Profile and Outcome of Children with Opsoclonus Myoclonus Ataxia: A Tertiary Care Hospital Experience from India

Opsoclonus myoclonus ataxia syndrome (OMAS) is a rare but treatable, often paraneoplastic neuroimmunologic condition. This is a retrospective chart review of 8 patients diagnosed in the past 11 years at a tertiary care hospital. The mean age of children with OMAS was 21.2 +/- 8 months. There was a female preponderance (62.5%). Median symptom duration was 24.5 days (interquartile range [IQR] 12.7; 97.5). All patients had ataxia and irritability; 6 had opsoclonus. An underlying neurogenic tumor was identified in 87.5% (7/8) of the patients by computed tomography (CT)/magnetic resonance imaging. Neuroblastoma was detected in 4/5 with normal 24-hour urinary vanillylmandelic acid and 2 had negative metaiodobenzylguanidine scan. All patients received adrenocorticotropic hormone/steroids for a median of 9.5 months (IQR 5.3; 13.5) with clonazepam. Five received intravenous immunoglobulin (IVIG), including repeated cycles in 4/5. Two received rituximab. One child with relapsing-remitting course received pulse dexamethasone and cyclophosphamide, resulting in improvement. Clonazepam restored ambulation in one with delayed diagnosis and failure of response to steroids. Six patients underwent tumor resection and four needed chemotherapies. Median follow-up was 15 months (IQR 10.7; 23.2). Mean OMAS-severity scale reduced from 10 to 1.4 in the IVIG group and 10.6 to 5.3 in those who did not receive IVIG. Cognitive delay and behavioral issues were seen in 100% treated with steroids only; 50 and 25%, respectively, treated with multimodal immunotherapy. Five had relapses, one with tumor recurrence. Thorax and abdomen CT scan was found to be a sensitive tool for tumor detection. Better motor and cognitive behavioral outcome were noted in patients who received adjunctive IVIG. Future studies on optimum investigation and treatment protocol in various resource settings are needed.