Outcomes of stereotactic radiosurgery for large vestibular schwannomas: a systematic review and meta-analysis

Management of treatment-naïve Koos grade IV vestibular schwannomas using hypofractionated Gamma Knife radiosurgery: a retrospective single-institution study

While single-fraction Gamma Knife radiosurgery (GKRS) has shown efficacy in managing vestibular schwannomas (VSs), some concerns have been raised regarding its safety profile, particularly in the context of hearing preservation. Hypofractionation has emerged as a promising approach to improving the safety profile. This retrospective, single-institution study evaluated patient outcomes following hypofractionated GKRS (hf-GKRS) for treatment-naïve Koos grade IV VSs. This study involved all patients with treatment-naïve Koos grade IV VSs who underwent hf-GKRS (3 or 5 fractions) between January 2018 and June 2021, with a follow-up period of ≥ 36 months. The outcomes assessed included local control (LC), the preservation of serviceable hearing as determined by the Gardner-Robertson hearing scale, and procedure-related adverse events. Twenty-nine patients (14 females, median age 49 years) were treated with three different dose regimens: 21 patients received 18 Gy in 3 fractions, 6 patients received 20 Gy in 5 fractions, and 2 patients received 25 Gy in 5 fractions. Prior to treatment, 13 patients (44.8%) had serviceable hearing, one (3.4%) presented with facial palsy, and four (13.8%) had trigeminal nerve dysfunction. The median tumor volume was 10.8 cm3. During a median radiological follow-up period of 60 months (range, 36-78 months), LC was achieved in all patients. All 13 patients retained serviceable hearing at the last follow-up. Trigeminal nerve dysfunction occurred in one patient (3.4%), while another patient (3.4%) needed a ventriculoperitoneal shunt insertion due to new-onset hydrocephalus. No new-onset facial palsy was observed. hf-GKRS shows promise as an effective and safe primary or adjuvant treatment for Koos grade IV VSs with non-life-threatening or debilitating symptoms. Future studies with larger cohorts and extended follow-up periods are needed to validate these findings and to refine fractionation schemes.

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.

Vestibular schwannoma surgery in the ninth decade of life: a case series

BACKGROUND AND PURPOSE

Large symptomatic Vestibular Schwannoma (VS) often requires surgical resection, regardless the patient's age. The aim of this study was to assess the surgical outcomes of patients in their ninth decade of life.

METHODS

This monocenter retrospective observational study included patients aged 80 years or older who underwent VS surgery between 2009 and 2020. We retrospectively analyzed their immediate post-surgical and long-term outcomes and complications.

RESULTS

Thirteen octogenarians who underwent VS surgery were included, with average age of 83.2 ± 1.97 years old (median 83.5, range 80-86 years). One patient had a Koos-Grade II tumor, and 12 patients had a grade IV. All patients had a preoperative ASA score ≤ 3 and underwent surgery in the supine position. Twelve patients underwent a pre-planned partial resection (PR) and one had a gross-total resection (GTR). Good facial function (House-Brackmann grade ≤ 2) was achieved in 10 patients (77%). We reported three Clavien-Dindo grade ≤ 3 treatment-related complications and no life-threatening complication. Two patients experienced tumor recurrence after PR.

CONCLUSION

In this series of patients who underwent VS surgery in their ninth decade of life, surgical outcomes were acceptable. Therefore, age alone should not serve as a contraindication for surgery. Preplanned PR is a reasonable attitude in elderly patients.

Imaging Findings Post-Stereotactic Radiosurgery for Vestibular Schwannoma: A Primer for the Radiologist

Noninvasive tumor control of vestibular schwannomas through stereotactic radiosurgery allows high rates of long-term tumor control and has been used primarily for small- and medium-sized vestibular schwannomas. The posttreatment imaging appearance of the tumor, temporal patterns of growth and treatment response, as well as extratumoral complications can often be both subtle or confusing and should be appropriately recognized. Herein, the authors present an imaging-based review of expected changes as well as associated complications related to radiosurgery for vestibular schwannomas.

Stereotactic radiosurgery for Koos grade IV vestibular schwannoma: a systematic review and meta-analysis

BACKGROUND

Stereotactic radiosurgery (SRS) is a well-established treatment option for Koos stage I-III vestibular schwannomas (VS), often used as the first line of treatment or after subtotal resection. However, the optimal treatment for Koos-IV VS remains unclear. Therefore, our study aimed to evaluate the effectiveness of SRS as a primary treatment for large VS classified as Koos-IV.

METHODS

A systematic search was performed on December 28th, 2022, based on PubMed, Web of Science, and Scopus according to the PRISMA statement. The review was updated on September 7th, 2023. The risk of bias was assessed using the NIH Quality Assessment Tool. The R software (ver. 4.3.2) was used for all quantitative analyses and preparation of the forest plots. Publication bias and sensitivity analysis were performed to evaluate the reliability of the obtained results.

RESULTS

Among 2941 screened records, ten studies (1398 patients) have been included in quantitative synthesis. The overall tumor control rate was 90.7% (95%CI 86.3-94.4). Kaplan-Meier estimates of tumor control at 2, 6, and 10 years were 96.0% (95% CI 92.9-97.6%), 88.8% (95% CI 86.9-89.8%), and 84.5% (95% CI, 81.2-85.8%), respectively. The overall hearing preservation rate was 56.5% (95%CI 37-75.1). Kaplan-Meier estimates of hearing preservation rate at 2, 6, and 10 years were 77.1% (95% CI 67.9-82.5%), 53.5% (95% CI 44.2-58.5%), and 38.1% (95% CI 23.4-40.7%), respectively. The overall facial nerve preservation rate was 100% (95%CI 99.9-100.0). The overall trigeminal neuropathy rate reached 5.7% (95%CI 2.9-9.2). The overall rate of new-onset hydrocephalus was 5.6% (95%CI 3-9). The overall rates of worsening or new-onset tinnitus and vertigo were 6.8% (95%CI 4.2-10.0) and 9.1% (95%CI 2.1-19.6) respectively. No publication bias was detected according to the used methods.

CONCLUSIONS

Our systematic review and meta-analysis demonstrated a high overall tumor control rate, excellent facial nerve preservation, and low incidence of new-onset or worsened tinnitus and vertigo. However, several drawbacks associated with SRS should be noted, such as the presence of post-SRS hydrocephalus risk, mediocre long-term hearing preservation, and the lack of immediate tumor decompression. Nevertheless, the use of SRS may be beneficial in appropriately selected cases of Koos-IV VS. Moreover, further prospective studies directly comparing SRS with surgery are necessary to determine the optimal treatment for large VS and verify our results on a higher level of evidence. Registration and protocol: CRD42023389856.

Transcanal Transpromontorial Approaches to the Internal Auditory Canal: A Systematic Review

OBJECTIVE

Exclusive endoscopic (EETTA) and expanded (ExpTTA) transcanal transpromontorial approaches have shown promising results for treating internal auditory canal (IAC) lesions. We reviewed the literature to answer the question: "Do EETTA and ExpTTA achieve high rates of complete resection and low rates of complications in treating patients with IAC pathologies?"

DATA SOURCES

PubMed, EMBASE, Scopus, Web of Science, and Cochrane were searched.

REVIEW METHODS

Studies reporting EETTA/ExpTTA for IAC pathologies were included. Indications and techniques were discussed and meta-analyzed rates of outcomes and complications were obtained with random-effect model meta-analyses.

RESULTS

We included 16 studies comprising 173 patients, all with non-serviceable hearing. Baseline FN function was mostly House-Brackmann-I (96.5%; 95% CI: 94.9-98.1%). Most lesions were vestibular/cochlear schwannomas (98.3%; 95% CI: 96.7-99.8%) of Koos-I (45.9%; 95% CI: 41.3-50.3%) or II (47.1%; 95% CI: 43-51.1%). EETTA was performed in 101 patients (58.4%; 95% CI: 52.4-64.3%) and ExpTTA in 72 (41.6%; 95% CI: 35.6-47.6%), achieving gross-total resection in all cases. Transient complications occurred in 30 patients (17.3%; 95% CI: 13.9-20.5%), with meta-analyzed rates of 9% (95% CI: 4-15%), comprising FN palsy with spontaneous resolution (10.4%; 95% CI: 7.7-13.1%). Persistent complications occurred in 34 patients (19.6%; 95% CI: 17.1-22.2%), with meta-analyzed rates of 12% (95% CI: 7-19%), comprising persistent FN palsy in 22 patients (12.7%; 95% CI: 10.2-15.2%). Mean follow-up was 16 months (range, 1-69; 95% CI: 14.7-17.4). Post-surgery FN function was stable in 131 patients (75.8%; 95% CI: 72.1-79.5%), worsened in 38 (21.9%; 95% CI: 18.8-25%), and improved in 4 (2.3%; 95% CI: 0.7-3.9%), with meta-analyzed rates of improved/stable response of 84% (95% CI: 76-90%).

CONCLUSION

Transpromontorial approaches offer newer routes for IAC surgery, but their restricted indications and unfavorable FN outcomes currently limit their use. Laryngoscope, 133:2856-2867, 2023.

Using the deformity index of vital structures to predict outcome of patients with large vestibular schwannomas after Gamma Knife radiosurgery

PURPOSE

Microsurgery is the mainstay of treatment for large vestibular schwannomas (VS), but the benefits of radiosurgery remain incompletely defined. Here, we aim to use automated volumetric analysis software to quantify the degree of brain stem deformity to predict long-term outcomes of patients with large VS following GKRS.

METHODS

Between 2003 and 2020, 39 patients with large VS (volume > 8 cc) undergoing GKRS with a margin dose of 10-12 Gy were analyzed. The reconstruction 3D MRI was used to evaluate the extent of deformity for predicting the long-term outcome of patients.

RESULTS

Their mean tumor volume was 13.7 ± 6.3 cc, and their mean follow-up after GKRS was 86.7 ± 65.3 months. Favorable clinical outcome was observed in 26 (66.7%) patients, while 13 (33.3%) patients had treatment failure. Patients with small tumor volumes, low vital structure deformity indice [(TV/(BSV + CerV) and (TV + EV)/(BSV + CerV)], and long distance of tumor to the central line were more likely to have favorable clinical outcome after GKRS. Significant prognostic value was with tumor shrinkage ratio (< 50%) were CV, CV/TV, TV/CerV, (TV + EV)/(BSV + CerV), and the distance of tumor to the central line. In cox regression, favorable clinical outcome was correlated with the Charlson comorbidity index and cochlear dosage (both p < 0.05). In multivariant analysis, tumor regression was highly correlated with the CV/TV ratio (p < 0.001).

CONCLUSIONS

The brainstem deformity ratio is likely a useful index to assess the clinical and tumor regression outcomes. Clinical outcomes are multifactorial and the tumor regression was highly correlated with the ratio of cystic components.

Long-term results of upfront, single-session Gamma Knife radiosurgery for large cystic vestibular schwannomas

Anecdotally, cystic vestibular schwannomas (cVSs) are regarded to have unpredictable biologic activity with poorer clinical results, and most studies showed a less favorable prognosis following surgery. While stereotactic radiosurgery (SRS) is a well-established therapeutic option for small- to medium-sized VSs, cVSs are often larger, thus making upfront SRS more complicated. The purpose of this retrospective study was to assess the efficacy and safety of upfront SRS for large cVSs. The authors reviewed the data of 54 patients who received upfront, single-session Gamma Knife radiosurgery (GKRS) with a diagnosis of large cVS (> 4 cm3). Patients with neurofibromatosis type 2, multiple VSs, or recurrent VSs and < 24 months of clinical and neuroimaging follow-up were excluded. Hearing loss (48.1%) was the primary presenting symptom. The majority of cVSs were Koos grade IV (66.7%), and the most prevalent cyst pattern was "mixed pattern of small and big cysts" (46.3%). The median time between diagnosis and GKRS was 12 months (range, 1-147 months). At GKRS, the median cVS volume was 6.95 cm3 (range, 4.1-22 cm3). The median marginal dose was 12 Gy (range, 10-12 Gy). The mean radiological and clinical follow-up periods were 62.2 ± 34.04 months (range, 24-169 months) and 94.9 ± 45.41 months (range, 24-175 months), respectively. At 2, 6, and 12 years, the tumor control rates were 100%, 95.7%, and 85.0%, respectively. Tumor shrinkage occurred in 92.6% of patients (n = 50), tumor volume remained stable in 5.6% of patients (n = 3), and tumor growth occurred in 1.9% of patients (n = 1). At a median follow-up of 53.5 months, the pre-GKRS tumor volume significantly decreased to 2.35 cm3 (p < 0.001). While Koos grade 3 patients had a greater possibility of attaining higher volume reduction, "multiple small thick-walled cyst pattern" and smaller tumor volumes decreased the likelihood of achieving higher volume reduction. Serviceable hearing (Gardner-Robertson Scale I-II) was present in 16.7% of patients prior to GKRS and it was preserved in all of these patients following GKRS. After GKRS, 1.9% of patients (n = 1) had new-onset trigeminal neuralgia. There was no new-onset facial palsy, hemifacial spasm, or hydrocephalus. Contrary to what was believed, our findings suggest that upfront GKRS seems to be a safe and effective treatment option for large cVSs.

Outcome after Radiotherapy for Vestibular Schwannomas (VS)—Differences in Tumor Control, Symptoms and Quality of Life after Radiotherapy with Photon versus Proton Therapy

Background: To evaluate differences in local tumor control (LC), symptoms and quality of life (QOL) of 261 patients with VS after stereotactic radiosurgery/hypofractionated stereotactic radiotherapy (SRS/HFSRT) vs. fractionated radiotherapy (FRT) vs. fractionated proton therapy (FPT) were studied. Methods: For SRS/HFSRT (n = 149), the median fraction dose applied was 12 Gy. For FRT (n = 87) and FPT (n = 25), the median cumulative doses applied were 57.6 Gy and 54 Gy (RBE), respectively. FRT and FPT used single median doses of 1.8 Gy/Gy (RBE). Median follow-up was 38 months. We investigated dosimetry for organs at risk and analyzed toxicity and QOL by sending out a questionnaire. Results: LC was 99.5% at 12 months after RT with no statistical difference between treatment groups (p = 0.19). LC was significantly lower in NF2 patients (p = 0.004) and in patients with higher tumor extension grade (p = 0.039). The hearing preservation rate was 97% at 12 months after RT with no statistical difference between treatment groups (p = 0.31). Facial and trigeminal nerve affection after RT occurred as mild symptoms with highest toxicity rate in FPT patients. Conclusion: SRS/HFSRT, FRT and FPT for VS show similar overall clinical and functional outcomes. Cranial nerve impairment rates vary, potentially due to selection bias with larger VS in the FRT and FPT group.

Assessing the long-term safety and efficacy of gamma knife and linear accelerator radiosurgery for vestibular schwannoma: A systematic review and meta-analysis

Background

Differences in long-term outcomes of single-fraction stereotactic radiosurgery (SRS) between gamma knife (GK) and linear accelerator (LINAC) systems for vestibular schwannoma (VS) management remain unclear. To investigate differences in safety and efficacy between modalities, we conducted a meta-analysis of studies over the past decade.

Methods

MEDLINE, EMBASE, and Cochrane databases were queried for studies with the following inclusion criteria: English language, published between January 2010 and April 2020, cohort size ≥30, and mean/median follow-up ≥5 years. Odds ratios (OR) compared rates of tumor control, hearing preservation, and cranial nerve toxicities before and after SRS.

Results

Thirty-nine studies were included (29 GK, 10 LINAC) with 6516 total patients. Tumor control rates were 93% (95% CI 91-94%) and 94% (95% CI 91-97%) for GK and LINAC, respectively. Both GK (OR 0.06, 95% CI 0.02-0.13) and LINAC (OR 0.47, 95% CI 0.29-0.76) reduced odds of serviceable hearing. Neither GK (OR 0.71, 95% CI 0.41-1.22) nor LINAC (OR 1.13, 95% CI 0.64-2.00) impacted facial nerve function. GK decreased odds of trigeminal nerve (TN) impairment (OR 0.55, 95% CI 0.32-0.94) while LINAC did not impact TN function (OR 1.45, 95% CI 0.81-2.61). Lastly, LINAC offered decreased odds of tinnitus (OR 0.15, 95% CI 0.03-0.87) not observed with GK (OR 0.70, 95% CI 0.48-1.01).

Conclusions

VS tumor control and hearing preservation rates are comparable between GK and LINAC SRS. GK may better preserve TN function, while LINAC decreases tinnitus rates. Future studies are warranted to investigate the efficacy of GK and LINAC SRS more directly.