Video-MEG: Integration of Digital Video to MEG Epilepsy Recordings

Abstract

Video-EEG is the gold standard in clinical epilepsy diagnostics. MEG systems have traditionally lacked video capabilities. Here we describe the addition of a synchronized digital video recording (DVR) system to a standard Elekta Neuromag® 306-channel MEG device operated at BioMag laboratory of the Helsinki University Central Hospital. We also provide some insights obtained from using the system for ictal MEG recordings. Video and audio were recorded simultaneously with MEG, using a separate digital video recording station. Synchronization was achieved by timestamping the video, audio and MEG streams and synchronizing all parts of the system via Network Time Protocol (NTP). Video was recorded at 25 fps with an infrared-sensitive camera necessary to study patients that have seizures during sleep. MEG and video are synchronized to the maximum achievable accuracy of one video frame. At this time, five epileptic patients have undergone video-MEG recordings with the setup described above. In three patients, ictal recordings were obtained. In two cases the video con siderably facilitated the exact temporal localization of the seizure onset, thus reducing the amount of time required for data analysis and improving the reliability of the spatial analysis.