Activating Effects of Sleep Deprivation on Synchronized MEG-EEG Recordings of Epilepsy Patients With Non-Diagnostic EEG

Objective: We would like to evaluate the activating effects of complete sleep deprivation (SD) on synchronized MEG-EEG recordings, and on each of the components singly, in relation to the degree of alertness during recording (awake vs. sleep) and the subjective degree of sleepiness as assessed by standardized scales. We postulate that acute SD will increase the diagnostic yield of synchronized MEG-EEG and activate both modalities (MEG, EEG) to the same degree. The increased diagnostic utility of MEG could improve the epilepsy surgery evaluation procedure for many patients by rendering invasive studies less necessary. The medical and economic utilization of such expensive resources as MEG could thus be rationalized. Population: Participants of this study will be epilepsy patients whose last routine interictal EEG (performed at least two weeks earlier), subsequent pre-screening EEG and screening MEG-EEG show no interictal epileptiform discharges (IEDs), and are therefore considered non-diagnostic. Study Design/Methods: We will use a 275-channel Whole-head MEG System (CTF Systems 2001 Inc.). Patients will have a screening, non-SD and SD MEG-EEG after their degree of sleepiness is assessed using the Epworth, Stanford and Karnolinska sleepiness scales. Starting one day after the MEG-EEG, SD and non-SDMEG-EEG will be performed in random order within 14-21 days of each other. This will ensure an equal amount of sampling effect in SD and non-SD data sets. The MEG-EEG session will last 90 to 180 minutes. Patients may take a break after at least 10 minutes in a scanner. We will attempt to record a comparable amount of awake and sleep data. At least thirty minutes of artifact-free baseline, non-SD and SD MEG-EEG will be analyzed. For the purpose of blinding, each modality will be read independently by two readers, each of whom will be blinded to the relationship of the MEG-EEG data to sleep deprivation, results obtained by the other modality and subjective degree of sleepiness. Only interpretations of each modality agreed upon by both readers will be accepted. When there is no agreement, a third independent reader will resolve the disagreement. Outcomes: The primary outcome measure will be the proportion of seizure foci detected and delineated after SD on synchronized MEG-EEG recordings. Comparisons will also be made for each recording modality and between them, according to the state of alertness during recording and subjective feeling of sleepiness before each recording.