Does magnetoencephalography add to scalp video-EEG as a diagnostic tool in epilepsy surgery?

To the Editor: We read with interest the article by Pataraia et al.1 who conclude that all patients in whom non-invasive video-EEG (V-EEG) studies are either only partially localizing or non-localizing should have magnetoencephalography (MEG). We feel this is a carefully done study but that the results do not justify the conclusions. Interictal MEG, the same as interictal EEG, is a technique used to define the irritative zone. The seizure onset zone usually is only a small subset of the irritative zone.2 It is difficult to understand why Pataraia et al lumped the irritative zone and ictal onset zone together and then compared them with the MEG defined irritative zone. A much more meaningful comparison would be to compare the irritative zone defined by EEG and by MEG.3,4 …