OBJECTIVE The authors describe their results using an endoscope as an adjunct to microsurgical resection of inferior vestibular schwannomas (VSs) with extension into the fundus of the internal auditory canal below the transverse crest. METHODS All patients who had undergone middle fossa craniotomy for VSs performed by the senior author between September 2014 and August 2016 were prospectively enrolled in accordance with IRB policies, and the charts of patients undergoing surgery for inferior vestibular nerve tumors, as determined either on preoperative imaging or as intraoperative findings, were retrospectively reviewed. Age prior to surgery, side of surgery, tumor size, preoperative and postoperative pure-tone average, and speech discrimination scores were recorded. The presence of early and late facial paralysis, nerve of tumor origin, and extent of resection were also recorded. RESULTS Six patients (all women; age range 40-65 years, mean age 57 years) met these criteria during the study period. Five of the 6 patients underwent gross-total resection; 1 patient underwent a near-total resection because of a small amount of tumor that adhered to the facial nerve. Gross-total resection was facilitated using the operative endoscope in 2 patients (33%) who were found to have additional tumor visible only through the endoscope. All patients had a House-Brackmann facial nerve grade of II or better in the immediate postoperative period. Serviceable hearing (American Academy of Otolaryngology-Head and Neck Surgery class A or B) was preserved in 3 of the 6 patients. CONCLUSIONS Endoscope-assisted middle fossa craniotomy for resection of inferior vestibular nerve schwannomas with extension beyond the transverse crest is safe, and hearing preservation is feasible.
Keywords: AAO-HNS = American Academy of Otolaryngology–Head and Neck Surgery; ABR = auditory brainstem response; CPA = cerebellopontine angle; IAC = internal auditory canal; MFC = middle fossa craniotomy; PTA = pure-tone average; RS = retrosigmoid; SDS = speech discrimination score; VS = vestibular schwannoma; endoscope; middle fossa craniotomy; vestibular schwannoma.