Opsoclonus-myoclonus-ataxia Syndrome: A Pediatric Oncology Hospital Experience

Background: Opsoclonus myoclonus ataxia syndrome (OMAS) is a rare, immune-mediated neurological disorder that usually starts in the second year of life. The triad of signs is composed of opsoclonus, myoclonus and ataxia. In addition, there is often irritability and sleep disturbance. In about 50% of children there is an underlying neuroblastoma.

Objective: The aim of study was to investigate and describe the epidemiology, clinical features, tumor association, treatment profile and outcome of patients with OMAS.

Methods: We conducted a retrospective study over 17 years (2005-2022) including all patients aged under 18 years who were managed for OMAS in an oncologic hospital (GRAACC Hospital in São Paulo – SP). Epidemiological and clinical data were analyzed.

Results: Eleven patients were included. The male–female ratio was 1:4,5. Median age of onset was 2.15 years (25.8 months). Time to diagnosis ranged between 10 days and 3 years. All patients had ataxia, tremor, dysmetria and irritability at some point. Acute ataxia was the predominant initial symptom, corresponding to 81% of the cases. Opsoclonus was the initial symptom in only 9% of cases. Eighty two percent of the patients had brain magnetic resonance imaging. Eighty one percent realized cerebrospinal fluid analysis. Most patients had association with tumor (72%), with neuroblastoma and ganglioneuroblastoma corresponding to half of the cases each. Time to diagnosis among OMAS and tumor ranged from 0 days to 1 year and 7 months, but the majority (63%) were diagnosed at the same time. Only one patient did not resect the tumor. All patients received immunomodulatory treatment, and 62% received combination therapy (immunoglobulin plus dexamethasone, or immunoglobulin plus methylprednisolone, or immunoglobulin plus prednisolone, or immunoglobulin plus dexamethasone and rituximab). Comparing the “tumor group” and the “no tumor group”, there were no differences in sex ratio and the main presenting symptom. Children in the tumor group had an earlier age of onset (mean 19.1 vs. 25.8 months). Of the total, there was relapse in 36% and 63% have sequelae, with language and cognition as the most affected areas. The percentage of sequelae was higher in the “Group of tumors” (75% vs 33%).

Conclusions: OMAS is a rare neurologic condition that can be associated with poor cognitive outcomes. An early diagnosis with aggressive immunomodulation might lead to a better outcome. The disorder requires careful monitoring and longer-term follow-up.

 

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No conflict of interest has been declared by the author(s).

Publication History

Article published online:
18 September 2023