Magnetoencephalography (MEG) measures cortically-generated magnetic fields and creates a map of current dipoles that is overlaid on Magnetic Resonance Imaging (MRI) images of the brain in order to predict the epileptogenic zone. It is a part of the armamentarium of diagnostic tests available in the presurgical workup in patients with pharmacoresistant focal epilepsy. Its efficacy and reliability in providing results concordant with other diagnostic studies and identifying additional epileptogenic foci is well-described in the literature. OHSU does not currently possess MEG as a diagnostic tool, requiring patients recommended for MEG evaluation to travel to out-of-state medical centers, often at significant personal cost. The study objective is to determine whether the spatial distribution of spike sources determined by MEG provides reliable information compared to intracranial electroencephalography (EEG) for planning surgery and predicting outcomes in patients with medically refractory epilepsy at OHSU.