Delayed Radiation Injury to the Brain : In Relation to Therapeutic View Point

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This report discusses the effects on normal brain tissue of radiotherapy in relation to age and irradiation dose as determined from whole-brain sections of the autopsied brains with tumors. Twenty eight patients were treated by cobaltor linear accelerator radiotherapy. Nine patients without brain disease (4 aged and 5 non-aged) were used as a control group. Hyalinization of the small vessels was observed within postradiation 12 months in fields exposed to total doses of less than 800 neuret. Hyalinization of the capillary vessels was greater in the irradiated group than in the control group. Demyelination was observed within the postradiation 12 months in fields irradiated by more than 800 neuret in aged patients and in fields irradiated by less than 800 neuret in non-aged patients. Fibrinoid nicrosis was observed after the post-radiation 12 months in fields irradiated by less than 800 neuret in aged patients and in fields irradiated by more than 800 neuret in non-aged patients. It is … More worth nothing that in non-aged patients with brain tumors, adverse effects of radiotherapy on vessels and parenchyma were very high even in low-dose radiation areas ; and in aged patients fibrinoid necrosis, which indicates irreversible damage of vessels, was observed in low-dose radiation areas.In CT scans, the enhanced area and the low density area were always observed within a zone of more than 80% of the total doses. A low density area was observed 4-15 months after radiotherapy, then the contrast-enhanced area appeared within the low-density area about 4 months later. In the histologically verified case, the fibrinoid necrosis of the blood vessel and demyelination appeared significantly higher in the enhanced area than in the low-density area.In conclusion, when a low-density area was observed by CT scan within the field of radiotherapy, we also suspected radiation injury and considered steroid or anticoagulant therapy in order to reverse it. However, if an enhanced area appeared within the injured lesion, the area seemed to have become irreversible and surgical therapy might also be needed. Less