Intraoperative Frontal Alpha-Band Power Correlates with Preoperative Neurocognitive Function in Older Adults

Abstract

Each year over 16 million older Americans undergo general anesthesia for surgery, and up to 40% develop postoperative delirium and/or cognitive dysfunction (POCD). Delirium and POCD are each associated with decreased quality of life, early retirement, increased 1-year mortality, and long-term cognitive decline. Multiple investigators have thus suggested that anesthesia and surgery place severe stress on the aging brain, and that patients with less ability to withstand this stress will be at increased risk for developing postoperative delirium and POCD. Delirium and POCD risk are increased in patients with lower preoperative cognitive function, yet preoperative cognitive function is not routinely assessed, and no intraoperative physiological predictors have been found that correlate with lower preoperative cognitive function. Since general anesthesia causes alpha-band (8–12 Hz) electroencephalogram (EEG) power to decrease occipitally and increase frontally (known as “anteriorization”), and anesthetic-induced frontal alpha power is reduced in older adults, we hypothesized that lower intraoperative frontal alpha power might correlate with lower preoperative cognitive function. Here, we provide evidence that such a correlation exists, suggesting that lower intraoperative frontal alpha power could be used as a physiological marker to identify older adults with lower preoperative cognitive function. Lower intraoperative frontal alpha power could thus be used to target these at-risk patients for possible therapeutic interventions to help prevent postoperative delirium and POCD, or for increased postoperative monitoring and follow-up. More generally, these results suggest that understanding interindividual differences in how the brain responds to anesthetic drugs can be used as a probe of neurocognitive function (and dysfunction), and might be a useful measure of neurocognitive function in older adults.

Association of electroencephalogram trajectories during emergence from anaesthesia with delirium in the postanaesthesia care unit: an early sign of postoperative complications

“…43,41 Further, in a patient population >60 yr old, intraoperative alpha power negatively correlated with cognitive performance before operation. 44 Our study supports a possible link between alpha power and the 'cognitive state' of the brain. A published case report describes a patient who repeatedly developed PACU-D and did not have any alpha spindle containing trajectory during emergence, and had alpha-spindle characteristics that resembled a much older patient.…”

Dynamic Cortical Connectivity during General Anesthesia in Surgical Patients

“…The sample size of 53 patients (maximum of 50 for any given data epoch, table 1) is consistent with (and exceeds) previous efforts investigating whole-scalp oscillatory electroencephalographic patterns in adult surgical patients. 5,26,27 For static connectivity analysis, statistical comparisons were performed using linear mixed models (IBM SPSS Statistics version 24.0 for Windows; IBM Corp. USA) to test (1) the difference between the nine studied epochs for both frontal-parietal and prefrontal-frontal connectivity measures, and (2) the difference between frontal-parietal and prefrontal-frontal connectivity. Linear mixed modeling analysis offers more flexibility with missing values and accounts for individual differences by including a random intercept associated with each participant.…”

Electroencephalogram dynamics during general anesthesia predict the later incidence and duration of burst-suppression during cardiopulmonary bypass

“…Giattino et al recently demonstrated that intraoperative frontal alpha oscillation power was positively correlated with neurocognitive function (Giattino et al , 2017). In other compelling studies, a thiopental challenge resulted in decreased frontal beta oscillation power in Alzheimer’s disease patients (Holschneider et al , 1997, Holschneider et al , 2000).…”