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.