Comparison of dense array EEG with simultaneous intracranial EEG for interictal spike detection and localization

Area of Science:

• Neuroscience
• Clinical Neurology
• Medical Imaging

Background:

• Mesial temporal lobe epilepsy (MTLE) is a common cause of drug-resistant epilepsy.
• Accurate localization of epileptogenic foci is crucial for successful epilepsy surgery.
• Conventional electroencephalography (EEG) and magnetoencephalography (MEG) have limitations in localizing deep or mesial temporal spikes.

Purpose of the Study:

• To assess the clinical utility of 256-channel dense array electroencephalography (dEEG) for detecting and localizing interictal spikes in MTLE.
• To compare the detection yield and localization accuracy of dEEG with intracranial EEG (icEEG).

Main Methods:

• Simultaneous recording of 256-channel dEEG and icEEG in patients with intractable epilepsy.
• Analysis of dEEG spike detection rates for spikes confirmed by icEEG.
• Application of source estimation to dEEG for noninvasive localization compared to invasive recordings.

Main Results:

• dEEG detected 45% of interictal spikes originating from the mesial temporal lobe.
• Spikes detected by dEEG had significantly higher intracranial amplitudes (1083 μV) than undetectable spikes (780 μV).
• 87% of detected spikes were accurately localized to the mesial temporal lobe, correlating well with subdural electrode placements.

Conclusions:

• 256-channel dEEG offers improved localization of interictal epileptiform discharges compared to conventional EEG or MEG, particularly for deep foci.
• dEEG shows clinical utility in epilepsy presurgical work-up, providing accurate noninvasive guidance for intracranial electrode placement.