Marinelli, John P.

Objective: Characterize pathogenic variants, rates of mosaicism, genetic testing yield, and disease severity among patients with NF2-related schwannomatosis dichotomized by diagnosis before or after the age of 30. Study design: Retrospective analysis. Setting: Tertiary referral center multidisciplinary NF2 clinic from 2021 to 2024. Patients: Patients with NF2-related schwannomatosis. Intervention: Next-generation sequencing. Main outcome measure: Rates of mosaicism, genetic testing rates and yield, and overall disease severity by tumor burden. Results: From 2021 to 2024, there were 32 patients ≥30 years of age and 39 patients diagnosed at younger ages. Patients diagnosed ≥30 years exhibited decreased likelihood of receiving genetic testing (53% vs. 85%; P =0.009) and decreased genetic yield (defined as identification of a pathogenic genetic variant in those undergoing testing; 65% vs. 85%; P =0.20). Both age groups demonstrated similar rates of pathogenic variant type with loss-of-function being the predominant variant detected in 73% vs. 67%, for ≥30 vs. <30 years of age; P =0.90. Those ≥30 years harbored fewer number of average anatomic regions involved by tumor (2.3 vs. 3.4; P <0.001) and decreased total number of tumors (7 vs. 12; P <0.001). Conclusions: Patients diagnosed with NF2-related schwannomatosis at age ≥30 years exhibited reduced disease severity compared with those diagnosed at a younger age despite harboring similar distributions of genetic pathogenic variants inclusive of loss-of-function pathogenic variants. These observations emphasize the importance of considering patient age in addition to genetic testing for diagnostic framing tailored to patients’ biology and clinical context to optimize care in the setting of NF2-related schwannomatosis.

ABSTRACT Background Cerebrospinal fluid (CSF) leak after retrosigmoid vestibular schwannoma resection remains a challenging complication. Historically, surgeons reopened the prior retrosigmoid incision for transmastoid repair because the safety of creating a separate postauricular incision was uncertain, with concerns regarding wound breakdown and infection. However, limited data support this practice, and a focused mastoid incision may offer improved access and patient tolerance. This study evaluated wound healing outcomes following transmastoid repair using a new postauricular incision for persistent CSF leak after retrosigmoid surgery in patients without serviceable hearing. Methods We retrospectively reviewed 27 patients who underwent transmastoid repair for persistent postoperative CSF leak after retrosigmoid craniotomy for vestibular schwannoma (2000–2025). Demographics, operative details, timing of leak diagnosis and repair, wound complications, readmissions, antibiotic use, and culture results were analyzed. Results Median age was 48 years (IQR 41–56); 67% were male, and mean BMI was 29.0 kg/m 2 . Mastoid obliteration was performed in 96%, with fat grafting in 93%. A new postauricular incision was used in all cases. Median time to leak diagnosis was 13 days (IQR 4–79), and median time to repair was 2 days (IQR 1–5). One patient (3.7%) developed a superficial wound abscess; no dehiscence or flap necrosis occurred. At median follow‐up of 34 months (IQR 2.9–87.7), all wounds were healed. CSF leak recurred in two patients (7.4%) and three (11.1%) required reoperation. Conclusion A separate postauricular incision for transmastoid CSF leak repair was not associated with increased wound morbidity. Durable wound healing was achieved in all patients, with 93% legal control, supporting this anatomy‐driven approach. Level of Evidence 4

Objective: To synthesize the available evidence on medical therapies investigated for the management of NF2-related vestibular schwannomas (VS). Study design: Systematic review. Setting: Not applicable. Patients: NF2-related VS patients. Interventions: Systemic medical therapies. Main outcome measures: Tumor control and hearing outcomes. Results: Thirty studies met inclusion criteria: 18 investigated bevacizumab, 5 mTOR inhibitors, 5 tyrosine kinase inhibitors (TKIs), and 2 the vascular endothelial growth factor receptor (VEGFR) vaccine. Bevacizumab demonstrated the most consistent activity, with hearing improvement in up to 61% of patients, stable hearing in up to 84%, and tumor response in up to 60% (Level 4 evidence). Outcomes for mTOR inhibitors were variable, with 1 study stopped for futility, while others reported up to 100% hearing and tumor stability (Level 4 evidence). Five different TKIs showed hearing improvement rates ranging from 17 to 60% and tumor responses of 10 to 23.5% (Level 4 evidence). The VEGFR vaccine appeared safe and immunologically active, with radiologic and hearing improvement in one-third of patients (Level 4 evidence). Conclusions: Bevacizumab remains the most studied and clinically active systemic therapy for NF2-related VS, although evidence is largely nonrandomized. Other systemic therapies have demonstrated variable results in terms of hearing outcomes or tumor control. High-quality prospective and randomized controlled trials are needed to clarify efficacy, durability, and comparative effectiveness.

ABSTRACT Objective Management of vestibular schwannoma (VS) remains controversial. Very small VSs represent a pivotal group: on one hand, they pose the least risk to the patient from the perspective of being small; yet, not recommending treatment may result in missing a critical window for achieving the best outcome. This debate fundamentally hinges on whether treatment improves upon the natural history of the disease. There is an unproven assumption that very small tumors behave similarly to the broader observed population. To address this central question, we conducted a multicenter retrospective review to compare the natural history of tumor growth and hearing for patients with very small VS (1–3 mm) with a referent cohort with larger tumors. Methods All patients diagnosed with sporadic VS 1–3 mm were reviewed at 3 large skull base referral centers and compared with a referent cohort of patients with tumors > 3 mm. Tumor growth‐free survival rates, treatment‐free survival rates, and rates of maintenance of class A, B, or C hearing were estimated using the Kaplan–Meier method. Results In total, 123 patients with very small VS and a referent cohort of 326 patients were studied. Seventeen patients with very small VS experienced tumor growth at a median of 3.2 years after diagnosis (IQR 2.6–5.1), demonstrating a median growth rate of 1.0 mm per year (IQR 0.9–1.8). In comparison, 167 of the patients in the referent cohort experienced tumor growth at a median of 1.7 years after diagnosis (IQR 0.8–3.1). Tumor growth‐free survival rates (95% CI, number still at risk) at 5 years after diagnosis for the 2 cohorts were 84% (75–93, 39) and 45% (40–52, 100), respectively ( p < 0.001). Six patients with very small VS underwent treatment after tumor growth at a median of 3.2 years after diagnosis (IQR 3.2–3.8), compared with 138 patients in the referent cohort at a median of 2.2 years after diagnosis (IQR 1.4–3.6). Treatment‐free survival rates (95% CI, number still at risk) at 5 years after diagnosis for the 2 cohorts were 92% (86–98, 55) and 54% (49–61, 125), respectively ( p < 0.001). Among the 105 patients with very small VS and class A, B, or C hearing at diagnosis, 3 progressed to class D. Comparatively, among the 225 patients in the referent cohort with class A, B, or C hearing at diagnosis, 70 progressed to class D at a median of 2.6 years after diagnosis (IQR 1.0–4.8). Rates of maintenance of class A, B, or C hearing (95% CI, number still at risk) at 5 years after diagnosis were 96% (92–100, 28) for patients with very small VS and 65% (57–73, 70) for the referent cohort ( p < 0.001). Conclusions The natural history of tumor growth and hearing for very small VS diverges favorably from the cumulative natural history data and provides a more appropriate benchmark to compare clinical outcomes of upfront surgery or radiosurgery for this population. At 5 years after diagnosis, 96% of very small VS maintained class A, B, or C hearing and only 8% received treatment for growth within this multicenter cohort. Cumulatively, these data substantiate initial wait‐and‐scan management via size threshold surveillance in this population. Level of Evidence 3.

Objective: To systematically review studies evaluating systemic medical therapies for sporadic vestibular schwannoma (VS) and perform meta-analyses to assess associations with tumor control. Study design: Systematic review and meta-analysis. Setting: Not applicable. Patients: Sporadic VS patients. Interventions: Systemic medical therapies. Main outcome measures: Tumor growth. Results: Nine retrospective studies met criteria: 5 on nonsteroidal anti-inflammatory drugs (NSAIDs), 3 on metformin, and 1 on losartan (all level 3 evidence). A meta-analysis of ORs from 5 studies demonstrated no significant association between aspirin use and tumor growth (pooled OR: 0.77; 95% CI: 0.48-1.23; I²: 76%). Conversely, a meta-analysis of ORs from 3 studies on metformin showed significantly lower odds of tumor growth (pooled OR: 0.46; 95% CI: 0.30-0.72; I²: 0%). The study on losartan did not identify a statistically significant association of losartan with tumor growth. Less than half of the studies reported HRs to appropriately reflect the inherently time-dependent nature of tumor growth. Conclusions: Evidence for systemic therapies in sporadic VS remains preliminary. Our meta-analysis of ORs demonstrates that NSAID use is not significantly associated with tumor growth, metformin users had lower odds of tumor growth, and evidence for losartan remains limited; however, all available studies provide only level 3 evidence. At present, there is insufficient data to recommend routine use of aspirin, metformin, or losartan with the intent of mitigating VS tumor growth during wait-and-scan management. High-quality prospective studies with appropriate time-to-event methodology to assess tumor growth are required to establish the clinical utility of systemic therapies in the management of patients with sporadic VS.

Objective: To survey critical areas of variation in published research methodology with a primary aim of highlighting fundamental aspects that contribute to ongoing controversy surrounding optimal management of patients with sporadic vestibular schwannoma. Interventions: Observation, stereotactic radiosurgery (SRS), and microsurgery. Main outcome measures: Variation in reported outcomes surrounding facial function, useful hearing, tumor pseudoprogression following SRS, and tumor growth/natural history. Results: Published research defines “good” post-treatment facial function as anything ranging from HB I, ≤HB II, to ≤HB III. While most studies define serviceable hearing as AAO Class A/B, others include Class C in published post-treatment hearing preservation results; meanwhile, patients report their greatest decrement in quality-of-life at a threshold around 75% in word recognition scores. Heterogeneously defined as post-SRS tumor growth 6 months after SRS to 5 years after SRS, the reported incidence of tumor pseudoprogression ranges from 7% to 77% within the published literature. Natural history studies that employ linear tumor measurements consistently suggest most tumors do not grow following diagnosis, whereas volumetric studies of natural history suggest the exact opposite is true. Limited follow-up and absent time-to-event analyses undermine many outcomes surrounding vestibular schwannoma that are inherently time-dependent. Conclusions: Disparate definitions used in vestibular schwannoma research beget variable outcome reporting and confuse interpretation of optimal management, particularly for the increasingly common scenario of a small tumor in a minimally symptomatic patient. Progress towards optimizing management requires re-evaluation and alignment on key outcome measures to improve consistency in reporting with renewed emphasis on clinically significant, patient-driven outcomes that often exceed the thresholds most frequently studied to date.

Objective: To examine microsurgical outcomes of medial sporadic vestibular schwannoma (VS), defined as a spherical tumor within the cerebellopontine angle (CPA) without tubular internal auditory canal (IAC) extension, compared with a referent cohort of “typical” VS with IAC extension. Study design: Historical matched cohort study. Setting: Tertiary referral center. Patients: Forty patients with medial sporadic VS who met the inclusion criteria were each matched to 3 referent patients by age, CPA tumor size, preoperative hearing class, and surgical approach. Interventions: Microsurgical resection. Main outcome measures: Extent of resection, immediate and long-term postoperative facial nerve weakness (House-Brackmann grade >I), and long-term hearing preservation were compared between patients with medial VS and the referent cohort using conditional logistic regression. Results: Medial VS and matched patients with IAC extension were not statistically significantly different in nongross total extent of resection (OR: 1.04, 95% CI: 0.47-2.31), immediate (OR: 0.82, 95% CI: 0.40-1.67) or long-term (OR: 0.59, 95% CI: 0.23-1.48) postoperative facial nerve weakness, or long-term nonserviceable hearing (OR: 0.84, 95% CI: 0.17-4.22). Conclusions: In this matched cohort study of medial VS, we found no statistically significant differences in the extent of resection, facial nerve function, or hearing preservation between tumors with and without IAC extension.

Objective: To explore the existing evidence on novel imaging modalities that may aid in prognostication of vestibular schwannoma (VS) clinical outcomes across various management approaches. Study design: Scoping review. Setting: Not applicable. Patients: Individuals diagnosed with VS. Interventions: Novel imaging techniques. Main outcome measures: Tumor growth and response to medical therapy. Results: A total of 18 articles were included in this review. Of these, 7 focused on pretreatment prognosis, 6 evaluated radiosurgery outcomes, 4 examined microsurgery outcomes, and 1 assessed response to bevacizumab. The imaging modalities investigated included radiomics (n = 10), positron emission tomography (PET; n = 2), dynamic contrast-enhanced MRI (DCE-MRI; n = 2), both PET and DCE-MRI (n = 1), magnetic resonance elastography (MRE; n = 1), contrast-enhanced CT (CE-CT; n = 1), and slip interface imaging (SII; n = 1). Radiomic studies yielded encouraging results in predicting tumor growth after wait-and-scan and radiosurgery, with reported accuracies ranging from 52% to 88%, sensitivities from 13% to 95%, specificities from 50% to 94%, and area under the curves from 0.65 to 0.99. PET studies identified several promising ligands associated with tumor growth during wait-and-scan, suggesting a potential role in prognostication. DCE-MRI also demonstrated associations with tumor growth and treatment response to bevacizumab. Studies on MRE, CE-CT, and SII identified novel imaging parameters associated with tumor stiffness and adhesion. Conclusions: Several emerging imaging modalities hold potential for improving clinical outcome prognostication in VS. Techniques such as radiomics, PET, and DCE-MRI have shown promising results; however, the supporting evidence is still limited and heterogeneous. Further research is necessary to validate and refine these approaches to enhance their clinical utility.