Introduction: Endovascular therapy (EVT) improves outcomes in the setting of acute ischemic stroke (AIS) in a time-dependent manner, highlighting the need for improved methods to rapidly identify eligible patients, particularly in the pre-hospital setting. Current pre-hospital assessments are imprecise for this goal. Pre-hospital measurement of brain injury via EEG might provide additional useful diagnostic information regarding EVT eligibility. As a first step, the current study examined (1) feasibility of obtaining EEG early during ER assessment of patients with suspected AIS, and (2) EEG metrics predicting infarct volume.
Methods: In subjects transported to the UC Irvine Medical Center for suspected AIS, a 3 min dense-array resting EEG was obtained during ED assessment.
Results: EEG was acquired in 25 subjects (mean age 65 yr), 12 of whom were discharged with a diagnosis of radiologically confirmed AIS and 13 of whom were discharged with a non-stroke diagnosis. Median time from ED arrival to EEG = 114 min (and as early as 32 min after arrival), and time from last known well to EEG = 333 min. EEG was acquired in 24 subjects, with data lost due to human error in 1 subject. Among patients with AIS, median NIHSS score = 4 (range 0-19) and median infarct volume = 12 cc (range 0.3- 83). Infarct volume was found to correlate inversely with power in the low beta (13-19Hz) frequency range, bilaterally: larger infarcts were associated with reduced beta power in the leads over motor cortex (C3, C4) on the ipsilesional side (rho = -0.57, p=0.03) and on the contralesional side (rho = -0.60, p=0.02).
Conclusions: The current findings support the potential of rapid EEG methods to identify patients with large infarcts who may be ideal candidates for EVT. Future studies will examine how well current findings extend to the pre-hospital setting, and how specific these EEG findings are for patients eligible for EVT.