[Late cerebral radionecrosis after conventional irradiation of cerebral tumors].

It is recognized that excessive irradiation for extra and intracranial tumor may be followed by delayed radiation necrosis of the brain. In recent years this untoward response has also been observed after conventional radiation therapy. Three patients are reported who had this irradiation complication. One had been treated for an ethmoidal sinus adenocarcinoma and another had a craniopharyngioma. The third had an astrocytoma of the pons. All developed their symptoms about a year after irradiation. Marked clinical deterioration of two patients was accompanied by brain edema and shift of midline structures. The patient who had received irradiation for ethmoidal adenocarcinoma was successfully treated by decompression and removal of the necrotic brain tissue. A later episode of recurrence of symptoms was treated successfully with prednisone. A similar favorable response with steroid therapy was evident in the patient who had x-ray therapy for craniopharyngioma. The third patient who had a pontine astrocytoma developed a leukoencephalopathy and severe changes in blood brain barrier function before her death. Pathologic changes were most profound in the white matter where a heterogeneous necrosis was encountered. In areas of severe necrosis no axis cylinders were present. Macrophages were rarely noted. Vascular changes were marked and consisted of endothelial hypertrophy, hyperplasia and neovascularization. Alterations in immunity, oligodendrocyte function and vascular changes have been independently evoked as possible causes of delayed radiation necrosis of brain. None of these alone however appears sufficient to account for the severe white matter reaction which may be delayed for years.(ABSTRACT TRUNCATED AT 250 WORDS)