Anti-CASPR2 antibody associated Morvan syndrome in adolescents: dramatic response to immunotherapy: a case series

Morvan Syndrome is an ultra rare autoimmune channelopathy characterized by neuromyotonia, autonomic instability, and central nervous system involvement. While typically associated with thymoma in adults, its manifestation in adolescents is exceptionally rare and poses significant diagnostic challenges.

We report two adolescent males (aged 16 and 14) presenting with progressive muscle stiffness, generalized myokymia, severe insomnia, and autonomic hyperactivity. The 16-year-old patient experienced 14 days of total agrypnia and described a sensation of "maggots crawling" beneath his skin. Electromyography confirmed pathognomonic discharges described as "marching soldiers on snow". Both patients tested positive for serum anti-CASPR2 antibodies with negative malignancy screenings. Management included carbamazepine alongside pulse methylprednisolone and Intravenous Immunoglobulin.

Both patients achieved complete clinical remission and remained asymptomatic at a 6 month follow-up. These cases emphasize that pediatric Morvan syndrome is a reversible channelopathy where early intervention is key.