Effectiveness of hypnosis with the Dave Elman technique in third molar extraction: Study protocol for a randomized controlled trial (HypMol)

Investigating functional brain connectivity patterns associated with two hypnotic states

While there's been clinical success and growing research interest in hypnosis, neurobiological underpinnings induced by hypnosis remain unclear. In this fMRI study (which is part of a larger hypnosis project) with 50 hypnosis-experienced participants, we analyzed neural and physiological responses during two hypnosis states, comparing them to non-hypnotic control conditions and to each other. An unbiased whole-brain analysis (multi-voxel- pattern analysis, MVPA), pinpointed key neural hubs in parieto-occipital-temporal areas, cuneal/precuneal and occipital cortices, lingual gyri, and the occipital pole. Comparing directly both hypnotic states revealed depth-dependent connectivity changes, notably in left superior temporal/supramarginal gyri, cuneus, planum temporale, and lingual gyri. Multi-voxel- pattern analysis (MVPA) based seeds were implemented in a seed-to-voxel analysis unveiling region-specific increases and decreases in functional connectivity patterns. Physiologically, the respiration rate significantly slowed during hypnosis. Summarized, these findings foster fresh insights into hypnosis-induced functional connectivity changes and illuminate further knowledge related with the neurobiology of altered consciousness.

Effectiveness of a Brief Hypnotic Induction in Third Molar Extraction: A Randomized Controlled Trial (HypMol)

Third molar extraction is a painful treatment for patients, and thus, it can be used to investigate the effects of analgesics on pain. Hypnosis can help to reduce pain and to decrease the intake of postoperative systemic analgesics. In this study, the effectiveness of a brief hypnotic induction for patients undergoing third molar extractions was investigated. Data were collected from 33 patients with third molar extractions on the right and left sides. Patients received 2 different types of pain interventions in this monocentric randomized crossover trial. Third molar extraction was conducted on 1 side with reduced preoperative local anesthetics and an additional brief hypnotic induction (Dave Elman technique). The other side was conducted with regular preoperative local anesthetics without a brief hypnotic induction (standard care). Intake of postoperative systemic analgesics was allowed in both treatments. Patients' expectations about hypnosis were assessed at baseline. The primary outcome was the area under the curve with respect to ground of pain intensity after the treatment. Secondary outcomes were the amount of postoperative analgesics consumed and the preferred treatment. There was no evidence that the area under the curve with respect to ground of pain differed between the 2 interventions (controlling for gender), but the patients' expectations affected the effectiveness of the brief hypnotic induction. This means that patients with high expectations about hypnosis benefit more from treatment with reduced preoperative local anesthetics and additional brief hypnotic induction. PERSPECTIVE: Hypnosis is used as a treatment to reduce pain in general and dental settings. In this study, additional a brief hypnotic induction with reduced preoperative local anesthetic use did not generally reduce posttreatment pain after third molar extraction more than regular local anesthetics. The expectation of the patients about the effectiveness of hypnosis affected the effectiveness of the brief hypnotic induction so that patients with high expectations had a larger benefit from a brief hypnotic induction than patients with low expectations.