Factors predicting growth of vestibular schwannoma in neurofibromatosis type 2.

We retrospectively reviewed characteristics of patients with neurofibromatosis type 2 to identify factors predicting further growth of bilateral vestibular schwannomas. Subjects comprised 27 neurofibromatosis type 2 patients with 54 vestibular schwannomas, followed for 24-204 months (mean, 86 months). This study investigated factors predictive of vestibular schwannoma growth in neurofibromatosis type 2. Features distinguishing actively growing from quiescent VS were determined for untreated course (28 vestibular schwannomas) and posttreatment course (including either resection or radiosurgery; 33 vestibular schwannomas). A general estimation equation was used to identify factors affecting tumor growth. During the untreated course, 19 vestibular schwannomas showed growth and 9 vestibular schwannomas were stable. No factors predictive of growth were shown. During the posttreatment course (23 surgical resections, ten radiosurgeries), ten treatments were followed by growth and 23 were followed by stability, with growth showing an association with onset at an early age (p = 0.007). Multivariate analysis identified no factors predictive of growth. After treatment, close follow-up is warranted for patients with onset at an early age.