A 25-Year Update on the Facial Nerve Sparing Approach for Vestibular Schwannoma.

[BACKGROUND] This study updates the results of a facial nerve preservation approach to treating vestibular schwannomas at a single institution by a single surgeon using retrosigmoid craniectomy with microsurgery (MS) and gamma knife stereotactic radiosurgery (SRS) over a 25-year interval.

[METHODS] We retrospectively reviewed 751 patients between 1998 and 2023 and grouped them by intervention: MS only (Group 1, 217 patients), SRS only (Group 2, 447 patients), MS then SRS (Group 3, 72 patients), SRS then MS (Group 4, 10 patients), and SRS then SRS (Group 5, 5 patients). The primary outcome variable was facial nerve function, defined as House-Brackmann grade ≤2 at last follow-up.

[RESULTS] Good outcomes by group were achieved in 98.2%, 99.6%, 93.1%, 90%, and 100% of patients, respectively. Upfront SRS (Group 2) resulted in significantly better facial nerve outcomes than upfront MS (Groups 1 and 3, 289 patients) (96.9% and 99.4%, P < 0.05). Mean tumor maximum linear diameters were 3.2, 1.32, 3.23, 1.98, and 1.64 cm. Subtotal resection rates in Groups 1, 3, and 4, were 68.2%, 81.9%, and 80%, respectively. The median (interquartile range) follow-up time among patients (minimum follow-up of 12 months) was 52 (26.75-88) months, with a maximum of 297 months (24.75 years). Overall, 98.1% of patients had a good facial nerve outcome with no operative mortality.

[CONCLUSIONS] For larger tumors, MS emphasizing facial nerve preservation over gross total resection followed by adjuvant SRS for any interval tumor regrowth yields excellent facial nerve outcomes and tumor control rates. For smaller tumors, upfront SRS achieves superior facial nerve preservation with MS and SRS both viable salvage options for treatment of tumor progression. This paradigm balances tumor control, facial nerve preservation, and low morbidity.