Dystonia in a 13-year-old boy with secondary progressive multiple sclerosis.

We report a patient who developed relapsing-remitting multiple sclerosis (MS) at 8 years old, and then had a progressive clinical course and dystonia. Dystonia of the patient is probably due to a lesion of the basal ganglia. Abnormal posture or movement disorder is very rarely found in MS, and progressive clinical course is also rare in childhood. The patient is worthy of attention because of his childhood onset, progressive clinical course and dystonia.