Abstract

We have treated 14 patients with glomus tumor during the 4 years (of 1993 to 1997) using Leksell Gamma Knife radiosurgery. The male: female ratio was 1:3.7, and the mean age 48.6 years (range 22-75 years). The mean tumor volume was 5.5 cm3 (range 0.7-11.3 cm3). The mean maximum dose was 37.4 Gy (range 20-44 Gy). The mean margin dose was 19.4 Gy (range 10-25 Gy). In 3 patients, infrabasal spread of the tumor could not be delineated on peroperative stereotactic CT scans. As a result, this portion of the tumor was treated in 2 patients at a second stage using stereotactic MRI. Follow-up in 11 patients ranged from 6 to 42 months (mean 20.5 months). Hearing on the affected side was further impaired in 3 patients. Tinnitus, vertigo and ataxia improved in 3 patients, headache and nausea in 2 patients. Angiography after radiosurgery was performed in 3 patients. In one patient 12 months after the radiosurgery, pathological vascularisation had completely disappeared. In another patient pathological vascularisation was still present 22 months after the first stage, despite two-stage radiosurgery, although the tumor volume decreased 30%. In the last patient, vascularisation and tumor volume partially decreased 12 months after radiosurgery. The volume of the tumor decreased in 4 patients. No change in tumor volume has been observed in any of the other patients to date. Radiosurgery proves to be a safe treatment for glomus tumor with no acute morbidity. Because of its naturally slow growth rate, up to 10 years follow-up will probably be necessary to establish the therapeutic effectiveness of radiosurgery for glomus tumor.