Radiosurgery For Vestibular Schwannoma Research Articles

A simple plan strategy to optimize the biological effective dose delivered in robotic radiosurgery of vestibular schwannomas

Using the concept of biologically effective dose (BED), the effect of sublethal DNA damage repair (SLR) on the bio-efficacy of prolonged radiotherapy treatments can be quantified (BEDSLR). Such treatments, lasting more than 20 min, are typically encountered in stereotactic radiosurgery (SRS) applications using the CyberKnife (CK) and Gamma knife systems. Evaluating the plan data from 45 Vestibular Schwannoma (VS) cases treated with single fraction CK-SRS, this work demonstrates a statistically significant correlation between the marginal BEDSLRdelivered to the target (m-BEDSLR) and the ratio of the mean collimator size weighted by the fraction of total beams delivered with each collimator (wmCs), to the tumor volume (Tv). The correlation betweenm-BEDSLRandwmCsTvdatasets was mathematically expressed by the power functionm-BEDSLR=85.21 (±1.7%)⋅(wmCsTv)(0.05±7%) enabling continuousm-BEDSLRpredictions. Using this formula, a specific range ofm-BEDSLRlevels cana prioribe targeted during treatment planning through proper selection of collimator size(s) for a given tumor volume. Inversely, for a selected set of collimators, the optimization range ofm-BEDSLRcan be determined assuming that all beams are delivered with the smallest and largest collimator size. For single collimator cases or when the relative usage of each collimator size is known or estimated, a specificm-BEDSLRlevel can be predicted within 3% uncertainty. The proposed equation is valid for the fixed CK collimators and a physical dose prescription (Dpr) of 13 Gy. For alternateDprin the range of 11-14 Gy, a linear relationship was found between relative changes ofm-BEDSLR(Dpr) andDprwith respect tom-BEDSLR(13 Gy) and 13 Gy, respectively. The proposed methodology is simple and easy to implement in the clinical setting allowing for optimization of the treatment's bio-effectiveness, in terms of the delivered BED, during treatment planning.

Stereotactic Radiosurgery for Vestibular Schwannoma - A Case-Based Practice Guide from the Radiosurgery Society.

Vestibular schwannomas (VS) are the most common benign intracranial nerve sheath tumors. Surgery and radiotherapy - particularly stereotactic radiosurgery (SRS) - are the primary treatment options. SRS is the dominant treatment for small- and medium-sized VS and selected larger tumors due to its excellent local control rates and favorable safety profile compared to surgery. However, careful treatment planning is essential, taking into account patient preferences, tumor location and size, symptoms, and anticipated treatment-related toxicity. Four clinical VS scenarios have been selected to illustrate the use of SRS, including a unilateral, small intracanalicular VS, a large VS with cystic components, reirradiation with SRS after local tumor recurrence, and bilateral VS in the setting of neurofibromatosis type 2-related schwannomatosis. SRS is an effective and safe treatment modality for the majority of VS cases, requiring careful treatment planning and a thorough understanding of potential limitations and challenges. This case-based practice guide aims to provide a concise overview of the treatment of VS with SRS. We present and discuss four different clinical scenarios of VS to illustrate the pitfalls and best practice recommendations.

Abstract B033: Long-Term quality of life and hearing preservation after stereotactic radiosurgery for vestibular schwannoma

Abstract Purpose/Objective(s): The aim of this study is to evaluate the long-term quality of life (QOL) and hearing preservation outcomes following definitive single-fraction Gamma Knife stereotactic radiosurgery (GKSRS) for vestibular schwannoma (VS). Materials/Methods: Baseline and follow-up QOL and audiogram data were collected from our prospectively maintained institutional database of VS patients treated with single-fraction GKSRS from 2006 to 2023. QOL metrics included the Hearing Handicap Inventory (HHI), Dizziness Handicap Inventory (DHI), Tinnitus Handicap Inventory (THI), and the 36-Item Short-Form Survey (SF-36). Serviceable hearing preservation was classified according to the Gardner-Robertson scale using pure-tone average (PTA) and speech discrimination (SD). Linear mixed-effects models were constructed for each QOL metric over time. Results: A total of 388 patients (median age 61 years) were included with a median follow-up of 48 months. Median tumor size was 1.6 cm (interquartile range [IQR] 1.1-2.1 cm), with a median tumor volume of 0.6 cc (IQR 0.2-1.6 cc). Most patients received a prescription marginal dose of 12.5 Gy with a median cochlear mean dose of 2.7 Gy (IQR 1.9-3.8 Gy). Baseline median HHI, DHI, THI, and SF-36 scores were 28, 12, 12, and 73 respectively. Linear mixed-effects analyses indicated no statistically significant decline in any of these QOL metrics up to 7 years after GKSRS. Of patients with serviceable hearing at baseline, hearing preservation was maintained in 79% at 12 months, 67% at 2 years, and 68% at 3 years. Conclusion: GKSRS preserves long-term patient quality of life and serviceable hearing in the definitive management of VS. Citation Format: Shayzal Siddiqui, Joseph S. Lee, Julia Abbo, Jessica Cummings, Avi Desai, Inga S. Grills, Peter Y. Chen, Jeffrey Jacob, Kuei C. Lee. Long-Term quality of life and hearing preservation after stereotactic radiosurgery for vestibular schwannoma. [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Translating Targeted Therapies in Combination with Radiotherapy; 2025 Jan 26-29; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(2_Suppl):Abstract nr B033.

Morphological changes in vestibular schwannomas after stereotac - tic radiosurgery and retrospective assessment of indications for tumor removal

Stereotactic radiosurgery (SRS) of vestibular schwannomas (VS) is an effective and safe treatment method, competitive with microsurgery (MS). However, given the possibility of pseudo-progression, if the tumor continues to grow after SRS, one of the methods of additional treatment is MS, which is associated with an increased risk of dysfunction of the acoustic-facial group. Given the risks associated with MS, the decision on surgical removal of VS after SRS should be justified, taking into account the timing of the possible course of pseudo-progression. Material: from 2005 to 2015, 541 patients received radiosurgical treatment on the Gamma Knife device for vestibular schwannoma. In 17 (3.1%) cases out of 541 patients after SRS, microsurgical removal of the VS was performed, of which in 7 cases (41.1%) the only indication for tumor removal was an increase in its volume on average 40.4 months after SRS. A repeated analysis of pathomorphological preparations was performed in 11 patients to assess the signs in the tumors indicating the presence or absence of true tumor growth (recurrence). Result: in the studied material after SRS, a complete absence of Antony A and Antony B patterns predominated (63.6%), in the remaining cases their individual elements were detected. Rarefaction of cellular structures was noted in all samples. Fibrosis of the tumor stroma was noted in all patients, often in combination with foci of angiomatosis. Severe or focal edema was detected in 81.8%. Thus, it was established that after SRS, despite the continued growth of the tumor, typical post-radiation changes dominate in morphological preparations, indicating the absence of the potential of VS for further true growth.

Delayed Facial Nerve Dysfunction Following CyberKnife® Radiosurgery for Vestibular Schwannoma.

The incidence and risk factors for facial nerve dysfunction (FND) following CyberKnife® therapy for vestibular schwannoma (VS) remain poorly understood. This study investigates whether differential radiation doses to vulnerable segments of the facial nerve may be associated with FND outcomes. Patients were identified who underwent CyberKnife® radiosurgery for VS at a single institution. Basic demographics, tumor characteristics, and facial nerve function were collected. Total radiation doses to tumor, internal auditory canal (IAC), and labyrinthine segment of facial nerve (LSFN) were evaluated. Six out of 64 patients experienced FND following CyberKnife® treatment for VS (9.38%, 6/64). Patients with FND were compared to those without FND (control). Of the 64 patients, complete radiation records were obtained for 30 patients (6 FND vs. 24 control). There were no significant differences in demographic or tumor characteristics between control and FND cohorts. More severe FND (HB ≥ 4) had significantly larger tumors (3.74 vs. 1.27 cm3, p = 0.037) with directionally decreased time to FND (3.50 vs. 33.5 months, p = 0.106) than patients with HB < 4, respectively. There were directionally, nonsignificant differences between maximum radiation doses to the LSFN (2492.4 vs. 2557.0 cGy, p = 0.121) and IAC (2877.3 vs. 2895.5 cGy, p = 0.824) between the control and FND cohorts, respectively. FND may represent an underrecognized sequelae of CyberKnife® radiosurgery for VS that can occur many months following treatment. Further studies are needed to elucidate the effect of differential radiation exposure to the facial nerve with FND following treatment. 3 (Retrospective Cohort Study) Laryngoscope, 134:5080-5086, 2024.

Risk analysis of radiosurgery for vestibular schwannoma: Systematic review and comparative study of 10-year outcomes.

Determine the benefit of stereotactic radiosurgery (SRS) compared to no treatment for sporadic vestibular schwannoma (VS) by calculating epidemiologic risk using 10-year data; apply the analysis to VS that have demonstrated linear growth. PubMed, Google Scholar, Web of Science, and Cochrane Library are systematically reviewed for VS tumor control 10 years after SRS and compared to a historical cohort of untreated VS (primary risk analysis). Subgroups of VS limited by size and observed growth are compared to the untreated cohort (secondary analysis). Twenty-four studies of 4079 SRS-treated VS exhibited tumor control in 90.93% (87.0%-100%; SD 4.1%), while 1959 untreated VS exhibited control in 65.24%. SRS reduces the absolute risk (ARR) of tumor progression by 25.7% compared to no treatment. The number needed to treat (NNT) is 4 (3.892, 95% CI: 3.619-4.210). Subgroup analyses of (1) VS with definite linear growth before SRS result in a similar ARR of 29.4% and NNT 4 (3.395, 95% CI: 2.966-3.968), and (2) Koos 1 VS result in lower ARR 18.31% and higher NNT 6 (5.209; 95% CI: 4.018-7.401). This "best-available" case-control study of 10-year data reveals that ARR and NNT are similar for VS with and without definite pretreatment linear growth. These comparisons may be applied to CPA diameters less than 2cm. Results for Koos 1 tumors are different. This analysis quantifies the therapeutic benefit of SRS by comparative risk analysis. The level of evidence on this topic is low.

NCMP-21. COMPARATIVE ANALYSIS OF VENTRICULOPERITONEAL SHUNT PLACEMENT FOR POST-TREATMENT HYDROCEPHALUS FOLLOWING VESTIBULAR SCHWANNOMA MANAGEMENT: SURGICAL INTERVENTION VERSUS STEREOTACTIC RADIOSURGERY

Abstract INTRODUCTION Hydrocephalus may present in patients with vestibular schwannoma (VS) at initial diagnosis, primarily due to the obstructive effects of tumor mass on cerebrospinal fluid (CSF) dynamics. Notably, occurrences of hydrocephalus following either radiosurgery or surgical interventions have also been documented in clinical literature. OBJECTIVE To compare the clinical features of patients who have undergone surgical resection or radiosurgery for VS and subsequently developed hydrocephalus necessitating shunt placement. METHODS We conducted a retrospective analysis of patients diagnosed with VS who underwent management via surgery or radiosurgery at Stanford Medical Center between 1998 and 2024, focusing on those who subsequently required shunt placement. RESULTS A total of 30 patients with VS underwent shunt placement due to hydrocephalus after tumor treatment; 5 patients (16.7%) were managed with radiosurgery and 25 patients (83.3%) with surgery. The median age at treatment was 64 years versus 57 years for the radiosurgery and surgery groups, respectively. There were no significant differences in age, sex, tumor volume, largest diameter at treatment, and tumor Koos grades, between the two groups. Nonetheless, the median time from tumor treatment to shunt placement was significantly longer in the radiosurgery group compared to the surgery group (21.53 versus 1.17 months, p-value=0.002). Regarding CSF parameters, mean white blood cell (WBC) and red blood cell (RBC) counts prior to shunt placement was significantly higher in the surgery versus the radiosurgery group (WBC=83.6 versus 2.0/mm3, p-value=0.001, RBC=3453.4 versus 313.33/mm3, p-value=0.02). CSF protein and glucose were not significantly different between the groups. CONCLUSION The median time from VS treatment to shunt placement due to hydrocephalus was longer in the radiosurgery group compared to the surgery group. Furthermore, pre-shunt CSF WBC and RBC counts were higher in the surgery group. Future studies are needed to better understand treatment outcomes and optimize management strategies for these patients.

Chronological characterization of hearing preservation after radiosurgery for vestibular schwannoma: a comprehensive meta-analysis.

Hearing outcomes following Gamma Knife radiosurgery (GKRS) for vestibular schwannoma (VS) are multifactorial and poorly characterized in prior literature. In this study the authors evaluated hearing outcomes chronologically to identify prognostic factors of serviceable hearing preservation (HP) rates following GKRS for VS. Six medical databases were queried according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Eligible studies reported VS treated with single-fraction GKRS and included the HP rate following GKRS. HP was defined as a postoperative Gardner-Robertson score ≤ 2 among patients with preoperative serviceable hearing. A meta-analysis with random-effects modeling was performed for variables of interest. Data from 42 articles with a total of 6582 patients were analyzed; the average age of patients was 54 years and the average follow-up time was 68 months. The pooled proportion of preoperative serviceable hearing was 76%, and the pooled HP rate was 60% at the last follow-up visit. At < 5 years after GKRS, age was significantly correlated with HP on both continuous and categorical analyses (p = 0.001 and p = 0.011, respectively). Between 5 and < 10 years of follow-up, HP was associated with a radiation dose of 12.5 Gy, but not with age or tumor volume. At ≥ 10 years after radiosurgery, a significant negative correlation was seen between marginal radiation dose and HP on both continuous and categorical analyses (p = 0.001 and p = 0.021, respectively). This meta-analysis identifies age and radiation dose as independent prognostic factors for HP. Age-related hearing deterioration appears to be concentrated in the first 5 years after GKRS, whereas radiation dose was associated with HP at last follow-up, between 5 and < 10 years, and at ≥ 10 years after radiosurgery. This meta-analysis offers an objective overview of the literature and a framework for clinical decision-making, with applications for treatment planning and patient counseling.

Minimum cochlear dose impacts hearing after radiosurgery for sporadic vestibular schwannoma.

It is uncertain which cochlear dose parameters significantly impact hearing after stereotactic radiosurgery (SRS) for sporadic vestibular schwannoma (VS). The objective of this study was to determine the impact of cochlear dose parameters on hearing outcomes for patients with serviceable hearing (SH). This was a historical cohort study performed at a single tertiary center that included patients with sporadic VS and SH who underwent single-session Gamma Knife radiosurgery treatment from 2007 to 2022. Associations of cochlear dose parameters with time to non-SH and rates of change in pure-tone average (PTA) and word recognition score (WRS) following SRS were assessed. A total of 205 patients with SH underwent SRS for a sporadic VS. At SRS, 54 (26%) tumors were confined to the internal auditory canal and 151 (74%) extended into the cerebellopontine angle. At 2, 5, and 10 years following SRS, 62%, 37%, and 15% of patients maintained SH, respectively. The median time to non-SH was 1.8 years. The median rates of change in PTA and WRS were 6.0 dB of hearing loss per year and -6.5% per year, respectively. In a multivariable analysis, each 1-Gy increase in minimum cochlear dose was significantly associated with time to non-SH (HR 1.5, 95% CI 1.2-1.9), rate of change in PTA decibel hearing loss per year (parameter estimate [PE] 3.4, 95% CI 0.6-6.2), and rate of change in WRS percentage per year (PE -6.4, 95% CI -11.2 to -1.5). The associations of each 1-Gy increase in mean cochlear dose with hearing outcomes were only significant among patients with class B hearing (time to non-SH HR 1.3, 95% CI 1.1-1.6; rate of change in PTA PE 3.6, 95% CI 1.2-5.9; and rate of change in WRS PE -5.7, 95% CI -9.7 to -1.7). The minimum cochlear dose impacts hearing outcomes after SRS for VS and should be considered in radiosurgical treatment planning. In this cohort, the mean cochlear dose was only associated with hearing outcomes in the subgroup of patients with class B hearing at SRS.

Erosion of the temporal bone by vestibular schwannoma: morphometrics and predictive modeling.

To perform a comprehensive morphometric analysis of vestibular schwannomas (VS) using multimodal imaging, focusing on the relationship between tumor characteristics and internal acoustic canal (IAC) changes. We analyzed a cohort of patients undergoing radiosurgery for VS, utilizing high-definition MRI and bone CT for detailed anatomical assessment. Image co-registration and fusion techniques were employed to examine VS and IAC dimensions. Advanced statistical methods, including logistic regression, were applied to identify patterns of IAC dilation and establish predictive indicators for these morphological changes. The study included 659 patients (51.1% female, mean age 56.37years) with evenly distributed tumor lateralization. Koos grades were I (22.9%), II (29.9%), III (38.2%), IVa (8.9%), and IVb (0.3%). Most tumors (90.9%) extended both inside and outside the IAC. Ipsilateral IAC (IIAC) dimensions were significantly larger than contralateral, with IIAC volume 49% greater (p < .0001). Higher Koos grades correlated with increased intra-canalicular lesion volume (icLV), which was strongly associated with IIAC size. Logistic regression identified icLV as the strongest predictor of IIAC dilation (AUC = 0.7674, threshold = 137.52 mm3). The icLV appears central to the pathophysiological development of VS and its impact on IAC anatomy. While limited by a selective patient base and static imaging data, these findings enhance the understanding of VS-IAC interactions, offering insights for improved clinical management and further research.

Dynamics of tumor evolution after Gammaknife radiosurgery for sporadic vestibular schwannoma: defining volumetric patterns characterizing individual trajectory.

Definition of tumor control and treatment failure after Gammaknife radiosurgery (GKRS) for vestibular schwannoma (VS) is still debated. The lack of knowledge on the dynamics of tumor evolution can lead to misinterpretation and subsequent inappropriate second treatment. The aim of this study was to evaluate the post-GKRS dynamics of evolution of tumor volume, and characterize volumetric patterns. We included patients with sporadic VS treated by GKRS with an MRI follow-up of minimum 3 years. A clustering in 2 steps was performed: definition of the patterns of evolution based on a subset of patients with the most comprehensive follow-up, then assignment of the remaining patients on a best fit basis. The minimum length of follow-up was assessed by measuring the consistency of the clusters over time (Adjusted Rand Index and Normalized Mutual Information). An analysis of the discriminant variables was finally performed. 1,607 patients were included (median follow-up: 67 months). Five patterns were defined with one pattern gathering almost all cases of treatment failure. The clustering at 5 years afforded the highest consistency with long-term follow-up. Discriminant variables for clusters were: sex, initial symptoms, delay of diagnosis, Koos grading, fundus invasion, and number of isocenters. The definition of these robust distinct patterns is likely to help tremendously the physicians to distinguish tumor control from potential failure. We advocate for no retreatment decision before 5 years post-GKRS. Further investigations are required to decide if the dynamics of evolution can be predicted at GKRS on an individual basis.

Predictors of Hydrocephalus Risk After Stereotactic Radiosurgery for Vestibular Schwannomas: Utility of the Evans Index.

Hydrocephalus after Gamma Knife® stereotactic radiosurgery (SRS) for vestibular schwannomas is a rare but manageable occurrence. Most series report post-SRS communicating hydrocephalus in about 1% of patients, thought to be related to a release of proteinaceous substances into the cerebrospinal fluid. While larger tumor size and older patient age have been associated with post-SRS hydrocephalus, the influence of baseline ventricular anatomy on hydrocephalus risk remains poorly defined. A single-institution retrospective cohort study examining patients who developed symptomatic communicating hydrocephalus after undergoing Gamma Knife® SRS for unilateral vestibular schwannomas from 2011 to 2021 was performed. Patients with prior hydrocephalus and cerebrospinal fluid diversion or prior surgical resection were excluded. Baseline tumor volume, third ventricle width, and Evans Index (EI)-maximum width of the frontal horns of the lateral ventricles/maximum internal diameter of the skull-were measured on axial postcontrast T1-weighted magnetic resonance imaging. A total of 378 patients met the inclusion criteria; 14 patients (3.7%) developed symptomatic communicating hydrocephalus and 10 patients (2.6%) underwent shunt placement and 4 patients (1.1%) were observed with milder symptoms. The median age of patients who developed hydrocephalus was 69 years (IQR, 67-72) and for patients younger than age 65 years, the risk was 1%. For tumor volumes <1 cm3, the risk of requiring shunting was 1.2%. The odds of developing symptomatic hydrocephalus were 5.0 and 7.7 times higher in association with a baseline EI > 0.28 (P = .024) and tumor volume >3 cm3 (P = .007), respectively, in multivariate analysis. Fourth ventricle distortion on pre-SRS imaging was significantly associated with hydrocephalus incidence (P < .001). Patients with vestibular schwannoma with higher baseline EI, larger tumor volumes, and fourth ventricle deformation are at increased odds of developing post-SRS hydrocephalus. These patients should be counseled regarding risk of hydrocephalus and carefully monitored after SRS.

Repeat stereotactic radiosurgery for progressive vestibular schwannomas after primary gamma knife radiosurgery

PurposeLimited data provides guidance on the management of vestibular schwannomas (VSs) that have progressed despite primary Gamma Knife radiosurgery (GKRS). The present article reports our long-term experience after repeat GKRS for VS with sustained progression after solely primary GKRS management.MethodsA retrospective review of 1997 patients managed between 1987 and 2023 was conducted. Eighteen patients had sustained tumor progression after primary GKRS and underwent repeat GKRS. The median repeat GKRS margin dose was 11 Gy (IQR: 11–12), the median tumor volume was 2.0 cc (IQR: 1.3–6.3), and the median cochlear dose in patients with preserved hearing was 3.9 Gy (IQR: 3-4.1). The median time between initial and repeat GKRS was 65 months (IQR: 38–118).ResultsThe median follow-up was 70 months (IQR: 23–101). After repeat GKRS, two patients had further tumor progression at 4 and 21 months and required partial resection of their tumors. The 10-year actuarial tumor control rate after repeat GKRS was 88%. Facial nerve function was preserved in 13 patients who had House-Brackmann grade 1 or 2 function at the time of repeat GKRS. Two patients with serviceable hearing preservation (Gardner-Robertson grade 1 or 2) at repeat GKRS retained that function afterwards. In patients with tinnitus, vestibular dysfunction, and trigeminal neuropathy, symptoms remained stable or improved for 16/16 patients, 12/15 patients, and 10/12 patients, respectively. One patient developed facial twitching in the absence of tumor growth 21 months after repeat GKRS.ConclusionsRepeat GKRS effectively controlled tumor growth and preserved cranial nerve outcomes in most patients whose VS had sustained progression after initial primary radiosurgery.

A retrospective cohort study of stereotactic radiosurgery for vestibular schwannomas: Comparison of two age groups (75 years or older vs. 65-74 years).

Treatment outcome data of stereotactic radiosurgery (SRS) for vestibular schwannomas (VS) in patients ≥75 years (late elderly) are lacking. Approximately 39% of patients ≥75 years with VS were reported to experience severe facial palsy after surgical removal. This study compared the treatment outcomes post-SRS for VS between patients ≥75 and 65-74 years (early elderly). Of 453 patients who underwent gamma knife SRS for VS, 156 were ≥65 years old. The late and early elderly groups comprised 35 and 121 patients, respectively. The median tumor volume was 4.4 cc, and the median radiation dose was 12.0 Gy. The median follow-up periods were 37 and 56 months in the late and early elderly groups, respectively. Tumor volume control was observed in 27 (88%) and 95 (83%) patients (P = 0.78), while additional procedures were required in 2 (6%) and 6 (6%) patients (P = 1.00) in the late and early elderly groups, respectively. At the 60th and 120th months post-SRS, the cumulative tumor control rates were 87%, 75%, 85%, and 73% (P = 0.81), while the cumulative clinical control rates were 93% and 87%, 95%, and 89% (P = 0.80), in the late and early elderly groups, respectively. In the early elderly group, two patients experienced facial pain, and one experienced facial palsy post-SRS; there were no adverse effects in the late elderly group (both P = 1.00). SRS is effective for VS and beneficial in patients ≥75 years old as it preserves the facial nerve.

Hearing Function after CyberKnife for Vestibular Schwannoma: A Systematic Review.

Introduction CyberKnife (CK) radiosurgery is a treatment strategy for vestibular schwannoma (VS). Objectives To evaluate hearing preservation (HP) after CK for VS. Data Synthesis The study was conducted following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement, and it was registered at the International Prospective Register of Systematic Reviews (PROSPERO, under number CRD42021250300). The inclusion criteria were based on the population, intervention, comparison, outcome, timing and study design (PICOTS) strategy: population - patients with VS; intervention - CK; Comparison - none; Outcome - serviceable HP defined by Gardner and Robertson as grades I or II, or by the American Academy of Otolaryngology and Head and Neck Surgery as classes A or B; timing - mean follow-up longer than 1 year; and study design - retrospective or prospective studies. The exclusion criteria were: studies not published in English; studies published before January 2000 and after October 2021; and studies only including patients with neurofibromatosis type 2 or submitted to a previous treatment. The PubMed/MEDLINE, EMBASE, Web of Science, Cochrane Library, LILACS, and IBECS databases were used and last searched on October 27th, 2021. Statistical heterogeneity was assessed using I 2 statistics. The appraisal checklist was used to assess the risk of bias in the included studies. A total of 222 studies were analyzed, and 13 were included in the synthesis, which represents 493 participants with serviceable hearing before intervention. The mean HP rate after CK using a random effects model was of 68% (95% confidence interval [95%CI]: 59-76%) at a mean follow-up of 42.96 months. Conclusion The longer follow-up period was associated with a lower HP rate after CK radiosurgery for VS in the qualitative synthesis.

Facial Nerve Preserving Subtotal Excision for Large Vestibular Schwannoma: An Institution-Based Functional Outcome Study.

The ideal goal of treatment for medium to large vestibular schwannoma is complete tumor removal with preservation of all cranial nerves. However, despite the advancements in microsurgery and intraoperative monitoring, the risk of facial nerve dysfunction following total resection varies between 31% and 57%. Currently, the goal of treatment for large tumors is shifting from total excision to facial nerve preservation. To evaluate the facial nerve outcome in patients who underwent subtotal excision with or without subsequent gamma knife radiosurgery for large vestibular schwannomas in our institute. All patients who underwent primary surgery for large vestibular schwannomas between January 2012 and December 2016 were analyzed retrospectively. Cases where total excision was not done and a residue was left behind to prevent facial nerve injury during surgery were included in the study. A total of 52 patients who met the inclusion criteria were analyzed. At final follow-up, 70% of patients had good facial nerve function (H-B grade 1 and 2). In patients with normal facial nerve function preoperatively, 81% (25/31) of them had good facial nerve outcomes (H-B grade 1 and 2), whereas in patients with preexisting facial nerve deficits, nearly 62% (13/21) of them either maintained or had improvement in their facial nerve grades. Good facial nerve outcomes and tumor control rate is obtained by subtotal excision of VS followed by upfront or delayed GKRS; however, there is a need for long-term follow-up to detect recurrences in these slow-growing tumors.

Repeat Radiosurgery for Sporadic Vestibular Schwannoma After Primary Radiosurgical Failure: An International Multi-institutional Investigation.

To describe outcomes of patients with sporadic vestibular schwannoma (VS) who underwent repeat stereotactic radiosurgery (SRS) after primary SRS failure. Multi-institutional historical cohort study. Five tertiary care referral centers. Adults ≥18 years old with sporadic VS. Primary and repeat treatment with SRS. Microsurgery-free survival after repeat SRS. Across institutions, 32 patients underwent repeat SRS after primary SRS. Most patients (74%) had tumors with cerebellopontine angle extension at primary SRS (median size, 13.5 mm [interquartile range, 7.5-18.8] mm). After primary SRS, patients underwent repeat SRS at a median of 4.8 years (interquartile range, 3.2-5.7 yr). For treatment modality, 30 (94%) patients received gamma knife for primary treatment and 31 (97%) patients received gamma knife as their repeat treatment. Median tumor volume increased from 0.970 cm3 at primary SRS to 2.200 cm3 at repeat SRS. Facial nerve function worsened in two patients after primary SRS and in two patients after repeat SRS. There were no instances of intracranial complications after repeat SRS. Microsurgery-free survival rates (95% confidence interval; number still at risk) at 1, 3, and 5 years after repeat SRS were 97% (90-100%, 24), 84% (71-100%, 13), and 68% (48-96%, 6), respectively. There was one occurrence of malignancy diagnosed after repeat radiosurgery. Overall, repeat SRS for sporadic VS has comparable risk profile, but lower rates of tumor control, compared with primary SRS.

In Reply to the Letter to the Editor: “Comparison of Stereotactic Radiosurgery (SRS) and Hypofractionated Radiosurgery (hSRS) for Vestibular Schwannomas: A Meta-Analysis of Available Literature”

In Reply to the Letter to the Editor: “Comparison of Stereotactic Radiosurgery (SRS) and Hypofractionated Radiosurgery (hSRS) for Vestibular Schwannomas: A Meta-Analysis of Available Literature”

Letter to the Editor Regarding “Comparison of Stereotactic Radiosurgery and Hypofractionated Radiosurgery for Vestibular Schwannomas: A Meta-Analysis of Available Literature”

Letter to the Editor Regarding “Comparison of Stereotactic Radiosurgery and Hypofractionated Radiosurgery for Vestibular Schwannomas: A Meta-Analysis of Available Literature”

Stereotactic radiosurgery for vestibular schwannomas: evolution of the philosophy of treatment

Vestibular schwannomas are the most common tumors in the cerebellopontine angle. Stereotactic radiosurgery is included in the armamentarium of methods for treating these tumors along with surgical treatment. Given the annual incidence of more than 15 radiosurgical cases of vestibular schwannomas per 1 million population, the expected need for stereotactic radiosurgery of these tumors in Russia is more than 2000 cases annually.Stereotactic radiosurgery is located at the intersection of several clinical specialties: neuroradiology, neurosurgery and radiation therapy, each of which has made a significant contribution to the development of this treatment method. The most commonly used for this is the cobalt‑based Leksell Gamma Knife, specifically intended for the treatment of intracranial neoplasms. Treatment is also possible with modern linear accelerators and proton accelerators, which provide high accuracy and conformity of irradiation. The experience gained since the first application of this method in the treatment of vestibular schwannomas has made it possible not only to optimize the radiation doses to the tumor and adjacent critical structures (brain stem, inner ear), but also to study the features of post‑radiation micro‑ and macro‑ changes, their impact on the clinical course, to develop recommendations for radiosurgery with schwannomas of various sizes. All this contributes to high control of tumor growth and a low level of functional disorders, which, along with easy tolerability and minimal hospitalization time, determines lower cost of this treatment compared to the traditional surgical approach and significant social and economic effect.This lecture is intended for neurosurgeons and radiation therapists and focuses on the most significant factors that influenced the development, promotion and active use of stereotactic radiosurgery of vestibular schwannomas in cli nical practice.