Opsoclonus myoclonus syndrome is a neurological disorder acquired in children as a result of the presence of a neuroblastoma (paraneoplastic syndrome) or, more rarely, a viral infection. The incidence is estimated at around 1 new case per five millions inhabitants per year. Three out of the four following criteria must be present for diagnosis: opsoclonus (involuntary, rapid eye movements), ataxia/myoclonus, behavioural and sleep disorders and neuroblastoma. Neuroblastomas are present in 80% of cases. The most efficient methods for detecting this tumour are whole-body magnetic resonance imaging with gadolinium injection or helicoidal scanning centred on the paravertebral region. Treatment requires ablation of the tumour, a bolus of high dose corticoids and, if the symptoms persist, injection of immunoglobulins, administration of cyclophosphamide or plasmapheresis, or utilisation of anti-CD20 monoclonal antibodies. The oncologic outcome of the neuroblastoma associated with this syndrome is usually favourable. However, in some children, the behavioural and cognitive manifestations respond only partially to treatment.
Last update: March 2006