Quantitative EEG Correlates of Low Cerebral Perfusion in Severe Stroke

Continuous EEG provides the unique possibility to monitor neuronal function non-invasively. In our pilot study, we evaluated EEG spectral power during spontaneous drops in cerebral perfusion pressure (CPP) in deeply sedated and mechanically ventilated patients with severe stroke. We aimed to identify parameters that may be used for continuous monitoring even in patients with a burst-suppression baseline EEG pattern. Twenty ventilated and sedated patients with severe hemorrhagic or ischemic stroke underwent continuous EEG monitoring with synchronous CPP recording. EEG monitoring duration was 83.9 hours on average per patient. Spectral power of EEG during drops of CPP was compared with epochs during normal CPP under the same levels of sedation. We found a significant decrease in faster EEG activity (3.5-20.7 Hz) during phases of low CPP (unaffected hemisphere P < 0.01, affected hemisphere P < 0.01, both P < 0.01). Despite considerable changes in baseline activity due to deep sedation and severe brain injury, we found evidence for disturbed neuronal function during drops in CPP. Thus, continuous EEG monitoring may add clinically relevant information on neuronal function in the setting of multimodality brain monitoring. Further studies are needed to implement real-time data analysis in the ICU setting.