Opsoclonus myoclonus: a non-epileptic movement disorder that may present as status epilepticus

We describe two cases of a non-epileptic florid movement disorder presenting as status epilepticus. Both patients presented with florid jerking of the limbs and eyes. Convulsive status epilepticus related to presumed meningitis or encephalitis was suspected in both cases. The patients received treatment for seizures, without resolution of the abnormal movements, resulting ultimately in anaesthetic, intubation and ventilation. EEGs showed no epileptic discharges. The diagnosis was opsoclonus myoclonus syndrome in both. One patient was treated with adrenocorticotropic hormone (40 IU/day), the other with prednisolone (4 mg/kg/day) with rapid resolution of symptoms. Neither patient had an underlying neoplasm or infectious agent identified. To date, neither patient has suffered a relapse of symptoms nor does either show any sign of developmental delay. These cases show that the movements in opsoclonus myoclonus syndrome can be sufficiently florid to mimic convulsive status epilepticus. Video footage of both patients at the time of diagnosis is presented online.