearing preoperatively. Fifty (21%) tumors were confined to the internal auditory canal, and the median tumor size was 16.2 mm (interquartile range [IQR] 11.3-23.2) for tumors with cerebellopontine angle extension. Serviceable hearing was maintained in 64% of patients with tumors confined to the internal auditory canal, 28% with cerebellopontine angle extension <15 mm, and 9% with cerebellopontine angle extension ≥15 mm. On multivariable analysis, the odds ratios of acquiring nonserviceable hearing postoperatively for tumors extending <15 mm and ≥15 mm into the cerebellopontine angle were 5.75 (95% confidence interval [CI] 2.13-15.53; P < .001) and 22.11 (95% CI 7.04-69.42; P < .001), respectively, compared with intracanalicular tumors. CONCLUSIONS: The strongest predictor of hearing preservation with microsurgery after multivariable adjustment is tumor size. Approximately 10% of patients with tumors ≥15 mm of cerebellopontine angle extension will retain serviceable hearing after microsurgery. Furthermore, hearing preservation techniques offer cochlear nerve preservation and cochlear patency allowing for possible future cochlear implantation. An attempt at hearing preservation, including avoiding surgical approaches that necessarily sacrifice hearing, is worthwhile even in larger tumors if serviceable hearing is present preoperatively. LEVEL OF EVIDENCE: 4 Laryngoscope, 132:1657-1664, 2022.

Degree of preoperative hearing loss predicts time to early mobilization following vestibular schwannoma microsurgery.

OBJECTIVE: To test the hypothesis that severe to profound preoperative hearing loss predicts less acute postoperative vestibulopathy following microsurgical removal of vestibular schwannoma (VS) allowing for earlier postoperative mobilization and hospital discharge. METHODS: Patients with VS who underwent microsurgery and were found to have preoperative severe to profound hearing loss (pure tone average [PTA] > 70 dB HL) were matched 1:1 by age and tumor size to a group of randomly selected controls with preoperative serviceable hearing. RESULTS: A total of 57 patients met inclusion criteria and were matched to controls. Median age at the time of microsurgery was 56 years. The median PTA and WRS for cases were 91 dB HL (interquartile range [IQR] 78-120) and 0% (IQR 0-0), respectively. Median tumor size was 14.2 mm (IQR 10.9-20.9). A total of 35 (61%) patients exhibited nystagmus after surgery associated with acute vestibular deafferentation. Median time to ambulation in the hallway was 2 days. Controls exhibited similar tumor size (12.7 mm, p = 0.11) and age (57 years, p = 0.52). Preoperative hearing loss did not predict severity or duration of postoperative nystagmus or days to discharge; however, those with Class D hearing exhibited a shorter time to ambulation (p = 0.04). CONCLUSION: Following microsurgical removal of VS, preoperative profound hearing loss was associated with a shorter time to postoperative mobilization; however, there were no observed associations with duration or severity of nystagmus and time to hospital discharge. Although not a predictor of nystagmus, preoperative profound hearing loss may portend quicker recovery from clinically significant postoperative vestibulopathy.

Increased cochlear radiation dose predicts delayed hearing loss following both stereotactic radiosurgery and fractionated stereotactic radiotherapy for vestibular schwannoma.

PURPOSE: Stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (fSRT) are noninvasive therapies for vestibular schwannomas providing excellent tumor control. However, delayed hearing loss after radiation therapy remains an issue. One potential target to for improving hearing rates is limiting radiation exposure to the cochlea. METHODS: We retrospectively reviewed 100 patients undergoing either SRS with 12 Gy (n = 43) or fSRT with 50 Gy over 28 fractions (n = 57) for vestibular schwannoma. Univariate and multivariate analysis were carried out to identify predictors of hearing loss as measured by the Gardner Robertson scale after radiation therapy. RESULTS: Deterioration of hearing occurred in 30% of patients with SRS and 26% with fSRT. The overall long term (> 2 year) progression rates were 20% for SRS and 16% for fSRT. Patients with a decrease in their Gardner Robertson hearing score and those that loss serviceable hearing had significantly higher average minimal doses to the cochlea in both SRS and fSRT cohorts. ROC analysis showed that a cut off of 5 Gy and 35 Gy, for SRS and fSRT respectively, predicted hearing loss with high sensitivity/specificity. CONCLUSION: Our data suggests the minimal dose of radiation that the cochlear volume is exposed to is a predictor of delayed hearing loss after either SRS or fSRT. A threshold of 5 Gy/35 Gy may lead to improved hearing preservation after radiotherapy. Further prospective multi center studies can further elucidate this mechanism.

A Retrospective Cohort Study of Longitudinal Audiologic Assessment in Single and Fractionated Stereotactic Radiosurgery for Vestibular Schwannoma.

BACKGROUND: Fractionated stereotactic radiosurgery (SRS) for vestibular schwannomas (VS) has been theorized to allow for tumor control with higher rates of hearing preservation in selected patients with useful hearing. However, there is a paucity of literature with formal audiologic measures of hearing preservation to support the standard use of fractionated SRS in VS. We hypothesized that fractionation would diminish the amount of hearing damage. OBJECTIVE: To evaluate the relationship between audiologic performance and SRS fractionation scheme. METHODS: We performed an IRB-approved retrospective review of patients treated with 1, 3, or 5 fraction SRS for VS at our institution from 1998 to 2016. Pre- and post-SRS audiograms with speech awareness threshold (SAT) in treated and contralateral ears were obtained. Contralateral ear measurements were used for hearing normalization to account for presbycusis. RESULTS: Fifty-six patients with median audiologic follow-up 2.0 yr (mean 2.66 yr, min-max 0.50-9.45 yr) were included. Patients treated with single fractionation had a significantly worsened SAT (dB) compared to patients treated with 5 fractions (P = .008) and compared to all multifraction patients (P = .009) at 12 to 24 mo follow-up. CONCLUSION: This retrospective analysis supports the use of fractionated SRS to preserve hearing in patients with VS. SAT can be used as an objective metric of hearing response to radiosurgery.