Association of sleep and anaesthesia EEG biomarkers with preoperative MoCA score: A pilot study

Introduction Preoperative cognitive impairments increase the risk of postoperative complications. The electroencephalogram (EEG) could provide information on cognitive vulnerability. The feasibility and clinical relevance of sleep EEG (EEGsleep) compared to intraoperative EEG (EEGintraop) in cognitive risk stratification remains to be explored. We investigated similarities between EEGsleep and EEGintraop vis‐a‐vis preoperative cognitive impairments. Methods Pilot study including 27 patients (63 year old [53.5, 70.0]) to whom Montreal cognitive assessment (MoCA) and EEGsleep were administered 1 day before a propofol‐based general anaesthesia, in addition to EEGintraop acquisition from depth‐of‐anaesthesia monitors. Sleep spindles on EEGsleep and intraoperative alpha‐band power on EEGintraop were particularly explored. Results In total, 11 (41%) patients had a MoCA <25 points. These patients had a significantly lower sleep spindle power on EEGsleep (25 vs. 40 μv2/Hz, p = .035) and had a weaker intraoperative alpha‐band power on EEGintraop (85 vs. 150 μv2/Hz, p = .001) compared to patients with normal MoCA. Correlation between sleep spindle and intraoperative alpha‐band power was positive and significant (r = 0.544, p = .003). Conclusion Preoperative cognitive impairment appears to be detectable by both EEGsleep and EEGintraop. Preoperative sleep EEG to assess perioperative cognitive risk is feasible but more data are needed to demonstrate its benefit compared to intraoperative EEG.