Opsoclonus Myoclonus Ataxia Syndrome in Israel: 7-year Experience

Objective. Opsoclonus myoclonus ataxia syndrome (OMS) is a chronically disabling neurologic illness with onset in early childhood. Tumor, usually neuroblastoma, is detected in 45% of patients. Long term outcome includes significant developmental and behavioral sequelae. Our aim is to summarize the experience of the multidisciplinary OMS Clinic at Wolfson Medical Center between 2006 and 2013. Methods. The charts of children with a diagnosis of opsoclonus myoclonus ataxia syndrome were reviewed for: neurologic evaluation, neuroblastoma work up, treatment and outcome. Results. 11 patients were diagnosed as having OMS by clinical criteria and CSF and blood tests. The age of the patients at presentation ranged from 5 months to 4.5 years. All patients underwent neuroblastoma work up by whole body MRI and MIBG. A neuroblastoma was detected in 27%. All children started treatment immediately after diagnosis or tumor resection. The interval between disease onset and the initiation of adequate treatment ranged from four weeks to four years. Ten patients were treated with a combination of ACTH, rituximab, and IVIG as first line therapy. In 3 the European protocol, which includes a combination of dexamethasone, cyclophosphamide, and IVIG was used due to multiple exacerbations and in one as first line therapy. All patients treated with ACTH were followed by an endocrinologist. Treatment complications included infection. All side effects disappeared after steroid tapering. 36% of the patients had a chronic-relapsing course, 18% experienced one to two acute exacerbations, and 33% had a monophasic course. 63% of patients finished treatment and are in clinical remission. Five of these patients (71%) have a normal intellectual outcome. Opsoclonus abated in all seven patients. 43% have residual motor problems, 86% have speech and language difficulties, 86% of the patients have learning disorders (three patients attend a special education class). Behavioral problems early in the course included severe irritability, inconsolability and sleep disorders in nearly all patients and were successfully treated with trazodone; later, oppositional and hyperactive behavior was diagnosed in 86% of patients. Conclusion: OMS is a chronic and debilitating illness. Presence or absence of tumor does not influence the clinical course and prognosis. Tumor resection alone does not provide adequate therapy. Delay in diagnosis and treatment, incomplete neurological remission, and multiple relapses carry a bad prognosis. Early diagnosis and treatment at a specialized center is important in order to ensure adequate immunomodulating therapy according to international protocols.