Simultaneous SEEG-MEG-EEG recordings Overcome the SEEG limited spatial sampling

Area of Science:

• Neuroscience
• Medical Imaging
• Epileptology

Background:

• Presurgical evaluation of pharmacoresistant partial epilepsies relies on electroencephalography (EEG) and magnetoencephalography (MEG) for global brain activity and stereoelectroencephalography (SEEG) for direct, localized recordings.
• SEEG offers high sensitivity but limited spatial sampling, while scalp EEG and MEG provide broader coverage but reduced sensitivity.
• Combining these modalities aims to leverage their complementary strengths for a more comprehensive understanding of epileptic brain sources.

Observation:

• A 19-year-old female patient with pharmacoresistant cryptogenic posterior cortex epilepsy underwent simultaneous EEG-MEG-SEEG recordings.
• Epileptologist identified focal SEEG spikes not visible on surface recordings.
• Scalp EEG and MEG signals were averaged, time-locked to SEEG spikes, and MEG sources were reconstructed using a moving dipole model.

Findings:

• The analysis identified an epileptic source in the left occipital pole, posterior to the SEEG electrodes with maximal spike activity.
• This identified source region was not covered by the SEEG leads, highlighting SEEG's spatial limitations.
• The trimodal approach successfully localized an epileptic focus missed by SEEG alone.

Implications:

• Simultaneous trimodal recordings offer a novel framework for epilepsy presurgical evaluation, enhancing the understanding of brain signal origins.
• This integrated approach overcomes the spatial sampling limitations inherent in SEEG, potentially improving surgical planning and outcomes.
• Combining local and global brain activity recording techniques provides a more complete picture of epilepsy networks.