Clinical exacerbation of multiple sclerosis following radiotherapy.

BACKGROUND: Radiation of the central nervous system in patients with demyelinating disease may have deleterious effects. OBJECTIVE: To describe a 30-year-old woman with multiple sclerosis who developed an attack of demyelination 2 months following radiotherapy for a parotid malignancy. RESULTS: Magnetic resonance imaging demonstrated new hyperintense lesions that corresponded to both the localization of the patient's symptoms and to the area defined by the 50% isodose radiation field. CONCLUSION: Radiation treatment likely triggered an exacerbation of multiple sclerosis.