Assessment of the duration of continuous EEG monitoring in aneurysmal subarachnoid hemorrhage

Background Electroencephalography (EEG) can detect seizures and delayed cerebral ischemia (DCI) in patients with aneurysmal subarachnoid hemorrhage (aSAH). Because a standard duration of continuous EEG monitoring to capture these complications has not been established in aSAH, we compared a standard 6- or 7-day cEEG monitoring protocol versus longer periods of monitoring. Methods We performed a retrospective analysis of aSAH patients ≥18 years old grouped by standard monitoring protocol (6–7 days, group 1) and those with longer monitoring (>7 days, group 2). Clinical characteristics, EEG features, length of stay (LOS) and functional outcome were compared using univariate analyses. Multivariable analyses tested the association between the groups and vasospasm, DCI, LOS, and modified Rankin Scale (mRS). Results 19 patients met criteria for group 1 and 16 patients for group 2. We found no difference in EEG's detection of worsening abnormal EEG activity, vasospasm and DCI. ICU and hospital LOS in group 2 were nearly double that of group 1 (ICU: 25.5 (19.5–35) vs. 14 (11–21) days, p = 0.0003; hospital: 32.5 (29.5–48) vs. 18 (13–29) days, p = 0.003). Good outcome (mRS ≤2) at discharge and at 6 months was similar in both groups (21.1% vs. 0% and 56.3% vs. 46.2%). In multivariable analysis, EEG duration was independently associated with ICU and hospital LOS but not with vasospasm, DCI, and mRS at 6 months. Conclusions Longer EEG monitoring correlated with significantly longer ICU and hospital LOS but not with vasospasm, DCI, and functional outcome at 6 months. Larger studies to confirm our findings are warranted.