Invariant Reversible QEEG Effects of Anesthetics

John, E. Roy; Prichep, Leslie S.; Kox, Wolfgang J.; Valdés‐Sosa, Pedro A.; Bosch-Bayard, Jorge; Aubert, Eduardo Henrik; Tom, MeeLee; diMichele, F.; Gugino, Laverne D.

doi:10.1006/ccog.2001.0507

Cited by 250 publications

(101 citation statements)

References 31 publications

(33 reference statements)

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“…41-43 Human and animal studies have demonstrated both local and long range gamma synchronization across neuronal networks. 44-47 Earlier studies of low gamma oscillations (≤50 Hz) showed that anterior-posterior corticocortical phase synchronization in rats, 48 and coherence in surgical patients, 49 decreased under anesthetic-induced unconsciousness. In a recent study conducted in surgical patients, Nicolaou and Georgiou reported 30 that global field synchrony in gamma band was significantly reduced during surgical anesthesia with propofol, sevoflurane, and desflurane.…”

Section: Discussionmentioning

confidence: 99%

Neural Correlates of Wakefulness, Sleep, and General Anesthesia

et al. 2016

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Background Significant advances have been made in our understanding of subcortical processes related to anesthetic- and sleep-induced unconsciousness, but the associated changes in cortical connectivity and cortical neurochemistry have yet to be fully clarified. Methods Male Sprague–Dawley rats were instrumented for simultaneous measurement of cortical acetylcholine and electroencephalographic indices of corticocortical connectivity—coherence and symbolic transfer entropy—before, during, and after general anesthesia (propofol, n = 11; sevoflurane, n = 13). In another group of rats (n = 7), these electroencephalographic indices were analyzed during wakefulness, slow wave sleep (SWS), and rapid eye movement (REM) sleep. Results Compared to wakefulness, anesthetic-induced unconsciousness was characterized by a significant decrease in cortical acetylcholine that recovered to preanesthesia levels during recovery wakefulness. Corticocortical coherence and frontal–parietal symbolic transfer entropy in high γ band (85 to 155 Hz) were decreased during anesthetic-induced unconsciousness and returned to preanesthesia levels during recovery wakefulness. Sleep-wake states showed a state-dependent change in coherence and transfer entropy in high γ bandwidth, which correlated with behavioral arousal: high during wakefulness, low during SWS, and lowest during REM sleep. By contrast, frontal–parietal θ connectivity during sleep-wake states was not correlated with behavioral arousal but showed an association with well-established changes in cortical acetylcholine: high during wakefulness and REM sleep and low during SWS. Conclusions Corticocortical coherence and frontal–parietal connectivity in high γ bandwidth correlates with behavioral arousal and is not mediated by cholinergic mechanisms, while θ connectivity correlates with cortical acetylcholine levels.

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Section: Discussionmentioning

confidence: 99%

Neural Correlates of Wakefulness, Sleep, and General Anesthesia

et al. 2016

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“…40–42 Additionally, gamma power is lower in UWS patients with chronic disorders of consciousness 14 and during loss of consciousness from general anesthesia. 43 Interestingly, some recent data of propofol-induced frontal gamma activity associated with loss of consciousness that persists after behavioral emergence form anesthesia challenges this notion. 18 This discordance of the anesthesia data may relate to a medication effect in the anesthesia model causing high frequency oscillations including in the gamma range and a potential limitation of these models to study impairment of consciousness.…”

Section: Discussionmentioning

confidence: 99%

Bedside quantitative electroencephalography improves assessment of consciousness in comatose subarachnoid hemorrhage patients

Claassen

Velázquez

Meyers

et al. 2016

Annals of Neurology

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Objective Accurate behavioral assessments of consciousness carry tremendous significance in guiding management, but are extremely challenging in acutely brain-injured patients. We evaluated whether EEG and multimodality monitoring parameters may facilitate assessment of consciousness in patients with subarachnoid hemorrhage. Methods A retrospective analysis was performed of 83 consecutively treated adults with subarachnoid hemorrhage. All patients were initially comatose and had invasive brain monitoring placed. Behavioral assessments were performed during daily interruption of sedation and categorized into three groups based on their best examination as (1) comatose, (2) arousable (eye opening or attending towards a stimulus), and (3) aware (command following). EEG features included spectral power and complexity measures. Comparisons were made using bootstrapping methods and partial least squares regression. Results We identified 389 artifact-free EEG clips following behavioral assessments. Increasing central gamma, posterior alpha, and diffuse theta-delta oscillations differentiated patients that were arousable from those in coma. Command following was characterized by a further increase in central gamma and posterior alpha, as well as an increase in alpha permutation entropy. These EEG features together with basic neurological examinations (e.g., pupillary light reflex) contributed heavily to a linear model predicting behavioral state while brain physiology measures (e.g., brain oxygenation), structural injury, and clinical course added less. Interpretation EEG measures of behavioral states provide distinctive signatures that complement behavioral assessments of patients with subarachnoid hemorrhage shortly after the injury. Our data support the hypothesis that impaired connectivity of cortex with both central thalamus and basal forebrain underlies decreasing levels of consciousness.

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“…In the mid-1990s, the reduction of the expected posterior alpha in the awake, eyes-closed state and the shift to more anterior structures was identified during propofol sedation and during unconsciousness induced by a combination of isoflurane and nitrous oxide. 19,20 In 2001, John et al 21 suggested that electroencephalographic anteriorization of alpha and slow-wave activity was an agent-independent feature of general anesthesia, based on the study of 176 surgical patients undergoing general anesthesia with a wide variety of intravenous and inhaled anesthetics. In 2004, Feschenko et al 22 demonstrated the disappearance of occipital alpha oscillations and the appearance of high-power frontal alpha oscillations during propofol-induced unconsciousness in 52 healthy human participants.…”

Section: Discussionmentioning

confidence: 99%

Neurophysiological Correlates of Sevoflurane-induced Unconsciousness

et al. 2015

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Background Recent studies of anesthetic-induced unconsciousness in humans have focused predominantly on the intravenous drug propofol and have identified anterior dominance of alpha rhythms and frontal phase-amplitude coupling patterns as neurophysiological markers. However, it is unclear whether the correlates of propofol-induced unconsciousness are generalizable to inhaled anesthetics, which have distinct molecular targets and which are used more commonly in clinical practice. Methods We recorded 64-channel electroencephalogram in healthy human participants during consciousness, sevoflurane-induced unconsciousness, and recovery (n=10; n=7 suitable for analysis). Spectrograms and scalp distributions of low-frequency (1 Hz) and alpha (10 Hz) power were analyzed, and phase-amplitude modulation between these two frequencies was calculated in frontal and parietal regions. Phase lag index was used to assess phase relationships across the cortex. Results At concentrations sufficient for unconsciousness, sevoflurane did not result in a consistent anteriorization of alpha power; the relationship between low-frequency phase and alpha amplitude in the frontal cortex did not undergo characteristic transitions. By contrast, there was significant cross-frequency coupling in the parietal region during consciousness that was not observed after loss of consciousness. Furthermore, a reversible disruption of anterior-posterior phase relationships in the alpha bandwidth was identified as a correlate of sevoflurane-induced unconsciousness. Conclusion In humans, sevoflurane-induced unconsciousness is not correlated with anteriorization of alpha and related cross-frequency patterns, but rather by a disruption of phase-amplitude coupling in the parietal region and phase-phase relationships across the cortex.

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Invariant Reversible QEEG Effects of Anesthetics

Cited by 250 publications

References 31 publications

Neural Correlates of Wakefulness, Sleep, and General Anesthesia

Neural Correlates of Wakefulness, Sleep, and General Anesthesia

Bedside quantitative electroencephalography improves assessment of consciousness in comatose subarachnoid hemorrhage patients

Neurophysiological Correlates of Sevoflurane-induced Unconsciousness

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