Spectral profile of early ictal EEG patterns in status epilepticus predicts therapy response

Status epilepticus (SE) is a life-threatening condition and requires prompt recognition and timely initiation of treatment. We aimed to define EEG characteristics in initial ictal EEG recordings predicting response to 1^st and 2^nd line SE therapy and allowing for early identification of refractory SE (rSE) with need for anesthesia and intensive care management.

All adult patients diagnosed with SE between 2018 and 2022 were screened for inclusion. The following inclusion criteria applied: baseline EEG demonstrating SE recorded within 48 h from symptom onset and without prior administration of 3^rd line SE therapy; follow-up EEG within 48 h from baseline EEG. The first artefact-free one to three minute EEG epochs containing unequivocal SE patterns according to ACNS criteria underwent EEG power spectral analysis.

Of the 50 patients included in our study, 22 (44 %) responded to 1^st and 2^nd line SE therapy (group non-rSE); in 28 patients (56 %) SE was still present in follow-up EEG and/or 3^rd line SE therapy had been initiated based on clinical judgement (group rSE). In group non-rSE the power spectrum contained significantly higher amounts of Delta (median, 78.5 % vs 66.5 %, p = 0.0002) and lower proportions of Alpha power (3 % vs 8 %, p < 0.0001) compared to group rSE; Alpha/Delta ratio also differed significantly in both groups (0.04 vs 0.12, p < 0.0001).

Spectral power analysis of initial SE EEG can help to stratify the risk of rSE development and facilitate timely targeted therapy with the aim to improve clinical outcome of affected patients.