Pediatric opsoclonus-myoclonus-ataxia syndrome: Experience from a tertiary care university hospital.

Background: Opsoclonus-myoclonus-ataxia syndrome (OMAS) is a rare disorder; there is limited experience regarding its clinical course and therapeutic response.

Aims and Objectives: To describe the clinical profile, investigations, and therapeutic outcome in pediatric OMAS.

Patients and Methods: Fourteen children (age: 27.1 ± 7 months; male: female = 1:2.3) suffering from OMAS seen over a period of 10 years (2006-2015) were included in the study. Their clinicodemographic profile, investigations, therapeutic outcome at follow-up, and relapses were reviewed.

Results: Ten children reported antecedent events (respiratory infection: 7; gastrointestinal infection: 1; vaccination: 2). The most common referral diagnosis was acute cerebellitis (n = 8). Hypotonia (n = 9), abnormal behavior (n = 10), and neuroregression (n = 6) were also the frequent manifestations. Brain magnetic resonance imaging, cerebrospinal fluid, and urinary vanillylmandelic acid were normal in all the patients. Seven patients had an underlying tumor (abdomen: 4; thorax: 2; neck: 1) detected by ultrasound (n = 2/14), computed tomography (CT) (n = 6/12), and fluorodeoxyglucose - positron emission tomography (n = 2/2). CT scan identified the tumor in 2 patients where metaiodobenzylguanidine scintigraphy was negative. All patients received steroids for 22.3 ± 20 months (3 months to 5 years). Eight required prolonged immunomodulation (>12 months). Complete remission after follow-up of 31.3 ± 19 months (7 months to 5 years) was noted in 5 patients, whereas the rest had persisting behavioral and cognitive abnormalities. Relapses were noted in 6 patients related to intercurrent infections (n = 5) and discontinuation of steroids (n = 1). The patients presented with isolated symptoms of the full-blown syndrome during their relapses.

Conclusion: OMAS in children runs an indolent course requiring careful monitoring and long-term immunomodulation. An abnormal behavior is common and the outcome is variable.