Detection of epileptic spikes by magnetoencephalography and electroencephalography after sleep deprivation

INTRODUCTION In diagnosis of epilepsies electrophysiological findings play a key role. While spontaneous electroencephalography (EEG) and EEG with sleep deprivation (EEGsd) are widely evaluated and used, application of magnetoencephalography (MEG) in this field is primarily limited to presurgical assessment of focal epilepsies. METHODS In this study we retrospectively compared MEG (M/EEG) and EEGsd in 63 (55) patients with focal and generalized epilepsy with regard to occurrence of epileptic spikes. RESULTS MEG could record epileptic spikes in 38 patients (60%), while EEGsd recorded spikes in only 32 patients (51%). In a group of 55 patients simultaneous MEG/EEG (M/EEG) was able to record spikes in 38 patients (71%) compared to epileptic spikes in 28 patients (51%) recorded by EEGsd. In a subgroup of 17 MR-negative patients simultaneous M/EEG could record epileptic spikes in all patients, while EEGsd was successful in only 11 (64%) of them. CONCLUSION In this study, MEG showed a tendency to record epileptic spikes in more patients than EEGsd. Furthermore, simultaneous M/EEG has been shown to be especially successful in detection of epileptic spikes in patients with MR-negative epilepsy. This might at least in parts be explained by neocortical predominance of MR-negative epilepsy. Thus, this study motivates prospective studies to evaluate the substitutability of EEGsd by MEG more extensively.