Introduction

Opsoclonus-myoclonus syndrome(OMS) is a rare immune-mediated disease in children. The main symptoms include opsoclonus, myoclonus and ataxia, irritability, and, over a long-term course, learning and behavioural disturbances. OMS can be idiopathic, parainfectious or occur as a paraneoplastic syndrome. Paraneoplastic OMS in children is almost exclusively associated with neuroblastoma. An autoimmune pathophysiology is suspected because childhood OMS have active autoantibodies, proinflammatory change and immunotherapy responses. Children appear to respond regularly to immunosuppressive treatment; though most children continue to have neuropsychological disturbances. As this is a rare but treatable disorder, a high index of suspicion is required.

Case report

12-year male presented with ataxia, myoclonia, jerky movements of eyes and behavioral disturbance since one week. He had fever, rash and headache a week prior to onset of these symptoms for 1-2 days. On examination, he was unable to walk, markedly ataxic with frequent myoclonia and opsoclonus along with significant aggression and emotional lability. Differentials like autoimmune encephalitis, malignancy and OMS were considered. Metabolic workup was negative. MRI Brain was normal. Blood and CSF for NMDA and autoimmune panel were negative. DOTATAC scan for malignancy was negative. He received simultaneous intramuscular Adrenocorticotropic Hormone(ACTH ) and intravenous Rituximab once a week for 4 weeks. Child gradually and completely recovered over 12-week period. On 4 month follow-up, he is back to school with normal behavior and no neurology deficit/sequel.

Conclusion

1)     Sequential treatment with immunosuppression is associated with significant neuromorbidity.

2)     Simultaneous immunosuppression therapy shows much better outcome in OMS.