2026 Poster Presentations
P506: REVIEW OF GUIDELINES AND STRATEGIES FOR LARGE VESTIBULAR SCHWANNOMAS
Ajay Patel; Hunter Elms; Douglas J Totten; Evan Cumpston; Rick F Nelson; Mitesh V Shah; Indiana University
Background: Globally, treatment guidelines and strategies for vestibular schwannomas have evolved over time, but unanimously microsurgery for tumor resection is the favored first line intervention. An upfront strategy of subtotal resection (STR) with planned stereotactic radiosurgery (SRS) afterwards has gained traction, due to purported better facial nerve outcomes and tumor control.
Objective: This work aims to review the International Stereotactic Radiosurgery Society (ISRS), European Association of Neuro-Oncology (EANO), and Congress of Neurological Surgeons (CNS) guidelines, summarize the STR with planned radiation strategy and compare this to our institutional strategy of near total or gross total resection followed by observation and delayed radiation if growth.
Methods: Retrospective chart review for institutional experience and systematic review of literature for guidelines and the STR followed by planned radiation experiences.
Results: Table 1 summarizes recommendations from different guidelines, where microsurgery is recommended as first line intervention for large VS. STR + SRS strategy reports have tumors > 3cm or Koos Grade 3 or 4, mean facial nerve (FN) preservation rates (House-Brackmann I or II) at last follow-up (median FU ranging from 7.2 -113) to be 94.4% (56%-100%) and mean tumor control (stable to reduced) at 89.9%. (78.6% - 100%). Median volume at radiosurgery for STR + SRS strategy varied from 2.50cc to 9.35cc.
Institutional experience of two senior skull base surgeons showed 26 patients with VS > 3cm had tumor resections from 2015-2022 with mean FU 49.9 mos (median 56 mos, 1-119mos. A GTR + NTR rate of 73.1% with growth of 15.4% (4/26) of tumors without GTR and 11.5% (3/26) of patients received radiation due to growth. Mean residual volume for tumors without GTR was 0.21cc (0.01-1.68) and the mean residual volume for tumors that grew was 0.46cc (0.04 – 0.96). Facial nerve preservation at last FU was 80.8%.
Combining the institutional experience with the literature experience of the GTR/NTR with salvage radiotherapy if growth strategy resulted in 81 patients with large VS >3cm, FN preservation (HB I-III) of 92.3%, with mean FU of 40.04 months, and mean residual volume oof tumors that did not grow (70/81) was 0.17cc, and mean volume of those that grew (11/81) was 0.52cc.
Conclusion: FN preservation and tumor control is comparable with both strategies. Both strategies are safe and longer term follow up needed for both. A multidisciplinary approach involoving neuro-otologists, neurosurgeons, and radiation oncologists is paramount when treating vestibular schwannomas. The experience of the skull base surgeons can not be overlooked when selecting the treatment strategy. Decision on strategy must be tailored to each patient and factors such as patient age, comorbidities, and clinical status of patient are important factors to consider.