Unusual Case of Radiation-Induced Cavernous Malformation after Gamma Knife Radiosurgery for Meningioma

We report an unusual case of delayed bleeding, highly suspected to be a radiation-induced cavernous malformation after gamma knife radiosurgery for meningioma. A 59-year-old woman underwent gamma knife radiosurgery with a marginal dose of 15 Gy with the 50% isodose line for parasagittal meningioma. After 5 years, magnetic resonance imaging (MRI) showed a marked decrease in the volume of the meningioma. The patient gradually developed right side weakness 7 years after the gamma knife radiosurgery. We performed another MRI scan and it showed a new hemorrhage compatible with cavernous malformation at the site of irradiation. Her weakness was conservatively treated and improved after about a month.prohibitio