Hypnotically induced somatosensory alterations: Toward a neurophysiological understanding of hypnotic anaesthesia

Whereas numerous studies have investigated hypnotic analgesia, few have investigated hypnotic anaesthesia. Using magnetoencephalography (MEG) we investigated and localized brain responses (event-related fields and oscillatory activity) during sensory processing under hypnotic anaesthesia. Nineteen right handed neurotypical individuals with moderate-to-high hypnotizability received 100 vibrotactile stimuli to right and left index fingers in a random sequence. Thereafter a hypnotic state was induced, in which anaesthetic suggestion was applied to the left hand only. Once anaesthetic suggestion was achieved, a second, identical, session of vibrotactile stimuli was commenced. We found greater brain activity in response to the stimuli delivered to the left (attenuated) hand before hypnotic anaesthesia, than under hypnotic anaesthesia, in both the beta and alpha bands. In the beta band, the reduction of activity under hypnotic anaesthesia was found around 214-413ms post-stimuli and was located mainly in the right insula. In the alpha band, it was found around 253-500ms post-stimuli and was located mainly in the left inferior frontal gyrus. In a second experiment, attention modulation per se was ruled out as the underlying cause of the effects found. These findings may suggest that the brain mechanism underlying hypnotic anaesthesia involves top-down somatosensory inhibition and, therefore, a reduction of somatosensory awareness. The result of this mechanism is a mental state in which individuals lose bodily sensation.

Effects of hypnosis as an adjunct to intravenous sedation for third molar extraction: a randomized, blind, controlled study

The effects of hypnosis/therapeutic suggestion in connection with intravenous sedation and surgery have been described in many clinical publications; however, few randomized, controlled, and blind studies have been performed in the outpatient area. This study aimed to evaluate the use of hypnosis/therapeutic suggestion as an adjunct to intravenous (IV) sedation in patients having 3rd molar removal in an outpatient setting. The patients were randomly assigned to a treatment (n = 46) or control (n = 54) group. The treatment group listened to a rapid conversational induction and therapeutic suggestions via headphones throughout the entire surgical procedure along with a standard sedation dose of intravenous anesthetic. The control group listened to only music without any hypnotic intervention. Intraoperative Propofol administration, patient postoperative pain ratings, and postoperative prescription pain reliever consumption were all significantly reduced in the treatment compared to the control group. Implications of these results are discussed.