Authors: Wang T et al.
Anesthesiology 144(4):837–852, April 2026
Summary:
This prospective study explores whether electroencephalogram (EEG) patterns—specifically phase–amplitude coupling (PAC)—can serve as a real-time marker of nociception and analgesic effectiveness during surgery. Traditional intraoperative monitoring of pain relies largely on indirect signs such as hemodynamics, but EEG-based measures may offer a more direct window into how the brain processes nociceptive input.
The study included 58 patients undergoing laparoscopic surgery with either standard general anesthesia or general anesthesia combined with a transversus abdominis plane (TAP) block. Researchers analyzed EEG signals during key surgical events, including incision, insufflation, and opioid administration.
They found that both alpha power and delta–alpha PAC decreased in response to surgical stimulation, indicating increased nociceptive input. However, only delta–alpha PAC was able to distinguish the effect of the TAP block. Patients who received the nerve block showed preservation of PAC during incision, suggesting reduced nociceptive signaling reaching the brain. In contrast, alpha power changes alone were not sensitive enough to detect this difference.
Despite these promising intraoperative findings, EEG patterns did not correlate with postoperative pain scores, indicating that postoperative pain is influenced by more complex factors beyond intraoperative nociceptive processing.
Overall, the study suggests that delta–alpha PAC may be a more sensitive and specific EEG-based marker for intraoperative nociception and analgesic effectiveness than traditional measures like alpha power alone.
Key Points:
- Surgical stimulation decreases EEG alpha power and delta–alpha PAC
- Delta–alpha PAC is more sensitive than alpha power in detecting nociception
- TAP block preserves PAC during incision, reflecting effective analgesia
- EEG measures did not predict postoperative pain outcomes
- PAC may serve as a future real-time intraoperative nociception monitor
What You Should Know:
This is where monitoring may be headed. Instead of guessing pain based on heart rate and blood pressure, we may be able to see it directly in the brain. PAC looks promising as a real-time nociception marker—but we’re not there yet, especially when it comes to predicting postoperative pain.
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