Acoustic neuroma: potential benefits of fractionated stereotactic radiosurgery.

BACKGROUND: Single-fraction radiosurgery of acoustic neuromas less than 3 cm in diameter is remarkable for high control but not infrequent incidence of facial and trigeminal neuropathy. Larger tumors treated surgically often result in deafness and facial neuropathy. Fractionated stereotactic radiosurgery was used in an effort to maintain effective therapy while minimizing toxicity of treatment.

METHODS: The authors described 38 patients with acoustic neuromas, with age range 35-89 years (mean, 60 years). 2,000 cGy in divided weekly doses of 400 or 500 cGy was most commonly prescribed. Tumors > or = 3 cm (n = 16) received the 5 fraction schema. Mean tumor volume was 6.9 cm3, with range from 0.1 to 32.0 cm3.

RESULTS: Median clinical follow-up was 27.1 months, while neuroimaging follow-up had a median of 16.3 months. All tumors were controlled. Of 23 tumors smaller than 3 cm, 14 (61%) decreased in size, and 9 showed cessation of growth. Thirteen of 16 (81%) large acoustic neuromas (3-5 cm) diminished in size. The remaining 3 showed cessation of growth. Median radiographic follow-up was 20 months, with a median clinical follow-up of 28 months. No patient developed fifth nerve symptoms after treatment nor did any patient require surgery for treatment failure. Only one had temporary seventh nerve palsy.

CONCLUSION: Fractionated stereotactic radiosurgery offers a therapeutic approach producing high control rates while avoiding morbidity frequently seen after single-fraction radiosurgery or microsurgery.