Childhood opsoclonus-myoclonus syndrome: diagnosis and treatment.

Opsoclonus-myoclonus syndrome (OMS) is a rare and primarily immune-mediated disease in children and adults. The main symptoms include opsoclonus, myoclonus and ataxia. In children, the symptoms also include irritability, and, over a long-term course, learning and behavioural disturbances. OMS can be idiopathic, parainfectious or occur as a paraneoplastic (tumour-associated) syndrome. Paraneoplastic OMS in children is almost exclusively associated with neuroblastoma, whereas in adults, small cell lung cancer and breast cancer are the main underlying tumours. An autoimmune pathophysiology is suspected because childhood OMS patients have functionally active autoantibodies, proinflammatory changes in the cytokine network and immunotherapy responses. Children appear to respond regularly to immunosuppressive treatment. However, although the neurological symptoms show a good response, most children continue to show neuropsychological disturbances.