Reversible oedema and necrosis after irradiation of the brain. Diagnostic procedures and clinical manifestations.

One hundred and twelve patients with primary brain tumour were followed every 3 months during and after brain irradiation and chemotherapy with brain scanning, EEG and neurological examination. Early delayed radiation reactions were seen in 6 patients. The symptoms developed 2-8 months after irradiation and lasted for 2-3 months. Two types of reactions were observed. One mild form appeared after 2-3 months and was characterized by low-attenuated expansive areas within the irradiated volume, without contrast enhancement on CT scan. Severe reactions appeared in some patients after 6 months, with exacerbation of earlier clinical signs and contrast enhancing lesions on CT. Regression of the CT finding was seen after 3 months. Recognition of this syndrome is important, as a new neurosurgical procedure might cause lasting neurological sequelae in patients who otherwise would recover without treatment.