Preserved critical ability and free will in deep hypnosis during oral surgery

Real-time assessment of hypnotic depth, using an EEG-based brain-computer interface: a preliminary study

OBJECTIVE

Hypnosis can be an effective treatment for many conditions, and there have been attempts to develop instrumental approaches to continuously monitor hypnotic state level ("depth"). However, there is no method that addresses the individual variability of electrophysiological hypnotic correlates. We explore the possibility of using an EEG-based passive brain-computer interface (pBCI) for real-time, individualised estimation of the hypnosis deepening process.

RESULTS

The wakefulness and deep hypnosis intervals were manually defined and labelled in 27 electroencephalographic (EEG) recordings obtained from eight outpatients after hypnosis sessions. Spectral analysis showed that EEG correlates of deep hypnosis were relatively stable in each patient throughout the treatment but varied between patients. Data from each first session was used to train classification models to continuously assess deep hypnosis probability in subsequent sessions. Models trained using four frequency bands (1.5-45, 1.5-8, 1.5-14, and 4-15 Hz) showed accuracy mostly exceeding 85% in a 10-fold cross-validation. Real-time classification accuracy was also acceptable, so at least one of the four bands yielded results exceeding 74% in any session. The best results averaged across all sessions were obtained using 1.5-14 and 4-15 Hz, with an accuracy of 82%. The revealed issues are also discussed.

A neurophenomenological theory of the three worlds

The Theory of the Three Worlds (TTW) was introduced by Popper and Eccles in 1977 in the attempt to overcome the narrow limits of materialism and determinism in the comprehension of mind–brain and inner–outer world relationships. TTW involved huge epistemological implications and raised strong criticism. Here, a new neurophenomenological version of the TTW is introduced, meeting previous criticism to the TTW. Hopefully, it may be a step toward comprehension of the mind–brain–world relationship.

Hypnosis as sole anesthesia for oral surgery: The egg of Columbus

BACKGROUND AND OVERVIEW

Hypnosis, despite its effectiveness, has been neglected. The aim of this study is to show the effectiveness and manageability of hypnosis as a stand-alone technique in dentistry.

CASE DESCRIPTION

Three patients underwent 6 oral surgery procedures (surgical third-molar removal, implant surgery, maxillary bone augmentation, and mucogingival surgery) with hypnosis as the only anesthetic. Two of the 3 patients had difficulties: 1 was sensitive to multiple chemicals, had Addison disease, and had previously experienced anaphylactic reactions to local anesthetics; the other was allergic to lidocaine and had undergone a paradoxical reaction to pharmacologic sedation in the past. All 3 patients had 2 preoperative sessions each to assess their perioperative risk, level of anxiety, hypnotic susceptibility, and capacity to develop full hypnotic analgesia. On a surgery day, hypnosis was induced and hypnotic analgesia was obtained according to a standard protocol, a procedure taking no more than 9 minutes in each case. Each surgical procedure was then completed successfully with the patient in a painless condition of full relaxation and sense of well-being, with stable cardiovascular parameters. None of the patients required postoperative analgesics, which were prescribed for use as needed.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

Hypnosis is a valuable tool in dentistry, enabling the safe and rapid relief of anxiety and phobia and raising patient pain thresholds to the level of surgical analgesia. Unlike drugs and equipment, it is always readily available, cost-free, and has no adverse effects when administered by competent professionals. Hypnosis can be used for sedation in most patients and as a stand-alone technique in those with appropriate hypnotic susceptibility, improving the well-being and safety of patients.