Late delayed post-radiation encephalopathy mainly occurs following whole brain irradiation and is very rarely associated with focused beam irradiation. The radiation lesions consist of areas of focal necrosis and of diffuse demyelization of the deep cerebral structures. Irradiating normal tissues leads to a chronic increases in reactive oxygen/reactive nitrogen oxide species. The clinical post-radiation symptoms are consistent with a progressive multifocal leukoencephalopathy. They include seizures, hemiparesis, cranial neuropathy, headaches, blindness, dementia, and ataxia. Neuroimaging is useful to distinct radiation-induced encephalopathy from tumour recurrence, but also to show the typical post-radiation features. For small, asymptomatic lesions, an observational wait strategy can be observed. Dexamethasone is the most used drug in symptomatic patients. Other types of treatment have also been investigated.

Late radiation encephalopathy, Pathogenesis

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