The value of nasopharyngeal recording in psychiatric patients

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

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.

Detection of epileptiform activity by different noninvasive EEG methods in complex partial epilepsy

The diagnostic utility of different noninvasive electrode placements for deriving the electroencephalogram and detecting interictal epileptiform discharges was compared. Anterior temporal and nasopharyngeal electrodes in combination with routine scalp electrodes detected over 97% of the spikes, whereas recording from only standard electrode placements detected 58%. Minisphenoidal and surface sphenoidal electrodes were generally not helpful. In some circumstances, however, the use of surface sphenoidal electrodes provided important confirmatory information. In no case did the minisphenoidal electrodes provide unique information, and their use seems unjustified, although the inclusion of other nonstandard electrodes in the recording montage is important to increase the yield.