Late delayed radiation neuronal necrosis (Q101030)

The pathological changes that occur several months to years following therapeutic cranial irradiation. The incidence is related to the total radiation dose and whether concurrent chemotherapy was used. Clinical features include cognitive impairment, dementia, gait disturbance, hypothalamic dysfunction resulting in endocrine disturbances, optic neuropathy and other cranial neuropathies and vascular disease. Differentiation from tumour can be difficult with conventional neuroimaging. A brain biopsy may demonstrate extensive necrotic tissue without a predominance of malignant cells. There is also loss of oligodendrocytes and demyelination.