Hypnotic hypo- and hyperalgesia: divergent effects on pain ratings and pain-related cerebral potentials

Abstract

Pain ratings and pain-related cerebral potentials in response to noxious stimuli were investigated under hypnotic hypo- or hyperalgesia. Out of a sample of 50 subjects the 10 most highly hypnotizable were selected using the Stanford Hypnotic Susceptibility Scale. Phasic pain was induced by brief electrical stimuli intracutaneously applied to the subject's left middle finger. The subjects took part in three experimental sessions. The first session was without hypnosis for familiarization with the experimental surroundings. In the two other sessions, the subjects were hypnotized and given a suggestion of analgesia or hyperalgesia with respect to pain sensation in the left hand. The sequence of hypnosis was matched within and between sessions. Pain ratings and late cerebral somatosensory evoked potentials (SEP) were used to quantify pain reactions. In addition, auditory evoked potentials (AEP) and spontaneous EEG were evaluated to differentiate between pain-specific and unspecific effects of hypnosis. Only the subjects' verbal reports of pain were drastically influenced by hypnosis: suggestion of analgesia diminished the mean pain ratings, suggestion of hyperalgesia enhanced them (P < 0.001). In contrast, the amplitudes of the late somatosensory potentials evoked by the pain-inducing stimuli were not modified in either of the suggestive states. Furthermore, no effects of hypnosis were found on AEPs and on the power spectra of the spontaneous EEG. The results are discussed on the basis of a dissociation of sensory and affective components of pain under hypnosis.

Cognitive‐behavioural group treatment with hypnosis: a randomized pilot trail in fibromyalgia

“…Hypnosis appeared more effective on the affective dimension of pain than over the sensory dimension, which is in line with other authors' fi ndings (e.g. Price, Hakins and Baker, 1987;Meier, Klucken, Soyka and Bromm, 1993;Price, 1999).…”

Laser‐evoked potentials to noxious stimulation during hypnotic analgesia and distraction of attention suggest different brain mechanisms of pain control

“…Further research has indicated that these late ERP components also reflect other aspects of stimulus processing, like stimulus probability and habituation, additionally supporting the notion that the magnitudes of these late ERP components more likely reflect cognitive aspects of pain processing than aspects related to the pure sensory properties of nociception~Miltner & Weiss, 1998& Weiss, , 2000 Whereas most studies of the effects of distraction on late ERP components elicited by noxious stimuli have replicated this finding, comparable studies on ERPs to painful stimuli during suggestions of hypnotic analgesia have produced rather inconsistent results. Some studies have reported decreased amplitudes of late ERP components to noxious stimuli when subjects were given hypnotic analgesia as compared to a control condition~Arendt-Nielsen, Zachariae, & Bjerring, 1990;Crawford, Pribram, & Xie, 1993!. However, other studies demonstrated no such decreases of ERP components~Meier, Klucken, Soyka, & Bromm, 1993;Miltner, Braun, & Revenstorf, 1992!. In some studies even larger ERP amplitudes were obtained during hypnotic analgesia~e.g., Sommer, 1966!. On the basis of these conflicting results, we suggest that hypnotic analgesia is not adequately explained by attentional mechanisms, but rather reflects some other information processing mechanisms.…”

Neurophysiological correlates of hypnotic analgesia

“…In addition, hypnotic suggestions alter pain sensation in both high and low susceptible subjects, but the changes are selective and somatotopically organized only in highly susceptible subjects (Benhaiem, Attal, Chauvi, Brasseur and Bouhassira, 2001) Electroencephalographic (EEG) and evoked potential (EP) studies done since the late 1970s have shown some physiological correlates refl ecting hypnotic analgesia (Halliday and Mason 1964;Meszaros, Banyai and Greguss, 1980; Barabasz and Lonsdale 1983;Spiegel, Bierre and Rootenberg, 1989; Arendt-Nielsen, Zachariae and Bjerring, 1990;Meier, Klucken, Soyka and Bromm, 1993;Zachariae and Bjerring 1994; Crawford, Knebel, Kaplan, Vendemia, Xie, Jamison and Pribram, 1998; De Pascalis, Magurano and Bellusci, 1999). In summary, these studies observed reductions in late somatosensory potentials evoked by nociceptive stimuli during hypnosis, linked to perceived pain intensity changes which seem not to be under conscious control.…”