INTRACRANIAL MENINGIOMAS - FACTORS THAT INFLUENCE THE DEVELOPMENT OF CEREBRAL EDEMA AFTER STEREOTAXIC RADIOSURGERY AND RADIATION-THERAPY

PURPOSE: To evaluate causative factors of cerebral edema after stereot actic radiosurgery or stereotactic radiation therapy in intracranial m eningiomas. MATERIALS AND METHODS: Of 43 adult patients with intracran ial meningiomas, three received 13.5-18-Gy single-fraction stereotacti c 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 fract ions of stereotactic radiation therapy; and seven received 45-54-Gy ex ternal-beam radiation with 20-28 Gy in five to seven fractions as conc omitant stereotactic boosts. Brain edema was estimated by calculating the edema index. RESULTS: After irradiation, all 11 patients with para sagittal and four patients with nonparasagittal tumors developed worse ning cerebral edema that necessitated the administration of steroids ( P < .001). The statistically significant factors for the development o f edema were parasagittal location, presence of pretreatment edema, sa gittal sinus occlusion, and the use of more than 6 Gy per fraction. Fi ve patients with parasagittal tumors developed life-threatening panhem ispheric edema, which was fatal in one. The causative factors of panhe mispheric edema were a large tumor, single-fraction stereotactic radio surgery, 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.