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

Abstract

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.

Review of Opsoclonus-Myoclonus Ataxia Syndrome in Pediatric Patients

“…At times, some symptoms may even be transient and self-resolve gradually [ 42 ]. Cases have been reported wherein such patients were started on anti-epileptic medications, without any improvement in their symptoms, and were eventually diagnosed with OMAS [ 43 , 44 ]. Thus, it is important to distinguish OMAS from other conditions that might present with similar symptoms, so that appropriate treatment may be started in a timely manner.…”

Acute Ataxia in Children: Approach to Clinical Presentation and Role of Additional Investigations

“…Also, opsoclonus is only intermittently present and may be unobserved or misdiagnosed as nystagmus or epileptic seizure. 68 Finally, behavioral abnormalities that distinguish OMS from other etiologies of acute ataxia can be misinterpreted.…”

Update on diagnosis, treatment, and prognosis in opsoclonus–myoclonus–ataxia syndrome

“…Although opsoclonus is the most distinctive finding, it may be completely absent [4,5 ]. Misdiagnoses include acute cerebellar ataxia, Guillain-Barre syndrome, and epileptic seizures [6,7 ]. Misdiagnoses include acute cerebellar ataxia, Guillain-Barre syndrome, and epileptic seizures [6,7 ].…”