EEG pre-burst suppression: characterization and inverse association with preoperative cognitive function in older adults

Abstract

The most common complication in older surgical patients is postoperative delirium (POD). POD is associated with preoperative cognitive impairment and longer durations of intraoperative burst suppression (BSup) – electroencephalography (EEG) with repeated periods of suppression (very low-voltage brain activity). However, BSup has modest sensitivity for predicting POD. We hypothesized that a brain state of lowered EEG power immediately precedes BSup, which we have termed “pre-burst suppression” (preBSup). Further, we hypothesized that even patients without BSup experience these preBSup transient reductions in EEG power, and that preBSup (like BSup) would be associated with preoperative cognitive function and delirium risk. Data included 83 32-channel intraoperative EEG recordings of the first hour of surgery from 2 prospective cohort studies of patients ≥age 60 scheduled for ≥2-h non-cardiac, non-neurologic surgery under general anesthesia (maintained with a potent inhaled anesthetic or a propofol infusion). Among patients with BSup, we defined preBSup as the difference in 3–35 Hz power (dB) during the 1-s preceding BSup relative to the average 3–35 Hz power of their intraoperative EEG recording. We then recorded the percentage of time that each patient spent in preBSup, including those without BSup. Next, we characterized the association between percentage of time in preBSup and (1) percentage of time in BSup, (2) preoperative cognitive function, and (3) POD incidence. The percentage of time in preBSup and BSup were correlated (Spearman’s ρ [95% CI]: 0.52 [0.34, 0.66], p < 0.001). The percentage of time in BSup, preBSup, or their combination were each inversely associated with preoperative cognitive function (β [95% CI]: −0.10 [−0.19, −0.01], p = 0.024; −0.04 [−0.06, −0.01], p = 0.009; −0.04 [−0.06, −0.01], p = 0.003, respectively). Consistent with prior literature, BSup was significantly associated with POD (odds ratio [95% CI]: 1.34 [1.01, 1.78], p = 0.043), though this association did not hold for preBSup (odds ratio [95% CI]: 1.04 [0.95, 1.14], p = 0.421). While all patients had ≥1 preBSup instance, only 20.5% of patients had ≥1 BSup instance. These exploratory findings suggest that future studies are warranted to further study the extent to which preBSup, even in the absence of BSup, can identify patients with impaired preoperative cognition and/or POD risk.

Intraoperative electroencephalogram patterns as predictors of postoperative delirium in older patients: a systematic review and meta-analysis

“…After careful reading of the full-text articles, 32 studies were excluded ( Supplementary Table S3 ). Ultimately, this systematic review included 19 studies published between 2015 and 2023 (Soehle et al, 2015 ; Fritz et al, 2016 ; Hesse et al, 2019 ; Momeni et al, 2019 ; Pedemonte et al, 2020 ; Jung et al, 2021 ; Koch et al, 2021 , 2023 ; Lele et al, 2022 ; Li et al, 2022 ; Lutz et al, 2022 ; Röhr et al, 2022 ; Windmann et al, 2022 ; Baron Shahaf et al, 2023 ; Dragovic et al, 2023 ; Khalifa et al, 2023 ; Kinoshita et al, 2023 ; Reese et al, 2023 ; Ostertag et al, 2024 ). Additionally, 10 of these articles were included in the meta-analysis (Soehle et al, 2015 ; Hesse et al, 2019 ; Pedemonte et al, 2020 ; Jung et al, 2021 ; Koch et al, 2021 , 2023 ; Lele et al, 2022 ; Lutz et al, 2022 ; Röhr et al, 2022 ; Ostertag et al, 2024 ).…”

Barefoot walking improves cognitive ability in adolescents

“…This observation aligns with the intriguing link between serotonin, which is a pivotal neurotransmitter, and brainwave frequencies such as gamma and H-beta waves, an area of significant interest in neuroscience. The presence of gamma waves in EEG signals has been widely associated with higher-order cognitive functions, such as memory encoding, attentional control, and perceptual processing [ 25 - 28 ]. The observed increase in gamma wave activity following barefoot walking suggests a potential enhancement in cognitive performance and information processing.…”

Anesthesia Dose and Delirium—A Picture Coming Into Focus

“…On the other hand, simply reducing the dose of anesthesia to the lowest safe level possible based on EEG guidance—as was done in BALANCED, CODA, and the study by Radtke et al—very well might. Indeed, debate persists as to whether intraoperative EEG suppression plays a causal role in delirium pathogenesis vs simply serving as a surrogate marker for underlying brain health . As such, a finding that reducing EEG suppression time does not impact rates of delirium after a surgical procedure does not on its own exclude the possibility that certain degrees of anesthesia dose reduction may be beneficial.…”