Authors report five patients(four males and one female, aged 28-54 years) with intracranial meningioma in which 60Co-irradiation produced a beneficial effect. Radiation was delivered over period from 39 to 51 days with total does of 5000 to 5500 cGy. Irradiation alone was performed in two patients including one recurrent case ; irradiation followed by surgery in one, and postoperative irradiation for the residual tumor in two. Histopathological examination was done in four cases and more of them were malignant or hemangiopericytic type. Two cases of highly vascular tumors showed marked shrinkage of the tumor after irradiation. Another highly vascular meningiomas showed decrease of the tumor vascularity and degree of contrast enhancement in magnetic resonance image(MRI). One recurrent case developed a prominent cystic change suggesting development of tumor necrosis due to irradiation and the tumor growth has been arrested for one year after irradiation. In one patient with a cavernous sinus meningioma, the tumor with progressive growth after incomplete resection showed a definite decrease in its size. With these observations, it is suggested that ; 1) benign meningiomas may develop marked shrinkage, cystic change or decreased vascularity in response to irradiation ; 2) there is a tendency that irration may be helpful for the operation on highly vascular meningiomas ; 3) in patient with a high surgical risk, irradiation alone may be performed to obtain reduction of the tumor volume or arrest of growth ; 4) preoperative irradiation may facilitate surgical removal of the tumor by reducing amount of intraoperative bleeding even in benign meningiomas ; 5) as a sole treatment or a preoperative adjuvant therapy, irradiation should be considered in patients who are not favorable candidates for operation or radiosurgery.
Cavernous Sinus ; Female ; Hemorrhage ; Humans ; Male ; Meningioma* ; Necrosis ; Neoplasm, Residual ; Radiosurgery ; Tumor Burden