Tag: Vestibular schwannoma

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Stereotactic radiosurgery for Koos grade IV vestibular schwannoma in patients ≥ 65 years old

Acta Neurochirurgica (2023) 165:211–220

Surgery is the preferred treatment for large vestibular schwannomas (VS). Good tumor control and cranial nerve outcomes were described in selected Koos IV VS after single-session stereotactic radiosurgery (SRS), but outcomes in elderly patients have never been specifically studied. The aim of this study is to report clinical and radiological outcomes after single-session SRS for Koos IV VS in patients ≥ 65 years old.

Method This multicenter, retrospective study included patients ≥ 65 years old, treated with primary, single-session SRS for a Koos IV VS, and at least 12 months of follow-up. Patients with life-threatening or incapacitating symptoms were excluded. Tumor control rate, hearing, trigeminal, and facial nerve function were studied at last follow-up.

Results One-hundred and fifty patients (median age of 71.0 (IQR 9.0) years old with a median tumor volume of 8.3 cc (IQR 4.4)) were included. The median prescription dose was 12.0 Gy (IQR 1.4). The local tumor control rate was 96.0% and 86.2% at 5 and 10 years, respectively. Early tumor expansion occurred in 6.7% and was symptomatic in 40% of cases. A serviceable hearing was present in 16.1% prior to SRS and in 7.4% at a last follow-up of 46.5 months (IQR 55.8). The actuarial serviceable hearing preservation rate was 69.3% and 50.9% at 5 and 10 years, respectively. Facial nerve function preservation or improvement rates at 5 and 10 years were 98.7% and 91.0%, respectively. At last follow-up, the trigeminal nerve function was improved in 14.0%, stable in 80.7%, and worsened in 5.3% of the patients. ARE were noted in 12.7%. New hydrocephalus was seen in 8.0% of patients.

Conclusion SRS can be a safe alternative to surgery for selected Koos IV VS in patients ≥ 65 years old. Further follow-up is warranted.

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Audiovestibular symptoms and facial nerve function comparing microsurgery versus SRS for vestibular schwannomas

Acta Neurochirurgica (2022) 164:3221–3233

Surgery and radiosurgery represent the most common treatment options forcvestibular schwannoma. A systematic review and meta-analysis were conducted to compare the outcomes of surgery versus stereotactic radiosurgery (SRS).

Methods The Cochrane library, PubMed, Embase, and clinicaltrials.gov were searched through 01/2021 to find all studies on surgical and stereotactic procedures performed to treat vestibular schwannoma. Using a random-effects model, pooled odds ratios (OR) and their 95% confidence intervals (CI) comparing post- to pre-intervention were derived for pre-post studies, and pooled incidence of adverse events post-intervention were calculated for case series and stratified by intervention type.

Results Twenty-one studies (18 pre-post design; three case series) with 987 patients were included in the final analysis. Comparing post- to pre-intervention, both surgery (OR: 3.52, 95%CI 2.13, 5.81) and SRS (OR: 3.30, 95%CI 1.39, 7.80) resulted in greater odds of hearing loss, lower odds of dizziness (surgery OR: 0.10; 95%CI 0.02, 0.47 vs. SRS OR: 0.22; 95%CI 0.05, 0.99), and tinnitus (surgery OR: 0.23; 95%CI 0.00, 37.9; two studies vs. SRS OR: 0.11; 95%CI 0.01, 1.07; one study). Pooled incidence of facial symmetry loss was larger post-surgery (14.3%, 95%CI 6.8%, 22.7%) than post-SRS (7%, 95%CI 1%, 36%). Tumor control was larger in the surgery (94%, 95%CI 83%, 98%) than the SRS group (80%, 95%CI 31%, 97%) for small-to-medium size tumors.

Conclusion Both surgery and SRS resulted in similar odds of hearing loss and similar improvements in dizziness and tinnitus among patients with vestibular schwannoma; however, facial symmetry loss appeared higher post-surgery.

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Matched Comparison of Hearing Outcomes in Patients With Vestibular Schwannoma Treated With Stereotactic Radiosurgery or Observation

Neurosurgery 91:641–647, 2022

Previous studies comparing hearing outcomes in patients managed with stereotactic radiosurgery (SRS) and a watch-and-wait strategy were limited by small sample sizes that prevented controlling for potential confounders, including initial hearing status, tumor size, and age.

OBJECTIVE: To compare hearing outcomes for patients with vestibular schwannomas (VS) managed with observation and SRS while controlling for confounders with propensity score matching.

METHODS: Propensity score matching was used to compare 198 patients with unilateral VS with initial serviceable hearing (99 treated with SRS and 99 managed with observation alone) and 116 with initial class A hearing (58 managed with SRS and 58 with observation), matched by initial hearing status, tumor volume, age, and sex. Kaplan–Meier survival methods were used to compare risk of losing class A and serviceable hearing.

RESULTS: Between patients with VS managed with SRS or observation alone, there was no significant difference in loss of class A hearing (median time 27.2 months, 95% CI 16.843.4, and 29.2 months, 95% CI 20.4-62.5, P = .88) or serviceable hearing (median time 37.7 months, 95% CI 25.7-58.4, and 48.8 months, 95% CI 38.4-86.3, P = .18). For SRS patients, increasing mean cochlear dose was not related to loss of class A hearing (hazard ratio 1.3, P = .17) but was associated with increasing risk of serviceable hearing loss (hazard ratio of 1.5 per increase in Gy, P = .017).

CONCLUSION: When controlling for potential confounders, there was no significant difference in loss of class A or serviceable hearing between patients managed with SRS or with observation alone.

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Stereotactic radiosurgery as the primary management for patients with Koos grade IV vestibular schwannomas

J Neurosurg 135:1058–1066, 2021

While extensive long-term outcome studies support the role of stereotactic radiosurgery (SRS) for smaller volume vestibular schwannomas (VSs), its role in the management for larger-volume tumors remains controversial.

METHODS Between 1987 and 2017, the authors performed single-session SRS on 170 patients with previously untreated Koos grade IV VSs (volumes ranged from 5 to 20 cm3). The median tumor volume was 7.4 cm3. The median maximum extracanalicular tumor diameter was 27.5 mm. All tumors compressed the middle cerebellar peduncle and distorted the fourth ventricle. Ninety-three patients were male, 77 were female, and the median age was 61 years. Sixtytwo patients had serviceable hearing (Gardner-Robertson [GR] grades I and II). The median margin dose was 12.5 Gy.

RESULTS At a median follow-up of 5.1 years, the progression-free survival rates of VSs treated with a margin dose ≥ 12.0 Gy were 98.4% at 3 years, 95.3% at 5 years, and 90.7% at 10 years. In contrast, the tumor control rate after delivery of a margin dose < 12.0 Gy was 76.9% at 3, 5, and 10 years. The hearing preservation rates in patients with serviceable hearing at the time of SRS were 58.1% at 3 years, 50.3% at 5 years, and 35.9% at 7 years. Younger age (< 60 years, p = 0.036) and initial GR grade I (p = 0.006) were associated with improved serviceable hearing preservation rate. Seven patients (4%) developed facial neuropathy during the follow-up interval. A smaller tumor volume (< 10 cm3, p = 0.002) and a lower margin dose (≤ 13.0 Gy, p < 0.001) were associated with preservation of facial nerve function. The probability of delayed facial neuropathy when the margin dose was ≤ 13.0 Gy was 1.1% at 10 years. Nine patients (5%) required a ventriculoperitoneal shunt because of delayed symptomatic hydrocephalus. Fifteen patients (9%) developed detectable trigeminal neuropathy. Delayed resection was performed in 4% of patients.

CONCLUSIONS Even for larger-volume VSs, single-session SRS prevented the need for delayed resection in almost 90% at 10 years. For patients with minimal symptoms of tumor mass effect, SRS should be considered an effective alternative to surgery in most patients, especially those with advanced age or medical comorbidities.

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Stereotactic radiosurgery as the first-line treatment for intracanalicular vestibular schwannomas

J Neurosurg 135:1051–1057, 2021

This report evaluates the outcomes of stereotactic radiosurgery (SRS) as the first-line treatment of intracanalicular vestibular schwannomas (VSs).

METHODS Between 1987 and 2017, the authors identified 209 patients who underwent SRS as the primary intervention for a unilateral intracanalicular VS. The median patient age was 54 years (range 22–85 years); 94 patients were male and 115 were female. Three patients had facial neuropathy at the time of SRS. One hundred fifty-five patients (74%) had serviceable hearing (Gardner-Robertson [GR] grades I and II) at the time of SRS. The median tumor volume was 0.17 cm3 (range 0.015–0.63 cm3). The median margin dose was 12.5 Gy (range 11.0–25.0 Gy). The median maximum dose was 24.0 Gy (range 15.7–50.0 Gy).

RESULTS The progression-free survival rates of all patients with intracanalicular VS were 97.5% at 3 years, 95.6% at 5 years, and 92.1% at 10 years. The rates of freedom from the need for any additional intervention were 99.4% at 3 years, 98.3% at 5 years, and 98.3% at 10 years. The serviceable hearing preservation rates in GR grade I and II patients at the time of SRS were 76.6% at 3 years, 63.5% at 5 years, and 27.3% at 10 years. In univariate analysis, younger age (< 55 years, p = 0.011), better initial hearing (GR grade I, p < 0.001), and smaller tumor volumes (< 0.14 cm3, p = 0.016) were significantly associated with improved hearing preservation. In multivariate analysis, better hearing (GR grade I, p = 0.001, HR 2.869, 95% CI 1.569–5.248) and smaller tumor volumes (< 0.14 cm3, p = 0.033, HR 2.071, 95% CI 1.059–4.047) at the time of SRS were significantly associated with improved hearing preservation. The hearing preservation rates of patients with GR grade I VS were 88.1% at 3 years, 77.9% at 5 years, and 38.1% at 10 years. The hearing preservation rates of patients with VSs smaller than 0.14 cm3 were 85.5% at 3 years, 77.7% at 5 years, and 42.6% at 10 years. Facial neuropathy developed in 1.4% from 6 to 156 months after SRS.

CONCLUSIONS SRS provided sustained tumor control in more than 90% of patients with intracanalicular VS at 10 years and freedom from the need for additional intervention in more than 98% at 10 years. Patients with initially better hearing and smaller VSs had enhanced serviceable hearing preservation during an observation interval up to 10 years after SRS.

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Large and small vestibular schwannomas: same, yet different tumors

Acta Neurochirurgica (2021) 163:2199–2207

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

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

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

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

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Stereotactic radiosurgery as the first-line treatment for intracanalicular vestibular schwannomas

J Neurosurg February 5, 2021: 1-7

This report evaluates the outcomes of stereotactic radiosurgery (SRS) as the first-line treatment of intracanalicular vestibular schwannomas (VSs).

METHODS Between 1987 and 2017, the authors identified 209 patients who underwent SRS as the primary intervention for a unilateral intracanalicular VS. The median patient age was 54 years (range 22–85 years); 94 patients were male and 115 were female. Three patients had facial neuropathy at the time of SRS. One hundred fifty-five patients (74%) had serviceable hearing (Gardner-Robertson [GR] grades I and II) at the time of SRS. The median tumor volume was 0.17 cm3 (range 0.015–0.63 cm3). The median margin dose was 12.5 Gy (range 11.0–25.0 Gy). The median maximum dose was 24.0 Gy (range 15.7–50.0 Gy).

RESULTS The progression-free survival rates of all patients with intracanalicular VS were 97.5% at 3 years, 95.6% at 5 years, and 92.1% at 10 years. The rates of freedom from the need for any additional intervention were 99.4% at 3 years, 98.3% at 5 years, and 98.3% at 10 years. The serviceable hearing preservation rates in GR grade I and II patients at the time of SRS were 76.6% at 3 years, 63.5% at 5 years, and 27.3% at 10 years. In univariate analysis, younger age (< 55 years, p = 0.011), better initial hearing (GR grade I, p < 0.001), and smaller tumor volumes (< 0.14 cm3, p = 0.016) were significantly associated with improved hearing preservation. In multivariate analysis, better hearing (GR grade I, p = 0.001, HR 2.869, 95% CI 1.569–5.248) and smaller tumor volumes (< 0.14 cm3, p = 0.033, HR 2.071, 95% CI 1.059–4.047) at the time of SRS were significantly associated with improved hearing preservation. The hearing preservation rates of patients with GR grade I VS were 88.1% at 3 years, 77.9% at 5 years, and 38.1% at 10 years. The hearing preservation rates of patients with VSs smaller than 0.14 cm3 were 85.5% at 3 years, 77.7% at 5 years, and 42.6% at 10 years. Facial neuropathy developed in 1.4% from 6 to 156 months after SRS.

CONCLUSIONS SRS provided sustained tumor control in more than 90% of patients with intracanalicular VS at 10 years and freedom from the need for additional intervention in more than 98% at 10 years. Patients with initially better hearing and smaller VSs had enhanced serviceable hearing preservation during an observation interval up to 10 years after SRS.

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A critical comparison between the semisitting and the supine positioning in vestibular schwannoma surgery: subgroup analysis of a randomized, multicenter trial

J Neurosurg 133:249–256, 2020

Patient positioning in vestibular schwannoma (VS) surgery is a matter of ongoing discussion. Factors to consider include preservation of cranial nerve functions, extent of tumor resection, and complications. The objective of this study was to determine the optimal patient positioning in VS surgery.

METHODS A subgroup analysis of a randomized, multicenter trial that investigated the efficacy of prophylactic nimodipine in VS surgery was performed to investigate the impact of positioning (semisitting or supine) on extent of resection, functional outcomes, and complications. The data of 97 patients were collected prospectively. All procedures were performed via a retrosigmoid approach. The semisitting position was chosen in 56 patients, whereas 41 patients were treated while supine.

RESULTS Complete resection was obtained at a higher percentage in the semisitting as compared to the supine position (93% vs 73%, p = 0.002). Logistic regression analysis revealed significantly better facial nerve function in the early postoperative course in the semisitting group (p = 0.004), particularly concerning severe facial nerve paresis (House- Brackmann grade IV or worse; p = 0.002). One year after surgery, facial nerve function recovered. However, there was still a tendency for better facial nerve function in the semisitting group (p = 0.091). There were no significant differences between groups regarding hearing preservation rates. Venous air embolism with the necessity to terminate surgery occurred in 2 patients in the semisitting position (3.6%). Supplementary analysis with a 2-tailed permutation randomization with 10,000 permutations of treatment choice and a propensity score matching showed either a tendency or significant results for better facial nerve outcomes in the early postoperative course and extent of resection in the semisitting group.

CONCLUSIONS Although the results of the various statistical analyses are not uniform, the data indicate better results concerning both a higher rate of complete removal (according to the intraoperative impression of the surgeon) and facial nerve function after a semisitting as compared to the supine position. These advantages may justify the potential higher risk for severe complications of the semisitting position in VS surgery. The choice of positioning has to consider all individual patient parameters and risks carefully.

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

Neurosurgery 2019 DOI:10.1093/neuros/nyz147

Vestibular schwannomas (VS) are benign tumors derived from Schwann cells ensheathing the vestibulocochlear nerve. The retrosigmoid (RS) surgical approach is useful to resect tumors of multiple sizes while affording the possibility of preserving postoperative hearing.

OBJECTIVE: To conduct a systematic review of published literature investigating hearing preservation rates in patients who underwent the RS approach for VS treatment.

METHODS: The PubMed, Scopus, and Embase databases were surveyed for studies that reported preoperative and postoperative hearing grades on VS patients who underwent RS treatment. Hearing preservation rates were calculated, and additional patient demographic data were extracted. Tumor size data were stratified to compare hearing preservation rates after surgery for intracanalicular, small (0-20 mm), and large (>20 mm) tumors.

RESULTS: Of 383 deduplicated articles, 26 studies (6.8%) met eligibility criteria for a total of 2034 patients with serviceable preoperative hearing, for whom postoperative hearing status was evaluated. Aggregate hearing preservation was 31% and 35% under a fixed and random effects model, respectively. A mixed effects model was used to determine hearing preservation rates depending on tumor size, which were determined to be 57%, 37%, and 12% for intracanalicular, small, and large tumors, respectively. Significant crossstudy heterogeneity was found (I2 = 93%, τ 2 = .964, P < .01; Q = 287.80, P = < .001), with rates of hearing preservation ranging from 0% to 100%.

CONCLUSION: Tumor size may have an effect on hearing preservation rates, but multiple factors should be considered. Discussion of a patient’s expectations for hearing preservation is critical when deciding on VS treatment plans.

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Is There a Need for a 6-Month Postradiosurgery Magnetic Resonance Imaging in the Treatment of Vestibular Schwannoma?

Neurosurgery, Volume 86, Issue 2, February 2020, Pages 250–256

Stereotactic radiosurgery (SRS) is a common treatment modality for vestibular schwannoma (VS), with a role in primary and recurrent/progressive algorithms. At our institution, routine magnetic resonance imaging (MRI) is obtained at 6 and 12 mo following SRS for VS.

OBJECTIVE: To analyze the safety and financial impact of eliminating the 6-mo post-SRS MRI in asymptomatic VS patients. METHODS: A prospectively maintained SRS database was retrospectively reviewed for VS patients with 1 yr of post-treatment follow-up, 2005 to 2015. Decisions at 6-mo MRI were binarily categorized as routine follow-up vs clinical action—defined as a clinical visit, additional imaging, or an operation as a direct result of the 6-mo study.

RESULTS: A total of 296 patients met screening criteria, of whom 53 were excluded for incomplete follow-up and 8 for NF-2. Nine were reimaged prior to 6 mo due to clinical symptoms. Routine 6-mo post-SRS MRI was completed by 226 patients (76% of screened cohort), following from which zero instances of clinical action occurred.When scaled using national insurance database-derived financials—which estimated the mean per-study charge for MRI of the brain with and without contrast at $1767—the potential annualized national charge reduction was approximated as $1 611 504.

CONCLUSION: For clinically stable VS, 6-mo post-SRS MRI does not contribute significantly to management. We recommend omitting routine MRI before 12 mo, in patients without new or progressive neurological symptoms. If extrapolated nationally to the more than 100 active SRS centers, thousands of patients would be spared an inconvenient, nonindicated study, and national savings in health care dollarswouldbe on the order ofmillions annually.

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Face-to-face four hand technique in vestibular schwannoma surgery: results from 256 Danish patients with larger tumors

Acta Neurochirurgica (2020) 162:61–69

The objective of this study was to investigate the clinical outcome after microsurgical treatment of vestibular schwannomas using face-to-face four hand technique in 256 Danish patients treated in the Department of Neurosurgery at the Copenhagen University Hospital from 2009 to 2018.

Methods Data were retrospectively collected from patient records.

Results The mean tumor size was 30.6 mm and approximately 46% of the patients had tumors >30 mm. In around 1/3 of the patients a retrosigmoid approach was used and in 2/3 a translabyrinthine. In 50% of the patients, the tumor was completely removed, and in 38%, only smaller remnants were left to preserve facial function. The median operative time was approximately 2.5 h for retrosigmoid approach, and for translabyrinthine approach, it was around 3.5 h. One year after surgery, 84% of the patients had a good facial nerve function (House-Brackmann grade 1–2). In tumors ≤ 30 mm approximately 89%preserved good facial function, whereas this was only the case for around 78% of the patients with tumors > 30 mm. In 60% of the patients who had poor facial nerve function at hospital discharge, the function improved to good facial function within the 1 year follow-up period. Four patients died within 30 days after surgery, and 6% underwent reoperation for cerebrospinal fluid leakage.

Conclusion Surgery for vestibular schwannomas using face-to-face four hand technique may reduce operative time and can be performed with lower risk and excellent facial nerve outcome. The risk of surgery increases with increasing tumor size.

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Treatment Outcomes and Dose Rate Effects Following Gamma Knife Stereotactic Radiosurgery for Vestibular Schwannomas

Neurosurgery 85:E1084–E1094, 2019

Gamma Knife radiosurgery (GKRS; Elekta AB) remains a well-established treatment modality for vestibular schwannomas. Despite highly effective tumor control, further research is needed toward optimizing long-term functional outcomes. Whereas dose-rate effects may impact post-treatment toxicities given tissue dose-response relationships, potential effects remain largely unexplored.

OBJECTIVE: To evaluate treatment outcomes and potential dose-rate effects following definitive GKRS for vestibular schwannomas.

METHODS: We retrospectively reviewed 419 patients treated at our institution between 1998 and 2015, characterizing baseline demographics, pretreatment symptoms, and GKRS parameters. The cohort was divided into 2 dose-rate groups based on the median value (2.675 Gy/min). Outcomes included clinical tumor control, radiographic progression-free survival, serviceable hearing preservation, hearing loss, and facial nerve dysfunction (FND). Prognostic factors were assessed using Cox regression.

RESULTS: The study cohort included 227 patientswith available follow-up. Following GKRS 2-yr and 4-yr clinical tumor control rates were 98% (95% CI: 95.6%-100%) and 96% (95% CI: 91.4%-99.6%), respectively. Among 177 patients with available radiographic follow-up, 2-yr and 4-yr radiographic progression-free survival rateswere 97% (95% CI: 94.0%-100.0%) and 88% (95% CI: 81.2%-95.0%). The serviceable hearing preservation rate was 72.2% among patients with baseline Gardner-Robertson class I/II hearing and post-treatment audiological evaluations. Most patients experienced effective relief from prior headaches (94.7%), tinnitus (83.7%), balance issues (62.7%), FND (90.0%), and trigeminal nerve dysfunction (79.2%), but not hearing loss (1.0%). Whereas GKRS provided effective tumor control independently of dose rate, GKRS patients exposed to lower dose rates experienced significantly better freedom from post-treatment hearing loss and FND (P = .044).

CONCLUSION:Whereas GKRS provides excellent tumor control and effective symptomatic relief for vestibular schwannomas, dose-rate effectsmay impact post-treatment functional outcomes. Further research remains warranted.

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Comparing costs of microsurgical resection and stereotactic radiosurgery for vestibular schwannoma

J Neurosurg 131:1395–1404, 2019

Given rising scrutiny of healthcare expenditures, understanding intervention costs is increasingly important. This study aimed to compare and characterize costs for vestibular schwannoma (VS) management with microsurgery and radiosurgery to inform practice decisions and appraise cost reduction strategies.

METHODS In conjunction with medical records, internal hospital financial data were used to evaluate costs. Total cost was divided into index costs (costs from arrival through discharge for initial intervention) and follow-up costs (through 36 months) for 317 patients with unilateral VSs undergoing initial management between June 2011 and December 2015. A retrospective matched cohort based on tumor size with 176 patients (88 undergoing each intervention) was created to objectively compare costs between microsurgery and radiosurgery. The full sample of 203 patients treated with resection and 114 patients who underwent radiosurgery was used to evaluate a broad range of outcomes and identify cost contributors within each intervention group.

RESULTS Within the matched cohort, average index costs were significantly higher for microsurgery (100% by definition, because costs are presented as a percentage of the average index cost for the matched microsurgery group; 95% CI 93–107) compared to radiosurgery (38%, 95% CI 38–39). Microsurgery had higher average follow-up costs (1.6% per month, 95% CI 0.8%–2.4%) compared to radiosurgery (0.5% per month, 95% CI 0.4%–0.7%), largely due to costs incurred in the initial months after resection. A major contributor to total cost and cost variability for both resection and radiosurgery was the need for additional interventions in the follow-up period, which were necessary due to complications or persistent functional deficits. Although tumor size was not associated with increased total costs for radiosurgery, linear regression analysis demonstrated that, for patients who underwent microsurgery, each centimeter increase in tumor maximum diameter resulted in an estimated increase in total cost of 50.2% of the average index cost of microsurgery (95% CI 34.6%–65.7%) (p < 0.001, R 2 = 0.17). There were no cost differences associated with the proportion of inpatient days in the ICU or with specific surgical approach for patients who underwent resection.

CONCLUSIONS This study is the largest assessment to date based on internal cost data comparing VS management with microsurgery and radiosurgery. Both index and follow-up costs are significantly higher when tumors were managed with resection compared to radiosurgery. Larger tumors were associated with increased resection costs, highlighting the incremental costs associated with observation as the initial management.

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Long-Term Hearing Outcomes Following Stereotactic Radiosurgery in Vestibular Schwannoma Patients

Neurosurgery, Volume 85, (4), October 2019, 550–559

An understanding of the hearing outcomes is needed for treatment counseling for patients with vestibular schwannomas (VS).

OBJECTIVE: To determine long-term hearing results following stereotactic radiosurgery (SRS) for VS and identify any influential variables.

METHODS: Tertiary hospital retrospective cohort.

RESULTS: There were 579 tumors (576 patients) treated with SRS. Eighty-two percent (473) of tumors had ≥1 yr and 59% (344 ≥3 yr follow-up. In the 244 tumor ears, with measurable hearing before SRS who were followed ≥1 yr, 14% (31) had improved hearing, 13% (29) unchanged hearing, and 74% (158) had worsened hearing. In 175 patients with ≥3 yr followup and who had measurable hearing pretreatment, 6% (11 ears) improved hearing, 31% (54 ears) unchanged hearing, and 63% (110 ears) had worsened hearing. Patients with tumors with larger target volumes (P = 0.040) and with neurofibromatosis type 2 (NF2; P = 0.017) were associated with poorer hearing (P = 0.040). Patients with word recognition scores (WRS) of 50% or poorer had tumors with a larger volume (P = 0.0002), larger linear size (P=0.032),andNF2(P=0.045).TraditionallyreportedhearingoutcomesusingtheGardner RobertsonmaintenanceofPTA ≤50dborWRS≥50%were48%at3yr,whichoverestimates hearing outcomes compared to the above reporting standards.

CONCLUSION: Hearing declines over time in VS treated with SRS in a high proportion of cases. The frequency and magnitude of long-term hearing decline following SRS argues against prophylactic radiation for small tumors in hearing ears with undetermined growth behavior.

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Koos Classification of Vestibular Schwannomas: A Reliability Study

Neurosurgery, Volume 85, Issue 3, September 2019, 409–414

The Koos classification of vestibular schwannomas is designed to stratify tumors based on extrameatal extension and compression of the brainstem. While this classification system is widely reported in the literature, to date no study has assessed its reliability.

OBJECTIVE: To assess the intra- and inter-rater reliability of the Koos classification system.

METHODS: After institutional review board approval was obtained, a cross-sectional group of the Magnetic Resonance imagings of 40 patients with vestibular schwannomas varying in size comprised the study sample. Four raters were selected to assign a Koos grade to 50 total scans. Inter- and intrarater reliability were calculated and reported using Fleiss’ kappa, Kendall’s W, and Intraclass correlation coefficient (ICC).

RESULTS: Inter-rater reliability was found to be substantial when measured using Fleiss’ kappa (.71), extremely strong using Kendall’sW(.92), and excellent as calculated by ICC (.88). Intrarater reliability was perfect for 3 out of 4 raters as assessed using weighted kappa, Kendall’s W and ICC, with the intrarater agreement for the fourth rater measured as extremely high.

CONCLUSION: We have demonstrated that the Koos classification system for vestibular schwannoma is a reliable method for tumor classification. This study lends further support to the results of current literature using Koos grading system. Further studies are required to evaluate its validity and utility in counseling patients with regard to outcomes.

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Surgical outcome in smaller symptomatic vestibular schwannomas. Is there a role for surgery?

Acta Neurochirurgica (2018) 160:2263–2275

Currently, there is no consensus in the initial management of small vestibular schwannomas (VSs). They are routinely watched and/or referred for radiosurgical treatment, although surgical removal is also an option. We hereby evaluate clinical outcomes of patients who have undergone surgical removal of smaller symptomatic VSs.

Methods Patients with vestibular schwannomas (grade T1–T3b according to Hannover classification) were reviewed. Patients with symptomatic tumors who underwent surgery were evaluated. Their preoperative hearing status was based on the guideline of the committee on hearing and equilibriumof the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) foundation. Their postoperative facial nerve function, hearing status, vestibular symptoms, and degree of tumor resection were assessed.

Results Thirty patients were selected for surgery via a retrosigmoid approach based on their age, symptoms, and their own decision-making after discussion of management options. Most patients presented with hearing loss. Seventeen patients had useful hearing preoperatively. Among them, 10 patients (59%) preserved useful hearing (class A or B) postoperatively. MRI at 1-year follow-up confirmed complete resection in 26/29 patients. Also, 29 patients (97%) had HB grade I–II, and 1 patient had HB III at 1-year follow-up. Except for 1 patient with CSF leak, 1 patient with delayed facial nerve palsy, and 2 patients with asymptomatic sigmoid sinus occlusion, there were no other new morbidities.

Conclusion Although both observation and radiosurgery are valid options in the management of smaller size vestibular schwannomas, surgical treatment seems to offer a high rate of facial nerve preservation, a reasonable rate of hearing sparing, and a high total resection rate. Clinicians should consider surgical treatment as a valid option in the initial management of symptomatic small vestibular schwannomas in younger patients.

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Gamma Knife radiosurgery for large vestibular schwannomas greater than 3 cm in diameter

J Neurosurg 128:1380–1387, 2018

Stereotactic radiosurgery (SRS) is an important alternative management option for patients with small and medium-sized vestibular schwannomas (VSs). Its use in the treatment of large tumors, however, is still being debated. The authors reviewed their recent experience to assess the potential role of SRS in larger-sized VSs.

METHODS Between 2000 and 2014, 35 patients with large VSs, defined as having both a single dimension > 3 cm and a volume > 10 cm3, underwent Gamma Knife radiosurgery (GKRS). Nine patients (25.7%) had previously undergone resection. The median total volume covered in this group of patients was 14.8 cm3 (range 10.3–24.5 cm3). The median tumor margin dose was 11 Gy (range 10–12 Gy).

RESULTS The median follow-up duration was 48 months (range 6–156 months). All 35 patients had regular MRI followup examinations. Twenty tumors (57.1%) had a volume reduction of greater than 50%, 5 (14.3%) had a volume reduction of 15%–50%, 5 (14.3%) were stable in size (volume change < 15%), and 5 (14.3%) had larger volumes (all of these lesions were eventually resected). Four patients (11.4%) underwent resection within 9 months to 6 years because of progressive symptoms. One patient (2.9%) had open surgery for new-onset intractable trigeminal neuralgia at 48 months after GKRS. Two patients (5.7%) who developed a symptomatic cyst underwent placement of a cystoperitoneal shunt. Eight (66%) of 12 patients with pre-GKRS trigeminal sensory dysfunction had hypoesthesia relief. One hemifacial spasm completely resolved 3 years after treatment. Seven patients with facial weakness experienced no deterioration after GKRS. Two of 3 patients with serviceable hearing before GKRS deteriorated while 1 patient retained the same level of hearing. Two patients improved from severe hearing loss to pure tone audiometry less than 50 dB. The authors found borderline statistical significance for post-GKRS tumor enlargement for later resection (p = 0.05, HR 9.97, CI 0.99–100.00). A tumor volume ≥ 15 cm3 was a significant factor predictive of GKRS failure (p = 0.005). No difference in outcome was observed based on indication for GKRS (p = 0.0761).

CONCLUSIONS Although microsurgical resection remains the primary management choice in patients with VSs, most VSs that are defined as having both a single dimension > 3 cm and a volume > 10 cm3 and tolerable mass effect can be managed satisfactorily with GKRS. Tumor volume ≥ 15 cm3 is a significant factor predicting poor tumor control following GKRS.

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Risk Factors for Readmission with Cerebrospinal Fluid Leakage Within 30 Days of Vestibular Schwannoma Surgery

Neurosurgery 82:630–637, 2018

Cerebrospinal fluid (CSF) leak is a well-recognized complication after surgical resection of vestibular schwannomas and is associated with a number of secondary complications, including readmission and meningitis. OBJECTIVE: To identify risk factors for and timing of 30-d readmission with CSF leak.

METHODS: Patients who had undergone surgical resection of a vestibular schwannoma from 1995 to 2010 were identified in the California Office of Statewide Health Planning and Development database. The most common admission diagnoses were identified by International Classification of Disease, ninth Revision, diagnosis codes, and predictors of readmission with CSF leak were determined using logistic regression.

RESULTS: A total of 6820 patients were identified. CSF leak, though a relatively uncommon cause of admission after discharge (3.52% of all patients), was implicated in nearly half of 490 readmissions (48.98%). Significant independent predictors of readmission with CSF leak were male sex (odds ratio [OR] 1.72, 95% confidence interval [CI] 1.32-2.25), first admission at a teaching hospital (OR 3.32, 95% CI 1.06-10.39), CSF leak during first admission (OR 1.84, 95% CI 1.33-2.55), obesity during first admission (OR 2.10, 95% CI 1.20-3.66), and case volume of first admission hospital (OR of log case volume 0.82, 95% CI 0.70-0.95). Median time to readmission was 6 d from hospital discharge.

CONCLUSION: This study has quantified CSF leak as an important contributor to nearly half of all readmissions following vestibular schwannoma surgery. We propose that surgeons should focus on technical factors that may reduce CSF leakage and take advantage of potential screening strategies for the detection of CSF leakage prior to first admission discharge.

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Quality of Life in Patients with Vestibular Schwannomas Following Gross Total or Less than Gross Total Microsurgical Resection: Should We be Taking the Entire Tumor Out?

Neurosurgery 82:541–547, 2018

The goal of microsurgical removal of a vestibular schwannoma is to completely remove the tumor, to provide long-term durable cure. In many cases, less than gross total resection (GTR) is performed to preserve neurological, and especially facial nerve function.

OBJECTIVE: To analyze long-term quality of life (QoL) in a cohort of patients who received either GTR or less than GTR.

METHODS: Patients operated for vestibular schwannoma less than 3.0 cm in posterior fossa diameter at 1 of 2 international tertiary care centers were surveyed using generic and disease-specific QoL instruments.

RESULTS: A total of 143 patients were analyzed. GTR was performed in 122, and 21 underwent less than GTR. QoL was assessed at a mean of 7.7 yr after surgery (interquartile range: 5.7-9.6). Patients who underwent GTR had smaller tumors; otherwise, there were no baseline differences between groups. Patients who underwent GTR, after multivariable adjustment for baseline features and facial nerve and hearing outcomes, reported statistically significantly better Short Form Health Survey-36 (SF-36) physical and mental scores, Patient-Reported Outcomes Measurement Information System (PROMIS-10) physical and mental scores, and Penn Acoustic NeuromaQuality of Life (PANQOL) facial, energy, general health, and total scores compared to patients receiving less than GTR.

CONCLUSION: GTR is associated with better QoL using the general QoL measures SF-36 and PROMIS-10 and the disease-specific PANQOL, even after controlling for baseline and outcome differences. This is especially significant in the assessment of mental health, indicating there may indeed be a psychological advantage to the patient that translates to overall well-being to have the entire tumor removed if microsurgical resection is undertaken.

 

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Role of electrophysiology in guiding near-total resection for preservation of facial nerve function in the surgical treatment of large vestibular schwannomas

J Neurosurg 128:903–910, 2018

In large vestibular schwannoma (VS) surgery, the facial nerve (FN) is at high risk of injury. Near-total resection has been advocated in the case of difficult facial nerve dissection, but the amount of residual tumor that should be left and when dissection should be stopped remain controversial factors. The objective of this study was to report FN outcome and radiological results in patients undergoing near-total VS resection guided by electromyographic supramaximal stimulation of the FN at the brainstem.

METHODS This study was a retrospective analysis of a prospectively maintained database. Inclusion criteria were surgical treatment of a large VS during 2014, normal preoperative FN function, and an incomplete resection due to the strong adherence of the tumor to the FN and the loss of around 50% of the response of supramaximal stimulation of the proximal FN at 2 mA. Facial nerve function and the amount and evolution of the residual tumor were evaluated by clinical examination and by MRI at a mean of 5 days postoperatively and at 1 year postoperatively.

RESULTS Twenty-five patients met the inclusion criteria and were included in the study. Good FN function (Grade I or II) was observed in 16 (64%) and 21 (84%) of the 25 patients at Day 8 and at 1 year postoperatively, respectively. At the 1-year follow-up evaluation (n = 23), 15 patients (65%) did not show growth of the residual tumor, 6 patients (26%) had regression of the residual tumor, and only 2 patients (9%) presented with tumor progression.

CONCLUSIONS Near-total resection guided by electrophysiology represents a safe option in cases of difficult dissection of the facial nerve from the tumor. This seems to offer a good compromise between the goals of preserving facial nerve function and achieving maximum safe resection.

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