Multifocal myoclonus following group A streptococcal infection

Movement disorders as postinfectious manifestation of group A streptococcal infections have been reported and are thought to occur on an autoimmune basis. We describe an unusual case of multifocal myoclonus following strep throat infection. Clinical description and chart review were the method used. A 10-year-old boy developed focal myoclonus involving his right arm and shoulder 1 week after streptococcal throat infection treated with penicillin. His magnetic resonance image was normal, and he initially responded to clonazepam but did not sustain a response. The myoclonus spread to involve all limbs and the trunk becoming multifocal over the next few weeks. He did not have choreoathetosis of Syndenham's chorea. He was given one course of intravenous immunoglobulin and became asymptomatic after treatment. He remained symptom free for 8 months following intravenous immunoglobulin treatment. Various symptoms have been reported following group A streptococcal infections in children. These neurobehavioral abnormalities may be mediated through antineuronal antibodies. Our case demonstrates multifocal myoclonus as a poststreptococcal autoimmune phenomenon. To our knowledge, only two other cases of poststreptococcal myoclonus have been reported in the literature. Recognition of this unusual condition as a manifestation of autoimmune poststreptococcal disease in children is essential to avoid overinvestigation and to ensure early treatment.