Vestibular schwannoma associated with neurofibromatosis type 2: Clinical course following stereotactic radiosurgery

Abstract

Objective: A lack of understanding of the clinical course of neurofibromatosis type 2 (NF2)-associated vestibular schwannoma (VS) often complicates the decision-making in terms of optimal timing and mode of treatment. We investigated the outcomes of stereotactic radiosurgery (SRS) in this population.Methods: We retrospectively analyzed NF2 patients treated with Gamma-Knife SRS for VS in our tertiary referral center. A total of 41 treated lesions from 33 patients were collected with a follow-up period of 69.1 (45.0-104.8) months. We reviewed the treatment history, hearing function, and other treatmentrelated morbidities in individual cases. We also analyzed pre-and posttreatment tumor volumes via imaging studies. Longitudinal volumetric analyses were conducted for the tumor volume response of the 41 treated lesions following SRS. The growth pattern of 22 unirradiated lesions during an observation period of 83.4 (61.1-120.4) months was separately evaluated.Results: Most treated lesions showed effective tumor control up to 85% at 60 months after SRS, whereas unirradiated lesions progressed with a relative volume increase of 14.0% (7.8-27.0) per year during the observation period. Twelve (29%) cases showed pseudoprogression with significant volume expansion in the early follow-up period, which practically reduced the rate of tumor control to 57% at 24 months. Among the patients with serviceable hearing, two (20%) cases lost the hearing function on the treated side during the early follow-up period within 24 months.

Long-term clinical outcomes of stereotactic radiotherapy for bilateral vestibular schwannomas in neurofibromatosis type 2 patients

“…In previous studies of SRS in VS-NF2, 10-year tumor control rates varied between 41% and 87% [12][13][14][15][16][17][18][19][20].…”

“…Hearing preservation is a critical challenge in NF2 patients with VSs. In previous SRS studies, the 5-year serviceable hearing preservation rates ranged from 10-50%; at 10 years, the rates decreased to between 25% and 30% [13,15,[17][18][19][20][21]. The reasons these rates are so low in NF2 patients are multifactorial and remain unclear.…”