Surgical outcomes in large vestibular schwannomas: should cerebellopontine edema be considered in the grading systems?

Purpose Large (> 3 cm) vestibular schwannomas pose complexity in surgical management because of narrow working corridors and proximity to the cranial nerves, brainstem, and inner ear structures. With current vestibular schwannoma classifications limited in information regarding cerebellopontine edema, our retrospective series examined this radiographic feature relative to clinical outcomes and its possible role in preoperative scoring. Methods Of 230 patients who underwent surgical resection of vestibular schwannoma (2014–2020), we identified 107 patients with Koos grades 3 or 4 tumors for radiographic assessment of edema in the middle cerebellar peduncle (MCP), brainstem, or both. Radiographic images were graded and patients grouped into Koos grades 3 or 4 or our proposed grade 5 with edema. Tumor volumes, radiographic features, clinical presentations, and clinical outcomes were evaluated. Results The 107 patients included 22 patients with grade 3 tumors, 39 with grade 4, and 46 with grade 5. No statistical differences were noted among groups for demographic data or complication rates. Unlike grades 3 and 4 patients, grade 5 patients presented with worse hearing ( p