Nasopharyngeal electrodes in temporal lobe epilepsy: A reappraisal of their diagnostic utility

Abstract

Objective: To compare electroencephalography (EEG) recordings with nasopharyngeal electrodes (NPEs) plus anterior temporal electrodes (ATEs) (NPE recordings) and those with only ATEs (non-NPE recordings) for the detection of interictal epileptiform discharges (IEDs) in patients with suspected temporal lobe epilepsy (TLE).

Methods: We retrospectively analyzed the initial EEGs of 229 patients that were recorded simultaneously with ATEs and NPEs in addition to the electrodes of the 10-20 system of electrode placement. Two data sets of NPE and non-NPE recordings were reviewed independently by three interpreters with differing degrees of experience. Discordant findings in the interpretation among the three interpreters were resolved by a consensus to yield final results.

Results: IEDs were detected in 76.4% of patients with NPE recordings compared to 55.5% with non-NPE recordings (p < 0.01). Bilateral independent IEDs were found in 26.2% and 11.4% of EEGs with NPE and non-NPE recordings (p < 0.01). The degree of agreement for the detection of IEDs among the three interpreters was higher with the NPE than with non-NPE recordings (κappa score, 0.70 vs. 0.54). The increased diagnostic yield of NPE recordings for the detection of IEDs was particularly prominent in patients with mesial and non-lesional TLEs.

Conclusions: EEG recordings using NPEs are useful to improve the sensitivity and level of agreement among interpreters for the detection of IEDs in patients with TLE.

Significance: NPE recordings may be recommended in routine EEGs for the evaluation of patients with suspected TLE.

Keywords: EEG; Interictal epileptiform discharges; Interrater agreement; Nasopharyngeal electrode; Temporal lobe epilepsy.