Volume reduction in meningiomas after gamma knife surgery

Object. The purpose of this study was to evaluate the volume-reducing effects of gamma knife surgery (GKS) of meningiomas with and without previous surgical treatment. Methods. A group of 127 patients with a mean age of 57.1 years (range 9-81 years) with 142 meningiomas (128 World Health Organization Grade I and 14 Grade H) were included in this study. The management strategy reduces tumor volume with surgery when necessary (81 patients). Stereotactic GKS with a Gamma Knife model C was performed in all tumors of suitable size. Magnetic resonance imaging follow-up examinations with volumetric tumor analysis was performed 6 months after treatment and annually thereafter. The mean tumor volume was 5.9 cm(3) (range < 5 to > 40 cm(3)). The mean follow-up time after GKS was 29.3 months (range 11-61 months). The mean prescription dose was 13.8 Gy (range 10-18 Gy). A reduction in volume occurred in 117 (82.4%) of all tumors, and in 20 tumors (14.1%) growth ceased. The overall tumor control rate of 96.4%. The mean volume reduction achieved with GKS was more than 46.1%. Only five tumors (3.5%) showed a volume increase. Conclusions. Gamma knife surgery was effective in reducing meningioma volume at short-term follow up. Further studies are needed to examine the development of these findings over a longer period.