Opsoclonus Myoclonus Syndrome (OMS), also known as Opsoclonus-Myoclonus-Ataxia (OMA), is a rare neurological disorder of unknown causes which appears to be the result of an autoimmune process involving the nervous system. It is an extremely rare condition, affecting as few as 1 in 10,000,000 people per year. It affects 2 to 3% of children with neuroblastoma and has been reported to occur with celiac disease.