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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. |