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CONGRESS OF NEUROLOGICAL SURGEONS SYSTEMATIC REVIEW AND EVIDENCE-BASED GUIDELINE ON HEARING PRESERVATION OUTCOMES IN PATIENTS WITH SPORADIC VESTIBULAR SCHWANNOMA: UPDATE

4. Hearing Preservation Outcomes In Patients With Sporadic Vestibular Schwannoma: Update

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NEUROSURGERY, 2025

Sponsored by: Congress of Neurological Surgeons (CNS) and the Section on Tumors

Endorsement: Reviewed for evidence-based integrity and endorsed by the American Association of Neurological Surgeons (AANS) and Congress of Neurological Surgeons

(CNS)

Authors: Ghazal S. Daher MD1, John P. Marinelli MD1, Jamie J. Van Gompel, MD1,2, Neil S. Patel MD3, Jeffrey J. Olson, MD4, Matthew L. Carlson, MD1,2

Departmental and institutional affiliations:

Department of Otorhinolaryngology, Mayo Clinic School of Medicine, Rochester, Minnesota, USA
Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, USA
Department of Otorhinolaryngology, University of Utah Hospital, Salt Lake City, UT, USA
Department of Neurosurgery, Emory University School of Medicine, Atlanta, Georgia, USA

Corresponding author:

Matthew L Carlson, MD

Professor in Otolaryngology and Neurosurgery

Chair, Division of Neurotology and Skull Base Surgery

Program Director, Neurotology and Skull Base Fellowship

200 First St. SW | Mayo Clinic | Rochester, MN 55905

Carlson.matthew@mayo.edu | Secretary: 507-284-8532 | Fax: 507-284-8855

Keywords: vestibular schwannoma; acoustic neuroma; hearing loss; hearing preservation; radiosurgery; skull base surgery

Running Title: Hearing Preservation in Sporadic Vestibular Schwannoma

No part of this manuscript has been published or submitted for publication elsewhere

ABSTRACT

Background: Given the increasing prevalence and shifting disease demographic of vestibular schwannoma toward smaller tumors in people with less advanced symptoms, increasing emphasis has been placed on functional hearing preservation.

Objective: To provide an update to the 2018 CNS Guideline on hearing preservation outcomes in patients with sporadic vestibular schwannoma.

Methods: Systematic review and clinical practice guideline summarizing data pertaining to hearing preservation outcomes within the first 10 years after contemporary stereotactic radiation, microsurgery, or observation with serial imaging. The analysis incorporates studies included in the 2018 guideline as well as additional literature published up to 2022, providing a comprehensive up-to-date review of published clinical outcome data over time.

Results: Pooled estimated rates of serviceable hearing preservation are presented for observation, radiosurgery, and microsurgery for adults with sporadic vestibular schwannoma who have documented serviceable hearing in the ipsilateral ear at the time of diagnosis. Overall estimated rates of maintaining serviceable hearing are 78% at 2 years, 59% at 5 years, and 47% at 10 years during observation; 71% at 2 years, 59% at 5 years, and 38% at 10 years after radiosurgery; and 48% at 2 years, 40% at 5 years, and 32% at 10 years after microsurgery. Additionally, features portending hearing outcome among management modalities are reported to guide accurate patient counseling.

Conclusion: Regardless of treatment modality, fewer than half of patients with sporadic vestibular schwannoma who present with serviceable hearing will maintain useful hearing by 10 years. Across all studies, microsurgery and radiosurgery appear to accelerate this decline over the natural history, although further research is needed given limitations of available evidence.

UPDATED QUESTIONS AND RECOMMENDATIONS

Question 1: Among patients with sporadic vestibular schwannoma and baseline serviceable hearing who are managed with a conservative wait-and-scan strategy, what factors are associated with accelerated progression to non-serviceable hearing <5 years following initial diagnosis? The following factors were explored: tumor size ≤1 cm vs >1 cm in maximum CPA diameter, tumor growth vs no growth, presence vs absence of fundal CSF fluid cap, presence vs absence of radiographic labyrinthine fluid change, baseline AAO-HNS class A vs B hearing (GR grade I vs II) or baseline word recognition score of 100% vs <100%.

Patient Population

These recommendations apply to adults with sporadic vestibular schwannoma who have documented serviceable hearing in the ipsilateral ear at the time of diagnosis.

Recommendations

Level 3: It is suggested that individuals with serviceable hearing at time of sporadic vestibular schwannoma diagnosis, who proceed with an initial wait-and-scan strategy, be informed that there is a high rate (>75% to 100%) of hearing preservation at 2 years, moderately high rate (>50% to 75%) of hearing preservation at 5 years, and moderately low rate (>25% to 50%) of hearing preservation at 10 years.

Level 3: It is suggested that individuals with serviceable hearing at time of sporadic vestibular schwannoma diagnosis, who proceed with an initial wait-and-scan strategy, be informed about the likelihood of maintaining serviceable hearing based on predictive factors including better baseline hearing level (AAO-HNS class A or GR I status) and absence of tumor growth during observation.

Question 2: Among patients with sporadic vestibular schwannoma and baseline serviceable hearing who are treated with single fraction stereotactic radiosurgery, what factors are associated with accelerated progression to non-serviceable hearing <5 years following radiosurgical treatment? The following factors were explored: tumor size ≤2 cm vs >2 cm in maximum CPA diameter, marginal dose ≤13 Gy vs >13 Gy, cochlear dose ≤4 Gy vs >4 Gy, presence vs absence of radiographic labyrinthine fluid change, presence vs absence of fundal CSF fluid cap, baseline AAO-HNS class A vs B hearing (GR grade I vs II) or baseline word recognition score of 100% vs <100%.

Target Population

These recommendations apply to adults with sporadic vestibular schwannoma who have documented serviceable hearing in the ipsilateral ear at the time of diagnosis.

Recommendations

Level 3: It is suggested that individuals with serviceable hearing prior to stereotactic radiosurgery be informed that after radiosurgery there is a moderately high rate (>50% to 75%) of hearing preservation at 2 years, moderately high rate (>50% to 75%) of hearing preservation at 5 five years, and moderately low rate (>25% to 50%) of hearing preservation at 10 years.

Level 3: It is suggested that individuals with serviceable hearing prior to stereotactic radiosurgery should be informed about the likelihood of maintaining serviceable hearing after treatment based on predictive factors including cochlear dose ≤4 Gy, marginal dose ≤13 Gy, and better baseline hearing level (AAO-HNS class A or GR grade I status).

Question 3: Among patients with sporadic vestibular schwannoma and baseline serviceable hearing who are treated with attempted hearing preservation microsurgery, what factors are associated with an elevated risk of acquiring non-serviceable hearing <6 months following surgery? The following factors were explored: tumor size ≤1 cm vs >1 cm in maximum CPA diameter, presence vs absence of fundal CSF fluid cap, retrosigmoid approach vs middle cranial fossa approach, presence vs absence of radiographic labyrinthine fluid change, baseline AAO-HNS class A vs B hearing (GR grade I vs II) or baseline word recognition score of 100% vs <100%.

Target Population

These recommendations apply to adults with sporadic vestibular schwannoma who have documented serviceable hearing in the ipsilateral ear at the time of diagnosis.

Recommendations

Level 3: It is suggested that individuals with serviceable hearing prior to microsurgery be informed that after surgery there is a moderately low rate (>25% to 50%) of hearing preservation immediately following surgery, moderately low rate (>25% to 50%) of hearing preservation at 2 years, moderately low rate (>25% to 50%) of hearing preservation at 5 years, and moderately low rate (>25% to 50%) of hearing preservation at 10 years.

Level 3: It is suggested that individuals with serviceable hearing prior to microsurgery should be informed about the likelihood of maintaining serviceable hearing after treatment based on predictive factors comprising better baseline hearing level (AAO-HNS class A and GR grade I status), smaller tumor size, and presence of a fundal CSF fluid cap.

INTRODUCTION

Rationale

The management of sporadic vestibular schwannoma has undergone a dramatic evolution over the last century.¹ Whereas skull base surgeons of the early-20th century were hailed for bringing perioperative mortality below 20%,^2,3 the early-21st century is being increasingly characterized by “chronic disease management” aimed at preserving neurologic function over achieving radical cure.^1,4-6 Paralleled by the advances in radiosurgical and microsurgical technique over the past half-century, disease detection underwent a similar reform with the advent of magnetic resonance imaging (MRI) and subsequent widespread adoption of screening protocols for asymmetrical sensorineural hearing loss. Consequently, the incidence of sporadic vestibular schwannoma has climbed nearly 5-fold over the past 30 years, with disease lifetime prevalence estimates exceeding 1 per 500 persons.^7,8 Across international population-based studies, improved detection of vestibular schwannoma has led to most patients being diagnosed in their 6th decade of life with less advanced symptoms and oftentimes with tumors that are confined to the internal auditory canal.^7,9,10

Stemming from this epidemiological shift, the primary symptom bringing patients with sporadic vestibular schwannoma to medical attention is asymmetric hearing loss.^1,9 As post-treatment facial nerve preservation has become the mainstay, attention has been increasingly directed to hearing preservation in recent years.¹¹ Perhaps unsuspectingly, significant controversy exists regarding the optimal treatment approach for patients wishing to maximize their long-term hearing.¹¹ Upfront radiosurgery, upfront microsurgery, and active surveillance have all been defended as reliable options for long-term hearing preservation.¹¹ To this end, studies have demonstrated that patients with similar tumors may receive very different recommendations and ultimately undergo varying treatments depending on the geographic location in which they seek care.^12,13

The 2022 update revisits the methodology of the 2018 guideline with refined PICO questions tailored to recent advancements in vestibular schwannoma management. Notably, the topics of pathology and emerging therapies, included in the 2018 guideline, were excluded in this update. This decision was made based on a focused scope intended to concentrate on the most impactful and recent evidence influencing clinical practice directly.¹ Over the past 5 years, the topic of hearing preservation in management of sporadic vestibular schwannoma has continued to receive considerable attention with multiple international publications during the intervening period.² For this reason, an updated systematic review and evidence-based guideline was pursued with the primary aim of describing modern rates of hearing preservation across the three management options for patients with sporadic vestibular schwannoma.

Objectives

This systematic review and clinical practice guideline aims to provide an updated summary of the rate of hearing preservation within the first 10 years after contemporary stereotactic radiation, microsurgery, or observation with serial imaging. Similar to the original review,¹ candidate prognostic features, such as tumor size and location, patient age, pretreatment hearing status, and others are explored for their potential contribution to long-term hearing preservation. Additionally, similar to the prior published guideline,¹ the current review focuses on patient and tumor-related factors, while detailed analyses of radiosurgical planning parameters, cochlear shielding strategies, comparison of microsurgical approaches, and methods of eighth nerve monitoring are deferred as they are reviewed in other updated guidelines.

Methodology

Literature Search

In updating the guideline, the task force conducted a comprehensive literature search for articles published from January 1, 2015, to May 20, 2022. This new evidence was evaluated de novo and then integrated with the abstracted data from prior to 2015. The integration of new studies was approached as a continuation of the prior abstracted data to maintain a cohesive evidence chain, ensuring that new insights were evaluated within the context of established knowledge. This method allowed us to systematically assess whether new evidence substantively shifted or reinforced existing recommendations. Each new study was weighed against the established criteria from 2018, with adjustments made to recommendations based on a synthesis of cumulative evidence, ensuring both rigor and continuity in our guidelines. Two electronic databases were searched: Ovid Medline and EMBASE. Strategies for searching electronic databases were constructed by the evidence-based clinical practice guideline task force members and the medical librarian using previously published search strategies to identify relevant studies (Appendix I).

The authors supplemented searches of electronic databases with manual screening of the bibliographies of all retrieved publications. The authors also searched the bibliographies of recent systematic reviews and other review articles for potentially relevant citations. All articles identified were subject to the study selection criteria listed above. As noted above, the guideline committee also examined lists of included and excluded studies for errors and omissions. The authors went to great lengths to obtain a complete set of relevant articles. Having a complete set ensures that the guideline is not based on a biased subset of articles.

Study Selection and Eligibility

Articles were retrieved and included only if they met specific inclusion/exclusion criteria. These criteria were also applied to articles provided by guideline task force members who supplemented the electronic database searches with articles from their own files. To reduce bias, these criteria were specified before conducting the literature searches.

Articles that did not meet the following criteria were, for the purposes of this evidence-based clinical practice guideline, excluded. To be included as evidence in the guideline, an article had to be a report of a study that:

Investigated patients with sporadic vestibular schwannoma.
Was a full article report of a clinical study.
Appeared in a peer-reviewed publication or a registry report.
Enrolled a minimum of 20 patients.
Was of humans.
Was published between January 1, 2015, and May 20, 2022.
Quantitatively reported serviceable hearing or raw data was available.
Was published in English.

Articles were excluded if it was determined they:

Were an in vitro study.
Were performed on cadavers.
Were medical records reviews, meeting abstracts, historical articles, editorial letters, or a commentary.
Were a systematic review, meta-analysis, or guideline developed by others.

Systematic reviews or meta-analyses conducted by others, or guidelines developed by others were not included as evidence to support this review due to the differences in article inclusion/exclusion criteria specified compared to the criteria specified by the Guidelines Task Force.

In the update of this guideline, the methodology employed remains consistent with that used in the 2018 edition. Table 4 presents side-by-side comparison of PICO elements for the 2018 and 2022 guidelines. The nine questions in the 2018 guidelines have been condensed to three questions (consolidating the 3 observation questions into one question, the 3 stereotactic radiation questions into one question and the 3 surgical questions into one question) for the current version. The literature review process, including the inclusion and exclusion criteria, continued to adhere to the established protocols previously set forth. This ensures continuity and comparability of the findings across different editions of the guidelines.

Assessment for Risk of Bias

All publications included in this review were retrospective or non-randomized prospective studies, which indicates a risk of treatment selection bias. Treatment modalities are often selected based on tumor size at presentation. For example, certain institutions choose to observe small tumors and only intervene on medium to large sized schwannomas, while other institutions prefer upfront intervention with radiosurgery or microsurgery in an attempt to preserve hearing. Most studies include a single treatment arm that hinders the ability to differentiate the effect of radiation on hearing loss from the natural history inherent to having a vestibular schwannoma. Lastly, the retrospective nature of most included studies poses risk of variability related to problems with erroneous data entry or incomplete data.

Data Analysis

Evidence tables for radiation treatment, microsurgery, and observation were constructed using key study parameters as outlined above. In addition, the percentages of patients who maintained serviceable hearing at time points between 1 and 10 years and who had serviceable hearing at baseline were recorded according to data available in each study. “Serviceable hearing” or “useful hearing” was defined by a word recognition score (WRS) of ≥50% and a pure tone average (PTA) or speech response threshold of ≤50 dB HL, which is equivalent to American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) class A-B and Gardner-Robertson (GR) grade I-II. The aggregate data obtained from individual studies were summarized via a weighted average to determine the overall percentage of patients with useful hearing at years 1 through 10 for each treatment modality. To accommodate a range of outcomes between studies, ordinal categories of rates were devised for the purpose of guideline formulation: “high rate” of hearing preservation defined by >75% to 100%, “moderately high rate” defined by >50% to 75%, “moderately low rate” defined by >25% to 50%, and “low rate” defined by 0% to 25%.

Rating Quality of Evidence

The American Medical Association and many specialty societies, including the AANS, the CNS, and the American Academy of Neurology formalized the concept of linking evidence to recommendations by designating specific relationships between the strength of evidence and the strength of recommendations to avoid ambiguity. In the paradigm for prognostication used in this guideline, evidence is classified into I of III tiers based upon the degree to which the study fulfills 5 technical criteria as outlined below:

Was a well-defined representative sample of patients assembled at a common (usually early) point in the course of their disease?
Was patient follow-up sufficiently long and complete?
Were objective outcome criteria applied in a “blinded” fashion?
If subgroups with different prognoses were identified, was there adjustment for important prognostic factors?
If specific prognostic factors were identified, was there validation in an independent “test set” group of patients?

Class I evidence is used to support recommendations of the strongest type, defined as Level 1 recommendations, and require that all 5 technical criteria are satisfied. Class II evidence supports intermediate strength recommendations, defined as level 2 recommendations, and require that 4 of the 5 technical criteria be met. Finally, Class III evidence supports level 3 recommendations, comprising all remaining studies that satisfy 3 or fewer of the 5 technical criteria. A basis for these guidelines and the hierarchy classification of evidence can be located here: https://www.cns.org/guidelines/guideline-development-methodology.

Revision Plans

In accordance with the National Academy of Medicine’s standards for developing clinical practice guidelines, the Guidelines Task Force will monitor related publications following the release of this document and will revise the entire document and/or specific sections “if new evidence shows that a recommended intervention causes previously unknown substantial harm; that a new intervention is significantly superior to a previously recommended intervention from an efficacy or harms perspective; or that a recommendation can be applied to new populations”³. In addition, the Guidelines Task Force will confirm within 5 years from the date of publication that the content reflects current clinical practice and the available technologies for the evaluation and treatment for patients with sporadic vestibular schwannoma. Given that the guideline development process is comprehensive and time-intensive, not all sections will be updated immediately to reflect newly published studies unless they are truly practice changing. Instead, newly available evidence is systematically reviewed and incorporated in scheduled updates rather than ad hoc revisions.

SUMMARY OF PREVIOUS GUIDELINE

The first version of the guideline summarized existent evidence at the time regarding rates of hearing preservation at different time points following treatment. Most patients eventually developed non-serviceable hearing as a result of disease or treatment. Given the class III and limited class II evidence, there was no clear advantage of one modality over another with regard to long-term hearing preservation. At 10 years following treatment, more than half of patients with baseline serviceable hearing will decline to non-useful hearing levels regardless of treatment modality.

RESULTS

The literature search yielded 439 abstracts. The authors reviewed all abstracts from the literature search and identified the articles for full-text review and extraction, addressing the clinical questions, in accordance with the literature search strategy. Task force members identified the best research evidence available to answer the targeted clinical questions.

The task force selected 114 full-text articles for full-text review. Of these, 85 were rejected for not meeting inclusion criteria or for being off topic. Twenty-nine were selected for systematic review (Figure 1 of the full online report). The authors supplemented searches from the electronic data bases with manual screening of the bibliographies of all retrieved publications. Additionally, bibliographies of systematic reviews and other review articles were screened for relevant citations. All articles identified were subject to the study selection criteria. Table 5 of the full report presents a side-by-side comparison of recommendations in the 2018 vs 2022 guidelines.

Observation

Recommendations

Level 3: It is suggested that individuals with serviceable hearing at time of sporadic vestibular schwannoma diagnosis, who proceed with an initial wait-and-scan strategy, be informed about the likelihood of maintaining serviceable hearing based on predictive factors including better baseline hearing level, including AAO-HNS class A or GR I status and absence of tumor growth during observation.

Seven observational studies were included in the final review.^15-21 Only studies evaluating outcomes of hearing preservation following conservative observation with serial imaging, a minimum of 20 patients, and a medium or mean of at least 2 years of follow-up were included. The key results of initial studies are outlined in Table 1 and are summarized within the guideline recommendations. There was 1 study that included both an irradiation cohort and an observation control arm. All included articles were retrospective and class III evidence.

In 2022, Gurewitz et al. reported outcomes on hearing preservation with the conservative approach.¹⁶ The study included 107 patients with AAO-HNS hearing class A or B and reported a 77.6% (83/107) hearing preservation rate at the last follow-up (median of 24 months). Patients with class A hearing retained serviceable hearing at a rate of 69.4% (50/72). There was no statistically significant association between time to non-serviceable hearing and age. Time to non-serviceable hearing was significantly associated with initial tumor volume and tumor growth rate. However, hearing deterioration was noted even in patients with slow growing tumors.

A retrospective study encompassing 213 patients with baseline serviceable hearing by Patel et al. reported rates of preservation of 88%, 74%, 67%, 65%, and 49% at 2-, 4-, 6-, 8-, and 10-years following diagnosis, respectively.²¹ Larger tumor volume at diagnosis was associated with increased PTA and decreased WRS. Tumor growth was not found to be significantly associated with time to non-serviceable hearing. Similarly, a study by Hunter et al. reported 76.8% (358/466) of patients retained serviceable hearing at a median of 2.4 years post diagnosis.¹⁷ The study quantified the risk of developing non-serviceable hearing based on patient’s presenting audiometric measures. Each 10% decrease in WRS and 10 dB increase in PTA was associated with a 1.5-fold and a 2-fold increased risk of developing non-serviceable hearing, respectively. In another retrospective study by Milner et al., hearing outcomes were assessed in vestibular schwannoma patients managed conservatively or treated with stereotactic radiosurgery (SRS).²⁰ Overall serviceable hearing at a mean of 6 years of follow-up was found to be 53% in the conservative management group versus 26% in the SRS group.

Kirchmann et al. reported long-term hearing outcomes in 156 patients with intracanalicular vestibular schwannoma.¹⁹ At 10 years, 34.2% (25/73) patients retained serviceable hearing. Risk of hearing loss was 82.7% (24/29) in patients with class A hearing at diagnosis. Another study by Elliott et al. compared serviceable hearing preservation between conservative management and stereotactic radiotherapy (SRT) in patients with sporadic vestibular schwannoma.¹⁵ Ninety-eight patients underwent conservative observation and 25 underwent fractionated SRT. At a median follow-up of 46 months, serviceable hearing was preserved in 54% and 40% for conservative observation and SRT, respectively. A multivariable model revealed both tumor growth rate and baseline hearing class were predictors of hearing preservation at the end of follow-up. Jethanamest et al. described hearing outcomes of 37 patients undergoing serial observation.¹⁸ Overall, 75.7% (28/37) of patients retained serviceable hearing at a median of 34.8 months. For 50% of patients, the median time to hearing loss worsening to non-serviceable hearing was 76 months.

Synthesis: Class III evidence supports the conclusion that risk of progression to non-serviceable hearing continually increases with time during conservative observation. When evaluating all patients with sporadic vestibular schwannoma and serviceable hearing at the initiation of an observation approach, 78% maintained serviceable hearing at 2 years, 59% at 5 years and 47% at 10 years.

Radiosurgery

Recommendations

Level 3: It is suggested that individuals with serviceable hearing prior to stereotactic radiosurgery should be informed about the likelihood of maintaining serviceable hearing after treatment based on predictive factors including cochlear dose ≤4 Gy, median marginal dose ≤13 Gy, and better baseline hearing level, including AAO-HNS class A or GR grade I status.

Nineteen radiosurgery studies were included in the final review.^20,22-39 Only studies evaluating single-fraction stereotactic radiosurgery using a contemporary low-dose treatment paradigm including a median dose of ≤13 Gy to the tumor margin, with a minimum of 20 patients, and a medium or mean of at least 2 years of follow-up were included. The key results of initial studies are outlined in Table 2 and are summarized within the guideline recommendations. There was 1 study that included both a radiosurgery cohort and an observation control arm²⁰ and two publications that included both radiation and microsurgery cohorts^25,26. All included articles reported class III evidence.

In 2022, Teyateeti et al. evaluated outcomes of gamma knife radiosurgery (GKS) in 21 patients with serviceable hearing over a median of 114 months. ³⁶ They reported estimated rates of hearing preservation at 2-, 5-, and 10-years post treatment of 84%, 72% and 39%, respectively. The study included two patient groups, one treated with 50% isodose line (IDL50) and the other with 40% isodose line (IDL40). The average time to loss of serviceable hearing for the IDL50 group was 82 months versus a more prolonged time to loss of hearing preservation of 128 months for the IDL40 group. Maksimoski et al. reported serviceable hearing preservation rates of 27%, 24%, 13%, and 4.1% at 3-, 5-, 7-, and 10-years post radiosurgery in 133 vestibular schwannoma patients with serviceable hearing at time of treatment.³⁰ The more rapid decline in hearing over time seen in this study may have been attributed to reported high cochlear dose range: median of 9.7 Gy and maximum range 3.7-19.9 Gy. Van Linge et al. evaluated change in hearing after stereotactic radiosurgery and radiotherapy (FRST) in 57 vestibular schwannoma patients with serviceable hearing. ³⁷One year after treatment, 84% of SRS and 71% of FSRT had preservation of serviceable hearing. Rates were dramatically lower at the 3 year mark, at 27% for SRS and 50% for FSRT. Hearing preservation was not statistically different between the two treatment groups. Multivariable regression revealed that restricted cochlear V90 (>5.3 Gy) and worse pretreatment PTA were associated with progression to non-serviceable hearing.

Three studies were published by Ogino et al. in 2021 investigating the effects of radiosurgery on rates of hearing deterioration.^32-34 The first study evaluated outcomes in 100 patients with small-to-medium sized tumors.³² All 100 patients were initially observed for 17 months and then treated and followed for a median of 4.4 years. At last followup, 63% (42/67) of patients who started with GR grade I maintained serviceable hearing in comparison to 24% (8/33) of those who started with GR grade II. Overall estimated hearing preservation rates were 65.9%, 52.5%, and 40.5% at 3-, 5-, and 10-years. Younger age (<55 years) and GR grade I were significantly associated with improved hearing preservation. The second study evaluated hearing preservation rates post SRS in 120 patients with serviceable hearing and intracanalicular tumors over a 10-year period.³⁴ Preservation rates of serviceable hearing at 3, 5, and 10 years were 77%, 64%, and 27%. Better hearing at the time of SRS and smaller tumor volume were associated with improved hearing preservation. The third study by Ogino et al. reported hearing preservation outcomes in 42 vestibular schwannoma patients with Koos grade IV tumors and serviceable hearing.³³ Hearing preservations rates were found to be 58%, 50%, and 36% at 3-, 5-, and 7-years post SRS. Furthermore, younger age and initial GR grade I were associated with better hearing outcomes. The authors concluded that SRS can be a reasonable option for large vestibular schwannoma in elderly patients and those with many medical comorbidities.

Wage et al. evaluated long-term hearing outcomes in 53 patients with serviceable hearing treated with GKS.³⁸ Serviceable hearing was maintained in 40% (21/53) of patients at 5 years. Median time to loss of serviceable hearing was 19 months. Rates of hearing loss in this study correlated with maximum cochlear modiolus dose. In a 2020 study by Han et al., 51 patients with small-to-medium sized tumors and serviceable hearing were treated with either GKS or microsurgery.²⁶ At 6 years of follow-up, hearing was preserved in 16/30 (53%) patients in the GKS cohort vs 15/21 (71%) in the microsurgery cohort, which was not noted to be significantly different.

Johnson et al. reported long-term outcomes of SRS in 326 patients with serviceable hearing and Koos I – VI tumor sizes.²⁸ Serviceable hearing preservation rates were 77%, 63%, and 51% at 3, 7, and 10 years. Pre-SRS GR grade I hearing, absence of subjective vestibulopathy, and younger age portended better rates of hearing preservation. Prabhuraj et al. reported treating 77 patients with small-to-medium sized vestibular schwannoma using a median marginal dose of 12 Gy.³⁵ The reported rate of serviceable hearing preservation was 79% at last follow-up, a median of 30 months following treatment.³⁵ Tumor volume was not found to affect hearing preservation. However, on multivariable analysis, pretreatment PTA <30, GR grade I, and age >40 were predictors of better hearing preservation.

Similarly, Frischer et al. reported outcomes in 132 patients with baseline serviceable hearing treated with GKS.²⁴ Hearing was preserved in 53%, 34%, and 34% of patients at 5-, 10-, and 15-years following treatment. In agreement with studies described above, the authors noted that lower GR hearing grade prior to GKS and smaller median dose to the cochlea were independent predictors of the GR grade at follow-up. Bowden et al. reported hearing preservation of 82% and 62% at 2- and 5-years post SRS in 111 patients with SH.²³ All patients starting with 100% WRS maintained serviceable hearing at 5 years following SRS. No significant differences in auditory outcomes were noted between the macrocystic and microcystic tumors. Watanabe et al. also found that older age (>65 years), large tumor volume (>8 cm3), and higher cochlear dose (>4.2 Gy) are unfavorable factors for hearing preservation following SRS.³⁹ Their study included 66 patients with serviceable hearing who underwent SRS with 12 Gy marginal dose (range 8.8-15.5 Gy) and median cochlear dose of 4.1 Gy (range 2.3-5.7 Gy). Hearing preservation rates were found to be 49%, 24%, and 12% at 5-, 10-, and 15-years post SRS.

In a study by Horiba et al., dose to the brainstem, cranial nerves, and cochlea were kept below 14 Gy, 12 Gy, and 4 Gy, respectively, with mean marginal dose of 11.9 Gy (range of 11-12 Gy).²⁷ Serviceable hearing was preserved in 57% (28/49) of patients at the last follow-up at a median of 56 months following treatment. Although not statistically significant, hearing preservation rates for tumors with and without extension of the intrameatal part of the neoplasm up to the fundus were 40% and 60%. Klijn et al. reported comparable hearing preservation rates of 64% and 42% at 3- and 5- years post treatment.²⁹ Their cohort consisted of 71 patients with serviceable hearing.

Three studies only included patients with baseline GR grade I.^22,25,31 Akpinar et al. reported a serviceable hearing preservation rate of 88% at 5 years when patients were treated within 2 years of diagnosis vs 55% when patients were treated greater than 2 years after diagnosis.²² However, the late treatment group had a significantly higher pre-SRS PTA and slightly lower WRS, which likely biased study results. Golfinos et al. demonstrated delayed loss of preoperative hearing in the SRS cohort when compared to an age- and tumor size-matched surgical cohort (21 patients in each group).²⁵ In their study, 86% of patients retained serviceable hearing at 3 years post SRS compared to 43% of microsurgery patients. However, preservation of serviceable hearing converged for the two cohorts by month 60. Lastly, Mousavi et al. reported hearing outcomes in patients having baseline GR grade I who underwent GKS.³¹ Their cohort was further divided into patients with and without subjective hearing loss. Patients with no subjective hearing loss retained 100% serviceable hearing at 3-year follow-up compared to 55% of those who had subjective hearing loss. Their overall hearing preservation rate was 72% (48/68) at 3 years post GKS. Patients with PTA <15 dB before GKS had significantly higher rates of serviceable hearing preservation.

Synthesis: Class III evidence supports the conclusion that the risk of losing serviceable hearing with radiosurgery increases with time at a slightly accelerated rate compared to observation. When evaluating all patients with serviceable hearing at baseline, approximately 71% maintain serviceable hearing at 2 years, 56% at 5 years, and 38% at 10 years.

Microsurgery

Recommendations

Level 3: It is suggested that individuals with serviceable hearing prior to microsurgery should be informed about the likelihood of maintaining serviceable hearing after treatment based on predictive factors comprising better baseline hearing level, including AAO-HNS class A and GR grade I status, smaller tumor size, and presence of a fundal CSF fluid cap.

Six microsurgery studies were included in the final review.^25,26,40-43 Only studies evaluating outcomes with intent of hearing preservation using the middle cranial fossa or retrosigmoid/suboccipital craniotomy, a minimum of 20 patients, and a median or mean of at least 2 years of follow-up were included. The key results of initial studies are outlined in Table 3 and are summarized within the guideline recommendations. There were 2 studies that included both an SRS cohort and a microsurgery control arm.^25,26 All included articles reported class III evidence.

In 2020, Han et al. reported long-term outcomes in 51 patients with small-to-medium sized vestibular schwannoma receiving GKS or microsurgery with baseline serviceable hearing.²⁶ In total, 71% (15/21) of patients treated with microsurgery maintained serviceable hearing at the last follow-up, 5 years after treatment. This rate was higher than the reported 53% serviceable hearing preservation for GKS patients, although this difference did not achieve statistical significance. Similarly, Ichimasu et al. reported hearing preservation rates of 74.9% and 64.6% at 8 and 10 years, respectively.⁴² Dowling et al. evaluated hearing outcomes in patients with tumors confined to the IAC or with 1 cm or less of CPA extension.⁴¹ In patients who had serviceable hearing preservation postoperatively (i.e., not including patients who lost serviceable hearing during microsurgical resection), the rate of hearing preservation at 5 years was 81%. For the same vestibular schwannoma size, another study by Zhu et al. reported 47% (33/70) rate of hearing preservation at 4 years of follow-up.⁴³ In the study, postoperative rates for preservation of serviceable hearing were 85.7% among those with preoperative class A hearing versus 46.5% among those with class B hearing. Similarly, Ahmed et al. reported that preoperative AAO-HNS class A hearing had significantly higher rates of successful serviceable hearing preservation at all postoperative intervals.⁴⁰ Preservation of serviceable hearing was 82% at 3-5 years, 67% at 6-8 years, 68% at 9-11 years, and 18% at 12 or more years. The study by Golfinos et al. only included patients with class A hearing, and preservation of serviceable hearing was found to be 43% (9/21) in the microsurgery group opposed to 86% (18/21) in the SRS group.²⁵ Despite the difference in reported outcomes, estimated rates of hearing preservation converged by month 60 for both groups. Two studies report data on 7 patients’ hearing status at 10 years following treatment, 4 of whom demonstrated serviceable hearing.^26,41

Synthesis: When evaluating all patients with preoperative serviceable hearing who are considered candidates for hearing preservation surgery, approximately 43% maintain serviceable hearing immediately postoperatively, 48% maintain serviceable hearing at 2 years, 40% at 5 years, and 32% at 10 years. Studies consistently indicate rates of serviceable hearing preservation are higher with better preoperative hearing. Although maintenance of serviceable hearing can be durable postoperatively, studies indicate a progressive decline over time following treatment for many patients.

Additional Comments:

Observation

Published rates of maintaining serviceable hearing during observation from 2015 to 2022 are consistent with the previously published guideline.¹¹ Overall, at 10 years following diagnosis, approximately 45% of patients can be expected to maintain serviceable hearing if observation is continued. These data are comparable to a recent large systematic review and meta-analysis that chronicled approximately 1,700 patients with serviceable hearing at the time of diagnosis, suggesting that the approximate rate of maintaining serviceable hearing was 75% at 3 years, 60% at 5 years, and 40% at 10 years.⁴⁴

Paralleling the radiosurgery and microsurgery data, better hearing at time of diagnosis is consistently associated with better maintenance of serviceable hearing long-term. Research has demonstrated a step-wise progression in risk of losing serviceable hearing during observation per 10% decrease in WRS and per 10 dB increase in PTA.¹⁷ For this reason, patient counseling must be tailored to the individual patient. For instance, a patient with an intracanalicular tumor who has 100% word recognition and a pure-tone average of 10 dB in the affected ear does not have the same 10-year risk of losing serviceable hearing as another patient with the same tumor who has a WRS of 65% and a pure-tone average of 35 dB – despite both having serviceable hearing. In this scenario, although this systematic review demonstrates that the overall chance of maintaining serviceable hearing during observation approximates 45% at 10 years, it is likely that the first patient has a much greater than a 45% chance of having serviceable hearing at 10 years whereas the latter patient likely has less than a 45% likelihood of this outcome. In any case, existing data exceeding 5 years of observation is limited, and further research into the broad array of patients who present with serviceable hearing is necessary.

Radiosurgery

The overall probability of maintaining serviceable hearing following radiosurgery was found to be consistent with the previously published CNS guideline.¹¹ In the short-term, patients are likely to maintain serviceable hearing following low-dose radiation therapy. However, protracted or delayed hearing loss is expected in most cases. Independent factors portending serviceable hearing preservation were marginal dose, cochlear dose, and baseline hearing at diagnosis. Cochlear dose continues to be an independent predictor of hearing preservation post radiosurgery treatment in many studies. ^24,30,37,39 In the study by Frischer et al., patients receiving a median cochlear dose of >6 Gy showed a significantly higher rate of acquiring non-serviceable hearing at last follow-up than patients receiving a lower dose.²⁴ This finding was supported by other authors verifying results at even lower cochlear doses.^30,37,39 Watanabe et al. noted a mean cochlear dose greater than 4.2 Gy was an unfavorable factor for hearing preservation.³⁹ Serviceable hearing preservation rates were notably poorer in studies that included high cochlear doses. Maksimoski et al. reported 27% hearing preservation rate at 3 years of follow-up with a median cochlear dose of 9.7 Gy.³⁰ Patients who started with GR grade I or a AAO-HNS class A when undergoing radiosurgery with medial marginal dose of <12.5 Gy were found to have significantly improved serviceable hearing preservation rates.^28,32,35 Further, Mousavi et al. showed that serviceable hearing in patients with GR grade I was preserved at a higher rate in people who reported no subjective hearing loss.³¹ Age at treatment was associated with improved serviceable hearing in some studies^21,28,39 and worse in others.³⁵ Therefore, a conclusion cannot be drawn regarding this factor considering these inconsistent outcomes.

Microsurgery

The previous CNS guideline and other publications indicate that if hearing can be successfully preserved immediately following surgery, 65-100% of patients maintain serviceable hearing long-term.¹¹^,⁴¹ This finding is consistent with the included studies in this updated guideline. Reported outcomes on microsurgical resection and hearing preservation suggest that proactive resection for small tumors with good preoperative hearing can be a way to preserve preoperative hearing levels.⁴¹ Similar to the radiosurgery group, postoperative hearing preservation rates were higher in patients with preoperative AAO-HNS class A compared to class B.⁴³ Additionally, success rates of serviceable hearing preservation following microsurgery are strongly associated with tumor size.²⁵ A recent study by Macielak et al. showed that the probability of incurring less optimal microsurgical outcomes begins to steeply increase at 14-20 mm of CPA extension.⁴⁵ Overall maintenance of hearing preservation at 2, 5, and 10 years were comparable in the studies included here to the previously 2018 published guideline with rates of 47%, 45%, and 43%, respectively.¹¹

DISCUSSION

The updated guideline continues to reflect the complexity of managing sporadic vestibular schwannoma, particularly concerning the preservation of serviceable hearing. As established in our 2018 guideline, most patients are likely to experience hearing degradation over time, irrespective of the treatment modality chosen. This ongoing risk underscores the importance of realistic patient counseling about the long-term prospects of hearing preservation as highlighted in our previous discussion and also recognizes the critical need to develop new and innovative strategies to improve hearing preservation and hearing rehabilitation in this population¹. The current systematic review integrates these foundational insights with new evidence from 2015 to 2022, maintaining consistency in our analytical framework while updating our recommendations based on the latest research findings.

Published following completion of the current systematic review, Schnurman et al. recently reported a study using propensity score matching to match 99 patients with serviceable hearing treated with GKRS to 99 patients also with serviceable hearing who underwent observation alone, with over half of the cohort having AAO-HNS class A hearing at time of diagnosis.⁴⁶ Interestingly, the rate of losing class A hearing did not statistically or clinically significantly differ between those undergoing radiosurgery compared with observation alone (median time of 27.2 months versus 29.2 months; p=0.88). Among the larger cohort inclusive of those with class B hearing, the median time to loss of serviceable hearing also did not significantly differ (37.7 months versus 48.8; p=0.18), although the difference may represent a clinically significant difference of almost one year. Among those with class A hearing, increasing mean cochlear dose was not significantly associated with loss of class A hearing. Taken together with the current systematic review, these data highlight that the long-term difference in maintenance of serviceable hearing, and particularly class A hearing, require further study.

On systematic review of the literature from 2015 to 2022, the most notable limitation that confound conclusions drawn from existing published data surrounds follow-up duration and selection bias. Very limited data exist beyond 5 years after diagnosis, and attrition in most studies is often significant by 3 years. As a result, published estimates of maintaining serviceable hearing are skewed by small numbers. This limitation was present across all three treatment modalities in the current review where less than 10 published cases inform the rate of maintaining serviceable hearing after microsurgery, 20 for radiosurgery, and 10 for observation. What is more, published rates of maintaining serviceable hearing may be susceptible to informative censoring, where patients in one arm are disproportionally censored for reasons directly related to the study – therefore violating one of the key assumptions of survival analysis.^47,48 As an illustrative example, this scenario would occur whenever a patient may experience a poor outcome and seek care elsewhere. They are therefore censored and “lost to follow-up” but actually experienced the endpoint of interest.

Perhaps the most critical issue surrounding hearing preservation in sporadic vestibular schwannoma is the ongoing controversy regarding the optimal management approach, particularly for patients with small tumors and useful hearing. Individual centers have published very promising reports regarding upfront microsurgery or upfront radiosurgery to achieve long-term tumor control while also preserving serviceable hearing at a rate comparable to observation long-term. Unfortunately, these results do not appear to be consistently reproducible across all publications, as evidenced by the current review and the previously published guideline.¹¹ To this end, the current review demonstrates that most patients with serviceable hearing, regardless of treatment modality, will ultimately lose serviceable hearing by 10 years of follow-up. When looking at recently published data, the difference among the three treatment modalities appears less than historically considered. Nonetheless, the level of evidence supporting these claims remains low secondary to pragmatic limitations surrounding the prospective randomized study of a relatively rare benign tumor where significant individual patient and provider preferences drive management. As prior research suggests similar patients may receive differing recommendations and ultimately undergo different treatment depending on where they seek care across the United States,^12,13 the pursuit of evidence-based practice should be paramount.

Extending from the observation that, regardless of treatment modality, most patients will ultimately lose serviceable hearing by 10 years following diagnosis, an emphasis on rehabilitation of single-sided deafness and asymmetrical sensorineural hearing loss is also critical. Recent studies have shown that about one third of patients with unilateral vestibular schwannoma ultimately use hearing assistive devices long-term.^49,50 This observation suggests that most patients either sufficiently adjust to unilateral hearing loss or are unsatisfied with the benefits achieved with current device options. Since the publication of the prior guideline in 2018,¹¹ one of the significant developments surrounds the United States Food and Drug Administration’s approval in 2019 of single-sided deafness and asymmetrical sensorineural hearing loss as an indication for unilateral cochlear implantation among patients 5 years and older. The literature investigating the utility of simultaneous or sequential cochlear implantation in unilateral vestibular schwannoma is growing rapidly, with roughly 150 related publications on the topic over the past 5 years. Recent investigations have employed cochlear implants in patients undergoing active surveillance,⁵¹ radiosurgery,⁵² and microsurgery,⁵³ all of which report promising results. Further research will be required to determine the ultimate utility of cochlear implantation in this patient population relative to tumor treatment modality.

CONCLUSIONS

Reflecting on both the current and past discussions, it is clear that the management of vestibular schwannoma is dynamic and requires a nuanced understanding of both the disease process and the evolving landscape of treatment options. Our guideline is committed to providing the most current, evidence-based recommendations to aid clinicians in delivering optimal care to their patients. Modern management of sporadic vestibular schwannoma has progressively shifted towards maximizing quality of life through preservation of neurologic function over “cure.” As a natural consequence of pragmatic limitations surrounding performing robust prospective randomized studies across the three management modalities, the currently available quality of evidence is low. Significant provider biases thus influence modern management, with studies demonstrating notably variant practice patterns for similar patients across the United States⁴. In this light, it is worth emphasizing that regardless of treatment modality, less than half of patients with sporadic vestibular schwannoma who present with serviceable hearing will maintain this useful hearing by 10 years. Across all studies, microsurgery and radiosurgery appear to accelerate this decline, although further research is needed given limitations of available evidence.

Conflicts of Interest

All Guideline Task Force members were required to disclose all potential COIs prior to beginning work on the guideline, using the COI disclosure form of the AANS/CNS Joint Guidelines Review Committee. The CNS Guidelines Committee and Guideline Task Force Chair reviewed the disclosures and either approved or disapproved the nomination and participation on the task force. The CNS Guidelines Committee and Guideline Task Force Chair may approve nominations of task force members with possible conflicts and restrict the writing, reviewing, and/or voting privileges of that person to topics that are unrelated to the possible COIs.

Disclosure of Funding

This evidence-based clinical practice guideline was funded exclusively by the Congress of Neurological Surgeons, which received no funding from outside commercial sources to support the development of this document.

Disclaimer of Liability

This clinical systematic review and evidence-based guideline was developed by a physician volunteer task force as an educational tool that reflects the current state of knowledge at the time of completion. Each chapter is designed to provide an accurate review of the subject matter covered. This guideline is disseminated with the understanding that the recommendations by the authors and consultants who have collaborated in their development are not meant to replace the individualized care and treatment advice from a patient’s physician(s). If medical advice or assistance is required, the services of a competent physician should be sought. The proposals contained in this guideline may not be suitable for use in all circumstances. The choice to implement any recommendation contained in this guideline must be made by a managing physician in light of the situation in each particular patient and on the basis of existing resources.

Acknowledgments

The Guidelines Task Force would like to acknowledge the CNS Guidelines Committee for their contributions throughout the development of the guideline, the AANS/CNS Joint Guidelines Review Committee, as well as the contributions Trish Rehring, MPH, Director for Evidence-Based Practice Initiatives for the CNS, and Janet Waters, MLS, BSN, RN, for assistance with the literature searches. Throughout the review process, the reviewers and authors were blinded from one another. At this time the Guidelines Task Force would like to acknowledge the following individual peer reviewers for their contributions: Patti Raksin, Tjoumakaris, Andrew Carlson, Neil Majmundar, Jeff Mullin and Koji Ebersole.

References

Carlson ML, Vivas EX, McCracken DJ, Sweeney AD, Neff BA, Shepard NT, Olson JJ. Congress of Neurological Surgeons Systematic Review and Evidence-Based Guidelines on Hearing Preservation Outcomes in Patients With Sporadic Vestibular Schwannomas. Neurosurgery. 2018;82(2):E35-E9. doi: 10.1093/neuros/nyx511. PubMed PMID: 29309683.
Carlson ML, Link MJ. Vestibular Schwannomas. N Engl J Med. 2021;384(14):1335-48. Epub 2021/04/08. doi: 10.1056/NEJMra2020394. PubMed PMID: 33826821.
Ransohoff DF, Pignone M, Sox HC. How to decide whether a clinical practice guideline is trustworthy. JAMA. 2013;309(2):139-40. doi: 10.1001/jama.2012.156703. PubMed PMID: 23299601.
Carlson ML, Glasgow AE, Grossardt BR, Habermann EB, Link MJ. Does where you live influence how your vestibular schwannoma is managed? Examining geographical differences in vestibular schwannoma treatment across the United States. J Neurooncol. 2016;129(2):269-79. Epub 20160622. doi: 10.1007/s11060-016-2170-5. PubMed PMID: 27334903.

Appendix I: Literature Searches

Search Strategies

MEDLINE

Ovid MEDLINE(R)

1 Radiosurgery/ 18595

2 (RADIOSURG* or RADIO-SURG*).mp. 24199

3 ((stereotactic or stereotaxic) and (radiation* or radiotherap* or RADIO-THERAP* or RADIOGRAPH*)).mp. [mp=title, abstract, original title, name of substance word, subject heading word, floating sub-heading word, keyword heading word, organism supplementary concept word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms] 19400

4 Radiotherapy/ and (stereotactic or stereotaxic).mp. [mp=title, abstract, original title, name of substance word, subject heading word, floating sub-heading word, keyword heading word, organism supplementary concept word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms] 693

5 Microsurgery/ or (micro-surger* or microscale surger* or microscopic surger* or microsurgical*).ti,ab,kw. 39078

6 Watchful Waiting/ 4898

7 (active surveillance or expectant management or watchful waiting).ti,ab,kw. 14821

8 Conservative Treatment/ 4588

9 (conservative management* or conservative therap* or conservative treatment* or CONSERVATIVE APPROACH*).ti,ab,kw. 63508

10 ('WAIT and SCAN').ti,ab,kw. 393

11 (WAIT adj2 SCAN*).mp. [mp=title, abstract, original title, name of substance word, subject heading word, floating sub-heading word, keyword heading word, organism supplementary concept word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms] 164

12 or/1-11 150465

13 exp Hearing/ 26179

14 HEARING.mp. 140534

15 (auditory function or auditory perception or noise perception or sound perception or AUDITION).ti,ab,kw. 7121

16 or/13-15 146032

17 12 and 16 2003

18 exp Neuroma, Acoustic/ 8763

19 ((vestib* or acoustic) adj3 (neuroma* or neurilemmoma* or neurilemoma* or neurinoma* or tumor* or tumour* or schwannoma*)).mp. [mp=title, abstract, original title, name of substance word, subject heading word, floating sub-heading word, keyword heading word, organism supplementary concept word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms] 11046

20 (acoustic nerve cancer* or acoustic neurofibroma* or acusticus neurinoma* or auditory nerve neurinoma* or ear schwannoma* or angle tumor* or angle tumour* or cerebellopontine angle tumor* or neurinoma of the acoustic nerve or neurosensory deafness* or sensoryneural deafness* or sensory neural deafness*).ti,ab,kw. 1211

21 18 or 19 or 20 12489

22 limit 21 to english language 10469

23 Animals/ not Humans/ 4974929

24 22 not 23 10374

25 comment/ or editorial/ or letter/ or review/ or systematic review/ 5102112

26 24 not 25 8685

27 exp adolescent/ or exp child/ or exp infant/ 3849849

28 exp Adult/ 7797507

29 27 not 28 2052582

30 26 not 29 8366

31 limit 30 to dt=20150101-20220522 2297

32 in vitro techniques/ 387712

33 Culture Techniques/ 47809

34 Drug Evaluation, Preclinical/ 54481

35 Disease Models, Animal/ 383220

36 Xenograft Model Antitumor Assays/ 44247

VS UPDATE HEARING PRESERVATION

Appendix IV. Evidence Tables

Table 1: Hearing preservation with wait and watch

Author/Year	Study Description	Data Class	Results and Conclusion
Gurewitz et al, 2022	Objective: To investigate the relationship between hearing loss and tumor volumetric growth rates in patient with unilateral VS. Design: Retrospective chart review. Number of patients: 107 patients with unilateral VS serviceable hearing; 72 were AAO-HNS hearing class A. Follow-up: Median of 24.3 months (IQR 8.5-48.8 months).	III	Results: 77.6% (83/107) retained serviceable hearing at last followup, 69.4% (50/72) of those with hearing class A retained it. No significant association between baseline time to non-serviceable hearing and age. Time to non-serviceable hearing was associated with initial tumor volume and tumor growth rate. Authors Conclusion: Larger initial tumors and faster growth rates are associated with elevated risk of losing serviceable hearing. Comments and Conclusions: The retrospective nature of this study yields class III data. Many patients with stable or slow growing tumors demonstrated a decline in hearing function thus stratifying patients based on hearing loss risk is problematic.
Patel et al, 2020	Objective: To ascertain relationship among VS tumor volume, growth and hearing loss. Design: Retrospective chart review, single center. Number of patients: 213 patients with serviceable hearing (AAO-HNS class A or B) and audiometric data were included. Follow-up: Median of 3 years.	III	Results: Rates of maintaining serviceable hearing at 2-, 4-, 6-, 8-, and 10-years following diagnosis were 88%, 74%, 67%, 65%, and 49%, respectively. Larger volume at diagnosis was associated with increased PTA and decreased WRS. Tumor growth was not significantly associated with time to non-serviceable hearing. Authors Conclusion: Larger initial tumor volume was associated with poorer hearing at baseline and with the development of non-serviceable hearing during observation. Comments and Conclusion: The retrospective nature of this study yields class III data.
Hunter et al, 2018	Objective: To characterize risk of progression to non-serviceable hearing in patient with VS undergoing observation. Design: Retrospective case series in two tertiary care centers. Number of patients: 466 patients with serviceable hearing with AAO-HNS hearing class A or B. Follow-up: Median of 2.3 years	III	Results: 76.8% (358/466) patients retained serviceable hearing at median of 2.4 years (IQR 1.0-4.2). 23.2% (108/466) developed non-serviceable hearing at a median of 1.9 years following diagnosis. Each 10% decrease in WRS and 10 dB increase in PTA was associated with a 1.5-fold and 2-fold increased risk of developing non-serviceable hearing, respectively. Authors Conclusion: Good baseline PTA and WRS are associated with maintenance of serviceable hearing. Comments and Conclusions: The retrospective nature of this study yields class III data. Objectively quantified the risk of developing non-serviceable hearing based on patient’s presenting audiometric measures.
Kirchmann et al, 2017	Objective: To report long-term occurrence of hearing loss in VS patients. Design: Retrospective chart review. Number of patients: 156 patients with intracanalicular VS managed conservatively. 73 of those has serviceable hearing class A or B, AAO-HNS. Follow-up: 9.5 years (range, 1-25 years).	III	Results: 34.2% (25/73) retained serviceable hearing at last followup. Tumor growth to extrameatal extension occurred in 23% of patients, with the majority occurring in the first years after diagnosis (4.6 years). Authors Conclusion: Serviceable hearing was preserved in 34% according to AAO-HNS and in 58% according to the WRS. Risk of hearing loss was small in patients with class A hearing at diagnosis. Comments and Conclusion: The retrospective nature of this study yields class III data. Also, there is potential selection bias with the selected tumor size population.
Milner et al, 2017	Objective: To assess audiological outcomes in patient with growing VS managed conservatively or treated with SRS (12-13 Gy marginal dose, single fraction gamma knife). Design: Retrospective chart review, single center Number of patients: 15 patients treated conservatively and 27 treated with SRS with serviceable hearing. Follow-up: Mean 69.6 months for SRS and 71.7 for months conservative management	III	Results: No significant difference in deterioration of AAO-HNS and GR between the two groups. 15/42 patient overall maintained serviceable hearing at last followup: 53% (8/15) in the conservative management cohort and 26% (7/27) in the SRS group. Authors Conclusion: Similar audiological outcomes and hearing preservation for SRS and conservative management of VS. Comments and Conclusion: The retrospective nature of this study yields class III data. Rate of progression to loss of functional hearing was not significantly different between SRS and conservative management.
Elliot et al, 2015	Objective: To compare hearing preservation between conservative treatment and SRT for patient with unilateral VS. Design: Retrospective case series, single institution. Number of patients: 123 patients with serviceable hearing, AAO-HNS hearing class A or B (98 underwent conservative therapy, 25 underwent SRT). SRT via LINAC of 31.25 Gy in 5 fractions or in one case 62.5 Gy in 25 fractions. Follow-up: median of 42.5 months for observation group and median of 44 months for SRT group.	III	Results: Hearing was preserved for median of 46 months at 51% (63/123) for both modalities with preservation of 54% (53/98) and 40% (10/25) for conservative observation and SRT, respectively. Multivariant model revealed that tumor growth status was an independent predictor for treatment modality with SRT. Median followup and hearing class were predictors of hearing preservation at the end of follow up. Authors Conclusion: No significant difference between the hearing survival of conservative versus SRT patients. Comments and Conclusion: The retrospective nature of this study yields class III data. Onset class A conferred significant hearing survival advantage over class B (62% vs 39%) at median of 46 months, irrespective of treatment modality.
Jethanamest et al, 2015	Objective: To describe clinical outcomes of VS patients undergoing serial observation. Design: Retrospective chart review. Number of patients: 94 patients managed conservatively. 37 of those has serviceable hearing class A or B, AAO-HNS. Follow-up: 34.8 months median	III	Results: 75.7% (28/37) patients retained serviceable hearing at a median of 34.8 months. Median time to hearing loss worsening to non-serviceable level for 50% of patients was 76 months. Median time to hearing loss worsening to non-serviceable level for 50% of patients was 76 months. Authors Conclusion: Serial observation is a viable treatment strategy for select VS. Comments and Conclusion: The retrospective nature of this study yields class III data.
AAO-HNS, American Academy of Otolaryngology-Head and Neck Surgery; dB, decibel; IQR, interquartile; GR, Gardner-Robertson hearing classification; LINAC, linear accelerator; PTA, pure tone average; SRS, stereotactic radiosurgery; SRT, stereotactic radiotherapy; VS, vestibular schwannoma; WRS, word recognition score.

Table 2: Hearing preservation with stereotactic radiosurgery

Author/year

Study Description

Data Class

Results and Conclusion

Teyateeti et al, 2022

Objective: To evaluate the outcomes of gamma knife SRS with 50% isodose line (IDL50) vs isodose 40% (IDL40).

Design: Single institution SRS registry.

Number of patients: 21 patients with serviceable hearing prior to SRS (8 in the IDL40 group and 13 in the IDL 50 group).

Follow-up: 114 months.

III

Results: Hearing preservation rates overall were 84%, 72% and 39% at 2, 5, and 10 years, respectively. IDL40 treatment was significantly associated with higher hearing preservation rate with a longer hearing preservation time, 128 months, versus 82 months for IDL50.

Authors Conclusion: Dose prescription at IDL40 or IDL50 provide excellent long-term tumor control and toxicity profile, however, IDL40 may be associated with improved long-term hearing preservation.

Comments and Conclusion: The retrospective nature of this study yields class III data. Small sample size. Prescription dose of 12-14 Gy with IDL40 may have a more favorable outcome with improved hearing preservation.

Maksimoski et al, 2021

Objective: To describe long-term hearing outcomes with modern SRS techniques for VS treatment.

Design: Retrospective chart review, single center.

Number of patients: 133 patients with serviceable hearing underwent SRS (11-16 Gy at the 50% isodose line).

Follow-up: No mean or median available. Half of study had data beyond 5 years.

III

Results: Serviceable hearing was maintained in 27%, 24%, 13% and 4.1% of patients at 3-, 5-, 7- and 10- year follow up.

Authors Conclusion: Stereotactic radiosurgery treatments for VS showed a continued reduction over time in serviceable hearing.

Comments and Conclusion: The retrospective nature of this study yields class III data. Ranges for maximum cochlear dose were 3.7-19.9 Gy with a median of 9.7 Gy.

Ogino et al, 2021

Objective: To evaluate whether hearing deterioration during observation reduced serviceable hearing after SRS (Median marginal dose of 12.5 Gy, range of 11-15 Gy) in VS patients with useful hearing.

Design: Retrospective chart review, single institution.

Number of patients: 100 patients with GR I were observed for median of 17.4 months. 67 patients remained GR I and 33 deteriorated to GR II. All then underwent SRS.

Follow-up: Median of 4.4 years.

III

Results: At the last followup, 63% (42/67) of patients that started with GR I maintained serviceable hearing compared to 24% (8/33) of those who started with GR II. The overall serviceable hearing preservation rate

was 65.9% at 3 years, 52.5% at 5 years and 40.5% at 10 years. In multivariate analysis, younger age (<55 years) and GR grade I were significantly associated with improved serviceable hearing preservation rates.

Authors Conclusion: SRS before hearing deterioration was recommended for hearing preservation.

Comments and Conclusion: The retrospective nature of this study yields class III data. Stereotactic radiosurgery has more favorable hearing preservation outcomes long term in younger patients with hearing maintained at GR I at time of treatment.

Ogino et al, 2021

Objective: To evaluate outcomes of SRS for intracanalicular VS.

Design: retrospective chart review, single center.

Number of patients: 120 patients with serviceable hearing (GR I or II) with a median marginal dose of 12.5 Gy (range 11-25 Gy) and median cochlear dose 3.2 Gy (range 0.8-6.9 Gy).

Follow-up: 43 months (range 6-232 months).

III

Results: 77%, 64%, and 27% patient had preservation of serviceable hearing at 3, 5 and 10 years. Better hearing and smaller tumor volume at time of SRS were significantly associated with improved hearing preservation.

Authors Conclusion: Patient with initially better hearing and smaller VSs has enhanced serviceable hearing preservation during long-term followup of up to 10 years post SRS.

Comments and Conclusion: The retrospective nature of this study yields class III data. Selection bias for tumor size.

Ogino et al, 2021

Objective: To report role of SRS as primary management option for Koos grade IV VS.

Design: Retrospective chart review, single center.

Number of patients: 170 patients in total. 42 patients with serviceable hearing and available data (GR grade I or II) were treated with median margin dose of 12.5 Gy (range 10.5-22 Gy).

Follow-up: 75.8 months median.

III

Results: Preservation of serviceable hearing was 58%, 50% and 36% at 3, 5 and 7 years. Younger age (<60 years) and initial GR grade I were associated with improved serviceable hearing preservation rate.

Authors Conclusion: Single session SRS prevented need for delayed resection even in large volume VS with lower serviceable hearing preservation rates.

Comments and Conclusion: The retrospective nature of this study yields class III data. SRS in large VS is a reasonable primary management for elderly patients with many medical comorbidities.

Wage et al, 2021

Objective: To evaluate long-term outcomes of VS patients treated with GKS.

Design: Retrospective chart review, single center study.

Number of patients: 53 patients had serviceable hearing (GR I and II) at treatment time (median marginal dose of 12.5 Gy to the 50% isodose line.

Follow-up: No mean or median available.

III

Results: 40% (21/53) maintain serviceable hearing at last followup with median time to hearing loss at 19 months (range 3-158).

Actuarial median time to loss of serviceable hearing 3.4 years with actuarial hearing preservation at 2, 5, and 10 years of 66.5%, 43.1%, and 37.6%, with rate of hearing loss correlating with maximum cochlea and modiolus doses.

Authors Conclusion: Modern GKS is a safe and effective treatment for VS on long-term follow-up.

Comments and Conclusion: The retrospective nature of this study yields class III data.

Han et al, 2020

Objective: To report long-term outcomes of patients with small to medium sized VS with serviceable hearing undergoing SRS or MS and evaluate potential prognostic factors for hearing preservation.

Design: Retrospective chart review, single institution

Number of patients: 51 patients total with serviceable hearing and a tumor <25 mm in greatest dimension; 21 patients underwent MS and 30 patients underwent GKS.

Follow-up: 5 years.

III

Results: 53% (16/30) of patients treated with GKS and 71% (15/21) of patient treated with MS maintained serviceable hearing at last followup. Difference was not found to be statistically significant.

Authors Conclusion: MS is more suitable for younger healthy patients with serviceable hearing preoperatively and medial type VS. SRS was more suitable for elderly patients with poor physical status and preoperative hearing AAO-HNS class A.

Comments and Conclusion: The retrospective nature of this study yields class III data. Number of included patients was small.

Johnson et al, 2019

Objective: To report long-term outcomes of SRS as a treatment modality for VS.

Design: Retrospective chart review, single institution.

Number of patients: 326 patients with serviceable hearing (GR I or II) that received SRS (median marginal dose of 13 Gy, range 12-25 Gy).

Follow-up: Median 5.2 years (range 1-25 years).

III

Results: The last audiological examination

demonstrated that 196/326 (60.1%) retained SH. Serviceable hearing preservation rates were 90% at 1 year, 77% at 3 years, 68% at 5 years, 63% at 7 years, and 51% at 10 years. Younger age, GR grade 1 at SRS, and absence of subjective vestibulopathy were associated with improved serviceable hearing preservation.

Authors Conclusion: Serviceable hearing at 10 years was maintained in 76% of patients younger than 45 years of age and tumors smaller than 0.56 cc in volume at the time of the SRS.

Comments and Conclusion: The retrospective nature of this study yields class III data. Study included an equal distribution of all 4 Koos classes. Analysis vestibulopathy as a separate predictor of hearing outcome added an interesting finding.

Prabhuraj et al, 2019

Objective: To find hearing preservation and tumor control rates for small and medium sized VS treated with GKS.

Design: Single center, retrospective cohort study.

Number of patients: 77 patients with GR grade I or II who underwent GKS (median marginal dose of 12 Gy, range 11.5-14).

Follow-up: 30 months.

III

Results: Hearing preservation rate was 79.2% (61/77). This was not affected by tumor volume. On multivariate analysis, age >40, pre-GKS PTA <30 dB and GR grade I were independent predictors of better hearing preservation.

Authors Conclusion: GKS is an effective treatment for patients with small VSs with retained serviceable hearing and good tumor control.

Comments and Conclusion: The retrospective nature of this study yields class III data. Well-conducted multivariate data analysis. Mean cochlear dose ranged from 2.3-6.5 Gy with a range of 3.75 Gy.

Frischer et al, 2018

Objective: To present long-term follow up data on VS patients treated with GKS.

Design: Single center retrospective chart review.

Number of patients: 132 patients had GR grade I or II serviceable hearing at time of GKS.

Follow-up: Median 5.1 years.

III

Results: At the last follow-up, functional hearing was preserved in 55% of patients who had been classified. Hearing preservation rates were 53%, 34%, and 34% at 5, 10, and 15 years after GKS. On multivariate regression analysis, GR hearing grade prior to GKRS and the median dose to the cochlea were independent predictors of the GR grade at follow-up.

Authors Conclusion: The retrospective nature of this study yields class III data. GKS should be a primary treatment for early stage small to medium sized VS. Authors do not recommend undertreating intracanalicular tumors in favor of low cochlear doses.

Comments and Conclusion: No tumor size selection bias. Patients who received a median cochlear dose > 6 Gy showed a significantly higher rate of nonserviceable hearing at the last follow-up than that in patients in whom the median cochlear dose was <6 Gy.

Van Linge et al, 2018

Objective: To assess change in hearing loss after SRT and identify prognostic factors affecting hearing preservation.

Design: Retrospective chart review, single center.

Number of patients: 37 patient received single fraction of 12 Gy and 20 patients received FSRT with 30 fraction of 1.8 Gy (all with GR grade I or II)

Follow-up: 36 months for SRS group and 63 months for FSRT group.

III

Results: One year after treatment, 84% of SRS and 71% of FRST has preservation of serviceable hearing. At 3 years, hearing was preserved at 27% for SRS and 50% for FSRT. Preservation of hearing did not differ significantly between the two groups. On multivariate regression, restricted cochlear V90 and worse pretreatment PTA were associated with progression of serviceable hearing loss.

Authors Conclusion: Hearing deteriorates after SRT for VS. Most rapid decline occurs shortly after treatment without significant difference between SRS and FSRT.

Comments and Conclusion: The retrospective nature of this study yields class III data. Better baseline PTA does not protect against changes in PTA however it provides and protective effect for overall preservation of serviceable hearing.

Bowden et al, 2017

Objective: To correlate radiographic appearance of VS before SRS with delayed volumetric response.

Design: Single center retrospective chart review.

Number of patients: 111 patients with serviceable hearing (GR grade I or II) at SRS (median dose 12.5 Gy, range 11-13 Gy).

Follow-up: Median of 37 months.

III

Results: Serviceable hearing was maintained in 82.2% and 61.5% patients at 2- and 5-years post SRS. 85% (29/34) of patients with 100% SDS at SRS maintained serviceable hearing at 5 years. There was no significant difference in auditory outcomes between the macrocystic and microcystic groups. Six patients (21.4%) who initially tested as GR grade 3 increased by >10% and moved into the serviceable hearing range at last follow-up.

Authors Conclusion: SRS provided VS tumor control in >95% of patients, regardless of radiographic characteristics.

Comments and Conclusion: The retrospective nature of this study yields class III data. Selection bias for cystic tumors. No statistical difference in hearing preservation rates regardless of the radiological characteristics of the VS.

Akpinar et al, 2016

Objective: To evaluate effect of SRS on long-term hearing preservation in VS patients.

Design: Retrospective chart review, single center.

Number of patients: 88 patients with GR grade I hearing at time of SRS: 57 underwent SRS early (≤2 years from diagnosis) and 31 underwent late SRS (>2 years after diagnosis).

Follow-up: median of 75 months

III

Results: At 5 years after SRS, 88% of early treatment group retained serviceable hearing and 77% retained normal hearing compared with 55% with serviceable hearing and 33% with normal hearing in the late treatment group.

Authors Conclusion: SRS within two years after VS diagnosis in normal hearing patients resulted in improved retention of all hearing measures compared with later SRS.

Comments and Conclusion: Late treatment group has pre-SRS significantly higher PTA and slightly lower SDS which may have biased the results.

Golfinos et al, 2016

Objective: To conduct matched cohort analysis to evaluate hearing outcomes in patients treated with SRS or MS.

Design: Retrospective chart review, single center.

Number of patients: 21 patients in SRS group (maximum marginal and cochlear dose of 14 Gy and 6.5 Gy) and 21 patients in MS group (matched by age and tumor size), all with class A hearing, AAO-HNS.

Follow-up: 43.7 months for MS and 30.3 months for SRS.

III

Results: 43% (9/21) in the MS group had serviceable hearing at last followup vs 86% (18/21) in the SRS group. Preservation of preoperative Class A hearing status was also better after SRS than MS (14.3% for MS vs 42.9% for SRS).

Authors Conclusion: VS resection or radiosurgery for tumors <2.8 cm in diameter was associated with low overall morbidity. SRS was associated with improved hearing rates but followup period was shorter.

Comments and Conclusion: The retrospective nature of this study yields class III data. Survival curve analysis shows the preservation of preoperative hearing status converges by month 60. Loss of postoperative hearing was delayed in the SRS cohort.

Klijn et al, 2016

Objective: To report long-term outcomes of GKS for VS patients.

Design: Retrospective chart review, single center.

Number of patients: 420 included in the study with 71 patients with serviceable hearing underwent GKS (11 Gy marginal dose).

Follow-up: Median of 5.1 years.

III

Results: Serviceable hearing was maintained in 64% and 42% of patients at 3- and 5- year follow up.

Authors Conclusion: Rates of hearing preservation were comparable to those in the literature.

Comments and Conclusion: The retrospective nature of this study yields class III data.

Watanabe et al, 2016

Objective: to report long-term outcomes of SRS for VS.

Design: Multicenter, retrospective chart review.

Number of patients: 183 patients included, 66 of which has serviceable hearing (GR I or II) and available audiometric data pretreatment with SRS (median marginal dose 12 Gy, range 8.8-15.5 Gy; median cochlear dose was 4.1 Gy and range 2.3-5.7 Gy).

Follow-up: 59 months.

III

Results: At last follow-up, 35% (23/66) of patients with serviceable hearing before SRS had preserved hearing. Actuarial serviceable hearing preservation rates were 49%, 24%,

and 12% at 5-, 10-, and 15- years post-SRS month, respectively. Older age (≥65 years), larger tumor volume (≥8 cm³) and higher cochlear dose (mean cochlear dose >4.2 Gy) are unfavorable factors for hearing preservation.

Authors Conclusion: Hearing preservation was not a satisfactory long-term outcome of SRS.

Comments and Conclusion: The retrospective nature of this study yields class III data. PTA was only audiometric follow-up method, without tracking SDS thus the results may be overestimated.

Horiba et al, 2015

Objective: To evaluate factors associated with hearing preservation after low dose GKS. Mean marginal dose of 11.9 Gy (range, 11-12 Gy). The doses for brain stem, cranial nerves, and cochlea were kept below 14 Gy, 12 Gy, and 4 Gy, respectively.

Design: Retrospective chart review, single institution.

Number of patients: 49 patients with GR grade I (22 cases) and II (27 cases).

Follow-up: Median and mean of 56 and 55 months.

III

Results: Serviceable hearing preserved at 57% (28/49) at the last followup. Patients who lost serviceable hearing after GKS experienced the loss within 1 (6/21, 29%), 2 (14/21, 67%), and 3 (18/21, 86%) posttreatment years. In cases

with and without extension of the intrameatal part up to fundus, preservation of the serviceable hearing was at 40% and 60% of cases, respectively, however the difference in not statistically significant (odds ratio, 2.6; 95%

confidence interval, 0.5–12.4).

Authors Conclusion: Low-dose GKS of vestibular schwannoma preserves serviceable hearing in more than half of the patients at the 3-year followup.

Comments and Conclusion: The retrospective nature of this study yields class III data. No multivariate analysis presented.

Mousavi et al, 2015

Objective: To evaluate hearing outcomes at 2 and 3 years in GR grade I patients who underwent GKS for VS.

Design: Retrospective chart review, single institution.

Number of patients: 68 patients total with GR grade I hearing divided into two groups. Group A: 25 patients with no subjective hearing loss (median PTA was 12 dB, and median SDS was 100). Group B: 43 patients all of whom reported subjective hearing dysfunction (median PTA 22 dB and SDS 90%). All underwent SRS with marginal dose of 12.5 Gy.

Follow-up: 33 months for group A and 35 months for group B.

III

Results: All 25 patients (100%) in group A retained serviceable hearing at the last follow-up, only 24/43 group B patients (55%) maintained serviceable hearing. Thus, 72.1% (49/68) of hearing was preserved at 3 years in both groups combined. Serviceable hearing retention were 100% for group A compared with 81% at 1 year, 60% at 2 years, and 57% at 3 years after GKS for group B patients. Group A patients had significantly higher rates of hearing preservation in either GR class I or GR class II. Patients with a PTA <15 dB before GKS had significantly higher rates of serviceable hearing preservation.

Authors Conclusion: Modification of the GR I hearing classification into 2 groups (group A, those with no subjective hearing loss and a PTA <15 dB; and group B, those with subjective hearing loss and a PTA >15 dB) may be useful to help predict hearing preservation rates at 2 to 3 years after GKS.

Comments and Conclusion: The retrospective nature of this study yields class III data. No meaningful long-term data beyond 3 years of followup. Median cochlear dose (4.0-4.15 Gy) had no statistical relationship to hearing status at last followup.

AAO-HNS, American Academy of Otolaryngology-Head and Neck Surgery; dB, decibel; FSRT, fractionated stereotactic radiotherapy; IQR, interquartile; GKS, gamma knife surgery; GR, Gardner–Robertson hearing classification; IDL50, 50% isodose line; IDL40, 40% isodose line; LINAC, linear accelerator; MS, microsurgery; PTA, pure tone average; SRS, stereotactic radiosurgery; SRT, stereotactic radiotherapy; SDS, speech discrimination score; VS, vestibular schwannoma.

Table 3: Hearing preservation with microsurgery

Author/Year	Study Description	Data Class	Results and Conclusion
Ichimasu et al, 2020	Objective: To report long-term hearing preservation in patient with serviceable hearing immediately after VS surgery and to identify prognostic of hearing function. Design: Retrospective chart review, multicenter. Number of patients: 91 patients with class A or B hearing (AAO-HNS). Follow-up: 63 months mean.	III	Results: At the last followup, 87% (79/91) patient maintained serviceable hearing. 61% (39/64) patient who were in class A deteriorated to class B. Rate of maintenance of useful earing at 1, 3, 5, 8 and 10 years was 98.9%, 98.9%, 94.1%, 74.9% and 64.6%, respectively. Authors Conclusion: Useful hearing was lost in 13% of patients and hearing class deteriorated in 55% during followup without signs of tumor recurrence. Comments and Conclusion: The retrospective nature of this study yields class III data. Selection bias is present; however, this article provides an estimate of hearing preservation in the long-term follow up in patient with preserved hearing post surgically.
Dowling et al, 2019	Objective: To evaluate hearing outcomes in patients with serviceable hearing following microsurgical resection in tumors confined to the IAC or with ≤ 1 cm of CPA extension. Design: Retrospective cohort, tertiary academic referral center. Number of patients: 43 patients with unilateral vestibular schwannoma and AAO-HNS class A or B. Follow-up: Median 3.3 years	III	Results: 19% (8/43) patients developed non-serviceable hearing at median 4.1 years followup. Rate of maintaining serviceable hearing at 5 years was 81%. Tumor control was achieved in 95% (41/43) patients. Authors Conclusion: Microsurgical resection provides durable tumor control and long-term hearing in patients with AAO-HNS class A or B hearing postoperatively. Comments and Conclusion: The retrospective nature of this study yields class III data. Proactive microsurgical resection for small tumors with good hearing can be a way to preserve preoperative hearing levels however a selection bias is present here.
Zhu et al, 2018	Objective: To report long-term hearing outcomes after retrosigmoid tumor removal for small VS in the IAC or <15 mm CPA tumor. Design: Retrospective chart review, single center. Number of patients: 70 patients with class A or B hearing (AAO-HNS) underwent surgery. Follow-up: 4 years mean follow up for surgery group.	III	Results: 47% (33/70) of patient with serviceable hearing at time of surgery achieved hearing preservation at 4-year followup. In all surgery patients (n = 110), the postoperative rate for preservation of serviceable hearing was 85.7% among those with preoperative Class A hearing, 46.5% among those with Class B hearing. Authors Conclusion: Better preoperative hearing predicted a higher rate of postoperative hearing preservation. Comments and Conclusion: The retrospective nature of this study yields class III data. Authors defined serviceable hearing as AAO-HNS classes A, B and C but they provided all data for the surgical subgroup so adjustment to include only classes A and B was possible.
Ahmed et al, 2017	Objective: to analyze postoperative long-term hearing outcome data in VS patients undergoing MCF approach. Design: Retrospective chart review, single center. Number of patients: 71 patients with serviceable hearing (AAO-HNS, class A or B) and long-term data. Follow-up: 7 years mean.	III	Results: Hearing preservation was 82% at 3-5 years, 67% at 6-8 years, 68% at 9-11 years and 18% at 12+ years. The rate of WRS preservation was 98% at 3-5 years. Patients with preoperative class A hearing had significantly higher rates of successful hearing preservation in all postoperative intervals. Authors Conclusion: In patients with preserved serviceable hearing immediately postoperatively, hearing loss occurs at different rates over time. Comments and Conclusion: The retrospective nature of this study yields class III data.
AAO-HNS, American Academy of Otolaryngology-Head and Neck Surgery; CPA, cerebropontine angle; ICA, intracanalicular; VS, vestibular schwannoma.

Table 4. Comparison of PICO Elements in 2018 and 2022 Guidelines

PICO Element	2018 Guideline	2022 Guideline
Population (P)	Adults with sporadic vestibular schwannomas who have serviceable hearing. No specific age limit mentioned, generally referring to adult patients.	Adults with sporadic vestibular schwannomas who have serviceable hearing at the time of diagnosis. Like the 2018 guideline, there is no specific age cut-off, but the focus remains on the adult population.
Intervention (I)	- Radiation Therapy: Single-fraction radiation using ≤ 13 Gy to the tumor margin. - Microsurgery: Microsurgical resection via middle cranial fossa or retrosigmoid approach for small to medium-sized tumors (< 2 cm). - Observation: Monitoring small to medium-sized tumors with serial imaging without immediate intervention.	- Radiation Therapy: Single-fraction stereotactic radiosurgery with specified dosages, including ≤ 13 Gy marginal dose and a recommended ≤ 4 Gy cochlear dose when possible. - Microsurgery: Criteria for selecting surgical approach based on tumor size and location, with emphasis on surgical techniques aimed at hearing preservation. - Observation: Emphasized watchful waiting with a focus on baseline characteristics like tumor size and initial hearing status.
Comparison (C)	Comparing outcomes of different treatment modalities (radiosurgery, microsurgery, observation), particularly focusing on hearing preservation across adult patients.	More detailed comparisons involving prognostic factors and treatment specifics, such as radiation dosages and surgical approaches, aimed at refining treatment efficacy predictions for adults.
Outcome (O)	Probability of maintaining serviceable hearing at various time intervals post-treatment (2, 5, and 10 years).	Provides detailed statistical probabilities of maintaining serviceable hearing post-treatment, integrating predictive factors for a more nuanced evaluation.

Table 5. Comparison of Recommendations: 2018 vs. 2022 Guidelines

Modality/Aspect	2018 Recommendations	2022 Recommendations
Radiosurgery	- Moderately high rate (>50% to 75%) of hearing preservation at 2 and 5 years, moderately low rate (>25% to 50%) at 10 years. - For AAO-HNS class A/GR I hearing: High rate (>75% to 100%) of hearing preservation at 2 years, moderately high (>50% to 75%) at 5 years, and moderately low (>25% to 50%) at 10 years. - Predictive factors for maintaining serviceable hearing comprise better preoperative word recognition/pure tone thresholds, smaller tumor size, marginal dose ≤12 Gy, cochlear dose ≤4 Gy.	- Moderately high rate (>50% to 75%) of hearing preservation at 2 and 5 years, moderately low rate (>25% to 50%) at 10 years. - Overall estimated rates of maintaining serviceable hearing after radiosurgery are 71% at 2 years, 59% at 5 years, 38% at 10 years. - Predictive factors for maintaining serviceable hearing comprise cochlear dose ≤ 4 Gy, marginal dose ≤ 13 Gy, and better baseline hearing level including AAO-HNS class A or GR I status.
Microsurgery	- Moderately low rate (>25% to 50%) of hearing preservation immediately after surgery and at 2, 5, and 10 years. - For AAO-HNS class A/GR I hearing: Moderately high rate (>50% to 75%) immediately, at 2 and 5 years, and moderately low (>25% to 50%) at 10 years. - Predictive factors for maintaining serviceable hearing comprise good preoperative word recognition/pure tone thresholds, smaller tumor size commonly <1 cm.	- Moderately low rate of hearing preservation post-surgery (>25% to 50%): 43% immediately, 48% at 2 years, 40% at 5 years, and 32% at 10 years. - Predictive factors for maintaining serviceable hearing comprise better baseline hearing level, including AAO-HNS class A and GR I status, smaller tumor size, and presence of a fundal CSF fluid cap.
Observation	- High rate (>75% to 100%) of hearing preservation at 2 years, moderately high (>50% to 75%) at 5 years, and moderately low (>25% to 50%) at 10 years. - For AAO-HNS class A/GR I hearing: High rate at 2 years (>75% to 100%), and moderately high at 5 years (>50% to 75%). Insufficient data for 10 years.	- High rate of hearing preservation at 2 years (>75% to 100%), moderately high rate at 5 years (>50% to 75%), and moderately low rate at 10 years (>25% to 50%). - Overall estimated rates of maintaining serviceable hearing with observation are 78% at 2 years, 59% at 5 years, 47% at 10 years. - Predictive factors for maintaining serviceable hearing comprise better baseline hearing level, including AAO-HNS class A or GR I status, and absence of tumor growth during observation.

Appendix V. Conflicts of Interest

Task Force Member	Disclosure
Julie Honaker PhD, AuD	Nothing to Disclose
Ben Allen Strickland, MD	Nothing to Disclose
Eric J. Lehrer, MD	Servier Pharmaceuticals, Novocure Inc.
Sheryl Green, MBBCh	Nothing to Disclose
John P. Marinelli MD	Medtronic
Christopher S. Graffeo MD, MS	Nothing to Disclose
Isabelle M. Germano, MD, MBA	Brianlab
Mateo Ziu, MD	Omniscient Neurotechnology America Ltd; GT Medical Technologies, Inc
Walavan Sivakumar, MD	Stryker Corporation
Sherwin Tavakol, MD	IRRAS USA, Inc.; Globus Medical, Inc.
Lucas Paul Carlstrom, MD, PhD	Kuros Biosciences USA, Inc
Jamie J. Van Gompel, MD	Medtronic, Cadence
Ian Dunn, MD	Nothing to Disclose
Jeffrey J. Olson, MD	Verastem, Inc., Research Grant American Cancer Society, Editorial Consultant; Azurity Pharmaceuticals, Inc.
Ghazal S. Daher MD	Nothing to Disclose
Matthew L. Carlson, MD	Cochlear Americas, Advanced Bionics, Stryker Corporation; iotaMotion, Inc.; Stryker Corporation
Neil S. Patel, MD	Cochlear Americas, Zeiss, Viridian Therapeutics, IotaMotion, Inc.
Michael Sughrue, MD	Omniscient Neurotechnology America Ltd
Constantinos G. Hadjipanayis, MD, PhD	Stryker Corporation; Integra LifeSciences Corporation; Omniscient Neurotechnology America Ltd
Jeffrey Jacob, MD	Stryker Corporation; KLS; Synthes

3. Intraoperative Cranial Nerve Monitoring In The Management Of Patients With Vestibular Schwannomas: Update

5. The Role Of Imaging In The Management Of Patients With Vestibular Schwannomas: Update

Sections

1. Guidelines For The Treatment Of Adults With Vestibular Schwannoma: Introduction And Methods Update

2. Audiologic Screening in the Diagnosis and Management of Patients with Vestibular Schwannomas: Update

3. Intraoperative Cranial Nerve Monitoring In The Management Of Patients With Vestibular Schwannomas: Update

4. Hearing Preservation Outcomes In Patients With Sporadic Vestibular Schwannoma: Update

5. The Role Of Imaging In The Management Of Patients With Vestibular Schwannomas: Update

6. The Role Of Radiosurgery (SRS) And Radiation Therapy In The Management Of Patients With Vestibular Schwannomas: Updates

7. Surgical Resection For The Treatment Of Patients With Vestibular Schwannomas: Update

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Appendix I: Literature Searches

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Classification of Evidence on Therapeutic Effectiveness and Levels of Recommendation

Classification of Evidence on Prognosis and Levels of Recommendation

Classification of Evidence on Diagnosis and Levels of Recommendation

Classification of Evidence on Clinical Assessment and Levels of Recommendation

Appendix III: PRISMA Flowchart

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Appendix I: Literature Searches

Search Strategies

Appendix II: Rating Evidence Quality

Classification of Evidence on Therapeutic Effectiveness and Levels of Recommendation

Classification of Evidence on Prognosis and Levels of Recommendation

Classification of Evidence on Diagnosis and Levels of Recommendation

Classification of Evidence on Clinical Assessment and Levels of Recommendation

Appendix III: PRISMA Flowchart

Appendix IV. Evidence Tables

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