Postoperative Hearing Preservation in Patients Undergoing Retrosigmoid Craniotomy for Resection of Vestibular Schwannomas: A Systematic Review of 2034 Patients

Plasma Matrix Metalloproteinase-9 Predicts Intraoperative Experience and Extent of Resection in Vestibular Schwannoma Surgery

OBJECTIVE

To evaluate the predictive value of plasma matrix metalloproteinase-9 (MMP-9) level in determining the extent of tumor resection (EOR) and tumor adherence in vestibular schwannoma (VS) surgery.

STUDY DESIGN

Prospective cohort study.

SETTING

Academic referral center.

METHODS

Plasma and tumor samples were prospectively collected from patients with nonradiated, sporadic VS undergoing microsurgical resection from July 2022 to June 2023. Plasma MMP-9 levels were measured by enzyme-linked immunosorbent assay, and their association with tumor adherence and postoperative outcomes were evaluated.

RESULTS

Thirty-three patients undergoing microsurgical resection agreed to participate (15 females, median age 54 years old, median tumor size 26.7 mm). A gross total resection (GTR) was performed in 18 patients (55%), and a near-total (NTR)/subtotal resection (STR) in 15 (45%). Tumor size was not significantly different between the GTR and NTR/STR groups (20.7 vs 24.8 mm, P= .185). Intraoperatively, a larger fraction of NTR/STR tumors were highly adherent to the brainstem and/or cranial nerves (93% vs 56%, P = .015). Preoperative plasma MMP-9 was higher in patients who underwent an NTR/STR compared to a GTR (229.9 vs 131.2ng/mL, P = .007). On multivariable logistic regression, preoperative plasma MMP-9 strongly predicted EOR by receiver operating characteristic analysis (area under the curve [AUC] = 0.77 P = .008). Combining plasma MMP-9 and age was an excellent predictor of EOR (AUC = 0.91, P = .0001).

CONCLUSION

Plasma MMP-9 levels strongly predicted intraoperative tumor adherence and postoperative extent of resection. This could provide crucial preoperative insights into surgical difficulty, potential complications, and the likelihood of gross total tumor removal, enhancing informed decision-making for both physicians/surgeons and patients.

Delayed Facial Nerve Dysfunction Following CyberKnife® Radiosurgery for Vestibular Schwannoma

OBJECTIVE

The incidence and risk factors for facial nerve dysfunction (FND) following CyberKnife® therapy for vestibular schwannoma (VS) remain poorly understood. This study investigates whether differential radiation doses to vulnerable segments of the facial nerve may be associated with FND outcomes.

METHODS

Patients were identified who underwent CyberKnife® radiosurgery for VS at a single institution. Basic demographics, tumor characteristics, and facial nerve function were collected. Total radiation doses to tumor, internal auditory canal (IAC), and labyrinthine segment of facial nerve (LSFN) were evaluated.

RESULTS

Six out of 64 patients experienced FND following CyberKnife® treatment for VS (9.38%, 6/64). Patients with FND were compared to those without FND (control). Of the 64 patients, complete radiation records were obtained for 30 patients (6 FND vs. 24 control). There were no significant differences in demographic or tumor characteristics between control and FND cohorts. More severe FND (HB ≥ 4) had significantly larger tumors (3.74 vs. 1.27 cm3, p = 0.037) with directionally decreased time to FND (3.50 vs. 33.5 months, p = 0.106) than patients with HB < 4, respectively. There were directionally, nonsignificant differences between maximum radiation doses to the LSFN (2492.4 vs. 2557.0 cGy, p = 0.121) and IAC (2877.3 vs. 2895.5 cGy, p = 0.824) between the control and FND cohorts, respectively.

CONCLUSIONS

FND may represent an underrecognized sequelae of CyberKnife® radiosurgery for VS that can occur many months following treatment. Further studies are needed to elucidate the effect of differential radiation exposure to the facial nerve with FND following treatment.

LEVEL OF EVIDENCE

3 (Retrospective Cohort Study) Laryngoscope, 134:5080-5086, 2024.

Establishment of Nomogram for Prediction of Hearing Preservation after Retrosigmoid Approach in Patients with Vestibular Schwannoma

OBJECTIVE

To derive and validate a prognostic nomogram for the prediction of hearing preservation (HP) after retrosigmoid approach (RSA) in patients with vestibular schwannoma (VS) and further assist in clinical decision-making.

STUDY DESIGN

Retrospective study.

SETTING

Tertiary referral center.

PATIENTS

A total of 111 patients diagnosed with VS with serviceable hearing from January 2013 to March 2023.

INTERVENTIONS

All patients underwent surgery via RSA, and hearing outcomes were reviewed 2 weeks postoperatively.

MAIN OUTCOME MEASURES

Preoperative and postoperative hearing were analyzed and stratified according to the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS).

RESULTS

In multivariate analysis of the primary group, preoperative hearing, tumor size, and tumor origin were significantly related to postoperative HP ( p = 0.029, p = 0.043, and p = 0.018, respectively). Factors derived from the multivariate analysis were all assembled into the nomogram. The receiver operating characteristic (ROC) curves showed good predictive accuracy of the nomogram model in both primary and validation groups with area under the ROC curve (AUC) values of 0.802 and 0.797, respectively.

CONCLUSION

Independent predictors of postoperative HP in patients with VS were selected to create the nomogram. The nomogram was able to stratify patients into different risk groups and assist in clinical decision making.

Natural History of Serviceable Hearing During Active Surveillance of Nongrowing Sporadic Vestibular Schwannoma Supports Consideration of Initial Wait-and-Scan Management

OBJECTIVE

The treatment paradigm of vestibular schwannoma (VS) focuses on preservation of neurologic function, with small tumors increasingly managed with active surveillance. Often, tumor size and hearing outcomes are poorly correlated. The aim of the current work was to describe the natural history of hearing among patients with nongrowing VS during observational management.

STUDY DESIGN

Historical cohort study.

PATIENTS

Adults with sporadic VS.

INTERVENTION

Wait-and-scan management.

MAIN OUTCOME MEASURE

Maintenance of serviceable hearing (SH) after diagnosis.

RESULTS

Among 228 patients with nongrowing VS, 157 patients had SH at diagnosis. Rates of maintaining SH (95% CI; number still at risk) at 1, 3, and 5 years after diagnosis were 94% (89-98; 118), 81% (74-89; 65), and 78% (71-87; 42), respectively. Poorer hearing at diagnosis (hazard ratio [HR] per 10 dB hearing level increase in pure-tone average of 2.51, p < 0.001; HR per 10% decrease in word recognition score of 1.70, p = 0.001) was associated with increased likelihood of developing non-SH during observation. When controlling for baseline hearing status, tumors measuring 5 mm or greater in the internal auditory canal or with cerebellopontine angle extension were associated with significantly increased risk of developing non-SH (HR, 4.87; p = 0.03). At 5 years after diagnosis, 95% of patients with nongrowing intracanalicular VS measuring less than 5 mm maintained SH.

CONCLUSIONS

Hearing worsens during periods of nongrowth in sporadic VS. Patients with small (<5 mm) intracanalicular tumors demonstrate robust maintenance of SH over time, reinforcing the consideration of initial observation in this patient subset.

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.

Patient-preferred outcomes in patients with vestibular schwannoma: a qualitative content analysis of symptoms, side effects and their impact on health-related quality of life

PURPOSE

During counseling and management of patients with vestibular schwannoma (VS), the emphasis is shifting from tumour control and nerve preservation towards maintaining or improving health-related quality of life (HRQoL). Understanding the patients' perspective and impact of VS is, therefore, of utmost importance. The current study aimed to identify treatment outcomes preferred by patients and to explore the patient-reported VS symptoms and management-related side effects and their impact on HRQoL.

METHODS

Patients with VS were contacted through the Dutch VS association Stichting Hoormij and questioned using a semi-structured, cross-sectional online survey. Patients were asked to report and rank symptoms and side effects, with their impact on HRQoL and frequency of occurrence. Results were structured through qualitative content analysis. Coded symptoms, side effects, impacts, frequencies, and patient-preferred outcomes were analysed and summarized with descriptive statistics.

RESULTS

Of the 231 respondents, 71% were actively treated. Hearing (symptoms vs. side effects: 78.8% vs. 63.6%), balance (62.3%; 48.8%), and energy issues (33.8%; 32.6%) were the most frequently mentioned symptoms and management-related side effects. Fatigue, deafness, headaches, and hearing loss had the highest impact on HRQoL. The majority of patients identified hearing preservation (61%), balance preservation (38.5%), and reduced tinnitus (34.6%) to be the patient-preferred outcomes.

CONCLUSION

This qualitative study demonstrates that in this population many patients with VS encounter participation difficulties in their daily physical and social activities and value hearing and balance preservation, reduced tinnitus, and restored energy as preferred outcomes as they are hampered by symptoms and side effects related to hearing, balance, and energy. Healthcare professionals should consider these key points and use these and the patient-preferred outcomes in consultation, shared decision making, treatment, and follow-up to optimize patient-centred care.

Retrosigmoid Approach for Sporadic Vestibular Schwannoma: Patient Selection, Technical Pearls, and Hearing Results

The retrosigmoid corridor provides the most broadly applied approach for resection of sporadic vestibular schwannoma. It may be utilized for any size tumor and for patients with intact hearing with the intention of hearing preservation. For larger tumors, the skull base surgeon must weigh the benefits the retrosigmoid approach against those of the translabyrinthine route. For smaller tumors where hearing preservation is a goal, the retrosigmoid approach is contrasted to the middle fossa route. Hearing preservation is most likely for patients with small and medially located intracanalicular tumors with minimal extension into the cerebellopontine angle, and excellent preoperative hearing.

Middle Cranial Fossa Approach for Sporadic Vestibular Schwannoma

The middle fossa approach is an excellent technique for removing appropriate vestibular schwannomas in patients with serviceable hearing. Knowledge of the intricate middle fossa anatomy is essential for optimal outcomes. Gross total removal can be achieved with preservation of hearing and facial nerve function, both in the immediate and long-term periods. This article provides an overview of the background and indications for the procedure, a description of the operative protocol, and a summary of the literature on postoperative hearing outcomes.

Analysis of the effect of neuroendoscopy-assisted microscopy in the treatment of Large (Koos grade IV) vestibular schwannoma

Introduction

This article aimed to investigate the effects of the endoscopic-assisted microsurgery technique on the resection of large (Koos grade IV) vestibular schwannoma (VS) and provide a prognosis analysis of the patients.

Methods

A retrospective analysis of the use of the endoscopic-assisted microsurgery technique in 16 cases of large vestibular schwannoma surgery was carried out. Intraoperative nerve electrophysiological monitoring was conducted to explore the effect of neuroendoscopy on the resection of internal auditory canal tumors, protection of the facial nerve, and minimizing postoperative complications.

Results

Tumors were completely removed in all 16 cases, and the facial nerve was anatomically preserved in 14 cases (87.5%). There was no postoperative cerebrospinal fluid leakage and no intracranial infection complications occurred.Following the House-Brackmann (H-B) grading system, post-operative facial nerve function was grade I in 5 cases, grade II in 6 cases, grade III in 3 cases, and grade V in 2 cases. As a result, the preservation rate of facial nerve function (H-B grade I-II) was 68.8%. All 16 patients were followed up for 3 to 24 months, and no tumor recurrence was found on enhanced MRI.

Discussion

Using the endoscopic-assisted microsurgery technique in the retrosigmoid approach has many advantages over the microscopic-only approach. When compared to the microscopy-only approach, the endoscope can provide a wide-angle surgical field superior to that of a microscope in areas such as the internal auditory canal in the resection of large VS, minimize iatrogenic injuries, ensure complete removal of internal auditory canal tumors, and well as reducing postoperative complications such as cerebrospinal fluid leakage and the loss of facial and auditory nerve functions.

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.

[Cochlear nerve continuity preservation during retrosigmoid ablative osteotomy of the internal auditory canal for advanced vestibular schwannomas]

The data of 86 patients with retrosigmoid microsurgical resection of vestibular schwannoma in tumor stage Koos II-IV were evaluated. In more than two thirds of the cases it was shown that the cochlear nerve followed the facial nerve, which is easily identified by electroneurography, in recurrent similar patterns in the region of the internal auditory canal. Starting from the fundus, this facilitated early identification and thus preservation of continuity of the cochlear nerve in the course of the internal auditory canal. This was of particular importance when safe functional preservation could not be guaranteed due to tumor size or formation despite intraoperative derivation of somatosenoric potentials, but when the possibility of subsequent hearing rehabilitation with a cochlear implant should be granted. Preoperative MRI sequences gave an indication of the possible nerve courses in some cases, but intraoperative imaging in the internal auditory canal was superior to MRI.

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.

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.

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.

Position of Retrosigmoid Craniotomy in Hearing Preservation Surgery for Vestibular Schwannoma

BACKGROUND

Surgical access to the internal auditory canal (IAC) fundus is a crucial aspect of the retrosigmoid approach for hearing preservation surgery in vestibular schwannoma. An appropriate positioning of the retrosigmoid craniotomy is necessary to obtain an adequate surgical corridor for full fundus exposure and labyrinth preservation.

OBJECTIVE

To describe how the position of the posterior edge of the access related to the probability of exposing the fundus and to propose novel criteria for positioning the retrosigmoid craniotomy.

METHODS

Data on fundus exposure were retrospectively collected in 33 consecutive cases of sporadic vestibular schwannoma, submitted to the retrosigmoid craniotomy in a park-bench position. Patients' computed tomography images were analyzed to calculate the position of the posterior edge of the craniotomy with reference to the fundus-labyrinth line (FLL), which starts at the fundus and, running just posterior to the labyrinth, reaches the occipital squama. A logistic regression model was used to correlate the craniotomy position with the probability of exposing the fundus.

RESULTS

The fundus exposure rate was significantly higher (P = .005) for craniotomies located posteromedially to the FLL. In a logistic regression model, the probability of exposing the fundus reached 95% for craniotomies located 11.3 mm posteromedially to the FLL.

CONCLUSION

This study showed a strong association between craniotomy position and fundus exposure rate. Our findings suggest that the posteromedial edge of the retrosigmoid craniotomy should lie approximately 11 mm posteromedially to FLL to maximize the chances of exposing the fundus.

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%).

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.

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.

Preoperative Radiographic Predictors of Hearing Preservation After Retrosigmoid Resection of Vestibular Schwannomas

OBJECTIVE

To identify preoperative radiographic predictors of hearing preservation (HP) after retrosigmoid resection of vestibular schwannomas (VSs).

STUDY DESIGN

Retrospective case series with chart review.

SETTING

Tertiary skull base referral center.

METHODS

Adult patients with VSs <3 cm and word recognition scores (WRSs) ≥50% who underwent retrosigmoid resection and attempted HP between February 2008 and December 2018 were identified. Pure tone average (PTA), WRS, and magnetic resonance imaging radiographic data, including tumor diameter and dimensional extension relative to the internal auditory canal (IAC), were examined.

RESULTS

A total of 151 patients were included. The average tumor size was 13.8 mm (range, 3-28). Hearing was preserved in 41.7% (n = 63). HP rates were higher for intracanalicular tumors than tumors with cerebellopontine angle (CPA) components (57.6% vs 29.4%, P = .03). On multivariate analysis, maximal tumor diameter (odds ratio [OR], 0.892; P < .001) and preoperative PTA (OR, 0.974; P = .026) predicted HP, while mediolateral tumor diameter predicted postoperative PTA (OR, 1.21; P = .005) and WRS (OR, -1.89; P < .001). For tumors extending into the CPA, younger age (OR, 0.913; P = .012), better preoperative PTA (OR, 0.935; P = .049), smaller posterior tumor extension (OR, 0.862; P = .001), and smaller caudal extension relative to the IAC (OR, 0.844; P = .001) all predicted HP.

CONCLUSION

Rates of HP are highest in patients with small intracanalicular VSs and good preoperative hearing. For tumors extending into the CPA, greater posterior and caudal tumor extension relative to the IAC may portend worse hearing outcomes.