Intractable epilepsy in 3 patients treated with low-dose irradiation to “strawberry” scalp nevi in infancy is reported from the Montreal Neurological Institute and Hospital, Montreal, Quebec, Canada. Focal seizures developed at ages 8 to 20 years. All patients had localized alopecia and EEG abnormalities corresponding with the irradiated site. MRI showed thinning of the cranial vault with expansion of the brain into the skull defect in one patient, and mild perisylvian atrophy in one other. Neurologic deficits were not progressive. [1]

COMMENT. Strawberry nevi invariably involute spontaneously before 10 years of age and scalp irradiation is no longer employed. The risk of epilepsy following low-dose irradiation is low, and may reflect induction of intracranial tumor or delayed cerebral radiation necrosis. The syndrome of delayed cerebral radiation necrosis is characterized by progressive neurological deficits and sometimes raised intracranial pressure developing months to years after irradiation. MRI shows cerebral atrophy, white matter lesions, and enhancing foci. In the above patient reports, the postradiation syndrome was nonprogressive but intractable, and one showed mild cerebral focal atrophy. Irradiation to the skull should be avoided whenever possible.