Fractionated stereotactic radiotherapy for bilateral vestibular schwannomas associated with neurofibromatosis type 2: early experiences in Ramathibodi Hospital.

ABSTRACT

PURPOSE: To evaluate the rates of tumor control and useful hearing preservation in patients with bilateral vestibular schwannomas (VSs) associated with neurofibromatosis type 2 (NF-2) treated with fractionated stereotactic radiotherapy (FSRT). MATERIAL AND METHOD: From August 1998--December 2002 there were 5 patients with NF-2 who underwent FSRT (Linac-based system) for bilateral CP angle tumors. Median age was 28 (18-47) years. Median tumor volume was 5.4 (2.2-9.4) cc. Eight lesions received a marginal dose of 44.2-59.9 (median = 46.2) Gy in 25-33 fractions. The other 2 lesions received 4.4 and 4.9 Gy/fraction for 6 fractions in 3 and 2 weeks. Median follow-up was 19 (14-44) months. RESULTS: Radiographic and clinical tumor control rate was 90%. One lesion progressed at 7 months after FSRT and was completely resected Of the 5 lesions with Gardner-Robertson class I-II hearing before FSRT 2 (40%) retained useful hearing at the last follow-up. One patient had left facial spasm at 10 months after FSRT which gradually improved. No patient had facial palsy, facial numbness or pain. CONCLUSIONS: FSRT provided good tumor control and hearing preservation rate in NF-2 patients with minimal morbidity. However, a longer follow-up is needed to evaluate long term results.