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Epileptic Disorders

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A de novo GABRB2 variant associated with myoclonic status epilepticus and rhythmic high-amplitude delta with superimposed (poly) spikes (RHADS) Volume 22, issue 4, August 2020

Figure 1

Polygraph of myoclonic status epilepticus (at three years and two months of age). The recording was performed at a sampling frequency of 512 Hz using a digital electroencephalograph manufactured by Nippon Denshi Kogyo and analysed by the FOCUS program developed by Nippon Denshi Kogyo. (A) Rhythmic EMG discharges correspond to rhythmic high-amplitude delta with superimposed (poly) spikes (RHADS) localized to both midfrontal-central-parietal regions with right-sided dominance. (B) The polygraph was averaged (n=11) at the trigger point, placing the onset of myoclonic EMG potentials at the right deltoid muscle. As a result, the first spike component of RHADS preceded the onset of myoclonic EMG potentials by 8 mseconds, suggesting that the myoclonic status epilepticus was derived from the contralateral primary motor cortex.

Figure 2

Interictal awake and sleep EEG at three years and two months of age. During wakefulness, the EEG frequently showed RHADS, localized predominantly to the bilateral central-parietal regions (A), whereas no physiological sleep discharges were observed on sleep EEG (B), however, the suppression-burst pattern was noted as sleep progressed.

Figure 3

Brain MRI (T2 weighted) at three years and two months of age, revealing moderate brain atrophy with diffuse T2 high intensity in the white matter.