The development of cerebrovascular disease manifested by strokes or transient ischemic attacks six months to four years after treatment of brain tumors in 11 children is reported from the Children’s Hospital of Los Angeles, University of Southern California School of Medicine, Los Angeles, CA. All patients had received radiation therapy and seven chemotherapy. One patient, aged 4, with an incompletely resected craniopharyngioma, developed a right hemiparesis two years after treatment followed by left-sided focal motor seizures with quick progression to decerebrate posturing, central hyperventilation, coma, and death. Autopsy revealed bilateral cerebral infarctions as well as diffuse gliosis. Branches of the carotid artery showed severe thickening with subintimal proliferation of connective tissue. Smaller vessels showed cellular intimal proliferation with areas of leukocytic infiltration. 
COMMENT. Damage to medium and large intracranial vessels in addition to small vessel damage may result in late onset of stroke or transient ischemic attacks caused by radiation and chemotherapy in children with brain tumors. The combination of methotrexate and cranial irradiation is more likely to produce a leukoencephalopathy than either treatment alone. The addition of chemotherapy may potentiate the damage to endothelial cells produced by radiation (mineralizing microangiopathy).