The Medical Neurology Branch of NINCDS, the Biomedical Engineering and Instrumentation Branch of DRS, and the Computer Systems Laboratory of DCRT are collaborating on a research project to noninvasively localize epileptic discharge sources within the human brain utilizing neuromagnetic recording in conjunction with conventional electroencephalogram (EEG) recording. Many patients with seizure disorders exhibit low-level cellular discharges between seizures, indicated by interictal spikes in their EEG and magnetoencephalogram (MEG) recordings. This project involves the development of computer techniques for automating and enhancing the procedure that is presently used by NINCDS neurologists for determining the intracranial locations of the sources of interictal spikes in patients with epilepsy. The required MEG and EEG signals are acquired with a system that was purchased from Biomagnetic Technologies, Inc. (BTi) and placed in operation during FY86. This system includes a seven-channel SQUID (superconducting quantum interference device) for measuring the MEG signal from seven sites on the head simultaneously, a combined BTi and Hewlett-Packard (HP) data acquisition system for acquiring the EEG and MEG signals, and an HP 9000 computer workstation for signal processing and graphical display functions. CSL designed and built a 32-channel signal selection and conditioning interface that was added to the data acquisition system. Methods are presently being developed to automate the real time detection of interictal spikes from the EEG and MEG signals and the extraction of relevant features characterizing the detected waveforms. The information obtained from these features will be used with values extracted from the raw waveforms to generate the graphical displays needed to determine the epileptic foci.
