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

Study Summary

This study will evaluate how the state of being completely deprived of sleep has an effect on recordings of magnetoencephalography (MEG) and electroencephalography (EEG), in relation to how alert someone is and how sleepy someone perceives himself or herself to be. EEG measures electronic potential differences on the scalp. On the other hand, MEG is a non-invasive technique for recording the activity of neurons in the brain, through recording of magnetic fields caused by synchronized neural currents. It has the ability to detect seizures. Because magnetic signals of the brain vary, this technique must balance two key problems: weakness of the signal and strength of the noise. The EEG is sensitive to extra-cellular volume currents, whereas the MEG primarily registers intra-cellular currents. Because electrical fields are quite dependent on the conductive properties of the tissues, and magnetic fields are significantly less distorted by tissue, the MEG has better spatial resolution. There is a great deal of evidence that EEG and MEG provide complementary data about underlying currents of ions. The complex relationship of sleep and epilepsy is well known. Sleep has been used for many years as a powerful EEG activator. Many researchers have supported the hypothesis that there is a specific activating effect of sleep deprivation on epileptic discharges. Sleep deprivation is defined as a sleepless state of longer than 24 hours. The increased use of MEG in diagnosis could improve the procedure for evaluating patients before surgery for epilepsy, by making invasive studies less necessary. Patients 18 years of age or older, with a diagnosis of epilepsy and with a documented last routine EEG (at least 2 weeks earlier) and routine EEG on the day of a baseline MEG-EEG without interictal epileptiform discharges (IEDs) may be eligible for this study. Participants will be rated according to the Epworth, Stanford, and Karolinska Sleepiness Scales, to determine their subjective s