On-scalp magnetoencephalography can detect mesial temporal lobe epileptiform discharges

Abstract

The validation of on-scalp magnetoencephalography based on optically pumped magnetometers (OPM-MEG) for clinical applications requires the assessment of the spatial concordance between reconstructed neural sources and intracranial data recorded simultaneously. We here report unprecedented data from an epileptic woman suffering from refractory focal epilepsy who underwent a 10-min simultaneous whole-scalp-covering video-OPM-MEG (118 channels) and stereo-electroencephalography (SEEG) recordings. The most active irritative zone involved the right amygdala despite multiple seizure-onset zones. The multimodal recording allowed to detect and localize 31 simultaneous interictal epileptiform discharges (IEDs) in OPM-MEG signals among the 52 IEDs detected in SEEG signals, and corresponded to the IEDs with the highest amplitude in SEEG. These IEDs were located at the right amygdala using both modalities, with sources distant from 14.1mm. This simultaneous recording demonstrates the ability of OPM-MEG to detect and localize IEDs from a deep mesiotemporal structure such as the amygdala with a localization value and an IED detection rate in line with previous simultaneous cryogenic MEG and SEEG studies. It paves the way for further on-scalp OPM-MEG recordings in patients with implanted materials and strengthens the potential of this growing technology for future clinical and research applications in patients with brain disorders.

Pushing the boundaries of MEG based on optically pumped magnetometers towards early human life

“…The compliance of OPM-MEG has been demonstrated over a wide range of ages, starting from two years old, for both physiological [16,17] and clinical [18][19][20] recordings. However, the use of OPM-MEG in younger subjects poses substantial methodological challenges.…”