Rising Incidence of Sporadic Vestibular Schwannoma: True Biological Shift Versus Simply Greater Detection

Comparing Cochlear Implant Outcomes in 100 Patients With Sporadic Vestibular Schwannoma Managed With Observation, Radiosurgery, or Microsurgery: A Multi-Institutional Review

OBJECTIVE

To compare cochlear implant (CI) speech perception outcomes in patients with sporadic vestibular schwannoma (VS) managed with observation, radiosurgery, or microsurgery.

STUDY DESIGN

Retrospective review.

SETTING

Eleven tertiary academic medical centers.

PATIENTS

One hundred patients with sporadic VS who received an ipsilateral CI.

INTERVENTIONS

Ipsilateral cochlear implantation.

MAIN OUTCOME MEASURES

Pure-tone thresholds, monosyllabic speech perception testing scores, and rates of open-set speech acquisition.

RESULTS

Of the 100 patients studied, 54 underwent microsurgery, 26 underwent radiosurgery, 19 continued observation, and 1 underwent multimodal therapy. Among all patients, the median post-implantation pure-tone average was 31 dB (interquartile range [IQR] 25-39 dB) and the median monosyllabic speech perception score was 30% (IQR 0-60%) at a median of 12 months (IQR 5-25 months) post-implantation. Patients who were managed with microsurgery (median speech perception score 11%, IQR 0-52%) exhibited poorer implant outcomes overall compared with those managed with observation (median speech perception score 52%, IQR 40-72%) or radiosurgery (median speech perception score 30%, IQR 16-60%). Open-set speech perception was achieved in 61% of patients managed with microsurgery, 100% with observation, and 80% with radiosurgery. In a multivariable setting, those managed with observation (p = 0.02) or who underwent radiosurgery (p = 0.04) were significantly more likely to achieve open-set speech perception compared with patients who underwent microsurgery.

CONCLUSIONS

Cochlear implants offer benefit in selected patients with sporadic VS. Although achieved in over half of people after microsurgery, open-set speech perception is more reliably attained in patients who are treated with observation or radiosurgery compared with microsurgical resection. These data may inform patient counseling and VS tumor management in people who may benefit from implantation.

Medicare Reimbursement and Utilization Trends Within Skull Base Surgery

BACKGROUND

Medicare reimbursements for otolaryngology and neurosurgery procedures have generally declined since 2000. We explore Medicare reimbursement trends for anterior cranial fossa, middle cranial fossa, posterior cranial fossa, pituitary surgery, and skull base reconstruction surgery from 2000-2022.

METHODS

Cross-sectional analysis of the Centers for Medicare and Medicaid Services Physician Fee Schedule was performed from 2000-2022 on approach, resection, and repair of the skull base (Current Procedural Terminology codes 31290-31291, 61546, 61548, 61575-61619, and 62165). Reimbursement data were adjusted for inflation to 2022 U.S. dollars, and annual and total changes calculated. The Centers for Medicare and Medicaid Services Part B National Summary Data File was analyzed for trends in Medicare procedure volume and total payment.

RESULTS

Adjusted for inflation since 2000, reimbursements for anterior cranial fossa, middle cranial fossa, posterior cranial fossa, pituitary surgery, and skull base reconstruction codes had an overall decrease of 22.85%, 32.43%, 28.09%, 44.22%, and 38.65%, respectively. Simultaneously, procedure volume increased at an average annual rate of 63.99%, 128.57%, 19.75%, 36.11%, and 12.79%, respectively.

CONCLUSIONS

While nominal per-service Medicare reimbursement has increased for skull base surgery codes, there has been a downward trend in inflation-adjusted procedural reimbursement. This parallels findings in other otolaryngology and neurosurgery procedures. Despite this, surgical volume in all skull base surgery subfields has increased, indicating increased utility and adoption of these techniques.

The Association Between Medicaid Expansion and Disparities in Vestibular Schwannoma Incidence

OBJECTIVES

The effect of Medicaid expansion as a part of the Affordable Care Act on vestibular schwannoma (VS) incidence overall and in marginalized populations has not yet been elucidated. The goal of this study was to determine if Medicaid expansion was associated with increases in VS incidence overall, as well as in patients of non-white race or in counties of low socioeconomic status (SES).

METHODS

We performed a difference-in-difference (DiD) analysis from January 1st 2010-December 31st 2017 utilizing the Surveillance, Epidemiology, and End Results (SEER) database. Our DiD method compared the change in VS rate between counties that did and did not expand Medicaid among patients of white and non-white race, in low and high SES counties, before and after expansion.

RESULTS

The study included 17,312 cases across 1020 counties. Medicaid expansion was associated with a 15% increase (incidence rate ratio 95% CI: [11%, 19]) in VS incidence. White populations saw a 10% increase (CI: [1.06, 1.19]), Black populations saw a 20% increase (CI: [1.10, 1.29]), and patients of other races saw a 44% increase in incidence associated with expansion (CI: [1.21, 1.70]). Low SES counties saw an increase in incidence 1.12 times higher than that of high SES counties (CI:[1.04, 1.20]).

CONCLUSION

Medicaid expansion was associated with increases in VS incidence across populations. Furthermore, this increase was more evident in disadvantaged populations, such as patients of non-white race and those from low SES counties. These findings emphasize the impact of Medicaid expansion on healthcare utilization for VS diagnosis.

LEVEL OF EVIDENCE

3-Retrospective Cohort Study Laryngoscope, 134:4383-4388, 2024.

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.

Spontaneous Regression of a Large Vestibular Schwannoma: Is Nonoperative Management Reasonable?

Vestibular schwannomas (VSs) are the most common cerebellopontine tumors. The natural history of smaller-sized VSs (<30 mm) has been well-studied, leading to the recommendation of a "watch and wait" approach. However, large VSs (>30 mm) have not been extensively studied, mainly because of their rarity. As such, most patients are conventionally offered surgery which carries a significant risk of neurological morbidity. Here, we report a case of a giant VS (>40 mm) in a 30-year-old man who regressed spontaneously. He was lost to follow-up for 18 years and, upon re-presentation, the symptomatology drastically improved and repeat imaging demonstrated a marked reduction in tumor size. Referring to similar cases in other studies, we postulate that most large and giant VSs undergo a phase of growth and stasis, followed by regression due to shifts in the balance between tumorigenic and regressive factors. Taken together with emerging molecular data, further studies are required to better understand the history of large and giant VSs to shape more personalized treatment options. This potentially includes non-operative management as a tenable option.

Incidence of vestibular schwannoma in Finland, 1990-2017

BACKGROUND

An increasing trend in incidence of vestibular schwannomas (VS) has been reported, though not consistently, across populations.  Materials and methods: We obtained data from the Finnish Cancer Registry on 1,149 VS cases diagnosed in 1990-2017 with tabular data up to 2022. We calculated age-standardised incidence rates (ASR) overall, by sex, and for 10-year age groups. We analysed time trends using Poisson and joinpoint regression.

RESULTS

The average ASR of VS in Finland during 1990-2017 was 8.6/1,000,000 person-years for women and 7.5/1,000,000 for men. A declining trend was found with an average annual percent change of -1.7% (95% confidence interval [CI]: -2.8%, -0.6%) for women, -2.2% (95% CI: -3.6%, -0.7%) for men, and -1.9% (95% CI: -2.9%, -1.0%) for both sexes combined. The ASR in women was 11.6/1,000,000 person-years in 1990 and it decreased to 8.2/1,000,000 by 2017. Correspondingly, the incidence in men was 7.1/1,000,000 in 1990 and decreased to 5.1/1,000,000 by 2017. Some decline in incidence over time was found in all age groups below 80 years, but the decline (2.3-3.1% per year) was statistically significant only in age groups 40-49, 50-59, and 60-69 years. In the oldest age group (80+ years), the incidence of VS increased by 16% per year. For 2018-2022, the ASR was 7.6/1,000,000 for both sexes combined, with a decline by -1.7% (95% CI: -2.3%, -1.2%) annually for the entire period 1990-2022.

CONCLUSION

In contrast to the increasing incidence reported in some studies, we found a decreasing trend in VS incidence for both sexes in Finland.

Utility of Targeted Positron Emission Tomography Imaging to Predict Schwannoma Growth in a Murine Tumor Model

OBJECTIVE

To identify if targeted positron emission tomography (PET) imaging with radiolabeled antibodies can predict tumor growth rate and ultimate tumor size in a murine flank schwannoma model.

STUDY DESIGN

Animal research study.

METHODS

Rat schwannoma cells were cultured and implanted into 40 athymic nude mice. Once tumors reached 5 mm in diameter, 30 mice were injected with zirconium-89 labeled antibodies (HER2/Neu, vascular endothelial growth factor receptor 2 (VEGFR2), or IgG isotype). PET/CT was performed, and standardized uptake values (SUV) were recorded. Tumors were serially measured until mice were sacrificed per IACUC protocol. Statistical analysis was performed to measure correlations between SUV values, tumor size, and growth.

RESULTS

Mean tumor sizes in mm3 on Day 0 were 144 ± 162 for anti-HER2/Neu, 212 ± 247 for anti-VEGFR2, and 172 ± 204 for IgG isotype groups respectively. Mean growth rates in mm3 /day were 531 ± 250 for HER2, 584 ± 188 for VEGFR2, and 416 ± 163 for the IgG isotype group. For both initial tumor size and growth rates, there was no significant difference between groups. There were significant correlations between maximum tumor volume and both the SUV max in the HER2 group (p = 0.0218, R2  = 0.5020), and we observed significant correlations between growth rate, and SUV values (p = 0.0156, R2  = 0.5394). Respectively, in the anti-VEGFR2 group, there were no significant correlations.

CONCLUSION

In a murine schwannoma model, immunotargeted PET imaging with anti-HER2/Neu antibodies predicted tumor growth rate and final tumor size. Laryngoscope, 134:1372-1380, 2024.

Socioeconomic determinants impact quality of life at vestibular schwannoma diagnosis

BACKGROUND

Socioeconomic variables including race, education, and income have been shown to affect vestibular schwannoma incidence, treatment, and outcomes. We sought to determine the impact of socioeconomic factors on quality of life at the time of vestibular schwannoma diagnosis.

METHODS

Retrospective cohort study conducted at a tertiary academic center. All patients evaluated for vestibular schwannoma from March 1, 2010 to December 31, 2021 who completed at least one Penn Acoustic Neuroma Quality of Life (PANQOL) questionnaire at presentation or prior to any intervention were included. PANQOL scores were compared across income quintiles, racial groups, and health insurance categories.

RESULTS

Two-hundred and ninety-six patients who had non-missing information on variables of interest were included. Compared to White/Caucasian patients (84.5 %), Black/African American patients (4.7 %) had significantly lower PANQOL total scores (b = -12.8[-21.7, -4.0], p = 0.005). Compared to patients with Commercial insurance (53 %), patients who were Uninsured/ Self-pay (1.7 %) had significantly lower PANQOL total scores (b = -16.7[-31.4, -1.9], p = 0.027). Patients in higher income quintiles had significantly higher PANQOL total scores (b = 11.7[3.9, 19.5], p = 0.004 comparing highest income quintile to lowest). After controlling for potential confounders, income quintile (b = 9.6[1.3, 17.9], p = 0.023 comparing highest quintile to lowest) and insurance (b = -17.0[-31.9, -21], p = 0.025 comparing Uninsured/Self-pay to Commercial insurance) remained predictors of total PANQOL score.

CONCLUSIONS

Socioeconomic factors including race, health insurance, and income appear to contribute to quality of life at the time of vestibular schwannoma diagnosis. These variables are interrelated and the effects of race may be mediated in part by differences in income and health insurance coverage.

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.

The Effect of Metformin on Vestibular Schwannoma Growth: A Systematic Review and Meta-analysis

OBJECTIVES

To systematically review and evaluate metformin's potential impact on vestibular schwannoma (VS) growth.

DATA SOURCES

PubMed, Cochrane Library, and Embase.

REVIEW METHODS

A retrospective cohort study was performed on sporadic VS patients undergoing initial observation who had at least two magnetic resonance imaging studies. Patients were stratified by metformin use during the observation period. Primary endpoint was VS growth, defined as at least a 2 mm increase in diameter. Survival free of tumor growth was evaluated between groups. Systematic review and meta-analysis were performed to produce a pooled odds ratio [OR]. Study heterogeneity was assessed and post-hoc power analysis was performed.

RESULTS

A total of 123 patients were included, of which 17% were taking metformin. Median patient age was 56.6 years (range, 25.1-84.5). There were no statistically significant differences between the groups. Survival analysis did not demonstrate a statistically significant difference in time to VS growth between groups (hazard ratio = 0.61, 95% confidence interval [CI] = 0.29-1.29). Furthermore, logistic regression analysis did not demonstrate a statistically significant difference between groups in the odds of VS growth (OR = 0.46, 95% CI = 0.17-1.27). Systematic review identified 3 studies. Meta-analysis suggested that metformin reduces the odds of developing VS growth (pooled OR = 0.45, 95% CI = 0.29-0.71). Studies demonstrated low between-study heterogeneity. Power analysis demonstrated a sample size of 220 patients with equal randomization would be required to prospectively identify a true difference with 80% power.

CONCLUSIONS

Metformin use may reduce the odds of VS growth. A randomized trial would be ideal to identify an unbiased estimate of metformin's effect on VS growth. Laryngoscope, 133:2066-2072, 2023.

Epidemiology and Risk Factors for Development of Sporadic Vestibular Schwannoma

Vestibular schwannomas (VSs) are benign, slow-growing tumors of the eighth cranial nerve. Sporadic unilateral VSs constitute approximately 95% of all newly diagnosed tumors. There is little known about risk factors for developing sporadic unilateral VS. Potential risk factors that have been reported are familial or genetic risk, noise exposure, cell phone use, and ionizing radiation, whereas protective factors may include smoking and aspirin use. More research is needed to elucidate the risk factors for development of these rare tumors.

Introducing an Evidence-Based Approach to Wait-And-Scan Management of Sporadic Vestibular Schwannoma

The advent of MRI has led to more sporadic vestibular schwannomas diagnosed today than ever before. Despite the average patient being diagnosed in their sixth decade of life with a small tumor and minimal symptoms, population-based data demonstrate that more tumors per capita are treated today than ever before. Emerging natural history data justify either an upfront treatment approach or the "Size Threshold Surveillance" approach. Specifically, if the patient elects to pursue observation, then existing data support the tolerance of some growth during observation in appropriately selected patients up until a specific size threshold range (about 15 mm of CPA extension). The current article discusses the rationale behind a shift in the existing observation management approach, where initial detection of growth typically begets treatment, and outlines the application of a more flexible and nuanced approach based on existing evidence.

Surgical Outcomes Following Vestibular Schwannoma Resection in Patients over the Age of Sixty-five

Objective  Vestibular schwannoma (VS) are benign, often slow growing neoplasms. Some institutions opt for radiosurgery in symptomatic patients of advanced age versus surgical resection. The aim of the study is to analyze surgical outcomes of VS in patients over the age of 65 who were either not candidates for or refused radiosurgery. Methods  This includes retrospective analysis of VS patients between 1988 and 2020. Demographics, tumor characteristics, surgical records, and clinical outcomes were recorded. Patient preference for surgery over radiosurgery was recorded in the event that patients were offered both. Facial nerve outcomes were quantified using House-Brackmann (HB) scores. Tumor growth was defined by increase in size of >2 mm. Results  In total, 64 patients were included of average age 72.4 years (65-84 years). Average maximum tumor diameter was 29 mm (13-55 mm). Forty-five patients were offered surgery or GKRS, and chose surgery commonly due to radiation aversion (48.4%). Gross total resection was achieved in 39.1% ( n  = 25), near total 32.8% ( n  = 21), and subtotal 28.1% ( n  = 18). Average hospitalization was 5 days [2-17] with 75% ( n  = 48) discharged home. Postoperative HB scores were good (HB1-2) in 43.8%, moderate (HB3-4) in 32.8%, and poor (HB5-6) in 23.4%. HB scores improved to good in 51.6%, moderate in 31.3%, and remained poor in 17.1%, marking a rate of facial nerve improvement of 10.9%. Tumor control was achieved in 95.3% of cases at an average follow-up time of 37.8 months. Conclusion  VS resection can be safely performed in patients over the age of 65. Advanced age should not preclude a symptomatic VS patient from being considered for surgical resection.

Quality of Life in Sporadic Vestibular Schwannoma

The focus of management in sporadic vestibular schwannoma has dramatically evolved over the last 100 years. The centrality of quality of life (QoL) is being underscored by an ongoing epidemiologic shift toward an older patient demographic that is being diagnosed with smaller tumors and often with few associated symptoms. Two disease-specific QoL instruments have been developed for sporadic vestibular schwannoma: the Penn Acoustic Neuroma Quality of Life Scale in 2010, and more recently, the Mayo Clinic Vestibular Schwannoma Quality of Life Index in 2022. The current article examines disease-specific quality-of-life outocmes in the management of ssporadic vestibular schwannoma.

Preservation of the integrity of facial nerve in vestibular schwannoma microsurgery: A consecutive study of 127 clinical cases focusing on nervus intermedius

Background

Nervus intermedius (NI) injuries are not given enough attention by neurosurgeons during vestibular schwannoma (VS) surgery. Preservation of NI function is essential for the integrity and continuity of the facial nerve, although this can be challenging. We identified the risk factors for NI injury and proposed our experience for optimizing NI preservation based on our cases.

Methods

We retrospectively analyzed clinical data from a consecutive series of 127 patients with VS who underwent microsurgery via the retrosigmoid approach from 2017 to 2021 at our institution. The baseline characteristics of the patients were collected from the medical records, and the incidence of NI dysfunction symptoms was obtained by outpatient and online video follow-up 6 months after surgery. The surgical procedures and techniques used were described in detail. The data were analyzed in relation to sex, age, tumor location (left or right), Koos grading scale, internal acoustic canal (IAC) invasion (TFIAC Classification), brainstem adhesion, tumor characteristics (cystic or solid), tumor necrosis, and preoperative House-Brackmann (HB) grading by univariate and multivariate analyses.

Results

Gross tumor removal was achieved in 126 (99.21%) patients. Subtotal removal was performed on one patient (0.79%). Twenty-three of our cases exhibited facial nerve palsy preoperatively; 21 patients had HB grade II facial palsy, and two had HB grade III. Two months after surgery, 97 (76.38%) patients had normal function of the motor portion of the facial nerve; 25 (19.69%) patients had HB Grade II facial palsy, five had Grade III (3.94%), and zero (0%) had Grade IV. Postoperatively, 15 patients experienced newly gained dry eyes (11.81%), whereas 21 cases of lacrimal disturbances (16.54%), nine of taste disturbances (7.09%), seven of xerostomia (5.51%), five of nasal hypersecretions (3.94%), and seven of hypersalivation (5.51%) were identified in our cases. Univariate and multivariate analyses revealed that the Koos grading scale and tumor characteristics (solid or cystic) were correlated with NI injury (p <0.01).

Conclusion

The data in this study demonstrate that although the motor function of the facial nerve is well preserved, NI disturbance is still common after VS surgery. Maintaining the integrity and continuity of the facial nerve is key to NI function. Performing bidirectional and subperineurium dissection based on even and adequate debulking is beneficial for NI preservation in VS surgery. Higher Koos grading and cystic characteristics of VS are associated with postoperative NI injuries. These two parameters can be used to guide the delineation of surgical strategy and predict the prognosis of NI function preservation.

Which Epidemiological Characteristics Drive Decision Making in the Management of Patients with Vestibular Schwannoma?

The incidence of sporadic vestibular schwannoma has significantly increased over the past few decades. However, there is no method currently available to accurately predict the risk of subsequent tumor growth. The difference in the management of five patient groups has been evaluated: wait and scan, conversion to microsurgery, conversion to stereoradiotherapy, sterioradiotherapy, and microsurgery. In total, 463 patients with vestibular schwannoma have been consulted in our department from 2010 through 2016. Of the 250 patients initially indicated for observation, 32.4% were later indicated for active treatment. Younger patients were more frequently indicated for surgery (mean age 48 years) compared to older patients, who were more often indicated for stereoradiotherapy (mean age 62 years). Tumor growth was observed more often in patients under 60 years of age and in patients with tumors greater than 10 mm. In elderly patients, including those with larger tumors, a conservative approach is the optimal solution. If tumor growth occurs in the wait-and-scan strategy, it is still possible to continue with a conservative approach in some situations. The duration of follow-up scans is still a matter of debate, as tumors can begin to grow after 5 years from the initial diagnosis.

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.

Hearing Preservation in Observed Sporadic Vestibular Schwannoma: A Systematic Review

OBJECTIVE

To characterize the natural history of hearing loss for patients presenting with serviceable hearing (SH) who undergo a wait-and-scan approach for sporadic vestibular schwannoma (VS) using aggregate time-to-event survival analysis.

STUDY DESIGN

Systematic review.

SETTING

Published international English literature, January 1, 2000 to May 31, 2020.

PATIENTS

Patients with sporadic VS entering a wait-and-scan approach with SH at diagnosis.

INTERVENTIONS

Observation with serial MRI and audiometry.

RESULTS

In total, 3,652 patients from 26 studies were included for analysis. Mean age at diagnosis was 58.8 years (SD, 4.1). Mean follow-up was 49.2 months (SD, 26.5). In total, 755 patients (21%) failed conservative treatment and underwent radiosurgery or microsurgery at the time of last follow-up. The average loss to follow-up was 6.9% (SD, 11.1). A total of 1,674 patients had SH at the time of diagnosis. Survival rates for maintaining SH were 96% at 1 year, 77% at 3 years, 62% at 5 years, and 42% at 10 years following diagnosis.

CONCLUSION

In this systematic review, aggregate data from 3,652 patients across 26 studies show consistent patterns in progression of hearing loss during observation for patients with sporadic VS as a function of time. As an easy-toremember conservative benchmark for those presenting with SH at diagnosis: approximately 75% retain SH at 3 years, 60% at 5 years, and 40% at 10 years.

Long non-coding RNA BRCAT54 sponges microRNA-21 in vestibular schwannoma to suppress cell proliferation

BRCAT54 (also known as MRPS30 divergent transcript) is an anti-tumor long non-coding RNA (lncRNA) in lung cancer, while its role in vestibular schwannoma (VS) is unclear. We predicted that BRCAT54 could interact with microRNA (miR)-21, which suppresses VS cell proliferation. This study was then carried out to study the interaction between BRCAT54 and miR-21 in VS. A total of 56 VS samples and 42 normal vestibular nerve (VN) samples were included in this study. The expression of BRCAT54 and miR-21 in these samples were analyzed with RT-qPCR. Subcellular location of BRCAT54 in primary VS cells was analyzed by subcellular fractionation assay. The direct interaction between BRCAT54 and miR-21 was analyzed through RNA pull-down assay. Overexpression assay was performed to explore the interaction between BRCAT54 and miR-21. The role of BRCAT54 and miR-21 in primary VS cell proliferation was analyzed using BrdU assay. We found that BRCAT54 was downregulated in VS samples than that in VN samples, while miR-21 was upregulated in VS samples. BRCAT54 and miR-21 were not closely correlated. BRCAT54 was detected in both nuclear and cytoplasm samples, and BRCAT54 directly interacted with miR-21. However, BRCAT54 and miR-21 did not affect the expression of each other. BRCAT54 suppressed primary VS cell proliferation and inhibited the role of miR-21 in promoting cell proliferation. Therefore, BRCAT54 may sponge miR-21 to suppress cell proliferation in VS.

Outcomes of Initial Observation Versus Upfront Microsurgical Resection for Small to Medium-sized Vestibular Schwannomas

OBJECTIVE

To assess postoperative outcomes and predictive factors of patients observed prior to microsurgery and those undergoing upfront resection for small and medium-sized VS.

STUDY DESIGN

Retrospective cohort.

SETTING

Tertiary referral center.

PATIENTS

VS patients who had microsurgery from 2003 to 2018 for tumors up to 2.5 cm.

MAIN OUTCOME MEASURES

Postoperative outcomes including facial nerve function and interventions, complications, extent of resection, and salvage therapy.

RESULTS

Of 220 patients, 120 were initially observed, and 100 pursued upfront microsurgery. There was no significant association between initial observation and upfront microsurgery for postoperative facial nerve function at 2 to 3 weeks (p = 0.18) or 12 months (p = 0.5), facial nerve intervention (p = 0.5), major/minor complications (p = 0.48/0.63), recurrence (p = 0.8), subtotal resection (p = 0.6), or salvage therapy (p = 0.9). Time from initial consultation to surgery did not significantly impact outcomes. Intrameatal tumors were more likely to be observed (odds ratios [OR] 2.93; 95% CI 1.53-5.63; p = 0.001). Patients with larger tumor volume (OR 0.52; 95% CI 0.37-0.72; p < 0.0001), brainstem compression (OR 0.28; 95% CI 0.09-0.91; p = 0.03), or higher PTA were less likely to undergo observation (OR 0.99; 95% CI 0.97-0.997; p = 0.02). On multivariable analysis, predictive factors for observation were smaller tumor volume (OR 0.53; 95% CI 0.38-0.75; p < 0.001), lower PTA (OR 0.99; 95% CI 0.98-0.999; p = 0.04), and diabetes (OR 2.54; 95% CI 0.95-6.83; p = 0.06).

CONCLUSIONS

Patients with worse hearing, larger tumor volume, and brainstem compression were more likely to pursue upfront microsurgery. A watchful waiting period does not appear to worsen outcomes and can be considered for patients with better hearing and smaller tumors without brainstem compression.

Global Incidence of Sporadic Vestibular Schwannoma: A Systematic Review

OBJECTIVE

Ubiquitous throughout the literature and during patient counseling, vestibular schwannoma is often quoted to affect about 1 per 100,000 people. Yet, reports from distinct international populations suggest that the incidence is likely much higher. The objective of the current work was to systematically characterize the global incidence of sporadic vestibular schwannoma.

DATA SOURCES

Scopus, Embase, and PubMed.

REVIEW METHODS

Population-based studies reporting incidence rates of sporadic vestibular schwannoma between January 2010 and August 2020 were searched with language restrictions requiring reports to be published in Chinese, English, German, Italian, or Spanish. The protocol was registered with PROSPERO (CRD42021228208) prior to commencement of data collection. PRISMA guidelines for transparent reporting of systematic reviews were followed.

RESULTS

Among 424 citations, 6 publications covering 4 distinct populations from Denmark, the Netherlands, Taiwan, and the United States met inclusion criteria. Most recent incidence rates of among all ages ranged between 3.0 and 5.2 per 100,000 person-years. Highest incidence rates were reported among patients aged ≥70 years, peaking at 20.6 per 100,000 person-years. One study from the United States reported the incidence of asymptomatic, incidentally diagnosed tumors at a rate of 1.3 per 100,000 person-years from 2012 to 2016.

CONCLUSIONS

Recent international incidence rates of sporadic vestibular schwannoma exceed the commonly quoted "1 per 100,000" figure by up to 5-fold among all ages and by up to 20-fold among age groups at highest risk. Based on modern incidence rates, the lifetime prevalence of developing sporadic vestibular schwannoma likely exceeds 1 per 500 persons.

Underreporting of Vestibular Schwannoma Incidence Within National Brain Tumor and Cancer Registries in the United States

OBJECTIVE

Reports using large brain tumor and cancer registries suggest that the incidence of vestibular schwannoma is considerably lower in the United States compared with other countries. The current study compares the incidence and disease characteristics of vestibular schwannoma within a large tertiary referral center's brain tumor and cancer registry using nationally mandated reporting protocols to disease incidence in the same population using an externally validated population-based consortium.

STUDY DESIGN

Population-based study spanning 1,945,007 person-years.

SETTING

Large tertiary referral center.

PATIENTS

Adults with sporadic vestibular schwannoma.

MAIN OUTCOME MEASURE

Disease incidence rates from 2004 to 2016.

RESULTS

From 2004 to 2016, the incidence of vestibular schwannoma in the tumor registry was 1.3 per 100,000 person-years whereas the population-based cohort had an incidence of 4.4 per 100,000 person-years. From 2012 to 2016, the incidence in the tumor registry was 1.4 per 100,000 person-years compared with 5.2 in the population-based cohort. Patients within the population-based cohort were significantly more likely to have smaller tumors at diagnosis (78% intracanalicular versus 45%; p = 0.004) and consequently more likely to undergo management consisting of observation with serial imaging as opposed to treatment with either microsurgery or radiosurgery (71% versus 28%; p = 0.001).

CONCLUSIONS

The reliance on pathology specimens and cancer-related treatment data for the national registration of new cancer and brain tumor diagnoses may introduce selection bias and underreporting of benign brain tumors that frequently involve observation as a primary treatment modality. This selection bias likely accounts for the discrepant incidence rates of vestibular schwannoma reported between the United States and other countries.

Natural History of Growing Sporadic Vestibular Schwannomas During Observation: An International Multi-Institutional Study

OBJECTIVE

Active treatment of small- or medium-sized vestibular schwannoma during wait-and-scan management is currently recommended at most centers globally once growth is detected. The primary aim of the current study was to characterize the natural history of growing sporadic vestibular schwannoma during observation.

STUDY DESIGN

Cohort study.

SETTING

Four tertiary referral centers across the United States and Denmark.

PATIENTS

Patients with two prior MRI scans demonstrating ≥2 mm of linear growth who continued observational management.

INTERVENTION

Observation with serial imaging.

MAIN OUTCOME MEASURE

Subsequent linear growth-free survival (i.e., an additional ≥2 mm of growth) following initial growth of ≥2 mm from tumor size at diagnosis.

RESULTS

Among 3,402 patients undergoing observation, 592 met inclusion criteria. Median age at initial growth was 66 years (IQR 59-73) for intracanalicular tumors (N = 65) and 62 years (IQR 54-70) for tumors with cerebellopontine angle extension (N = 527). The median duration of MRI surveillance following initial detection of tumor growth was 5.2 years (IQR 2.4-6.9) for intracanalicular tumors and 1.0 year (IQR 1.0-3.3) for cerebellopontine angle tumors. For intracanalicular tumors, subsequent growth-free survival rates (95% CI; number still at risk) at 1, 2, 3, 4, and 5 years following the initial MRI that demonstrated growth were 77% (67-88; 49), 53% (42-67; 31), 46% (35-60; 23), 34% (24-49; 17), and 32% (22-47; 13), respectively. For cerebellopontine angle tumors, subsequent growth-free survival rates were 72% (68-76; 450), 47% (42-52; 258), 32% (28-38; 139), 26% (21-31; 82), and 22% (18-28; 57), respectively. For every 1 mm increase in magnitude of growth from diagnosis to tumor size at detection of initial growth, the HRs associated with subsequent growth were 1.64 (95% CI 1.25-2.15; p < 0.001) for intracanalicular tumors and 1.08 (95% CI 1.01-1.15; p = 0.02) for cerebellopontine angle tumors.

CONCLUSIONS

Growth detected during observation does not necessarily portend future growth, especially for slowly growing tumors. Because early treatment does not confer improved long-term quality of life outcomes, toleration of some growth during observation is justifiable in appropriately selected cases.

Predicting Schwannoma Growth in a Tumor Model Using Targeted Imaging

INTRODUCTION

Vestibular schwannoma (VS) is a common pathology encountered in neurotology clinics. Many patients are observed with a "wait and scan" approach. Previous efforts to determine radiographic indicators of future growth have been unsuccessful. Using a mouse subcutaneous tumor model, we seek to determine if fluorescent imaging with directed immunotargets could be used to predict schwannoma growth rate.

METHODS

Anti-VEGFR2 and anti-Her2/Neu monoclonal antibodies were covalently linked to a near-infrared probe (IRDye800). Immunodeficient mice underwent subcutaneous injections with a rat-derived schwann (R3) cell line. When tumor growth was evident, either Anti-VEGFR2-IRDye800, anti-Her2/Neu-IRDye800, or Immunoglobulin G (IgG) Isotype-IRDye800 (control) were injected via tail vein. The mice were serially imaged in a closed field near-IR device. Fluorescent data were analyzed for tumor signal and correlated with tumor sie and growth rate. Heterogeneity of fluorescent tumor signal was also assessed.

RESULTS

In both anti-VEGFR2 and anti-Her2/Neu groups, there were strong correlations between day 1 mean tumor fluorescence and eventual maximum tumor volume (p = 0.002, 0.001; r2 = 0.92, 0.86). There was also strong correlation with maximum tumor signal on day 1 and maximum tumor volume (p = 0.003, 0.008; r2 = 0.90, 0.91). There was no such correlation in the control group (p = 0.99, 0.75; r2 = 0.0002, 0.028).

CONCLUSION

Given the potential morbidity in VS intervention, observation is an appropriate approach for patients with slow-growing or stagnant tumors. We seek to identify immunotargets in a murine model that show promise in predicting schwannoma growth with advanced imaging techniques. Both Her2/Neu and VEGFR2 correlated strongly wth tumor size and growth rates and are promising targets that merit further investigation.

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.

Sudden and Asymmetric Hearing Loss Among Active Duty Service Members: Underscoring the Importance of Active Screening

Military personnel are at increased risk of asymmetric hearing loss secondary to noise exposure. This report illustrates the importance of expeditiously evaluating for retrocochlear pathology even in young active duty service members with asymmetric or sudden hearing loss. A 36-year-old male presented with right-sided sudden hearing loss and dizziness. Audiometry revealed profound mid-to-high-frequency sensorineural hearing loss in the right ear. A 10-day course of oral steroid therapy and two intratympanic steroid injections were unsuccessful in restoring hearing. MRI revealed a 4.2 cm contrast-enhancing cerebellopontine angle tumor, consistent with a vestibular schwannoma (VS). Microsurgical resection utilizing a retrosigmoid craniotomy approach was performed with near-total resection of the tumor and preservation of the facial nerve but not the cochlear nerve. Despite preservation of the facial nerve, progression of post-operative facial weakness required gold weight placement to prevent exposure keratopathy. The patient had recovered partial function in all facial nerve branches at last follow-up. In light of the rising global incidence of VS, any asymmetric or sudden hearing loss in military service members should be evaluated with audiometry and referral to otolaryngology for workup of retrocochlear pathology.

Histopathologic Evaluation of Intralabyrinthine Schwannoma

OBJECTIVES

The aim of this study is to perform a histopathologic analysis of temporal bones with an intralabyrinthine schwannoma (ILS) in order to characterize its extension.

METHODS

Archival temporal bones with a diagnosis of sporadic schwannoma were identified. Both symptomatic and occult nonoperated ILS were included for further analysis.

RESULTS

A total of 6 ILS were identified, with 4 intracochlear and 2 intravestibular schwannomas. All intracochlear schwannomas involved the osseous spiral lamina, with 2 extending into the modiolus. The intravestibular schwannomas were limited to the vestibule, but growth into the bone next to the crista of the lateral semicircular canal was observed in 1 patient.

CONCLUSIONS

Complete removal of an ILS may require partial removal of the modiolus or bone surrounding the crista ampullaris as an ILS may extend into these structures, risking damage of the neuronal structures. Due to the slow growth of the ILS, it remains unclear if a complete resection is required with the risk of destroying neural structures hindering hearing rehabilitation with a cochlear implant.

Pregnancy, Estrogen Exposure, and the Development of Otosclerosis: A Case-Control Study of 1196 Women

OBJECTIVE

This study sought to determine whether a history of pregnancy or bilateral oophorectomy is associated with subsequent otosclerosis development or disease severity.

STUDY DESIGN

Population-based case-control study.

SETTING

Olmsted County, Minnesota.

METHODS

Women diagnosed with otosclerosis were matched to 3 women without otosclerosis based on age and historical depth of medical records. Associations of prior delivery and bilateral oophorectomy with subsequent development of otosclerosis and with pure-tone average (PTA) at the time of otosclerosis diagnosis were evaluated.

RESULTS

We studied 1196 women: 299 cases of otosclerosis and 897 matched controls. The odds ratio for the association of ≥1 delivery with otosclerosis was 1.16 (95% confidence interval [CI] 0.85-1.60; P = .35). Odds ratios for the associations of 1, 2, 3, or ≥4 deliveries with otosclerosis were 1.22 (0.83-1.80), 1.09 (0.71-1.68), 1.28 (0.77-2.12), and 1.00 (0.54-1.84), respectively. The odds ratio for the association of prior bilateral oophorectomy with otosclerosis was 1.12 (0.58-2.18; P = .73). In cases with otosclerosis, PTA at diagnosis was not significantly higher for women with ≥1 delivery as compared with those without (median 45 dB hearing loss [HL] [interquartile range {IQR} 36-55] vs 43 [IQR 34-53]; P = 0.18) but was significantly higher for women with bilateral oophorectomy compared with those without (median 54 dB HL [IQR 44-61] vs 44 [IQR 34-53]; P = .03).

CONCLUSION

These data do not support a relationship between endogenous estrogen exposure and development of otosclerosis. Women with otosclerosis who had a history of pregnancy did not have significantly worse hearing at the time of diagnosis, suggesting that pregnancy is not associated with disease severity.

Epidemiology of vestibular schwannoma in the United States, 2004-2016

Background

Vestibular schwannomas (VS) are nonmalignant tumors of the eighth cranial nerve and are the most common nonmalignant nerve sheath tumor. This study provides the most comprehensive and current analysis of VS epidemiology in the United States.

Methods

Incidence data were obtained from the Central Brain Tumor Registry of the United States, from 2004 to 2016 for VS. Age-adjusted incidence rates (AAIRs), rate ratios (AAIRRs), and prevalence ratios (AAPRs) per 100 000 were analyzed by age, sex, race and ethnicity, and laterality. Additional analyses were performed to assess differences in treatment, laterality, and diagnostic confirmation.

Results

Incidence of VS was highest among adults (aged 65–74 years, AAIR: 3.18, 95% confidence interval [CI]: 3.15–3.25). However, there was a much higher distribution of bilateral tumors compared to unilateral in children aged 0–19 years (28.5% vs 1.0%, P < .001). VS incidence was highest among white non-Hispanics (AAIR:1.30, 95% CI: 1.29–1. 31) and lowest among black non-Hispanics. Incidence of radiographically confirmed VS increased from 2004 to 2016 (annual percent change: 1.64, 95% CI: 0.15–3.16, P = .03). For treatment, 40.1% received surgery, while only 23.7% received radiation. There were an estimated 44 762 prevalent cases of VS in 2016 (AAPR: 12.17, 95% CI: 12.06–12.29).

Conclusions

VS incidence and prevalence are highest among adults and white non-Hispanics. Bilateral VS was more common among children. There was an increase of radiographically confirmed VS over time. A higher proportion of patients received surgical treatment than radiotherapy. Population-based statistics provide healthcare professionals with vital information regarding disease burden and help improve patient care.