Preoperative evaluation using magnetoencephalography: Experience in 382 epilepsy patients

Area of Science:

• Neurology
• Neurophysiology
• Medical Imaging

Background:

• Identifying the epileptogenic zone (EZ) is crucial for epilepsy surgery.
• Magnetoencephalography (MEG) is an advanced neuroimaging technique used in epilepsy evaluation.
• Ancillary investigations for epilepsy can be burdensome for patients.

Purpose of the Study:

• To determine if MEG's ability to hypothesize the location of the EZ can be predicted upfront.
• To identify patient characteristics associated with successful MEG localization.
• To characterize patients for whom MEG fails to localize the EZ.

Main Methods:

• MEG recordings from 382 epilepsy patients with inconclusive EZ localization were analyzed.
• Demographic, clinical, and MEG variables were assessed for association with MEG localization ability.
• Patients with and without MEG localization were compared to identify distinguishing factors.

Main Results:

• MEG localization ability could not be predicted upfront in this highly-selected patient group.
• Absence of a tumor and presence of widespread MRI abnormalities increased the odds of MEG localization.
• Patients without MEG localization more frequently had tumors and non-concordant MEG/EEG findings.

Conclusions:

• MEG can provide valuable EZ location information in epilepsy patients with complex etiologies.
• Clinical recommendation is to not withhold MEG for epilepsy surgery candidates.
• Further refinement of MEG methods is needed for patients with inconclusive EEG/MRI findings and without clear epileptiform activity.