Video-EEG monitoring in respiratory chain disorders

Subclinical epileptiform activity in patients with respiratory chain disorders (RCDs) has not been previously investigated by video-EEG monitoring. The purpose of this study was to look for the type and frequency of epileptiform activity during a 24 h-video-EEG recording in RCD patients. Eleven patients with RCD, 7 women and 4 men, aged 24-72 years, underwent a clinical neurologic examination, blood tests, CT/MRI scans of the brain, routine scalp EEG and continuous video-EEG monitoring over 24 consecutive hours. Ten patients had normal 24 h-video-EEG recordings. One of these patients had no CNS involvement; her resting EEGs showed diffuse background slowing. In one patient, automatic spike detection revealed 12 spikes during a 6 hour period. Resting scalp EEG in this patient showed extensive, bilaterally synchronous, pseudoperiodic polyspike-waves. In conclusion, subclinical epileptiform activity could be recorded by 24 h-video-EEG monitoring in only 1 of 11 RCD patients. The single patient with subclinical epileptiform activity presented with intermittent myoclonic jerks.