An Electric Source Imaging Approach Demonstrating Diagnostic Value of Nasopharyngeal Electrodes in Temporal Lobe Epilepsy.

PURPOSE: To investigate the different regions covered by nasopharyngeal (NPEs) and anterior temporal (anterior temporal electrodes [ATEs]) electrodes in assessing temporal lobe epilepsy, to overcome the limitations of the 10 to 20 electroencephalography (EEG) in diagnosing the basal and mesial temporal regions.

METHODS

EEG data from 229 patients diagnosed with temporal lobe epilepsy were simultaneously analyzed with attached NPEs and ATEs. In case of discrepancies in EEG interpretation, a consensus interpretation was reached among three epilepsy experts. Spike detection was conducted using the Curry9 program for secondary analysis of electric source localization, with source location performed using standard brain MRI data.

RESULTS

In total, 2,721 interictal epileptiform discharges (IEDs) from 175 patients were analyzed. Of these, 734 IEDs from 48 patients were detected exclusively with NPEs, while 1,987 IEDs from 127 patients were detected simultaneously by both NPEs and the standard international 10 to 20 electrodes system supplemented with ATEs, respectively. The former IEDs exhibited clustering dipoles in the basal and mesial temporal regions, while the latter were localized solely to the frontotemporal and lateral temporal regions.

CONCLUSIONS

Nasopharyngeals can identify IEDs in the mesial and basal temporal region that cannot be detected by ATEs. Nasopharyngeals offer additional diagnostic value in regions not confirmed by the existing 10 to 20 EEG electrode system, including those covered by ATE.