Adjuvant gamma knife radiosurgery after meningioma resection.

We evaluated the usefulness of adjuvant treatment with gamma knife radiosurgery following meningioma surgery. During the past 8 years, we operated on 78 patients with meningiomas. Among these, 28 patients (36%) received gamma knife radiosurgery postoperatively. The indications for radiosurgery were as follows: residual tumour after surgery in 13 patients (46.4%), regrowth of residual tumour during the follow-up period in 7 patients (25%), recurrence after total removal (Simpson grade 1 or 2) in 7 patients (25%), and another intracranial meningioma in one patient (3.6%). The tumour diameter at the time of radiosurgery ranged from 5.2 to 48.1 mm (median 21.6 mm). Larger tumours with a mean diameter above 40 mm in two patients were treated with two-staged radiosurgery. The tumor marginal dose ranged from 8 to 23 Gy (median 12 Gy). The follow-up period was 3-84 months (median 30 months) after radiosurgery. The tumour size decreased in 17 patients (60.7%), remained unchanged in 9 patients (32.1%), and increased in 2 patients (7.2%). No radiation injury was experienced. Adjuvant therapy using gamma knife radiosurgery for meningiomas can achieve control of tumour growth and may improve patient outcomes. Careful surgical planning and follow-up are required to understand the usefulness and limitations of radiosurgery in this setting.