National Trends in Vestibular Schwannoma Surgery: Influence of Patient Characteristics on Outcomes

Automatic Segmentation of Vestibular Schwannomas: A Systematic Review

BACKGROUND

Vestibular schwannomas (VSs) are benign tumors often monitored over time, with measurement techniques for assessing growth rates subject to significant interobserver variability. Automatic segmentation of these tumors could provide a more reliable and efficient for tracking their progression, especially given the irregular shape and growth patterns of VS.

METHODS

Various studies and segmentation techniques employing different Convolutional Neural Network architectures and models, such as U-Net and convolutional-attention transformer segmentation, were analyzed. Models were evaluated based on their performance across diverse datasets, and challenges, including domain shift and data sharing, were scrutinized.

RESULTS

Automatic segmentation methods offer a promising alternative to conventional measurement techniques, offering potential benefits in precision and efficiency. However, these methods are not without challenges, notably the "domain shift" that occurs when models trained on specific datasets underperform when applied to different datasets. Techniques such as domain adaptation, domain generalization, and data diversity were discussed as potential solutions.

CONCLUSIONS

Accurate measurement of VS growth is a complex process, with volumetric analysis currently appearing more reliable than linear measurements. Automatic segmentation, despite its challenges, offers a promising avenue for future investigation. Robust well-generalized models could potentially improve the efficiency of tracking tumor growth, thereby augmenting clinical decision-making. Further work needs to be done to develop more robust models, address the domain shift, and enable secure data sharing for wider applicability.

Vestibular Schwannoma and Tinnitus: A Systematic Review of Microsurgery Compared to Gamma Knife Radiosurgery

Background: Vestibular schwannoma (VS) is a benign tumor of the eighth cranial nerve formed from neoplastic Schwann cells. Although VS can cause a variety of symptoms, tinnitus is one of the most distressing symptoms for patients and can greatly impact quality of life. The objective of this systematic review is to comprehensively examine and compare the outcomes related to tinnitus in patients undergoing treatment for VS. Specifically, it evaluates patient experiences with tinnitus following the removal of VS using the various surgical approaches of traditional surgical resection and gamma knife radiosurgery (GKS). By delving into various aspects such as the severity of tinnitus post-treatment, the duration of symptom relief, patient quality of life, new onset of tinnitus after VS treatment, and any potential complications or side effects, this review aims to provide a detailed analysis of VS treatment on tinnitus outcomes. Methods: Following PRISMA guidelines, articles were included from PubMed, Science Direct, Scopus, and EMBASE. Quality assessment and risk of bias analysis were performed using a ROBINS-I tool. Results: Although VS-associated tinnitus is variable in its intensity and persistence post-resection, there was a trend towards a decreased tinnitus burden in patients. Irrespective of the surgical approach or the treatment with GKS, there were cases of persistent or worsened tinnitus within the studied cohorts. Conclusion: The findings of this systematic review highlight the complex relationship between VS resection and tinnitus outcomes. These findings underscore the need for individualized patient counseling and tailored treatment approaches in managing VS-associated tinnitus. The findings of this systematic review may help in guiding clinicians towards making more informed and personalized healthcare decisions. Further studies must be completed to fill gaps in the current literature.

Refining the predictive value of preoperative apparent diffusion coefficient (ADC) by whole-tumor analysis for facial nerve outcomes in vestibular schwannomas

BACKGROUND

Apparent diffusion coefficient (ADC) in MRI has been shown to correlate with postoperative House-Brackmann (HB) scores in patients with vestibular schwannoma despite limited methodology. To rectify limitations of single region of interest (ROI) sampling, we hypothesize that whole-tumor ADC histogram analysis will refine the predictive value of this preoperative biomarker related to postoperative facial nerve function.

METHODS

Of 155 patients who underwent resection of vestibular schwannoma (2014-2020), 125 patients were included with requisite clinical and radiographic data. After volumetric analysis and whole-tumor ADC histogram, regression tree analysis identified ADC cutoff for significant differences in HB grade. Outcomes were extent of resection, facial nerve function, hospital length of stay (LOS), and complications.

RESULTS

Regression tree analysis defined three quantitative ADC groups (× 10-6 mm2/s) as high (> 2248.77; HB 1.7), mid (1468.44-2248.77; HB 3.1), and low (< 1468.44; HB 2.3) range (p 0.04). The mid-range ADC group had significantly worse postoperative HB scores and longer hospital LOS. Large tumor volume was independently predictive of lower rates of gross total resection (p <0.0001), higher postoperative HB score (p 0.002), higher rate of complications (p 0.04), and longer LOS (p 0.003).

CONCLUSIONS

Whole-tumor histogram yielded a robust regression tree analysis that defined three ADC groups with significantly different facial nerve outcomes. This likely reflects tumor heterogeneity better than solid-tumor ROI sampling. Whole-tumor ADC warrants further study as a useful radiographic biomarker in patients with vestibular schwannoma who are considering surgical resection.

Disparities in Sporadic Vestibular Schwannoma Initial Presentation Between a Public Safety Net Hospital and Tertiary Academic Medical Center at the Same Zip Code 2010 to 2020

INTRODUCTION

Treatment of vestibular schwannoma (VS) has been extensively studied, but a gap in knowledge exists demonstrating how racial and socioeconomic status influence VS presentation. Our institution has a unique setting with a public safety net hospital (PSNH) and tertiary academic medical center (TAMC) in the same zip code, which we study to evaluate initial VS presentation disparities in patient populations presenting to these hospital settings.

METHODS

Retrospective chart review was performed of all adult patients (n = 531) presenting 2010 to 2020 for initial VS evaluation at TAMC (n = 462) and PSNH (n = 69). Ethnicity, insurance, maximum tumor size, audiometry, initial treatment recommendation, treatment received, and follow up were recorded and statistical analysis performed to determine differences.

RESULTS

Average age at diagnosis (51.7 ± 13.6 TAMC vs 52.3 ± 12.4 PSNH) and gender (58.4% TAMC vs 52.2% PSNH female) were similar. Patients' insurance (TAMC 75.9% privately insured vs PSNH 82% Medicaid) and racial/ethnic profiles (TAMC 67.7% White and 10.0% Hispanic/Latinx, vs PSNH 4.8% White but 59.7% Hispanic/Latinx) were significantly different. Tumor size was larger at PSNH (20.2 ± 13.3 mm) than TAMC (16.6 ± 10.0 mm). Hearing was more impaired at PSNH than TAMC (mean pure tone average 58.3 dB vs 43.9 dB, word recognition scores 52.3% vs 68.2%, respectively). Initial treatment recommendations and treatment received may include more than 1 modality. TAMC patients were offered 66.7% surgery, 31.2% observation, and 5.2% radiation, while PSNH patients offered 50.7% observation, 49.3% surgery, and 8.7% radiation. TAMC patients received 62.9% surgery, 32.5% observation, and 5.3% radiation, while PSNH patients received 36.2% surgery, 59.4% observation, and 14.5% radiation. Follow up and treatment at the same facility was not significantly different between hospitals.

CONCLUSIONS

Hearing was worse and tumor size larger in patients presenting to PSNH. Despite worse hearing status and larger tumor size, the majority of PSNH patients were initially offered observation, compared to TAMC where most patients were initially offered surgery.

Immune Profiling of Secreted Factors from Human Vestibular Schwannoma Cells and Tumor-associated Macrophages

OBJECTIVES

This study compared the immune-related secretory capacity of human vestibular schwannoma (VS) and tumor-assisted macrophages (TAMs) with their normal counterparts (Schwann cells [SC] and peripheral blood monocyte-derived macrophages [Mo-MFs], respectively), and examined relationships with presurgical hearing and tumor size.

METHODS

VS tumors (n = 16), auditory nerve (n = 1), blood (n = 9), and great auricular nerves (n = 3) were used. SCs (S100B+ ) and TAMs (CD68+ ) were isolated from VS tissue for culture. The secreted levels of 65 immune-related factors were measured and compared using unpaired t-tests with Welch correction (schwannoma vs. SCs) or Mann-Whitney tests (TAMs and Mo-MFs). Associations between factor concentration and word recognition (WR), pure-tone average (PTA), and tumor size were evaluated with Spearman correlation.

RESULTS

Secreted factors with significantly higher concentrations in schwannoma versus SC supernatants included IL-2 and BAFF, whereas MMP-1, IL-6, FGF-2, VEGF-A, MIP-3α, and GRO-α concentrations were significantly higher in TAMs versus Mo-MFs (all p < 0.05). Worse WR was significantly associated with higher secretion of fractalkine, eotaxin-3, CD30, and IL-16 by VS cells; IP-10, eotaxin-3, multiple interleukins, GM-CSF, SCF, and CD30 by TAMs; and TNF-α and MIP-1α by Mo-MFs (all p < 0.05). Worse PTA was significantly correlated with higher secretion of IL-16 by VS cells (p < 0.05). Larger tumor size was significantly correlated with higher secretion of eotaxin by VS cells, and of IL-7, IL-21, and LIF by TAMs (all p = 0.017).

CONCLUSIONS

Differential secretion of immune-related factors was observed in schwannoma versus normal SCs and in TAMs versus Mo-MFs, some of which were correlated with worse hearing and larger VS tumors.

LEVEL OF EVIDENCE

N/A Laryngoscope, 134:S1-S14, 2024.

Identification of Follow-Up Markers for Rehabilitation Management in Patients with Vestibular Schwannoma

This study delves into the absence of prognostic or predictive markers to guide rehabilitation in patients afflicted with vestibular schwannomas. The objective is to analyze the reweighting of subjective and instrumental indicators following surgery, at 7 days and 1 month postoperatively. This retrospective cohort encompasses 32 patients who underwent unilateral vestibular schwannoma surgery at the Marseille University Hospital between 2014 and 2019. Variations in 54 indicators and their adherence to available norms are calculated. After 1 month, one-third of patients do not regain the norm for all indicators. However, the rates of variation unveil specific responses linked to a preoperative error signal, stemming from years of tumor adaptation. This adaptation is reflected in a postoperative visual or proprioceptive preference for certain patients. Further studies are needed to clarify error signals according to lesion types. The approach based on variations in normative indicators appears relevant for post-surgical monitoring and physiotherapy.

Impact of Obesity on Postoperative Complications after Lateral Skull Base Surgery: A Systematic Review

INTRODUCTION

The relationship between obesity and complications after lateral skull base tumor resection is not clear. There is conflicting evidence regarding the incidence of postoperative complications in this patient population. The purpose of this study is to examine the relationship between obesity and outcomes following lateral skull base tumor resection.

DATA SOURCES

Data were extracted from PubMed, Embase, CINAHL, and Cochrane CENTRAL.

METHODS

Included studies assessed the relationship between obesity and outcomes following lateral skull base tumor removal. Studies with ≤5 patients, pediatric patients, duplicate patient populations, or insufficient data were excluded. Two independent investigators reviewed each study for inclusion. A third reviewer served as a tie-breaker for any conflicts. Extracted data includes patient demographics, tumor pathology, surgical approach, and postoperative outcomes including incidence of cerebrospinal fluid (CSF) leak and other postoperative complications, length of stay (LOS), and readmission and reoperation rates. Descriptive statistics were used to compare postoperative outcomes for obese and nonobese controls.

RESULTS

14 studies met final inclusion criteria. Nine studies evaluated the relationship between obesity and CSF leaks. Four studies found a significant increase in postoperative CSF leak in obese patients compared to nonobese controls. The remaining studies trended toward an increased incidence of CSF leak in the obese population but did not reach statistical significance. One out of seven studies found that obesity increased postoperative LOS, and one out of five studies found that obesity increased reoperation rates following tumor resection.

CONCLUSIONS

Based on the results, obesity does not appear to increase LOS, readmission, or reoperation rates after lateral skull base tumor resection. The relationship between obesity and postoperative CSF leak, however, warrants further analysis.

Association Between Facility Surgical Volume and Excess Time in the Hospital After Surgical Resection of Vestibular Schwannomas

Importance

High surgical vestibular schwannoma case volume in a medical institution may decrease the risk of adverse outcomes among patients undergoing vestibular schwannoma surgery.

Objective

To study the association between surgical vestibular schwannoma case volume and excess time in the hospital after vestibular schwannoma surgery.

Design, Setting, and Participants

This cohort study evaluated data from the National Cancer Database from January 1, 2004, through December 31, 2019, on Commission on Cancer-accredited facilities in the US. The hospital-based sample comprised adult patients aged 18 years or older with a vestibular schwannoma treated with surgery.

Exposures

Facility case volume, defined as the mean number of surgical vestibular schwannoma cases per year in the 2 years preceding the index case.

Main Outcomes and Measures

The primary outcome was a composite of prolonged hospital stay (>90th percentile) or 30-day readmission. Risk-adjusted restricted cubic splines were used to model the probability of the outcome according to facility volume. The inflection point (in cases per year) when the declining risk of excess time in the hospital began to plateau was selected as the threshold to define high- and low-volume facilities. Outcomes were compared among patients treated at high- and low-volume facilities, with mixed-effects logistic regression models adjusting for patient sociodemographic characteristics, comorbidities, tumor size, and clustering within facilities. Collected data were analyzed between June 24 and August 31, 2022.

Results

Among 11 524 eligible patients (mean [SD] age, 50.2 [12.8] years; 53.5% female; 46.5% male) who underwent surgical resection of vestibular schwannoma at 66 reporting facilities, the median length of stay was 4 (IQR, 3-5) days, and 655 patients (5.7%) were readmitted within 30 days. The median case volume was 16 (IQR, 9-26) cases per year. An adjusted restricted cubic spline model identified a downtrending probability of excess time in the hospital with increasing volume. The declining risk of excess time in the hospital began to plateau at a facility volume of 25 cases per year. Surgery at a facility with an annual case volume at or above this threshold was independently associated with a 42% reduction in the odds of excess time in the hospital compared with surgery at a low-volume center (odds ratio, 0.58; 95% CI, 0.44-0.77).

Conclusions and Relevance

This cohort study found that among adults undergoing vestibular schwannoma surgery, a higher facility case volume was associated with a reduced risk of prolonged hospital stay or 30-day readmission. A facility case volume of 25 cases per year may represent a risk-defining threshold.

Unruptured anterior Inferior cerebellar artery aneurysm following stereotactic irradiation for vestibular schwannoma: Case report and literature review

Background

The clinical features and therapeutic measures of vestibular schwannoma (VS) radiation-related aneurysm (RRA) have not been well described. We reported the first VS RRA case admitted for acute anterior inferior cerebella artery (AICA) ischemic symptoms. Literature was reviewed to present the research fruits about VS RRAs, and some therapeutic advices were given.

Materials and methods

A 54-year-old woman who had undergone GKS 10 years previously for a right VS was admitted to our hospital in 2018 because of sudden onset of severe vertigo and vomiting, accompanied with unsteady gait. During tumor resection, a dissecting aneurysm arose from the main trunk of AICA was encountered accidently within the tumor. The aneurysm was successfully treated with direct clip ligation, sparing the parent vessel. Data about this case were combined with those of other 11 radiation-related AICA aneurysm cases retrieved from the current literature. The following parameters were evaluated: Age, Sex, Diagnostic method, Location of aneurysm, Age of radiotherapy (Years)/Latency, Rupture, x-ray dosage, Type of radiotherapy, History of surgical resection of VS, Aneurysm Type, Morphology, Number, Treatment, Operative complications, Sequela, Outcome. VS RRAs mainly occurred in women (75%) with a median age of 62.5 years and were mainly located on AICA. Ruptured aneurysms accounted for 75.0% of the total cases. This paper reported the first VS case admitted with acute AICA ischemic symptoms. Cases with sacciform-like, irregular and fusiform-shaped aneurysms accounted for 50.0%, 25.0% and 25.0% of the total, respectively. After surgical treatment, 75.0% patients recovered, except for 3 patients who developed new ischemic consequence.

Conclusion

Patients should be informed of the risk of RRAs after receiving radiotherapy for VS. In these patients, RRAs should be suspected when subarachnoid hemorrhage or AICA ischemic symptoms occurred. Active intervention should be conducted considering the high instability and bleeding rate of VS RRAs.

Clinical outcomes of benign brain tumors treated with single fraction LINAC-based stereotactic radiosurgery: Experience of a single institute

Objectives

Accelerator-based stereotactic radiosurgery (SRS) is a noninvasive and effective treatment modality widely used for benign brain tumors. This study aims to report 20-year treatment outcomes in our institute.

Materials and Methods

From May 2001 to December 2020, 127 patients treated with LINAC-based single-fraction SRS for their benign brain lesions were included. A neurosurgeon and two radiation oncologists retrospectively reviewed all data. Computed tomography (CT) simulation was performed after head-frame fixation under local anesthesia. All planning CT images were co-registered and fused with gadolinium-enhanced magnetic resonance imaging taken within 3 months for lesions targeting and critical organs delineation. The marginal dose was prescribed at 60%-90% isodose lines, respectively, to cover ≥95% planning target volume. Outcome evaluations included clinical tumor control rate (TCR), defined as the need for salvage therapy, and radiological response, defined as no enlargement of >2 cm in the maximal diameter. Overall survival (OS) and adverse reaction (defined according to CTCAE 5.0) were also analyzed.

Results

The present study included 76 female and 51 male patients for analysis. The median age was 59 years (range, 20-88 years). Their diagnoses were vestibular schwannoma (VS, n = 54), nonvestibular cranial nerve schwannoma (n = 6), meningioma (n = 50), and pituitary adenoma (n = 17). Totally 136 lesions were treated in a single fraction, predominantly skull base tumors, accounting for 69.1%. Median and mean follow-up duration was 49 and 61 months (range, 1-214 months), Overall TCR was 92.9%. The 5-year disease-specific TCR for VS, nonvestibular schwannoma, meningioma, and pituitary adenoma were 97.4%, 91.7%, 93.8%, and 83.3%. Salvage therapy was indicated for eight patients at 4-110 months after SRS. Among symptomatic patients, post-SRS symptom(s) was improved, stable, and worse in 68.2%, 24.3%, and 3.6%, respectively. Radiological response rate for 111 evaluable patients was 94.6% (shrinkage, 28.8%; stable, 65.8%). OS was 96.1% without treatment-related mortality. One patient with post-SRS cranial nerve injury (0.8%, involving the trigeminal nerve, grade 2 toxicities). No grade 3-4 acute or late toxicity was found.

Conclusion

Our results suggested that LINAC-based SRS effectively controls tumor growth and tumor-related neurological symptoms for patients with benign brain tumors. SRS is less aggressive, associated with low neurological morbidity and no mortality. Continuous follow-up is indicated to conclude longer outcomes.

Applicability of contemporary quality indicators in vestibular surgery-do they accurately measure tumor inherent postoperative complications of vestibular schwannomas?

Background

Due to rising costs in health care delivery, reimbursement decisions have progressively been based on quality measures. Such quality indicators have been developed for neurosurgical procedures, collectively. We aimed to evaluate their applicability in patients that underwent surgery for vestibular schwannoma and to identify potential new disease-specific quality indicators.

Methods

One hundred and three patients operated due to vestibular schwannoma were subject to analysis. The primary outcomes of interest were 30-day and 90-day reoperation, readmission, mortality, nosocomial infection and surgical site infection (SSI) rates, postoperative cerebral spinal fluid (CSF) leak, facial, and hearing function. The secondary aim was the identification of prognostic factors for the mentioned primary outcomes.

Results

Thirty-day (90-days) outcomes in terms of reoperation were 10.7% (14.6%), readmission 9.7% (13.6%), mortality 1% (1%), nosocomial infection 5.8%, and SSI 1% (1%). A 30- versus 90-day outcome in terms of CSF leak were 6.8% vs. 10.7%, new facial nerve palsy 16.5% vs. 6.1%. Hearing impairment from serviceable to non-serviceable hearing was 6.8% at both 30- and 90-day outcome. The degree of tumor extension has a significant impact on reoperation (p < 0.001), infection (p = 0.015), postoperative hemorrhage (p < 0.001), and postoperative hearing loss (p = 0.026).

Conclusions

Our data demonstrate the importance of entity-specific quality measurements being applied even after 30 days. We identified the occurrence of a CSF leak within 90 days postoperatively, new persistent facial nerve palsy still present 90 days postoperatively, and persisting postoperative hearing impairment to non-serviceable hearing as potential new quality measurement variables for patients undergoing surgery for vestibular schwannoma.

Risk Factors for Complications Following Lateral Skull Base Surgery and the Utility of ICU Monitoring

OBJECTIVE

To examine the role of intensive care unit (ICU) management following lateral skull base surgery for vestibular schwannoma and identify risk factors for complications warranting admission to the ICU.

STUDY DESIGN

Retrospective review.

SETTING

Tertiary referral center.

PATIENTS

Two hundred consecutive patients undergoing lateral skull base surgery for vestibular schwannomas.

INTERVENTION

Lateral skull base approach for resection of vestibular schwannoma and postoperative monitoring.

MAIN OUTCOME MEASURES

Patients were grouped if they sustained an ICU complication, a non-ICU complication, or no complication. Analysis was performed to determine patient or treatment factors that may be associated with ICU complications. Multivariate and three-way analysis of variance compared groups, and multivariate logistic regression determined adjusted odds ratios (aOR) for analyzed factors.

RESULTS

Seventeen of 200 patients sustained ICU complications (8.5%), most commonly hypertensive urgency (n = 15). Forty-six (23%) sustained non-ICU complications, and 137 (68.5%) had no complications. When controlling for age, sex, obesity, and other comorbidities, only hypertension (aOR 5.43, 95% confidence interval (CI) 1.35-21.73, p = 0.017) and tumor volume (aOR 3.29, 95% CI 1.09-9.96, p = 0.035) were independently associated with increased risk of ICU complications.

CONCLUSIONS

The necessity of intensive care following lateral skull base surgery is rare, with the primary ICU complication being hypertensive urgency. Preoperative hypertension and large tumor volume (>4500 mm3) were independently associated with increased risk for ICU complications. These findings may allow for risk stratification of patients appropriate for admission to stepdown units following resection of vestibular schwannomas. Further prospective, multi-center, randomized studies are necessary to validate these findings before systematic changes to current postoperative care practices.

Health Disparities in Otology: A PRISMA-Based Systematic Review

OBJECTIVE

Social determinants of health (SDOHs), including but not limited to sex, race, socioeconomic status, insurance status, and education level, play a significant role in health disparities and affect health outcomes. The purpose of this systematic review is to examine health disparities in otology within the United States and highlight areas warranting further research.

DATA SOURCES

PubMed, Ovid MEDLINE.

REVIEW METHODS

Our search encompassed all years through January 10, 2021. All peer-reviewed primary literature of any design and publication date regarding health disparities and otology outcomes in the United States was eligible for inclusion. Eligibility assessment was performed via 3 independent investigators.

RESULTS

Of the 6326 unique abstracts identified, 188 studies underwent full-text review, and 52 remained in the final review. The most frequently examined otologic condition was hearing loss (36.5%), followed by cochlear implantation (28.8%) and infection/effusion (15.4%). Vertigo/dizziness (1.9%), Ménière's disease (1.9%), and tinnitus (1.9%) were the least represented otologic conditions. Comprehensive articles on multiple disparity topics were the most common (n = 18), followed by articles on race/ethnicity (n = 11) and socioeconomic status (n = 9). Language (n = 2), education (n = 2), and gender (n = 1) were the least discussed. Over 5-fold the number of articles were published between 2011 and 2020 compared to the preceding decade (42 vs 8).

CONCLUSION

This study captures the existing literature regarding health disparities and outcomes in otology. The lack of robust data suggests the need for future quality studies aimed at investigating disparities in otologic care, as well as a broader push for recording and reporting SDOHs.

Resection of vestibular schwannomas after stereotactic radiosurgery: a systematic review

OBJECTIVE

Multiple short series have evaluated the efficacy of salvage microsurgery (MS) after stereotactic radiosurgery (SRS) for treatment of vestibular schwannomas (VSs); however, there is a lack of a large volume of patient data available for interpretation and clinical adaptation. The goal of this study was to provide a comprehensive review of tumor characteristics, management, and surgical outcomes of salvage of MS after SRS for VS.

METHODS

The Medline/PubMed, Scopus, CINAHL, Cochrane Library, and Google Scholar databases were queried according to PRISMA guidelines. All English-language and translated publications were included. Studies lacking adequate study characteristics and outcomes were excluded. Cases involving neurofibromatosis type 2, previous MS, or malignant transformation were excluded when possible.

RESULTS

Twenty studies containing 297 cases met inclusion criteria. Three additional cases from Rush University Medical Center were added for 300 total cases. Tumor growth with or without symptoms was the primary indication for salvage surgery (92.3% of cases), followed by worsening of symptoms without growth (4.6%) and cystic enlargement (3.1%). The average time to MS after SRS was 39.4 months. The average size and volume of tumor at surgery were 2.44 cm and 5.92 cm3, respectively. The surgical approach was retrosigmoid (42.8%) and translabyrinthine (57.2%); 59.5% of patients had a House-Brackmann (HB) grade of I or II. The facial nerve was preserved in 91.5% of cases. Facial nerve preservation and HB grades were lower for the translabyrinthine versus retrosigmoid approach (p = 0.31 and p = 0.18, respectively); however, fewer complications were noted in the translabyrinthine approach (p = 0.29). Gross-total resection (GTR) was completed in 55.7% of surgeries. Studies that predominantly used subtotal resection (STR) were associated with a lower rate of facial nerve injury (5.3% vs 11.3%, p = 0.07) and higher rate of HB grade I or II (72.9% vs 48.0%, p = 0.00003) versus those using predominantly GTR. However, majority STR was associated with a recurrence rate of 3.6% as compared to 1.4% for majority GTR (p = 0.29).

CONCLUSIONS

This study showed that the leading cause of MS after SRS was tumor growth at an average of 39.4 months after radiation. There were no significant differences in outcomes of facial nerve preservation, postoperative HB grade, or complication rate based on surgical approach. Patients who underwent STR showed statistically significant better HB outcomes compared with GTR. MS after SRS was considered by most authors to be more difficult than primary MS. These data support the notion that the surgical goals of salvage surgery are debulking of tumor mass, decreasing compression of the brainstem, and not necessarily pursuing GTR.

Predictors of Postoperative Complications in Vestibular Schwannoma Surgery-A Population-Based Study

OBJECTIVE

To investigate preoperative patient demographics and comorbidities in relation with postsurgical complications following vestibular schwannoma surgery.

STUDY DESIGN

Retrospective population-based cohort study.

SETTING

All hospitals in the Canadian province of Ontario.

PATIENTS

This study includes 1,456 patients who underwent vestibular schwannoma surgery from April 1, 2002 to March 31, 2018 in Ontario, Canada.

INTERVENTION/OUTCOME MEASURES

For all surgical patients, the demographic data, preoperative comorbidities, and postoperative complications were evaluated. Postoperative complications were examined immediately following surgery in the hospital as well as 1 year following the hospital discharge.

RESULTS

The most common comorbidities in this cohort were hypertension (30.22%), diabetes (9.48%), asthma (13.53%), and chronic obstructive pulmonary disease (6.73%). Diabetes was the most impactful comorbidity and was associated with higher risk of myocardial infarction (RR = 4.58, p < 0.01), pneumonia (RR = 1.80, p = 0.02), dysphagia (RR = 1.58, p < 0.01), and meningitis (RR = 3.62, p < 0.01). Analysis of surgical approaches revealed that the translabyrinthine approach, compared with the open craniotomy approach, was negatively associated with postoperative complications including pneumonia (RR = 0.43, p < 0.01), urinary tract infection (RR = 0.55, p = 0.01), dysphagia (RR = 0.66, p < 0.01), and readmission (RR = 0.45, p < 0.01).

CONCLUSION

This study examines patient demographics, preoperative comorbidities, and postoperative complications in patients who have undergone vestibular schwannoma surgery. The results highlight associations between patient characteristics and postoperative outcomes that can aid in preoperative decision-making and counselling.

Losartan prevents tumor-induced hearing loss and augments radiation efficacy in NF2 schwannoma rodent models

Hearing loss is one of the most common symptoms of neurofibromatosis type 2 (NF2) caused by vestibular schwannomas (VSs). Fibrosis in the VS tumor microenvironment (TME) is associated with hearing loss in patients with NF2. We hypothesized that reducing the fibrosis using losartan, an FDA-approved antihypertensive drug that blocks fibrotic and inflammatory signaling, could improve hearing. Using NF2 mouse models, we found that losartan treatment normalized the TME by (i) reducing neuroinflammatory IL-6/STAT3 signaling and preventing hearing loss, (ii) normalizing tumor vasculature and alleviating neuro-edema, and (iii) increasing oxygen delivery and enhancing efficacy of radiation therapy. In preparation to translate these exciting findings into the clinic, we used patient samples and data and demonstrated that IL-6/STAT3 signaling inversely associated with hearing function, that elevated production of tumor-derived IL-6 was associated with reduced viability of cochlear sensory cells and neurons in ex vivo organotypic cochlear cultures, and that patients receiving angiotensin receptor blockers have no progression in VS-induced hearing loss compared with patients on other or no antihypertensives based on a retrospective analysis of patients with VS and hypertension. Our study provides the rationale and critical data for a prospective clinical trial of losartan in patients with VS.

Tumor-Related and Patient-Related Variables Affecting Length of Hospital Stay Following Vestibular Schwannoma Microsurgery

OBJECTIVE

Review a single institution's vestibular schwannoma (VS) microsurgery experience to determine (1) correlations between demographics, comorbidities, and/or surgical approach on hospital length of stay (LOS) and discharge disposition and (2) trends in surgical approach over time.

METHODS

Retrospective case series from a multidisciplinary skull base program at a tertiary care, academic hospital. All adult (>18 years) patients undergoing primary microsurgery for VS between 2008 and 2018 were included.

RESULTS

A total of 147 subjects were identified. Surgical approach was split between middle fossa (MF) (16%), retrosigmoid (RS) (35%), and translabyrinthine (TL) (49%) craniotomies. For the 8% of patients had other than routine (OTR) discharge. Mean LOS was significantly longer for patients undergoing RS than either MF or TL. Brainstem compression by the tumor was associated with longer LOS as were diagnoses of chronic obstructive pulmonary disease (COPD) and peripheral vascular disease (PVD). For all discharges, the 40 to 50- and 50 to 60-year-old subgroups had significantly shorter LOS than the 70-years-and-older patients. For the 92% of patients routinely discharged, there was a significantly shorter LOS in the 40 to 50-year-olds compared to the 70-years-and-older patients. There was a significant shift in surgical approach from RS to TL over the study period.

CONCLUSION

Over 90% of VS microsurgery patients were routinely discharged with a median hospital LOS of 3.2 days, both of which are consistent with published data. There is an inverse relationship between age and LOS with patients older than 70 years having significantly longer LOS. Brainstem compression, COPD, PVD, and the RS approach negatively affect LOS.

LEVEL OF EVIDENCE

4.

Investigating Predictors of Increased Length of Stay After Resection of Vestibular Schwannoma Using Machine Learning

OBJECTIVE

To evaluate the predictors of prolonged length of stay (LOS) after vestibular schwannoma resection.

STUDY DESIGN

Retrospective chart review.

SETTING

Tertiary referral center.

PATIENTS

Patients who underwent vestibular schwannoma resection between 2008 and 2019.

INTERVENTIONS

Variables of interest included age, body mass index, comorbidities, symptoms, previous intervention, microsurgical approach, extent of resection, operative time, preoperative tumor volume, and postoperative complications. Predictive modeling was done through multivariable linear regression and random forest models with 80% of patients used for model training and the remaining 20% used for performance testing.

MAIN OUTCOME MEASURES

LOS was evaluated as the number of days from surgery to discharge.

RESULTS

Four hundred one cases from 2008 to 2019 were included with a mean LOS of 3.0 (IQR = 3.0-4.0). Postoperatively, 14 (3.5%) of patients had LOS greater than two standard deviations from the mean (11 days). In a multivariate linear regression model (adjusted R2 = 0.22; p < 0.001), preoperative tumor volume (p < 0.001), coronary artery disease (p = 0.002), hypertension (p = 0.029), and any major complication (p < 0.001) were associated with increased LOS (by 0.12, 3.79, 0.87, and 3.20 days respectively). A machine learning analysis using a random forest identified several potential nonlinear relationships between LOS and preoperative tumor dimensions (length, volume) and operative time that were not captured on regression. The random forest model had lower prediction error compared to the regression model (RMSE 5.67 vs. 44.59).

CONCLUSIONS

Tumor volume, coronary artery disease, hypertension, and major complications impact LOS. Machine learning methods may identify nonlinear relationships worthy of targeted clinical investigation and allow for more accurate patient counseling.

Fluorescent Detection of Vestibular Schwannoma Using Intravenous Sodium Fluorescein In Vivo

BACKGROUND

Vestibular schwannoma (VS) are intracranial tumors caused by merlin deficiency. Sodium fluorescein (SF) is a fluorescent compound that accumulates in various intracranial tumors, causing tumors to emit green fluorescence after blue light excitation.

HYPOTHESIS

Intravenous SF preferentially deposits in VS, helping surgeons differentiate tumor from surrounding tissue.

METHODS

Merlin-deficient Schwann cells were grafted onto cochleovestibular nerves of immunodeficient rats. Rats were randomized to receive SF (7.5 mg/kg; n = 5) or saline (n = 3). Tissues were harvested at 1 hour and photographed in white and blue light. Sixteen surgeons identified and marked the tumor-tissue interfaces on images. Fluorescence was measured on tissue specimens using the IVIS imaging system and on tissue cross-sections obtained with confocal microscopy. Western blot was performed to measure levels of organic anion transporting polypeptide (OATP), a drug transporter specific for SF.

RESULTS

Under blue light, tumors from SF rats demonstrated bright green fluorescence under direct visualization, higher fluorescence measurements on tissue specimens (p < 0.001), and more SF deposition on tissue cross-sections (p < 0.001), when compared with surrounding tissues and placebo rats. Surgeons were better able to distinguish the tumor-tissue interfaces in SF rats. Furthermore, the expression level of OATP1C1 was significantly higher in tumors than in surrounding tissues (p < 0.0001).

CONCLUSION

In a xenograft model of VS, intravenous SF preferentially deposits in tumors, compared with normal surrounding tissue. Under blue light, tumors emit an intense green fluorescence that can help surgeons differentiate tumor from critical structures nearby, which may improve clinical outcomes in complicated VS surgery.

Clinical Predictors of Facial Nerve Outcomes After Surgical Resection of Vestibular Schwannoma

OBJECTIVE

To identify clinical predictors of facial nerve (FN) outcomes after microsurgical resection of vestibular schwannoma (VS).

STUDY DESIGN

Prospective cohort study.

SETTING

Academic medical center.

METHODS

Consecutive patients undergoing VS resection from November 2017 to October 2019 were included. FN function was evaluated with the House-Brackmann (HB) scale and stratified into good (HB I-II) and poor (HB III-VI) function. Analyses included descriptive statistics, correlation, and logistic regression.

RESULTS

Of 256 patients who met criteria (mean age, 47.7 years; 62.5% female), 227 (88.7%) achieved good FN function postoperatively and 238 (93.0%) at latest follow-up (mean, 154.8 days). Operative approaches consisted of translabyrinthine (50.8%), retrosigmoid (25.0%), and middle fossa craniotomies (24.2%). Extent of resection was decided intraoperatively, and gross or near total resection was accomplished in 237 (92.6%) cases. Postoperative HB grade correlated with latest HB grade (0.615, P < .001). Factors associated with good postoperative FN function included small tumor size (≤15 mm; odds ratio [OR], 2.425; P = .042), gross or near total resection (OR, 3.170; P = .041), and ≥100-µV intraoperative FN electromyographic response to a 0.05-mA stimulus (OR, 22.242; P < .001). Factors associated with good FN function at latest follow-up included gross total resection (OR, 7.764; P = .003) and ≥100-µV FN electromyographic response (OR, 8.518; P < .001), accounting for surgical approach and tumor size.

CONCLUSION

Microsurgical resection of VS can be accomplished with excellent FN outcomes. Gross total resection and ≥100-µV intraoperative FN electromyographic response predicted excellent FN outcomes. Immediate postoperative FN function is a prognosticator of long-term FN function.

National Trends in Surgical Resection of Vestibular Schwannomas

OBJECTIVE

To characterize the national trend for surgical resection of vestibular schwannoma (VS) and to assess changes in demographics, length of stay (LOS), discharge patterns, and hospital charges.

STUDY DESIGN

Population-based inpatient registry analysis.

SETTING

National Inpatient Sample and SEER database (Surveillance, Epidemiology, and End Results).

PATIENTS AND METHODS

Retrospective review of the US National Inpatient Sample and the SEER database from 2001 to 2014 of all patients who underwent resection of VS.

RESULTS

A total of 24,380 VS resections were performed. While the annual incidence of VS remained stable at 1.38 per 100,000, surgical volume declined by 36.1%, from 2807 in 2001 to 1795 in 2014 (R² = 0.58). Total hospital charges more than doubled, from $52,475 in 2001 to $115,164 in 2014 ($4478 per year, R² = 0.96). While most procedures were performed at large-sized hospitals, this decreased from 89% in 2002 to 75.8% in 2014. Average LOS remained stable at 5.2 days during the study period. The number of discharges to a nursing facility increased from 113 (5.5%) in 2002 to 245 (13.6%) in 2014 (P = .0002).

CONCLUSION

VS resection has evolved in the United States. While the incidence remained stable, surgical volume decreased by 36%, and hospital charges more than doubled. More cases are being performed at smaller hospitals. Although LOS did not vary significantly, there is an increase in nonroutine discharges. These data may guide future research in resource utilization in neurotology.

The Clinical Implications of Spontaneous Hemorrhage in Vestibular Schwannomas

Background  Spontaneous hemorrhage into vestibular schwannomas (VSs) is rare and can render more rapid symptom onset and a seemingly poorer prognosis for an otherwise benign pathology. We describe our series of hemorrhagic VS (HVSs) and systematically reviewed the literature to better understand relevant clinical factors and outcomes. Methods  Retrospective case review series and systematic review of the literature using PRISMA guidelines. Results  Fifty-three patients with HVS met inclusion criteria. Compared with historical data for all VS, patients with HVS had relatively higher rates of perioperative mortality, significant preoperative facial weakness, and harbored relatively larger tumors. Regardless of the extent of resection (EOR), surgery for HVS resulted in significant improvement of facial weakness ( p  = 0.041), facial numbness ( p  < 0.001), vertigo ( p  < 0.001), and headache ( p  < 0.001). Patients with facial weakness tended to have larger tumors ( p  = 0.058) on average and demonstrated significant improvement after surgery, irrespective of EOR ( p  < 0.01). The use of blood-thinning medications did not affect patient health outcome. Histopathology of HVS samples showed an increased number of dilated/ectatic thin-walled vascular channels, reflective of potentially increased vascular permeability and hypervascularity. Conclusion  HVS may be an aggressive subgroup of VS, associated with a surprisingly high mortality rate. When features of HVS are identified on imaging, these patients should be treated expeditiously, especially given that facial nerve dysfunction, which is identified in more than half of patients with HVS, appears to be reversible. Overall, this study has significant implications in the management of VS, raising awareness of a small, but highly morbid subgroup.

Surgical Management of Vestibular Schwannoma: Practice Pattern Analysis via NSQIP

Objective:

Characterize current perspectives in the surgical management of vestibular schwannoma (VS) to guide otolaryngologists in understanding United States practice patterns.

Methods:

A retrospective analysis of ACS-NSQIP database was performed to abstract all patients from 2008 to 2016 who underwent VS resection using ICD-9/10 codes 225.1 and D33.3, respectively. The specific surgical approach employed was identified via CPT codes 61520, 61526/61596, and 61591, which represent retrosigmoid (RS), translabyrinthine (TL) and middle cranial fossa (MCF) approaches, respectively. Analyzed outcomes include general surgical complications, total length of stay, and reoperation.

Results:

A total of 1671 VS cases were identified, 1266 (75.7%) were RS, 292 (17.5%) were TL, and 114 (6.8%) were MCF. The annual number of cases increased over the study period from 15 to 375, which is chiefly attributed to increased institutional participation in ACS-NSQIP. Perioperative variables including BMI ( P < .001), ASA class ( P = .004), ethnicity ( P = .008), operative time ( P < .001), and reoperation ( P < .001) were found to be statistically significant between cohorts. Increased utilization of RS approach was consistent over the entire study period, with significantly more RS performed than either TL or MCF. Finally, a statistically significant difference with respect to general surgical complication rates was not noted between surgical approaches.

Conclusions:

There is increased employment of RS approach for the operative management of VS, which likely is the result of increased reliance on both stereotactic radiosurgery and observation as alternative treatment strategies.

Characteristics and Outcomes of Pediatric Vestibular Schwannomas

OBJECTIVE

To review the demographics, treatment modalities, and survival of children with vestibular schwannomas.

STUDY DESIGN

Analysis using the Surveillance, Epidemiology, and End Results (SEER) database.

SUBJECTS AND METHODS

Pediatric patients from birth to 18 years in the SEER database were included from 2004 to 2014 based on a diagnosis of vestibular schwannoma using the primary site International Classification of Diseases (ICD) O-3 code of C72.4: acoustic nerve and the ICD O-3 histology codes of 9540/1: neurofibromatosis, Not Otherwise Specified (NOS); 9560/0: neurilemoma, NOS; or 9570/0: neuroma, NOS.

RESULTS

One hundred forty-eight pediatric vestibular schwannomas (VSs) cases were identified. The mean age at diagnosis was 13.9 years (range, 4.0-18.0). Eighty-five (57.4%) patients were women. Seventy-seven (52.0%) patients had isolated unilateral VSs while 71 (48.0%) patients had either bilateral VSs or unilateral VSs with other brain, spinal cord, or cranial nerve tumors. Eighty two (55.4%) patients received surgical resection only, 45 (30.4%) received no treatment, 6 (4.1%) received radiation only, and 12 (8.1%) received surgery and radiation. The median tumor size for patients who received no treatment was 9.5 mm (interquartile range [IQR]: 8.0) compared with 33.5 mm (IQR: 23.0) for patients who received surgical care and 41.0 mm (IQR: 1.5) for patients who received both surgery and radiation (p < 0.001). The 5-year overall survival rate was 97%.

CONCLUSION

Pediatric VSs tend to be diagnosed in adolescence. No men or women predominance was appreciated. Treatment varied according to tumor size. Survival rates for children with vestibular schwannomas are excellent. These data may assist healthcare providers when counseling children with vestibular schwannomas and their families.

Short-Term Surgical Outcome for Vestibular Schwannoma in Sweden: A Nation-Wide Registry Study

Background: Vestibular Schwannoma (VS) is a benign neoplasm arising from the 8th cranial nerve, with surgery one of the treatment modalities. In a nation-wide registry study, we describe the baseline, treatment characteristics, and short-term outcome in patients surgically treated for VS.

Methods: We performed a nationwide study with data from the Swedish Brain Tumor Registry (SBTR) for all adults diagnosed with VS 2009–2015. Patient symptoms, tumor characteristics, and postoperative complications were analyzed.

Results: In total 348 patients underwent surgery for VS. Mean age was 50.6 ± 14.5 years and 165 patients (47.4%) were female. The most common symptom was focal neurological deficit (92.0%), with only 25 (7.2%) being asymptomatic prior to surgery, and 217 (63.6%) had no restriction in activity. Following surgery, 100 (28.7%) patients developed new deficit(s). In terms of postoperative complications; 11 (3.2%) had a hematoma, 35 (10.1%) an infection, 10 (2.9%) a venous thromboembolism, and 23 (6.6%) had a reoperation due to complication. There were no deaths within 30-days after surgery. When grouped according to tumor size (< 4 vs. ≥4 cm), those with ≥4 cm tumors were more often males (p = 0.02), had more often ICP related symptoms (p = 0.03) and shorter time from imaging to surgery (p < 0.01). Analysis of the younger (< 65 years) vs. elderly (≥65 years) revealed no difference in outcome except increased 1-year mortality (p = 0.002) in elderly.

Conclusion: In this nation-wide registry-study, we benchmark the 30-day complication rate after VS surgery as collected by the SBTR. Further, we present the current neurosurgical outcome data from both VS smaller than 40 mm compared to larger tumors, as well as younger vs. elderly VS patients. Since surgical decision making is a careful consideration of short term risk vs. long term benefit, this information can be useful in clinical decision making.