Link, Michael J.

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.