Epilepsy with myoclonic-atonic seizures (Doose syndrome): When video-EEG polygraphy holds the key to syndrome diagnosis

Abstract

An electroclinical epilepsy syndrome diagnosis enables physicians to predict outcomes as well as select appropriate treatment options. We report a child who presented with reflex myoclonus at the age of 9 months and was initially diagnosed with myoclonic epilepsy in infancy. After 9 years of medically resistant myoclonic seizures, extensive investigations, and emerging learning difficulties, she was referred for video-telemetry to characterize her seizures in an attempt to make a syndromic diagnosis. A three-day video-telemetry assessment was performed to document seizures. Neck and deltoid EMG channels were applied from the onset of the recording. Frequent generalized bursts of 3- to 5-Hz spike/polyspike and slow wave discharges, associated with clinical manifestations, mostly myoclonic seizures, were noted. In addition, definite atonic components were noted on the neck EMG as well as the deltoids associated with the slow component of the ictal discharges. The EEG and polygraphy findings are suggestive of a generalized epilepsy characterized by predominantly myoclonic seizures with atonic components. This raises the possibility whether a variant of epilepsy with myoclonic-atonic seizures (Doose syndrome) may be the underlying diagnosis for this girl. A trial of the ketogenic diet would therefore be considered as an option in her future management in view of its beneficial effect in this condition.

Keywords: Childhood; Doose syndrome; Myoclonic epilepsy; Myoclonic–astatic epilepsy; Myoclonic–atonic seizures; Video-telemetry.

Fig. 1

Ictal EEG with polygraphy of a myoclonic–atonic seizure showing initial myoclonus associated with the burst of polyspikes and atonia on the EMG (arrow) associated with the slow wave component of the discharge (see calibration marker bottom right of figure).