Jonathan M. Coutinho

Background Endovascular thrombectomy is standard treatment for patients with anterior circulation large vessel occlusion stroke (LVO‐a). Prehospital identification of these patients would enable direct routing to an endovascular thrombectomy‐capable hospital and consequently reduce time‐to‐endovascular thrombectomy. Electroencephalography (EEG) has previously proven to be promising for LVO‐a stroke detection. Fast and reliable electrode application, however, can remain a challenge. A potential alternative is subhairline EEG. We evaluated the diagnostic accuracy of subhairline EEG for LVO‐a stroke detection. Methods and Results We included adult patients with a suspected stroke or known LVO‐a stroke and symptom onset time <24 hours. A single 3‐minute EEG recording was performed at the emergency department, before endovascular thrombectomy, using 9 self‐adhesive electrodes placed on the forehead and behind the ears. We evaluated the diagnostic accuracies of EEG features quantifying frequency band power and brain symmetry (pairwise derived Brain Symmetry Index) for LVO‐a stroke detection using receiver operating characteristic analysis. EEG data were of sufficient quality for analysis in 51/52 (98%) included patients. Of these patients, 16 (31%) had an LVO‐a stroke, 16 (31%) a non‐LVO‐a ischemic stroke, 5 (10%) a transient ischemic attack, and 14 (27%) a stroke mimic. Median symptom‐onset‐to‐EEG‐time was 266 (interquartile range 130–709) minutes. The highest diagnostic accuracy for LVO‐a stroke detection was reached by the pairwise derived Brain Symmetry Index in the theta frequency band (area under the receiver operating characteristic curve 0.90; sensitivity 86%; specificity 83%). Conclusions Subhairline EEG could detect LVO‐a stroke with high diagnostic accuracy and had high data reliability. These data suggest that subhairline EEG is potentially suitable as a prehospital stroke triage instrument.