Intracranial meningiomas: Factors that influence the development of cerebral edema after stereotactic radiosurgery and radiation therapy

PURPOSE: To evaluate causative factors of cerebral edema after stereotactic radiosurgery or stereotactic radiation therapy in intracranial meningiomas. MATERIALS AND METHODS: Of 43 adult patients with intracranial meningiomas, three received 13.5-18-Gy single-fraction stereotactic radiosurgery; one received 19.8 Gy in three fractions, one received 42 Gy in six fractions, and 31 received 32-36 Gy in six to eight fractions of stereotactic radiation therapy; and seven received 45-54-Gy external-beam radiation with 20-28 Gy in five to seven fractions as concomitant stereotactic boosts. Brain edema was estimated by calculating the edema index. RESULTS: After irradiation, all 11 patients with parasagittal and four patients with nonparasagittal tumors developed worsening cerebral edema that necessitated the administration of steroids (P < .001). The statistically significant factors for the development of edema were parasagittal location, presence of pretreatment edema, sagittal sinus occlusion, and the use of more than 6 Gy per fraction. Five patients with parasagittal tumors developed life-threatening panhemispheric edema, which was fatal in one. The causative factors of panhemispheric edema were a large tumor, single-fraction stereotactic radiosurgery, or use of more than 6 Gy per fraction. CONCLUSION: A smaller dose per fraction and aggressive use of steroids may help prevent life-threatening complications due to worsening edema.