Objective: To report the cases of 2 patients who developed the features of radiation encephalopathy 33 and 28 years after cranial irradiation.
Design: Case reports; clinical data were available for 2 years in each instance.
Conclusion: Latent intervals approaching 2 decades have been reported in cases of radiation necrosis following cranial irradiation, but a similar or greater delay before the onset of radiation encephalopathy has not been described previously. This report indicates that a diagnosis of radiation encephalopathy must be considered when any individual who has received cranial irradiation presents with deterioration in intellectual or motor function, whatever the interval.