Multichannel Magnetoencephalography in Ablative Seizure Surgery Outside the Anteromesial Temporal Lobe

Magnetoencephalography (MEG) was used to evaluate 40 candidates for seizure surgery thought to have foci outside the anteromesial temporal lobe. Of 29 cases with electrographic data suggesting a convexity focus, MEG spikes were recorded from 28. In 21, MEG and electrographic data were localized to the same area. Invasive studies were, or could have been, avoided in 13 cases based on MEG and other noninvasive data. MEG was not localizing value in 4 orbitofrontal or 7-depth-nonlocalized cases. Seventeen patients with MEG epileptiform data have had postoperative follow-up. Eight of 13 with electrographic and MEG data localized to the same area are seizure free. None of 4 with spatial discordance of MEG electrographic data are seizure free.