Congress of Neurological Surgeons Systematic Review and Evidence-Based Guidelines on Hearing Preservation Outcomes in Patients With Sporadic Vestibular Schwannomas

Losartan May Not Prevent Vestibular Schwannoma Growth or Related Hearing Loss During Observation

OBJECTIVE

To evaluate the impact of losartan on vestibular schwannoma (VS) growth and related hearing loss during observation.

STUDY DESIGN

Retrospective cohort study.

SETTING

Tertiary referral center.

PATIENTS

Sporadic VS patients undergoing initial observation with at least two magnetic resonance imaging and audiologic examinations.

INTERVENTION

Losartan.

MAIN OUTCOME MEASURES

Endpoints included VS growth, quantitative audiologic changes, survival free of tumor growth, and survival free of nonserviceable hearing. Patient characteristics and endpoints were compared by losartan use.

RESULTS

Seventy-nine patients were included, of which 33% were taking losartan. Tumor growth was observed in 50% of patients in the losartan group and 36% in the non-losartan group (p = 0.329). Survival analysis failed to show a significant difference in the hazard rate of VS growth between groups (hazard ratio, 1.38; 95% confidence interval, 0.70-2.70; p = 0.346). Throughout observation, mean decreases in normalized pure-tone average were 5.5 and 9.3 dB in the losartan and non-losartan groups, respectively (p = 0.908). Mean decreases in normalized word recognition score were 11.0 and 16.6% in the losartan and non-losartan groups, respectively (p = 0.757). Nonserviceable hearing developed in 19% of patients in the losartan group and 28% in the non-losartan group (p = 0.734). Survival analysis did not demonstrate a significant difference in the hazard rate of developing nonserviceable hearing between groups (hazard ratio, 1.71; 95% confidence interval, 0.56-5.21; p = 0.337).

CONCLUSIONS

Losartan use may not reduce the risk of VS growth or hearing loss during observation. A randomized trial would be ideal to further identify the true effect on growth and hearing.

Tumors of the nervous system and hearing loss: Beyond vestibular schwannomas

Hearing loss is a common side effect of many tumor treatments. However, hearing loss can also occur as a direct result of certain tumors of the nervous system, the most common of which are the vestibular schwannomas (VS). These tumors arise from Schwann cells of the vestibulocochlear nerve and their main cause is the loss of function of NF2, with 95 % of cases being sporadic and 5 % being part of the rare neurofibromatosis type 2 (NF2)-related Schwannomatosis. Genetic variations in NF2 do not fully explain the clinical heterogeneity of VS, and interactions between Schwann cells and their microenvironment appear to be critical for tumor development. Preclinical in vitro and in vivo models of VS are needed to develop prognostic biomarkers and targeted therapies. In addition to VS, other tumors can affect hearing. Meningiomas and other masses in the cerebellopontine angle can compress the vestibulocochlear nerve due to their anatomic proximity. Gliomas can disrupt several neurological functions, including hearing; in fact, glioblastoma multiforme, the most aggressive subtype, may exhibit early symptoms of auditory alterations. Besides, treatments for high-grade tumors, including chemotherapy or radiotherapy, as well as incomplete resections, can induce long-term auditory dysfunction. Because hearing loss can have an irreversible and dramatic impact on quality of life, it should be considered in the clinical management plan of patients with tumors, and monitored throughout the course of the disease.

Novel standardized indexes of brainstem auditory evoked potentials for predicting hearing preservation in vestibular schwannomas

Hearing preservation (HP) during vestibular schwannomas (VSs) surgery poses a significant challenge. Although brainstem auditory evoked potentials (BAEPs) on the affected side are commonly employed to monitor cochlear nerve function, their low signal-to-noise ratio (SNR) renders them susceptible to interferences, compromising their reliability. We retrospectively analyzed the data of patients who underwent tumor resection, while binaural brainstem auditory evoked potentials (BAEPs) were simultaneously recorded during surgery. To standardize BAEPs on the affected side, we incorporated the synchronous healthy side as a reference (interval between affected and healthy side ≤ 3 min). A total of 127 patients were enrolled. Comparison of the raw BAEPs data pre- and post-tumor resection revealed that neither V-wave amplitude (Am-V) nor latency (La-V) could serve as reliable predictors of HP simultaneously. However, following standardization, V-wave latency (STIAS-La-V) and amplitude (STIAS-Am-V) emerged as stable predictors of HP. Furthermore, the intraoperative difference in V-wave amplitude (D-Am-V) predicted postoperative HP in patients with preoperative HP and remained predictive after standardization. The utilization of intraoperative synchronous healthy side BAEPs as a reference to eliminate interferences proves to be an effective approach in enhancing the reliability of BAEPs for predicting HP in VSs patients.

Reported Hearing Outcome Measures Following Stereotactic Radiosurgery for Vestibular Schwannoma: A Scoping Review

Background  Evidence on hearing outcome measures when assessing hearing preservation following stereotactic radiosurgery (SRS) for adults with vestibular schwannoma (VS) has not previously been collated in a structured review. Objective  The objective of the present study was to perform a scoping review of the evidence regarding the choice of hearing outcomes and other methodological characteristics following SRS for adults with VS. Methods  The protocol was registered in the International Platform of Registered Systematic Review and Meta-Analysis Protocols (INPLASY) and reported according to the Preferred Reporting Items for Systematic Review and Meta-Analyses extension guidelines for scoping reviews. A systematic search of five online databases revealed 1,591 studies, 247 of which met the inclusion criteria. Results  The majority of studies ( n  = 213, 86%) were retrospective cohort or case series with the remainder ( n  = 34, 14%) prospective cohort. Pure-tone audiometry and speech intelligibility were included in 222 (90%) and 158 (64%) studies, respectively, often summarized within a classification scheme and lacking procedural details. Fifty-nine (24%) studies included self-report measures. The median duration of follow-up, when reported, was 43 months (interquartile range: 29, 4-150). Conclusion  Evidence on hearing disability after SRS for VS is based on low-quality studies which are inherently susceptible to bias. This review has highlighted an urgent need for a randomized controlled trial assessing hearing outcomes in patients with VS managed with radiosurgery or radiological observation. Similarly, consensus and coproduction of a core outcome set to determine relevant hearing and communication outcome domains is required. This will ensure that patient priorities, including communication abilities in the presence of background noise and reduced participation restrictions, are addressed.

Coordinated Same- or Next-Day Radiosurgery and Cochlear Implantation for Vestibular Schwannoma

OBJECTIVE

To describe the experience and results from coordinated and closely scheduled radiosurgery and cochlear implantation (CI) in a vestibular schwannoma (VS) cohort.

PATIENTS

Patients with VS who underwent radiosurgery followed by CI on the same or next day.

INTERVENTIONS

Interventions included sequential radiosurgery and CI.

MAIN OUTCOME MEASURES

Tumor control defined by tumor growth on posttreatment surveillance and audiometric outcomes including consonant-nucleus-consonant words and AzBio sentences in quiet.

RESULTS

In total, six patients were identified that met the inclusion criteria, with an age range of 38 to 69 years and tumor sizes ranging from 2.0 to 16.3 mm. All patients successfully underwent radiosurgery and CI on the same or immediately successive day. Postoperatively, all patients obtained open-set speech recognition. Consonant-nucleus-consonant word scores ranged from 40 to 88% correct, and AzBio scores ranged from 44 to 94% correct. During posttreatment magnetic resonance imaging surveillance, which ranged from 12 to 68 months, all tumors were noted to be adequately visualized, and no tumor progression was noted.

CONCLUSION

Coordinated radiosurgery and CI can be safely performed in patients with VS on the same or next day, serving to decrease burden on patients and increase access to this vital rehabilitative strategy.

Sporadic vestibular schwannoma in a pediatric population: a case series

PURPOSE

To describe the characteristics, management, and outcomes of pediatric patients with sporadic vestibular schwannoma (sVS).

METHODS

This was a case series at a tertiary care center. Patients were identified through a research repository and chart review. Interventions were microsurgery, stereotactic radiosurgery (SRS), and observation. Outcome measures were tumor control, facial nerve function, and hearing.

RESULTS

Eight patients over 2006-2022 fulfilled inclusion criteria (unilateral VS without genetic or clinical evidence of neurofibromatosis type 2 (NF2); age ≤ 21) with a mean age of 17 years (14-20). Average greatest tumor length in the internal auditory canal was 9.7 mm (4.0-16.1). Average greatest tumor dimension (4/8 tumors) in the cerebellopontine angle was 19.1 mm (11.3-26.8). Primary treatment was microsurgery in five (62.5%) patients, observation in two (25%), and SRS in one (12.5%). Four (80%) surgical patients had gross total resections, and one (20%) had regrowth post-near total resection and underwent SRS. One observed patient and the primary SRS patient have remained radiographically stable for 3.5 and 7 years, respectively. The other observed patient required surgery for tumor growth after 12 months of observation. Two surgical patients had poor facial nerve outcomes. All post-procedural patients developed anacusis. Mean follow-up was 3 years (0.5-7).

CONCLUSIONS

We describe one of the largest reported cohorts of pediatric sVS in the USA. Diligent exclusion of NF2 is critical. Given the high likelihood of eventually requiring intervention and known adverse effects of SRS, microsurgery remains the preferred treatment. However, observation can be considered in select situations.

[Vestibular Schwannoma: Factors in Therapy Decision-Making]

The treatment of vestibular schwannomas (VS) has always posed a challenge for physicians. Three essential treatment principles are available: wait-and-scan, surgery, and stereotactic radiotherapy. In addition to the type of treatment, decisions must be made regarding the optimal timing of therapy, the combination of different treatment modalities, the potential surgical approach, and the type and intensity of radiation. Factors influencing the therapy decision include tumor location and size or stage, patient age, comorbidities, symptoms, postoperative hearing rehabilitation options, patient preferences, and, not least, the experience of the surgeons and the personnel and technical capabilities of the clinical site. This article begins with a brief overview of vestibular schwannomas, then outlines the fundamental interdisciplinary treatment options, and finally discusses the ENT (ear, nose, and throat)-relevant factors in the therapy decision.

Clinical practice guideline on the management of vestibular schwannoma

INTRODUCTION

Vestibular schwannoma (VS) is the most common tumour of the cerebellopontine angle. The greater accessibility to radiological tests has increased its diagnosis. Taking into account the characteristics of the tumour, the symptoms and the age of the patient, three therapeutic strategies have been proposed: observation, surgery or radiotherapy. Choosing the most appropriate for each patient is a frequent source of controversy.

MATERIAL AND METHODS

This paper includes an exhaustive literature review of issues related to VS that can serve as a clinical guide in the management of patients with these lesions. The presentation has been oriented in the form of questions that the clinician usually asks himself and the answers have been written and/or reviewed by a panel of national and international experts consulted by the Otology Commission of the SEORL-CCC.

RESULTS

A list has been compiled containing the 13 most controversial thematic blocks on the management of VS in the form of 50 questions, and answers to all of them have been sought through a systematic literature review (articles published on PubMed and Cochrane Library between 1992 and 2023 related to each thematic area). Thirty-three experts, led by the Otology Committee of SEORL-CCC, have analyzed and discussed all the answers. In Annex 1, 14 additional questions divided into 4 thematic areas can be found.

CONCLUSIONS

This clinical practice guideline on the management of VS offers agreed answers to the most common questions that are asked about this tumour. The absence of sufficient prospective studies means that the levels of evidence on the subject are generally medium or low. This fact increases the interest of this type of clinical practice guidelines prepared by experts.

CyberKnife Stereotactic Radiosurgery for Growing Vestibular Schwannoma: Longitudinal Tumor Control, Hearing Outcomes, and Predicting Post-Treatment Hearing Status

OBJECTIVES

(1) To determine tumor control rates for treating growing vestibular schwannoma (VS) with CyberKnife stereotactic radiosurgery (CK SRS); (2) to determine hearing outcomes after CK SRS; (3) to propose a set of variables that could be used to predict hearing outcomes for patients receiving CK SRS for VS.

STUDY DESIGN

Retrospective case series review.

METHODS

127 patients who received CK SRS for radiographically documented growing VS were reviewed. Tumors were monitored for post-procedure growth radiographically with linear measurements and three-dimensional segmental volumetric analysis (3D-SVA). Hearing outcomes were reviewed for 109 patients. Cox proportional hazard modeling was used to identify variables correlated with hearing outcomes.

RESULTS

Tumor control rate was 94.5% for treating VS with CK SRS. Hearing outcomes were categorized using the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) classification system. As of their last available audiogram, 33.3% of patients with pre-treatment class A and 26.9% of patients with class B retained their hearing in that class. 15.3% of patients starting with class A or B with extended follow-up (>60 months), maintained hearing within this same grouping. Our final model proposed to predict hearing outcomes included age, fundal cap distance (FCD), tumor volume, and maximum radiation dose to the cochlea; however, FCD was the only statistically significant variable.

CONCLUSION

CK SRS is an effective treatment for control of VS. Hearing preservation by class was achieved in a third of patients. Finally, FCD was found to be protective against hearing loss.

LEVEL OF EVIDENCE

4 Laryngoscope, 134:S1-S12, 2024.

Brazilian Society of Otology task force - Vestibular Schwannoma ‒ evaluation and treatment

OBJECTIVE

To review the literature on the diagnosis and treatment of vestibular schwannoma.

METHODS

Task force members were educated on knowledge synthesis methods, including electronic database search, review and selection of relevant citations, and critical appraisal of selected studies. Articles written in English or Portuguese on vestibular schwannoma were eligible for inclusion. The American College of Physicians' guideline grading system and the American Thyroid Association's guideline criteria were used for critical appraisal of evidence and recommendations for therapeutic interventions.

RESULTS

The topics were divided into 2 parts: (1) Diagnosis - audiologic, electrophysiologic tests, and imaging; (2) Treatment - wait and scan protocols, surgery, radiosurgery/radiotherapy, and systemic therapy.

CONCLUSIONS

Decision making in VS treatment has become more challenging. MRI can diagnose increasingly smaller tumors, which has disastrous consequences for the patients and their families. It is important to develop an individualized approach for each case, which highly depends on the experience of each surgical team.

COX inhibitor use during definitive radiotherapy is associated with worse hearing preservation in patients with vestibular schwannoma

PURPOSE

Patients with vestibular schwannoma undergoing definitive radiotherapy commonly experience hearing loss due to tumor and treatment effects; however, there is limited data evaluating concurrent medication use and other clinicopathologic factors associated with hearing preservation during and after radiotherapy. We performed a retrospective cohort study reviewing consecutive patients from 2004 to 2019 treated with radiotherapy for vestibular schwannoma at our institution.

METHODS

Ninety four patients with concurrent medications, baseline audiograms, and post-radiotherapy audiograms available were evaluable. We performed chi-squared analyses of the frequency of various clinicopathologic factors and t-tests evaluating the degree of hearing loss based on audiograms.

RESULTS

At a median follow-up of 35.7 months (mean: 46.5 months), the baseline pure-tone average (PTA) of the ipsilateral ear worsened from 38.4 to 59.5 dB following completion of radiotherapy (difference: 21.1, 95% CI 17.8-24.4 dB, p < 0.001). 36 patients (38.3%) reported regular use of cyclooxygenase (COX) inhibitors (including acetaminophen and NSAIDs) during radiotherapy. The mean increase in PTA was significantly higher for patients taking COX inhibitors (25.8 dB vs 18.1 dB, p = 0.024) in the ipsilateral ear but not for the contralateral side. COX inhibitor use remained independently associated with worse PTA in the multivariate analysis.

CONCLUSION

COX inhibitor use during definitive radiotherapy is associated with worse hearing loss in the affected ear but not for the contralateral side. This suggests the ototoxic effects of COX inhibitors may influence the effects of radiotherapy. These results could have clinical implications and warrant further investigation.

Impact of Cochlear Dose on Hearing Preservation Following Stereotactic Radiosurgery in Treatment of Vestibular Schwannomas: A Multi-Center Study

OBJECTIVE

Stereotactic radiosurgery (SRS) is a well-established treatment for vestibular schwannomas (VS). Hearing loss remains a main morbidity of VS and its treatments, including SRS. The effects of radiation parameters of SRS on hearing remain unknown. The goal of this study is to determine the effect of tumor volume, patient demographics, pretreatment hearing status, cochlear radiation dose, total tumor radiation dose, fractionation, and other radiotherapy parameters on hearing deterioration.

METHODS

Multicenter retrospective analysis of 611 patients who underwent SRS for VS from 1990-2020 and had pre- and post-treatment audiograms.

RESULTS

Pure tone averages (PTAs) increased and word recognition scores (WRSs) decreased in treated ears at 12-60 months while remaining stable in untreated ears. Higher baseline PTA, higher tumor radiation dose, higher maximum cochlear dose, and usage of single fraction resulted in higher post radiation PTA; WRS was only predicted by baseline WRS and age. Higher baseline PTA, single fraction treatment, higher tumor radiation dose, and higher maximum cochlear dose resulted in a faster deterioration in PTA. Below a maximum cochlear dose of 3 Gy, there were no statistically significant changes in PTA or WRS.

CONCLUSIONS

Decline of hearing at one year in VS patients after SRS is directly related to maximum cochlear dose, single versus 3-fraction treatment, total tumor radiation dose, and baseline hearing level. The maximum safe cochlear dose for hearingtbrowd preservation at one year is 3 Gy, and the use of 3 fractions instead of one fraction was better at preserving hearing.

Incidence and presentation of vestibular schwannoma: a 3-year cohort registry study

BACKGROUND

Vestibular schwannoma (VS) is the most common benign tumour arising in the lateral skull base. Reported incidence rates of VS vary across geographical locations and over time. There is scarce updated evidence over the past decade on the epidemiology and mode of presentation of VS.

OBJECTIVE

To describe the epidemiology and mode of presentation of VS in the East of England between 2013 and 2016.

METHODS

A retrospective epidemiological analysis of data from a national VS registry and electronic patient records was conducted, including all newly diagnosed adult patients in a UK tertiary referral centre, between April 1st, 2013, and March 31st, 2016.

RESULTS

There were 391 new cases identified resulting in an overall mean incidence of 2.2 VS cases per 100,000 person-year. The incidence rate for all patients in the <40 age group ranged between 0.3 and 0.7 per 100,000 person-year, increasing to a range of 5.7 to 6.1 per 100,000 person-year in the 60-69 age group. The top three combinations of symptoms on presentation per patient were hearing loss and tinnitus (97, 24.8%), hearing loss alone (79, 20.2%) and hearing loss, tinnitus, and balance symptoms (61, 15.6%). The median duration of symptoms was 12 months, with a wide range from 1.4 to 300 months. Age was negatively correlated with tumour size (r = -0.14 [-0.24 to -0.04], p=0.01) and positively correlated with symptom duration (r = 0.16 [0.03-0.29], p=0.02).

CONCLUSIONS

The incidence of vestibular schwannoma has increased compared to previous studies in the UK and is similar to incidence rates reported in other countries during the past decade. It peaks in the seventh decade of life, mainly because of an increase in the diagnosis of small tumours with a long duration of audio-vestibular symptoms in older patients, compared to earlier studies.

Presbycusis and Hearing Preservation in Observed Vestibular Schwannomas

OBJECTIVE

We reviewed a cohort of patients with untreated sporadic vestibular schwannoma (VS) and examined the relationship between high-frequency hearing loss (HFHL) in the non-VS ear and long-term hearing outcomes in the VS-affected ear. We hypothesized that the progression of HFHL is associated with accelerated hearing decline in sporadic VS.

STUDY DESIGN

Retrospective cohort study.

SETTING

Tertiary center.

PATIENTS

We studied 102 patients with sporadic VS diagnosed from 1999 to 2015 with ≥5 years of observation (median, 6.92; interquartile range, 5.85-9.29). Sixty-six patients had AAO-HNS class A/B hearing at presentation and were included in analysis.

INTERVENTIONS

Audiometry, serial magnetic resonance imaging for observation of VS.

MAIN OUTCOME MEASURES

Four-frequency pure tone average (PTA) and word recognition scores (WRS) in the VS-affected ear. Decline in high-frequency PTA (average of thresholds at 4000, 6000, and 8,000 Hz) was defined as ≥10 dB during the study period. Decline in WRS was defined as ≥10%.

RESULTS

Compared with those without, patients with progressive HFHL in the non-VS ear were more likely to experience a decline in WRS in the VS ear (80% vs. 54%, p = 0.031). However, the same group showed no difference (52% vs. 41%, p = 0.40) in decline in PTA of the VS ear.

CONCLUSIONS

Patients with observed VS who experience progressive HFHL in the non-VS ear are more likely to experience significant declines in speech understanding in the VS-affected ear over time. Patients with a history of presbycusis may have an increased risk of losing serviceable hearing because of sporadic VS.

Cochlear Implant Outcomes between Patients with Sporadic and Neurofibromatosis Type 2-Associated Vestibular Schwannoma

OBJECTIVE

Compare cochlear implant (CI) performance between patients with ipsilateral sporadic vestibular schwannoma (VS) and NF2-related schwannomatosis (NF2). Compare CI performance according to VS management modality.

STUDY DESIGN

Historical cohort.

SETTING

Tertiary academic center.

PATIENTS

Forty-nine patients (52 ears) undergoing cochlear implantation in the setting of ipsilateral sporadic (n = 21) or NF2-associated VS (n = 28).

INTERVENTIONS

CI ipsilateral to VS.

MAIN OUTCOME MEASURES

Auditory thresholds, consonant-nucleus-consonant (CNC) word scores, and AzBio sentences in quiet scores.

RESULTS

Among all patients, median post-CI pure tone average was 28 dB HL (interquartile range [IQR], 21-38), CNC word score was 39% (IQR, 6-62), and AzBio sentences in quiet score was 60% (IQR, 11-83) at a median of 12.5 months postimplantation. Despite the NF2 cohort having larger tumors, when comparing patients with sporadic versus NF2-associated VS, there were no statistically significant differences in CNC word (49% [30-70] vs. 31% [0-52]) or AzBio sentences in quiet (66% [28-80] vs. 57% [5-83]) scores. Regardless of NF2 status, all patients managed with observation, and radiosurgery achieved open-set speech. In patients who underwent microsurgery, 6 (46%) of 13 with NF2 achieved open-set speech recognition compared with 4 (67%) of 6 with sporadic disease.

CONCLUSION

Select patients with VS achieve successful hearing rehabilitation with a CI. In this cohort, tumor management strategy significantly influenced CI performance, whereas differences in NF2 status exhibited less effect. Specifically, all patients managed with observation or radiosurgery achieved open-set speech perception, whereas approximately half of people with NF2-related VS and two-thirds of people with sporadic VS achieved this outcome after tumor microsurgery. When disease permits, observation and radiosurgery should be considered in patients who may later pursue a CI.

Upfront Radiosurgery vs a Wait-and-Scan Approach for Small- or Medium-Sized Vestibular Schwannoma: The V-REX Randomized Clinical Trial

Importance

Current guidelines for treating small- to medium-sized vestibular schwannoma recommend either upfront radiosurgery or waiting to treat until tumor growth has been detected radiographically.

Objective

To determine whether upfront radiosurgery provides superior tumor volume reduction to a wait-and-scan approach for small- to medium-sized vestibular schwannoma.

Design, Setting, and Participants

Randomized clinical trial of 100 patients with a newly diagnosed (<6 months) unilateral vestibular schwannoma and a maximal tumor diameter of less than 2 cm in the cerebellopontine angle as measured on magnetic resonance imaging. Participants were enrolled at the Norwegian National Unit for Vestibular Schwannoma from October 28, 2014, through October 3, 2017; 4-year follow-up ended on October 20, 2021.

Interventions

Participants were randomized to receive either upfront radiosurgery (n = 50) or to undergo a wait-and-scan protocol, for which treatment was given only upon radiographically documented tumor growth (n = 50). Participants underwent 5 annual study visits consisting of clinical assessment, radiological examination, audiovestibular tests, and questionnaires.

Main Outcomes and Measures

The primary outcome was the ratio between tumor volume at the trial end at 4 years and baseline (V4:V0). There were 26 prespecified secondary outcomes, including patient-reported symptoms, clinical examinations, audiovestibular tests, and quality-of-life outcomes. Safety outcomes were the risk of salvage microsurgery and radiation-associated complications.

Results

Of the 100 randomized patients, 98 completed the trial and were included in the primary analysis (mean age, 54 years; 42% female). In the upfront radiosurgery group, 1 participant (2%) received repeated radiosurgery upon tumor growth, 2 (4%) needed salvage microsurgery, and 45 (94%) had no additional treatment. In the wait-and-scan group, 21 patients (42%) received radiosurgery upon tumor growth, 1 (2%) underwent salvage microsurgery, and 28 (56%) remained untreated. For the primary outcome of the ratio of tumor volume at the trial end to baseline, the geometric mean V4:V0 was 0.87 (95% CI, 0.66-1.15) in the upfront radiosurgery group and 1.51 (95% CI, 1.23-1.84) in the wait-and-scan group, showing a significantly greater tumor volume reduction in patients treated with upfront radiosurgery (wait-and-scan to upfront radiosurgery ratio, 1.73; 95% CI, 1.23-2.44; P = .002). Of 26 secondary outcomes, 25 showed no significant difference. No radiation-associated complications were observed.

Conclusion and relevance

Among patients with newly diagnosed small- and medium-sized vestibular schwannoma, upfront radiosurgery demonstrated a significantly greater tumor volume reduction at 4 years than a wait-and-scan approach with treatment upon tumor growth. These findings may help inform treatment decisions for patients with vestibular schwannoma, and further investigation of long-term clinical outcomes is needed.

Trial Registration

ClinicalTrials.gov Identifier: NCT02249572.

Factors associated with hearing outcomes after a middle fossa approach in 131 consecutive patients with vestibular schwannomas

OBJECTIVE

The middle fossa approach is an effective option for the treatment of small (Koos grade I and II) vestibular schwannomas (VSs) when the goal is hearing preservation. The authors evaluated the rates of hearing preservation and examined the factors associated with improved hearing outcomes after the middle fossa approach for VSs.

METHODS

In this retrospective, single-center cohort study evaluating the clinical outcomes after resection of small VSs using the middle fossa approach, consecutive adult patients (> 18 years) who underwent surgery between January 2000 and December 2021 were included. Clinical and imaging characteristics were analyzed, including baseline hearing status, duration of surgery, anesthetic parameters, and imaging characteristics of the surgically treated tumors.

RESULTS

Among the 131 included patients, 102 had valid and discoverable pre- and postoperative audiology assessments. The mean follow-up was 26 months (range 1-180 months). There were 85 patients with serviceable hearing preoperatively, defined as American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) class A or B, of whom 78% retained class A or B hearing at the last follow-up. Binary logistic regression demonstrated that preoperative hearing AAO-HNS class (OR 0.19, 95% CI 0.05-0.77; p = 0.02), overlap between fundus and cochlea (OR 0.32, 95% CI 0.11-0.96; p = 0.04), and duration of anesthesia (OR 0.98, 95% CI 0.97-0.99; p = 0.03) were independent predictors of hearing outcomes. Additionally, 75% of patients with high diffusion-weighted imaging signal in the tumor (p = 0.009) and 67% of patients with the tumor originating at the modiolus of the cochlea (p = 0.004) had poor hearing outcomes.

CONCLUSIONS

The hearing preservation rates after microsurgical resection of small VSs using the middle fossa approach are high, with 78% of patients maintaining AAO-HNS class A or B hearing. Poor hearing status at baseline, longer duration of anesthesia, and large overlap between the fundus of the internal auditory canal and the cochlea were independently associated with unfavorable hearing outcomes. Imaging characteristics can be used to stratify patients' risk of hearing loss.

The Effect of Immediate Microsurgical Resection of Vestibular Schwannoma on Hearing Preservation

OBJECTIVE

Evaluate for differences in postoperative hearing in patients who undergo immediate versus delayed hearing preservation microsurgical resection of vestibular schwannomas (VS).

STUDY DESIGN

Retrospective single-institution cohort study spanning November 2017 to November 2021.

SETTING

Single-institution tertiary care hospital.

PATIENTS

Sporadic VS in patients with American Academy of Otolaryngology-Head and Neck Surgery hearing classification A or B, with tumor size less than or equal to 2 cm and undergoing hearing preservation microsurgical resection.

INTERVENTIONS

Delayed surgical intervention defined by time from first diagnostic MRI to date of surgery being greater than 3 months.

MAIN OUTCOME MEASURES

Preoperative and postoperative audiometric performance.

RESULTS

In total, 193 patients met inclusion criteria. Within the cohort, 70 (36%) proceeded with surgery within 3 months of diagnostic MRI with a mean observation time of 62 days, whereas 123 (63%) underwent surgery after 3 months with a mean observation time of 301 days. There was no difference in preoperative hearing between the two groups with word recognition score 99% in early intervention group and 100% in delayed intervention group ( p = 0.6). However, 64% of those who proceeded with immediate surgery had successful hearing preservation, compared to a 42% of those who had delayed intervention ( p < 0.01). In a multivariable logistic regression accounting for preoperative word recognition score, tumor size, and age at diagnosis, the odds of hearing preservation were lower in those who delayed surgery compared to immediate surgery (odds ratio, 0.31; 95% confidence interval, 0.15-0.61).

CONCLUSIONS

Patients who underwent microsurgical resection within 3 months of diagnosis demonstrated a hearing preservation advantage compared to those who did not. Findings of this study highlight the counseling challenges associated with the timing of surgical treatment of VS in patients presenting with good preoperative hearing and small tumors.

Cognitive Performance in Patients With Sporadic Vestibular Schwannoma

BACKGROUND

To date, few data are available on the cognitive function of patients with vestibular schwannoma (VS) before treatment.

OBJECTIVE

To provide a cognitive profile of patients with VS.

METHODS

This cross-sectional observational study recruited 75 patients with an untreated VS and 60 age-, sex-, and education-matched healthy control subjects. A set of neuropsychological tests were administered to each participant.

RESULTS

Compared with the matched controls, patients with VS exhibited impaired general cognitive function, memory, psychomotor speed, visuospatial ability, attention and processing speed, and executive function. The subgroup analyses displayed that patients with severe-to-profound unilateral hearing loss were more cognitively impaired than patients with no-to-moderate unilateral hearing loss. In addition, patients with right-sided VS scored worse than those with left-sided VS on tests of memory, attention and processing speed, and executive function. No differences were observed in cognitive performance between patients with or without brainstem compression and those with or without tinnitus. We also found that worse hearing and longer hearing loss duration were associated with poorer cognitive performance in patients with VS.

CONCLUSION

The findings of this study provide evidence for cognitive impairment in patients with untreated VS. It can thus be said that including cognitive assessment in the routine clinical management of patients with VS may facilitate more appropriate clinical decision-making and improve patients' quality of life.

Single Fraction and Hypofractionated Radiation Cause Cochlear Damage, Hearing Loss, and Reduced Viability of Merlin-Deficient Schwann Cells

BACKGROUND

Vestibular schwannomas (VS) are benign intracranial tumors caused by loss of function of the merlin tumor suppressor. We tested three hypotheses related to radiation, hearing loss (HL), and VS cell survival: (1) radiation causes HL by injuring auditory hair cells (AHC), (2) fractionation reduces radiation-induced HL, and (3) single fraction and equivalent appropriately dosed multi-fractions are equally effective at controlling VS growth. We investigated the effects of single fraction and hypofractionated radiation on hearing thresholds in rats, cell death pathways in rat cochleae, and viability of human merlin-deficient Schwann cells (MD-SC).

METHODS

Adult rats received cochlear irradiation with single fraction (0 to 18 Gray [Gy]) or hypofractionated radiation. Auditory brainstem response (ABR) testing was performed for 24 weeks. AHC viabilities were determined using immunohistochemistry. Neonatal rat cochleae were harvested after irradiation, and gene- and cell-based assays were conducted. MD-SCs were irradiated, and viability assays and immunofluorescence for DNA damage and cell cycle markers were performed.

RESULTS

Radiation caused dose-dependent and progressive HL in rats and AHC losses by promoting expression of apoptosis-associated genes and proteins. When compared to 12 Gy single fraction, hypofractionation caused smaller ABR threshold and pure tone average shifts and was more effective at reducing MD-SC viability.

CONCLUSIONS

Investigations into the mechanisms of radiation ototoxicity and VS radiobiology will help determine optimal radiation regimens and identify potential therapies to mitigate radiation-induced HL and improve VS tumor control.

Radiation for Sporadic Vestibular Schwannoma

Stereotactic radiosurgery (SRS) is a valid option for most patients undergoing treatment of small- and medium-sized vestibular schwannoma. Predictors of hearing preservation are the same for observation or surgery: when pretreatment hearing is normal, the tumor is smaller, and when a cerebrospinal fluid fundal cap exists. Hearing outcomes are poor when hearing loss exists pre-treatment. Rates of facial and trigeminal neuropathy are higher post-treatment after fractionated plans than single-fraction SRS. Subtotal resection and adjuvant radiation appears to offer patients with large tumors optimal outcomes for hearing, tumor control, and cranial nerve function versus gross total resection.

Diagnosis and Treatment of Peripheral and Cranial Nerve Tumors with Expert Recommendations: An EUropean Network for RAre CANcers (EURACAN) Initiative

The 2021 WHO classification of the CNS Tumors identifies as "Peripheral nerve sheath tumors" (PNST) some entities with specific clinical and anatomical characteristics, histological and molecular markers, imaging findings, and aggressiveness. The Task Force has reviewed the evidence of diagnostic and therapeutic interventions, which is particularly low due to the rarity, and drawn recommendations accordingly. Tumor diagnosis is primarily based on hematoxylin and eosin-stained sections and immunohistochemistry. Molecular analysis is not essential to establish the histological nature of these tumors, although genetic analyses on DNA extracted from PNST (neurofibromas/schwannomas) is required to diagnose mosaic forms of NF1 and SPS. MRI is the gold-standard to delineate the extension with respect to adjacent structures. Gross-total resection is the first choice, and can be curative in benign lesions; however, the extent of resection must be balanced with preservation of nerve functioning. Radiotherapy can be omitted in benign tumors after complete resection and in NF-related tumors, due to the theoretic risk of secondary malignancies in a tumor-suppressor syndrome. Systemic therapy should be considered in incomplete resected plexiform neurofibromas/MPNSTs. MEK inhibitor selumetinib can be used in NF1 children ≥2 years with inoperable/symptomatic plexiform neurofibromas, while anthracycline-based treatment is the first choice for unresectable/locally advanced/metastatic MPNST. Clinical trials on other MEK1-2 inhibitors alone or in combination with mTOR inhibitors are under investigation in plexiform neurofibromas and MPNST, respectively.

Hearing After Vestibular Schwannoma Surgery: Is It Preserved Forever?

INTRODUCTION

Currently, it is possible to preserve the auditory nerve in a large number of cases, but the preservation of the hearing itself is unpredictable. Apart from wait and scan strategy and stereoradiotherapy, hearing after vestibular schwannoma surgery is considered to remain stable even in long-term follow-up.

MATERIALS AND METHODS

Twenty-eight patients had preserved hearing after retrosigmoid suboccipital microsurgery of the vestibular schwannoma between 2008 and 2014. A standard audiological protocol was performed together with an magnetic resonance imaging evaluation of the fluid content of the inner ear.

RESULTS

The mean difference in pure-tone average between the direct and final postsurgical examination was 12.758 dB ( p = 2.5E - 06). The word recognition score deteriorated by 17.45% ( p = 0.03516). The mean American Academy of Otolaryngology-Head and Neck Surgery score on the second examination was 2.5, and that on the second examination was 3.111 ( p = 0.00483). There was no significant deterioration in the healthy ear.The signal intensity ratio in the basal turn of the cochlea increased by an average of 0.13 points ( p < 0.05).Patients with persistent tumor or nodular enhancement in the internal acoustic meatus deteriorated significantly in hearing according to the American Academy of Otolaryngology-Head and Neck Surgery scale compared with patients without any finding in the meatus ( p = 0.01299).

CONCLUSIONS

There is a discrete but gradual deterioration of the hearing in the postoperative period. Hearing impairment is more pronounced in patients with a nodular process in the internal acoustic meatus, regardless of whether it is growth active. After surgery, the pathological content of the inner ear normalizes (evaluated on T2 magnetic resonance imaging sequences).

Management of Vestibular Schwannoma with Normal Hearing

INTRODUCTION

This work aimed to study the management of vestibular schwannoma (VS) patients with normal hearing (NH).

METHODS

A retrospective study was undertaken in a Quaternary referral center for skull base pathologies. Among 4,000 VS patients 162 met our strict audiological criteria for NH. These patients were divided into 2 management groups, wait and scan (W&S) (45/162, 25%) and operated patients (123/162, 75%), and 6 patients were included in both groups.

RESULTS

Our management strategy achieved the goals for treatment of VS. First goal, all tumors were completely removed except for 2 intentional residuals. Second goal, facial nerve (FN) function preservation (House Brackmann I, II, and III) was 95.9%. Third goal, possible hearing preservation (HP) attempts occurred in (50/122) (40.9%) with an HP rate in 44% of the patients. Additionally, there were only 2 cases of postoperative complications with no CSF leakage. The prospect of HP in NH patients did not differ with respect to tumor size. However, patients with normal preoperative ABR seemed to have better chances of HP and good FN function and vice versa. HP rate was superior for the MCFA as opposed to the RS + RLA. W&S group demonstrated hearing stability in 88.9% of the patients and FN function stability of HB I in 100% of the patients.

CONCLUSIONS

Surgical resection is a reasonable and definitive management option for VS with NH. Nevertheless, choosing to manage cases with observation remains an appropriate management option for NH patients. ABR might be considered as an adjuvant tool indicating better prognosis for HP.

Cochlear sparing in LINAC-based radiosurgery for vestibular schwannoma: a dosimetric comparison of dynamic conformal arc, IMRT and VMAT treatment plans

BACKGROUND

Stereotactic radiosurgery (SRS) is the preferred treatment for vestibular schwannoma (VS) in patients with preserved hearing and tumour diameter < 3 cm. Emerging evidence suggests restricting cochlear dose could preserve hearing. This retrospective replanning study aims to compare dynamic conformal arc therapy (DCAT), intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) plans for superiority of cochlear dose sparing without compromising tumour coverage.

METHODS

Eligibility criteria included sporadic VS, serviceable hearing and availability of CT and MRI for planning. The original gross tumour volume and brainstem OAR volume were retained; the cochlea was newly contoured on the planning CT scan (bone window). Each case was replanned using the three above techniques, prescribing 12 Gy to the 80% isodose line. No dose constraint was applied to the cochlea.

RESULTS

Eighteen patients were replanned. Mean tumour volume was 2.25 cc. Tumour coverage and tumour mean dose (DCAT: 14.2, IMRT: 14.6, VMAT: 14.5 Gy) were comparable. Paddick and RTOG conformity indices were better for DCAT (0.66 and 1.6) and VMAT (0.69 and 1.5) compared to IMRT (0.56 and 1.9). DCAT had superior gradient index (3.0) compared to VMAT (3.4) and IMRT (3.4). VMAT delivered the lowest mean brainstem maximum dose (8.3 Gy) and decreased the mean cochlear dose (3.4 Gy) by 2.3 and 2.1 Gy, and the mean cochlear maximum dose (3.6 Gy) by 2.4 and 2.5 Gy relative to DCAT and IMRT, respectively.

CONCLUSION

LINAC-based SRS treatment using VMAT can achieve better cochlear dose sparing than DCAT or IMRT while maintaining tumour coverage.

Tumor Biology and Microenvironment of Vestibular Schwannoma-Relation to Tumor Growth and Hearing Loss

Vestibular schwannoma is the most common benign neoplasm of the cerebellopontine angle. It arises from Schwann cells of the vestibular nerve. The first symptoms of vestibular schwannoma include hearing loss, tinnitus, and vestibular symptoms. In the event of further growth, cerebellar and brainstem symptoms, along with palsy of the adjacent cranial nerves, may be present. Although hearing impairment is present in 95% of patients diagnosed with vestibular schwannoma, most tumors do not progress in size or have low growth rates. However, the clinical picture has unpredictable dynamics, and there are currently no reliable predictors of the tumor's behavior. The etiology of the hearing loss in patients with vestibular schwannoma is unclear. Given the presence of hearing loss in patients with non-growing tumors, a purely mechanistic approach is insufficient. A possible explanation for this may be that the function of the auditory system may be affected by the paracrine activity of the tumor. Moreover, initiation of the development and growth progression of vestibular schwannomas is not yet clearly understood. Biallelic loss of the NF2 gene does not explain the occurrence in all patients; therefore, detection of gene expression abnormalities in cases of progressive growth is required. As in other areas of cancer research, the tumor microenvironment is coming to the forefront, also in vestibular schwannomas. In the paradigm of the tumor microenvironment, the stroma of the tumor actively influences the tumor's behavior. However, research in the area of vestibular schwannomas is at an early stage. Thus, knowledge of the molecular mechanisms of tumorigenesis and interactions between cells present within the tumor is crucial for the diagnosis, prediction of tumor behavior, and targeted therapeutic interventions. In this review, we provide an overview of the current knowledge in the field of molecular biology and tumor microenvironment of vestibular schwannomas, as well as their relationship to tumor growth and hearing loss.

Diagnostic accuracy of intraoperative brainstem auditory evoked potential for predicting hearing loss after vestibular schwannoma surgery

Objective

This meta-analysis evaluated the diagnostic value of intraoperative brainstem auditory evoked potential (BAEP) for predicting post-operative hearing loss.

Methods

Research articles in MEDLINE, Embase, and Cochrane Library databases were searched and selected up to 20 January 2022, and data were extracted following a standard procedure. A diagnostic accuracy test meta-analysis was performed using a mixed-effect binary regression model.

Results

A total of 693 patients from 15 studies were extracted. The change in intraoperative BAEP showed high sensitivity (0.95) but low specificity (0.37), with an area under the curve of 0.83. Diagnostic accuracy of the loss of potentials showed high sensitivity (0.82) and specificity (0.79). The area under the curve was 0.88. No factor was found to account for the heterogeneity of the results according to the meta-regression and subgroup analyses (all P-values > 0.05).

Conclusions

Our results showed that the loss of BAEP has meaningful value for predicting hearing loss after vestibular schwannoma surgery. The change in BAEP is also important for its high sensitivity during hearing preservation surgery.

Single-fraction stereotactic radiosurgery versus microsurgical resection for the treatment of vestibular schwannoma: a systematic review and meta-analysis

BACKGROUND

Vestibular schwannomas are benign tumours for which various treatments are available. We performed a systematic review of prospective controlled trials comparing the patient-relevant benefits and harms of single-fraction stereotactic radiosurgery (sfSRS) with microsurgical resection (MR) in patients with vestibular schwannoma.

METHODS

We searched for randomized controlled trials (RCTs) and non-randomized prospective controlled trials in MEDLINE, Embase, the Cochrane Central Register of Controlled Trials, and study registries (last search: 09/2021) and also screened reference lists of relevant systematic reviews. Manufacturers were asked to provide unpublished data. Eligible studies investigated at least one patient-relevant outcome. We assessed the risk of bias (high or low) at the study and outcome level. If feasible, meta-analyses were performed. We graded the results into different categories (hint, indication, or proof of greater benefit or harm).

RESULTS

We identified three non-randomized prospective controlled trials of generally low quality with evaluable data on 339 patients with unilateral vestibular schwannoma. There was an indication of greater benefit of sfSRS compared with MR for facial palsy (OR 0.06, 95% CI 0.02-0.21, p < 0.001, 2 studies), hearing function (no pooled estimate available, 2 studies), and length of hospital stay (no pooled estimate available, 2 studies). We found no clinically relevant differences for mortality, vertigo, headaches, tinnitus, balance function, work disability, adverse events, and health-related quality of life.

CONCLUSIONS

Our systematic review indicates that sfSRS has greater benefits than MR in patients with unilateral vestibular schwannoma. However, it is unclear whether this conclusion still holds after 2 years, as long-term studies are lacking. It is also unclear whether the effects of sfSRS are similar in patients with bilateral vestibular schwannomas. Long-term prospective studies including patients with this condition would therefore be useful.

SYSTEMATIC REVIEW REGISTRATION

The full (German language) protocol and report (Commission No. N20-03) are available on the institute's website: www.iqwig.de/en/projects/n20-03.html.

The Learning Curve in Skull Base Surgery Part 1–From Historical-Philosophical Concepts to Microsurgical Lab Training

The learning curve reflects surgeons' experience in managing several patients with the same disease. In skull base surgery, the professional's place on the curve could be related to the number of times the same procedure was performed. Where does curve begin? What amount of training is necessary prior to its application in surgical settings? What were the results of the first few skull base tumor surgeries performed by a surgeon who goes on to produce excellent results, and how is reflected in the start of their learning curve? The only way for neurosurgeons to improve their results from the start is with prior training in the microsurgery laboratory. This learning technique is essential to maximize the chance of success of a neurosurgical procedures, minimizing the morbidity rate to which patients are subjected by less experienced neurosurgeons. This article is divided in two parts, and its purpose is to show how training in the microsurgical laboratory fits into the construction of knowledge about skull base surgery, based on authors' experience and reflections. This first part discusses the technical, psychological, and philosophical aspects of medical knowledge, primarily addressing those training in skull base surgery, the principles of some selected philosophical currents, and their influence on the development of current medical knowledge.

Impact of Demographics and Clinical Features on Initial Treatment Pathway for Vestibular Schwannoma

OBJECTIVE

To identify demographic and clinical features impacting initial treatment pathway for vestibular schwannoma.

STUDY DESIGN

Retrospective chart review.

SETTING

Tertiary care academic medical center.

PATIENTS

Patients diagnosed with vestibular schwannoma between 2009 and 2019.

INTERVENTIONS

Observation, stereotactic radiosurgery, or microsurgical resection.

MAIN OUTCOME MEASURES

χ 2 Test, one-way analysis of variance, and multivariate logistic regression were used to correlate demographic and clinical factors with initial treatment pathway for 197 newly diagnosed vestibular schwannoma patients.

RESULTS

Among 197 patients, 93 (47%) were initially treated with observation, 60 (30%) with stereotactic radiation (Gamma Knife) and 44 (22%) with surgical resection. Age univariately had no statistically significant impact on initial pathway, but those undergoing surgery trended toward a younger demographic (49.1 yr [surgery] versus 57.2 yr [observation] versus 59.0 yr [Gamma Knife]). Men were more likely to be initially observed than women ( p = 0.04). Patients initially observed were more likely to have a lower Koos classification ( p < 0.001) and have better tumor-ear hearing ( p = 0.03). Only 34.4% of patients living outside the local geographic region were initially observed compared with 53.0% living locally ( p = 0.055). Surgeon correlated with initial treatment ( p = 0.04) but did not maintain significance when adjusting for hearing level or tumor size. A multiple linear regression model found age, maximum tumor diameter, and Koos class to correlate with initial treatment pathway ( p < 0.0001, r2 = 0.42).

CONCLUSION

Initial treatment pathway for newly diagnosed vestibular schwannoma is impacted by demographic factors such as age, sex, and geographic proximity to the medical center. Clinical features including hearing level and tumor size also correlated with initial treatment modality.

Hearing Preservation After Intervention in Vestibular Schwannoma

OBJECTIVE

This study aimed to assess the durability of audiological outcomes after radiation and surgery in the management of vestibular schwannoma.

STUDY DESIGN

Retrospective review.

SETTING

Tertiary academic center.

PATIENTS

Adults with sporadic vestibular schwannoma and serviceable hearing at the time of intervention.

INTERVENTIONS

Gamma Knife, middle cranial fossa, or retrosigmoid approaches.

MAIN OUTCOME MEASURES

Pure-tone audiometry and speech discrimination scores.

RESULTS

Postintervention serviceable hearing (class A/B) was preserved in 70.4% (n = 130; mean follow-up, 3.31 yr; range, 0-15.25 yr). Of the 49 patients treated with radiation, 19 (39.6%) had serviceable hearing at last follow-up, compared with 38 (46.9% of 81) who underwent retrosigmoid (n = 36 [44.4%]) and middle cranial fossa (n = 45 [55.6%]) approaches (odds ratio [OR], 1.40; 95% confidence interval [CI], 0.67-2.82; p = 0.47). A matched analysis by age, tumor volume, and preintervention hearing (n = 38) also found no difference in hearing preservation (HP) likelihood between surgery and radiation (OR, 2.33; 95% CI, 0.24-35.91; p = 0.59). After initial HP, 4 (9.5%) surgical versus 10 (37.0%) radiated patients subsequently lost residual serviceable (A/B) hearing (OR, 0.18; 95% CI, 0.06-0.69; p = 0.01) at a mean 3.74 ± 3.58 and 4.73 ± 3.83 years after surgery and radiation, respectively. Overall, 5- and 10-year HP rates (A/B) after initially successful HP surgery were 84.4 and 63.0%, respectively. However, survival estimates declined to 48.9% at 5 years and 32.7% at 10 years when patients with immediate postoperative serviceable hearing loss were also included, which were comparable to radiation-HP rates at 5 and 10 years of 28.0 and 14.2%, respectively ( p = 0.75).

CONCLUSIONS

After vestibular schwannoma intervention, overall HP was similar between radiated and surgical cohorts. However, when successful, surgical approaches offered more durable hearing outcomes at long-term follow-up.

Application of Subperineural Resection Technique in Vestibular Schwannomas: Surgical Efficacy and Outcomes in 124 patients

Objective

We aimed to explore the application and prospects of the subperineural resection technique for tumor separation and removal under the perineurium during surgery for vestibular schwannomas (VSs).

Methods

This study retrospectively analyzed 124 patients with VSs who underwent surgery via a retrosigmoid approach from July 2015 to October 2020 in the Department of Neurosurgery, Tangdu Hospital, Air Force Military Medical University. The data will be discussed with regard to the following aspects: clinical features, surgical strategies, tumor resection extent, facial–acoustic function preservation, and postoperative complications.

Results

Gross total resection (GTR) of the tumor was achieved in 104 patients, with a GTR rate of 83.9%, and subtotal resection (STR) of the tumor was achieved in 20 patients. There was no significant difference in facial and acoustic nerve functional preservation between GTR and STR, as well as in tumor resection between solid and cystic tumors. The retention rate reached 97.6% in terms of complete anatomical facial nerve preservation. Facial nerve function was assessed using the House–Brackmann (HB) grading score. Consequently, HB grades of I–II, III–IV, and V–VI were determined for 96 (77.4%), 25 (20.2%), and 3 (2.4%) cases, respectively, 1 week postoperatively and accounted for 110 cases (88.7%), 13 cases (10.5%), and 1 case (0.8%), respectively, at 6 months. Fifteen of 35 (42.9%) patients with serviceable hearing before the operation still had serviceable hearing at 6 months postoperatively. There were 5 cases of cerebellar or brainstem bleeding after the operation, and one patient died. Multivariate logistic regression analysis showed that older age (≥60 years, p = 0.011), large tumor (>3 cm, p = 0.004), and cystic tumor (p = 0.046) were independent risk factors associated with the extent of adhesion between the tumor and the brainstem and facial–acoustic nerve.

Conclusion

We successfully applied the subperineural resection technique to a large series of patients with VSs and achieved satisfactory results. Accurate identification of the perineurium and subperineural resection of the tumor can effectively reduce the disturbance of the facial–acoustic nerve during the operation and provide an intuitive basis for judging the tumor boundary. The subperineural resection technique may be conducive to improving the rate of total tumor resection and facial–acoustic nerve functional preservation in the surgical treatment of VSs.

Acoustic neuromas associated with sudden sensorineural hearing loss

BACKGROUND

Several studies have reported sudden sensorineural hearing loss (SHL) as an initial symptom of acoustic neuromas (ANs).

AIMS/OBJECTIVES

We aimed to retrospectively evaluate the incidence of SHL and the associated rates of post-treatment improvement in patients diagnosed with ANs.

MATERIALS AND METHODS

We analysed the clinical data of 686 patients with ANs and examined tumour size, correlation with hearing loss, number of episodes of SHL, extent of auditory recovery, and associated audiogram patterns.

RESULTS

Among 686 enrolled patients with ANs, 232 (86 with intracanalicular and 146 with extrameatal tumours) experienced SHL at some point in their clinical history. The incidence of SHL was not significantly associated with tumour size. Of the 172 patients analysed, 119, 44, and 9 patients experienced one, two, or three or more episodes of SHL, respectively. Confirmed auditory recovery occurred in 61%, 45.3%, and 33.3% of the patients after the first, second, or third or later episodes of SHL, respectively. The audiograms of 78/172 (45.3%) patients showed a typical trough-shaped pattern of hearing loss at medium-level frequencies.

CONCLUSIONS AND SIGNIFICANCE

Among patients with ANs, 7.7% experienced two or more episodes of SHL. The recovery rate of SHL decreased with each successive occurrence.

Defining clinically significant tumor size in vestibular schwannoma to inform timing of microsurgery during wait-and-scan management: moving beyond minimum detectable growth

OBJECTIVE

Detection of vestibular schwannoma (VS) growth during observation leads to definitive treatment at most centers globally. Although ≥ 2 mm represents an established benchmark of tumor growth on serial MRI studies, 2 mm of linear tumor growth is unlikely to significantly alter microsurgical outcomes. The objective of the current work was to ascertain where the magnitude of change in clinical outcome is the greatest based on size.

METHODS

A single-institution retrospective review of a consecutive series of patients with sporadic VS who underwent microsurgical resection between January 2000 and May 2020 was performed. Preoperative tumor size cutpoints were defined in 1-mm increments and used to identify optimal size thresholds for three primary outcomes: 1) the ability to achieve gross-total resection (GTR); 2) maintenance of normal House-Brackmann (HB) grade I facial nerve function; and 3) preservation of serviceable hearing (American Academy of Otolaryngology-Head and Neck Surgery class A/B). Optimal size thresholds were obtained by maximizing c-indices from logistic regression models.

RESULTS

Of 603 patients meeting inclusion criteria, 502 (83%) had tumors with cerebellopontine angle (CPA) extension. CPA tumor size was significantly associated with achieving GTR, postoperative HB grade I facial nerve function, and maintenance of serviceable hearing (all p < 0.001). The optimal tumor size threshold to distinguish between GTR and less than GTR was 17 mm of CPA extension (c-index 0.73). In the immediate postoperative period, the size threshold between HB grade I and HB grade > I was 17 mm of CPA extension (c-index 0.65). At the most recent evaluation, the size threshold between HB grade I and HB grade > I was 23 mm (c-index 0.68) and between class A/B and C/D hearing was 18 mm (c-index 0.68). Tumors within 3 mm of the 17-mm CPA threshold displayed similarly strong c-indices. Among purely intracanalicular tumors, linear size was not found to portend worse outcomes for all measures.

CONCLUSIONS

The probability of incurring less optimal microsurgical outcomes begins to significantly increase at 14-20 mm of CPA extension. Although many factors ultimately influence decision-making, when considering timing of microsurgical resection, using a size threshold range as depicted in this study offers an evidence-based approach that moves beyond reflexively recommending treatment for all tumors after detecting ≥ 2 mm of tumor growth on serial MRI studies.

Treatment for vestibular schwannoma: Systematic review and single arm meta-analysis

OBJECTIVE

Vestibular schwannoma is a benign tumor in the schwannoma cells of the 8th cranial nerve. It causes symptoms like tinnitus, vertigo and end up with loss of hearing so the appropriate treatment is very important. There are many treatment techniques including conservative, surgery and radiosurgery. We aimed to systematically review and single arm meta-analysis the different treatment techniques of vestibular schwannoma.

METHODS

A comprehensive literature search using thirteen databases including PubMed, Scopus, and Web of Science was performed. All clinical trials about treatment vestibular schwannoma were included and single arm meta-analyzed. We assessed the risk of bias using ROBIN-I's tool and scale of Council Australia's Cancer Guidelines Wiki. The protocol was registered in PROSPERO (CRD42018089784) and has been updated on 17 April 2019.

RESULTS

A total of 35 clinical trials studies were included in the final analysis. The pooled proportion of stable hearing capability in patients receiving gamma knife radiosurgery (GKRS) was 64% (95% CI: 52%-74%). GKRS favored increased hearing capability 10% (95% CI: 7%-16%). Regarding tumor size, GKRS is the most protective method 53% (95% CI: 37%-69%). Complications occurred most commonly in single fractional linac stereotactic radiosurgery (SFSRT) 37% (95% CI: 12%-72%).

CONCLUSION

Our analysis suggested gamma knife radiosurgery could be the most ideal treatment for vestibular schwannoma based on stabilizing hearing capability, increasing hearing capability, decreasing tumor size and complications.

Analysis of Hearing Preservation in Middle Cranial Fossa Resection of Vestibular Schwannoma

OBJECTIVE

Describe the effect of preoperative hearing on the likelihood of hearing preservation after middle cranial fossa (MCF) approach for resection of vestibular schwannoma (VS) and the effect of hearing preservation on disease-specific quality of life (QOL).

STUDY DESIGN

Retrospective chart review.

SETTING

Academic tertiary care skull base surgery program.

PATIENTS

Sixty three adult patients with preoperative word recognition score (WRS) ≥50% who underwent MCF resection of VS between 2017 and 2020.

INTERVENTIONS

All patients underwent MCF VS resection with attempted hearing preservation.

MAIN OUTCOME MEASURES

Hearing preservation (postoperative WRS ≥50%), hearing-related Penn Acoustic Neuroma Quality of Life (PANQOL) score.

RESULTS

Sixty three patients with mean age 47.4 (±9.6) years and tumor size 11.5 (±0.5) mm were analyzed. Hearing was preserved (+HP) and lost (-HP) in 37 (58.7%) and 26 (41.3%) patients, respectively. Preoperatively, pure tone average audiometry was significantly lower among the +HP group (20.0 dB) versus -HP (31.0 dB, p < 0.003). WRS was higher among +HP versus -HP (94% vs. 84%, respectively; p < 0.002). Linear regression showed that intra- versus extra-canalicular tumor location, sudden hearing loss history, fundal fluid cap thickness, and tumor size had no relationship to hearing preservation outcomes. When evaluating postoperative QOL data (n = 37) hearing-related PANQOL score differed between +HP and -HP (t35 = 2.458, p = 0.0191) groups.

CONCLUSIONS

In this cohort of patients undergoing MCF resection of VS, rates of HP were higher for patients with excellent preoperative hearing. Postoperatively, +HP patients reported improved hearing-related PANQOL scores compared to -HP patients.

Hearing Rehabilitation with Cochlear Implants after CyberKnife Radiosurgery of Vestibular Schwannoma: A Report Based on Four Clinical Cases

Severe sensorineural hearing loss can be a symptom of the benign tumor vestibular schwannoma (VS). The treatment of VS with non-invasive stereotactic radiosurgery (SRS) offers a high local tumor control rate and an innovative possibility of sequential hearing rehabilitation with cochlear implantation. This study evaluated the feasibility, complications, and auditory outcomes of such a therapeutic approach. Three males and one female (mean age 65.3 ± 9.4 years) scheduled for cochlear implantation and diagnosed with sporadic VS classified as T1 or T2 (according to Samii) were enrolled in this study. All patients had progressive hearing loss qualifying them for cochlear implantation. First, the tumor was treated using CyberKnife SRS. Next, sequential auditory rehabilitation with a cochlear implant (CI) was performed. Clinical outcomes and surgical feasibility were analyzed, and audiological results were evaluated using pure tone audiometry and speech recognition tests. All patients exhibited open-set speech understanding. The mean word recognition score (at 65 dB SPL, Freiburg Monosyllabic Test, FMT) improved after cochlear implantation in all four patients from 5.0 ± 10% (with hearing aid) preoperatively to 60.0 ± 22.7% six months postoperatively. Our results suggest that in patients with profound hearing loss caused by sporadic vestibular schwannoma, the tumor removal with SRS followed by cochlear implantation is an effective method of auditory rehabilitation.

Multicentre cohort study of cochlear implantation outcomes in Thailand

OBJECTIVES

To report the status and outcomes of cochlear implantation in Thailand.

DESIGN

Cohort study.

SETTING

Tertiary care and university hospitals.

PARTICIPANTS

Patients who underwent cochlear implant surgery in Thailand.

INTERVENTIONS

This project collected data from all government and university hospitals in Thailand where cochlear implant surgery was performed between 2016 and 2020.

PRIMARY AND SECONDARY OUTCOME MEASURES

Baseline characteristics, operation data, complications, audiological outcomes and quality of life were reported.

RESULTS

This study included 458 patients, and nearly half of the patients were children and adolescents (46.94%). The mean age of the patients was 2.96±5.83 years. At 1 year postoperatively, the mean pure tone average of the hearing threshold in the implanted ear significantly improved from unaided preoperative baseline (mean difference (MD) 64.23 dB HL; 95% CI 59.81 to 68.65; p<0.001). The mean speech recognition threshold also improved (MD 55.96 dB HL; 95% CI 49.50 to 62.42, p<0.001). The quality-of-life scores of the EQ-5D-5L, PedsQL and HUI3 questionnaires at 1 year showed improved mobility (range, 0-5; MD 0.65; 95% CI 0.05 to 1.25; p=0.037), hearing (range, 0-6; MD 0.96; 95% CI 0.30 to 1.61; p=0.006) and speech (range, 0-5; MD 0.44; 95% CI 0.04 to 0.84; p=0.031). Common complications included electrode dislodgement (2.18%), vertigo (1.23%) and meningitis (1.93%).

CONCLUSIONS

Excellent audiological outcomes and improvement in the quality of life in the mobility, hearing and speech domains were observed in patients who underwent cochlear implantation in Thailand.

Primary treatment of small-to-medium (<3cm) sporadic vestibular schwannomas: A systematic review and meta-analysis on hearing preservation and tumor control rates for microsurgery versus radiosurgery

BACKGROUND

A meta-analysis of sporadic VS patients primarily treated with stereotactic radiosurgery (SRS) or microsurgery (MS) was performed, and hearing preservation outcome (HPO), tumor control (TC), and facial nerve dysfunction (FND) were analyzed.

METHODS

A systematic review was conducted (Medline and Scopus database) for the period, January 2010 to June 2020 with appropriate MeSH. English language articles for small-to-medium sporadic VS (<3cm) utilizing SRS or MS as primary treatment modality, with minimum follow-up of 3 years, were included. Studies had to report an acceptable standardized hearing metric.

RESULTS

Thirty-two studies met inclusion criteria: 10 (microsurgery); 23 (radiosurgery); (one comparative study included in both). HPO, at ∼65 months follow-up, were comparable between MS group (10 studies; 809 patients) and SRS group (23 studies; 1234 patients) (56% versus 59%, p=0.1527). TC, at ∼70 months follow-up, was significantly better in MS group (9 studies; 1635 patients) versus SRS group (19 studies; 2260 patients) (98% versus 92%, p < 0.0001). FND, at ∼ 12 months follow-up, was significantly higher in MS group (8 studies; 1101 patients) versus SRS group (17 studies; 2285 patients) (10% versus 2%, p < 0.0001).

CONCLUSION

MS and SRS are comparable primary treatments for small (<3cm) sporadic VS with respect to HPO at 5-year follow-up in patients with serviceable hearing at presentation; ∼50% patients for both modalities will likely lose serviceable hearing by that time-point. High TC rates (>90%) were seen with both modalities; MS (98%) versus SRS (92%). The post-treatment FND was significantly less with SRS group (2%) versus MS group (10%).

Lifetime Cost and Quality-Adjusted Life-Years Across Management Options for Small- and Medium-Sized Sporadic Vestibular Schwannoma

OBJECTIVE

Despite the growing emphasis on healthcare costs, limited data address this aspect of care within the vestibular schwannoma (VS) literature. We sought to determine which strategy confers the lowest lifetime cost and greatest quality-adjusted life-years (QALYs) for patients with small- to medium-sized sporadic VS tumors.

STUDY DESIGN

A Markov model was created to determine the most cost-effective management algorithm. Tumor characteristics, magnetic resonance imaging surveillance schedule, treatment outcomes, and health-related quality of life values were derived from previously published data. Cost estimates were based on CMS Fee Schedule reimbursement rates.

SETTING

Economic Evaluation Service within the Kern Center for the Science of Healthcare Delivery.

PATIENTS

Patients diagnosed with small- to medium-sized sporadic VS.

INTERVENTIONS

Upfront microsurgery following diagnosis, upfront radiosurgery following diagnosis, observation with microsurgery reserved for observed tumor growth, and observation with radiosurgery reserved for observed tumor growth.

RESULTS

Across patient ages at time of diagnosis ranging from 18 to 70 years, observation with subsequent radiosurgery used for tumor growth was the most cost-effective management algorithm while upfront microsurgery was the least. When presented with a hypothetical 50-year-old patient, the strategy with the lowest lifetime cost and highest QALYs was observation with subsequent radiosurgery reserved for tumor growth ($32,161, 14.11 QALY), followed by observation with microsurgery reserved for tumor growth ($34,503, 13.94 QALY), upfront radiosurgery ($43,456, 14.02 QALY), and lastly, upfront microsurgery ($47,252, 13.60 QALY). Sensitivity analyses varying mortality rates, estimated costs, health-related quality of life, and progression to nonserviceable hearing demonstrated consistent ranking among treatments.

CONCLUSIONS

When considering initial management of small- and medium-sized sporadic VSs, neither lifetime cost nor QALYs support upfront microsurgery or radiosurgery, even for younger patients. Initial observation with serial imaging, reserving radiosurgery or microsurgery for patients exhibiting tumor growth, confers the greatest potential for optimized lifetime healthcare cost and QALY outcomes.

Cochlear T2 Signal May Predict Hearing Outcomes After Resection of Acoustic Neuroma

OBJECTIVE

Examine the impact of preoperative cochlear Fast Imaging Employing Steady-state Acquisition (FIESTA) and Constructive Interference in Steady State (CISS) signal intensity on hearing outcomes after middle cranial fossa (MCF) resection of acoustic neuroma (AN).

METHODS

Adult patients (≥18 years) who underwent MCF AN resection for hearing preservation (HP) between November 2017 and September 2019 were retrospectively reviewed. All patients had preoperative word recognition score (WRS) ≥50%. HP was defined as postoperative WRS ≥50%. A neuroradiologist blinded to patients' clinical and audiometric outcomes reviewed patients' preoperative magnetic resonance images. Ipsilateral-to-contralateral cochlear FIESTA/CISS signal intensity ratios were determined using hand-drawn regions of interest focused on the cochlear fluid. Preoperative and postoperative pure tone average (PTA) and WRS were reviewed.

RESULTS

Fifty-one patients were reviewed (60.8% female). Mean age was 47 years and mean tumor size 9.2 mm (±3.8). Hearing was preserved in 56.9% (n = 29). FIESTA/CISS signal ratios did not significantly differ between patients with and without HP. Lower FIESTA/CISS signal ratios correlated with greater declines in hearing (r = 0.322, p = 0.011 for PTA; and r = 0.384, p = 0.004 for WRS). On multivariate analysis accounting for tumor size and preoperative PTA/WRS, decreases in FIESTA/CISS signal ratios independently predicted greater declines in hearing by PTA (b = -100.9, p = 0.012) and WRS (b = 76.208), although the latter result was not statistically significant (p = 0.078).

CONCLUSIONS

Cochlear FIESTA/CISS signal intensity may be a predictor of postoperative hearing loss after MCF AN resection. In this cohort, degraded preoperative cochlear FIESTA/CISS signal strongly predicted postoperative hearing loss.Level of Evidence: IV.

Defining current practice patterns of vestibular schwannoma management in Italy: results of a nationwide survey

Objective

Despite the increasing incidence rate of vestibular schwannomas (VS), controversies in their management are still present.

Methods

A 35-item multiple-choice survey investigating the current practice patterns of VS care was sent to the members of the Italian Society of Otolaryngology, Head and Neck Surgery (SIO) and of the Italian Society of Neurosurgery (SINCH).

Results

Among 66 respondents, 37 (56.0%) claimed to be actively involved in VS management. Most interviewees (35.1%) declared > 20 years of experience and 59.5% claimed to work in an academic practice. The number of cases evaluated in each centre per year varied widely, with 54.0% evaluating > 25 cases/year and only 13.6% > 100 cases/year. Multidisciplinary care for VS evaluation was confirmed by 50.0% of respondents, and multidisciplinary surgical care by 62.2%. Observation and surgery were the most common management options proposed. Further details regarding VS care are presented.

Conclusions

The present study provides the first overview on the current practice patterns of VS care in Italy. Although integrated in most centres, a multidisciplinary model of care needs to be encouraged. Wide heterogeneity in experience and practices is mostly influenced by the surgeon’s different specialties and by the lack of shared guidelines.

Large and small vestibular schwannomas: same, yet different tumors

BACKGROUND

Vestibular schwannomas (VS) present at variable size with heterogeneous symptomatology. Modern treatment paradigms for large VS include gross total resection, subtotal resection (STR) in combination with observation, and/or radiation to achieve optimal function preservation, whereas treatment is felt to be both easier and safer for small VS. The objective is to better characterize the presentation and surgical outcomes of large and small VS.

METHODS

We collected data of patients who had surgically treated VS with a posterior fossa diameter of 4.0 cm or larger (large tumor group, LTG) and smaller than 1.0 cm in cisternal diameter (small tumor group, STG). Statistical significance was defined as p < 0.05.

RESULTS

LTG included 48 patients (average tumor size: 44.9 mm) and STG 38 (7.9 mm). Patients in STG presented more frequently with tinnitus and sudden hearing loss. Patients in LTG underwent more STR than STG (50.0% vs. 2.6%, p < 0.0001). LTG had more complications (31.3% vs. 13.2%, p = 0.049). Postoperative facial nerve function in STG was significantly better than LTG. STG had better hearing preoperatively (p < 0.0001) and postoperatively than LTG (p = 0.0002). Postoperative headache was more common in STG (13.2% vs. 2.1%, p = 0.045). The rate of recurrence/progression needing treatment was not statistically different between the groups (12.5% in LTG vs. 7.9% in STG, p = 0.49). Those patients who required periprocedural cerebrospinal fluid diversion had higher risk of infection (20.8% vs 4.8%, p = 0.022).

CONCLUSION

Large and small VS present differently. LTG showed more unsatisfactory outcomes in facial nerve function and postoperative hearing despite maximal efforts undertaken toward function-preservation strategy; however, similar tumor control was achieved.

Impact of vestibular nerve preservation on facial and hearing outcomes in small vestibular schwannoma surgery: a technical feasibility study

BACKGROUND

Management of small vestibular schwannomas (VSs) remains controversial. When surgery is chosen, the preservation of facial and cochlear nerve function is a priority. In this report, we introduce and evaluate a technique to anatomically preserve the vestibular nerves to minimize manipulation and preserve the function of the facial and cochlear nerves.

METHODS

The vestibular nerve preservation technique was prospectively applied to resect small VS tumors in patients with serviceable preoperative hearing (American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) class A or B). Clinical and radiological data were recorded and analyzed.

RESULTS

Ten patients met the inclusion criteria. The mean (SD) age was 40.4 (12.5) years. Follow-up ranged from 6 weeks to 2 years. The maximum tumor diameter parallel to the internal auditory canal ranged from 10 to 20 mm (mean, 14.9 (3.1) mm). There were three Koos grade 3 and seven Koos grade 2 tumors. Gross total resection was achieved in all cases. Both the facial and cochlear nerves were anatomically preserved in all cases. Postoperatively, 7 patients (70%) remained in the AAO-HNS class A or B hearing category. None of the patients had new vestibular symptoms, and all had House-Brackmann grade 1 facial function. Nervus intermedius dysfunction was observed in 1 patient preoperatively, which worsened postoperatively. Two patients had new nervus intermedius symptoms postoperatively.

CONCLUSION

Improvement of facial nerve and hearing outcomes is feasible through the intentional preservation of the vestibular nerves in the resection of small VSs. Longer follow-up is required to rule out tumor recurrence.

Preoperative Sudden Hearing Loss May Predict Hearing Preservation After Retrosigmoid Resection of Vestibular Schwannoma

OBJECTIVES

Describe the effect of preoperative sudden hearing loss (SHL) on likelihood of hearing preservation (HP) after surgical resection of vestibular schwannoma (VS).

STUDY DESIGN

Retrospective chart review.

SETTING

Tertiary referral center.

PATIENTS

Adult patients (≥18 years) who underwent retrosigmoid VS resection for HP between February 2008 and December 2018 were reviewed. All patients had preoperative word recognition score (WRS) of at least 50%. Similarly, HP was defined as postoperative WRS of more than or equal to 50%. Regression analysis was used to describe the effect of SHL on HP, accounting for tumor size, and preoperative hearing quality.

INTERVENTIONS

All patients underwent retrosigmoid VS resection for HP.

MAIN OUTCOME MEASURES

WRS of at least 50%.

RESULTS

Of 160 patients who underwent retrosigmoid VS resection during the study period, 153 met inclusion criteria. Mean tumor size was 14.0 (±6) mm. Hearing was preserved in 41.8% (n = 64). Forty patients (26.1%) had a history of preoperative SHL. Among 138 patients (90.2%) in whom the cochlear nerve was anatomically preserved during surgery, HP was achieved in 61.8% of those with SHL (21 of 34) and 41.3% of those without SHL (43 of 104) (p = 0.0480). On univariate and multivariate analysis (accounting for tumor size and preoperative hearing quality), SHL was a significant positive predictor of HP (odds ratio 2.292, p = 0.0407 and odds ratio 2.778, p = 0.0032, respectively).

CONCLUSION

In patients with VS and retained serviceable hearing, SHL is an independent predictor of HP after retrosigmoid microsurgical resection when the cochlear nerve is preserved.

Prediction of Hearing Preservation in Vestibular Schwannoma Surgery According to Tumor Size and Anatomic Extension

OBJECTIVE

Vestibular schwannoma (VS) surgery is feasible for various tumor sizes that are inappropriate for wait and scan or radiosurgery. The predictive value of 2 grading systems was investigated for postoperative hearing preservation (HP) in a large series.

STUDY DESIGN

Retrospective analysis.

SETTING

Neurosurgical patient database of the University of Erlangen was queried between 2014 and 2017.

METHODS

Retrospective single-center analysis on 138 VSs operated on via a retrosigmoidal approach. The mean tumor size was 20.4 mm (SD, 7.6 mm) with fundal infiltration in 67.4%. The overall resection rate was 93.5%. Tumors were classified preoperatively by the 3-tier Erlangen grading system depending on size or the anatomically based 4-tier Koos grading system.

RESULTS

Preoperative hearing preservation was found in 70.3% of patients and was significantly correlated to tumor size (P = .001). For Erlangen grading, a mean postoperative serviceable hearing preservation rate of 32% was achieved: 83.3% for tumors <12 mm, 30.3% for tumors between 12 and 25 mm, and 5.3% for tumors >25 mm. In contrast, according to Koos grading, postoperative serviceable hearing preservation was 100% for grade 1 tumors (meatal), 35.6% for grade 2 (cisternal), 23.1% for grade 3 (brainstem contact), and 21.7% for grade 4 (brainstem compression). Of the total cohort, 86% had normal or nearly normal postoperative facial function (House-Brackmann grades 1 and 2).

CONCLUSION

Surgery on small VSs can achieve excellent hearing preservation. Different grading has a significant influence on and correlates with postoperative hearing preservation. Tumor size seems more important than anatomic relationship.

A Protective Cap: Fundal Fluid Cap Facilitates a Reduction in Inner Ear Radiation Dose in the Radiosurgical Treatment of Vestibular Schwannoma

OBJECTIVE

Assess inner ear radiation dose magnitude as it relates to fundal cap length and hearing outcomes in the radiosurgical treatment of vestibular schwannoma.

STUDY DESIGN

Retrospective case series.

SETTING

Tertiary neurotology referral center.

PATIENTS

Patients treated with Gamma Knife radiosurgery for vestibular schwannoma between March 2007 and March 2017 were considered for this study. Exclusion criteria included pretreatment pure-tone average (PTA) >90 dB, neurofibromatosis type II, history of previous surgical resection, and follow-up less than 1 year.

MAIN OUTCOME MEASURE

(s): Hearing function was assessed by maintenance of class A/B hearing level and maintenance of baseline hearing (≤20 dB change in PTA following Gamma Knife radiosurgery).

RESULTS

Lower radiation doses delivered to the inner ear were associated with longer fundal cap lengths: mean cochlear dose (r = -0.130; p = 0.184), mean labyrinth dose (r = -0.406; p < 0.001), max cochlear dose (r = -0.326; p = 0.001), and max labyrinth dose (r = -0.360; p < 0.001). Kaplan-Meier analysis with log-rank testing revealed that patients with a mean labyrinth dose < 3 Gy achieved higher rates of preserving baseline hearing (≤20 dB change in PTA) following radiosurgery, compared to patients with a mean labyrinth dose ≥3 Gy (p < 0.001). A fundal fluid cap length of 2.5 mm was associated with the 3 Gy mean labyrinth dose threshold.

CONCLUSIONS

We report that fundal cap presence facilitated the creation of treatment plans with a lower dose delivered to the labyrinth. By affording this dose reduction, a fundal cap may be associated with a slight improvement in hearing outcomes.

The Effect of Tumor Size on Likelihood of Hearing Preservation After Retrosigmoid Vestibular Schwannoma Resection

OBJECTIVES

1) Describe the effect of tumor size on the likelihood of hearing preservation after retrosigmoid approach for resection of vestibular schwannoma (VS).2) Describe the effect of preoperative hearing status on the likelihood of hearing preservation.

STUDY DESIGN

Retrospective chart review.

SETTING

Tertiary referral center.

PATIENTS

Adult (18 years or older) patients underwent retrosigmoid VS resection and postoperative audiometry between 2008 and 2018 and had a preoperative word recognition score (WRS) of at least 50%. Patients with a history of neurofibromatosis 2, radiation, or previous resection were excluded.

INTERVENTIONS

All patients underwent retrosigmoid VS resection with attempted hearing preservation.

MAIN OUTCOME MEASURES

WRS of at least 50%.

RESULTS

Data from 153 patients were analyzed. Mean age was 50.8 (±11.3) years and mean tumor size 14 (±6) mm. Hearing was preserved and lost in 64 (41.8%) and 89 (58.2%) patients, respectively. Hearing preservation rates were higher for intrameatal tumors than for tumors with extrameatal extension (57.6% versus 29.4%, p = 0.0005). On univariate and multivariate regression analysis, tumor size (per mm increase) was a negative predictor of hearing preservation (odds ratio [OR] 0.893, p = 0.0002 and 0.841, p = 0.0005, respectively). Preoperative American Academy of Otolaryngology-Head & Neck Surgery Hearing Class was also predictive of hearing preservation (p = 0.0044). Class A hearing (compared with class B hearing) was the strongest positive risk factor for hearing preservation (OR 3.149, p = 0.0048 and 1.236, p = 0.0005, respectively).

CONCLUSION

Small tumor size and preoperative class A hearing are positive predictors of hearing preservation in patients undergoing the retrosigmoid approach for VS resection.