HP21: Utility of interior temporal electrodes in short term surface EEG in a general neurology ward

Abstract

Several previous studies have revealed that adding six inferior temporal electrodes increase the diagnostic yield of both long-term and short-term EEG recordings, especially in patients with suspected temporal lobe seizures (Rosenzweig et al., 2014; Beniczky et al.,2018). Both studies were carried out in dedicated epilepsy centers with restrictive inclusion criteria. In our study, we explored usefulness of inferior temporal electrodes in short-term surface EEG in a general neurology ward settings. Methods: EEG was performed during wakefulness according to standard routine short-term EEG protocol. Six electrodes in the inferior temporal chain (F9-T9-P9 and F10-T10-P10) were added to basic 19 electrodes of 10-20 international system of electrode placement. Isolated inferior temporal chain related focal slowing or epileptiform discharges or peak negativity of focal changes or epileptiform discharges in any of inferior temporal leads unilaterally were considered as clinically significant and their prevalence was assessed. Results: 218 EEG recordings out of 343 were abnormal and were further analyzed. In three patients (1,4%) abnormal slowing was detected only in inferior temporal leads and in 16 cases (7,3%) peak negativity of focal changes in inferior temporal leads was detected. Two patients (0,9%) had epileptiform discharges isolatedly at the inferior temporal electrodes and in 17 (7,8%) cases there was inferior temporal peak negativity of epileptiform discharges. Conclusion: The use of inferior temporal electrodes can improve identification and localization of EEG abnormalities in short-term surface EEG also in unspecialized neurology wards.