Perioperative neurocognitive disorders are a major public health issue, though there are no validated neurophysiologic biomarkers that predict cognitive function after surgery. This study tested the hypothesis that preoperative posterior electroencephalographic alpha power, alpha frontal-parietal connectivity, and cerebral oximetry would each correlate with postoperative neurocognitive function.
This was a single-center, prospective, observational study of adult (>18 years old) male and female non-cardiac surgery patients. Whole-scalp, 16-channel electroencephalography and cerebral oximetry were recorded in the preoperative, intraoperative, and immediate postoperative settings. The primary outcome was the mean postoperative T-score of three NIH Toolbox Cognition tests – Flanker Inhibitory Control and Attention, List Sorting Working Memory, and Pattern Comparison Processing Speed. These tests were obtained at preoperative baseline and on the first two postoperative mornings. The lowest average score from the first two postoperative days was used for the primary analysis. Delirium was a secondary outcome (via 3-minute Confusion Assessment Method) measured in the postanesthesia care unit and twice daily for the first three postoperative days. Lastly, patient-reported outcomes related to cognition and overall well-being were collected three months post-discharge.
Sixty-four participants were recruited with a median (interquartile range) age of 59 (48 – 66) years. After adjustment for baseline cognitive function scores, no significant partial correlation (ρ) was detected between postoperative cognition scores and preoperative relative posterior alpha power (%) (ρ, = -0.03, p=0.854), alpha frontal-parietal connectivity (via weight phase lag index) (ρ = -0.10, p=0.570, respectively), or preoperative cerebral oximetry (%) (ρ = 0.21, p=0.246). Only intraoperative frontal-parietal theta connectivity was associated with postoperative delirium (F(1,6,291)=4.53, p=0.034). No electroencephalographic or oximetry biomarkers were associated with cognitive or functional outcomes three months post-discharge.
Preoperative posterior alpha power, frontal-parietal connectivity, and cerebral oximetry were not associated with cognitive function after non-cardiac surgery.