Radiosurgery as primary management for meningiomas extending into the internal auditory canal

Stereotactic radiosurgery is increasingly utilized as primary management for patients with skull base meningiomas. This study reviews the results of stereotactic radiosurgery for patients with meningiomas extending into the internal auditory canal (IAC) to determine the risk of facial weakness or hearing loss. From 1990 to 2002, 16 patients had radiosurgery for meningiomas extending into the IAC. The median patient age was 63 years. Ten patients had symptoms of vestibulocochlear nerve dysfunction before radiosurgery. The median tumor volume was 5.1 cm3; the median tumor extension into the IAC was 7 mm (range, 3-12). The median tumor margin dose was 15 Gy. The median follow-up was 36 months. Ten meningiomas (63%) decreased in size, and 6 tumors were unchanged. No patient developed facial weakness. One patient (6%) had worsened facial sensation. Three of 14 patients (21%) with either normal hearing clinically (n = 5) or documented Gardner-Robertson class 1-2 before radiosurgery (n = 9) had decreased hearing after radiosurgery. The 1-, 2- and 5-year actuarial incidences of hearing preservation were 93, 84 and 42%, respectively. Three patients (19%) had improved hearing after radiosurgery. One patient with class 2 hearing improved to class 1; 2 patients with no speech discrimination before radiosurgery (class 5) improved to a class 3 status following the procedure. The risk of facial weakness or hearing loss is low after radiosurgery for patients with meningiomas extending into the IAC. Radiosurgery is an excellent alternative to surgical excision for meningiomas in this location, especially if a subtotal resection is likely or a hearing-sacrificing operation such as a translabyrinthine approach is contemplated.