This study was designed to describe regional changes in blood oxygenation level dependent signals in functional magnetic resonance images (fMRI) elicited by thermal pain in hypnotized subjects. These signals approximately identify the neural correlates of the applied stimulation to identify neuroanatomic structures involved in the putative effects of clinical hypnosis on pain perception.
After determination of the heat pain threshold of 12 healthy volunteers, fMRI scans were performed at 1.5 Tesla by using echoplanar imaging technique during repeated painful heat stimuli. Activation of brain regions in response to thermal pain during hypnosis (using a fixation and command technique of hypnosis) was compared with responses without hypnosis.
With hypnosis, less activation in the primary sensory cortex, the middle cingulate gyrus, precuneus, and the visual cortex was found. An increased activation was seen in the anterior basal ganglia and the left anterior cingulate cortex. There was no difference in activation within the right anterior cingulate gyrus in our fMRI studies. No activation was seen within the brainstem and thalamus under either condition.
Our observations indicate that clinical hypnosis may prevent nociceptive inputs from reaching the higher cortical structures responsible for pain perception. Whether the effects of hypnosis can be explained by increased activation of the left anterior cingulate cortex and the basal ganglia as part of a possible inhibitory pathway on pain perception remains speculative given the limitations of our study design.
1Department of Anesthesia, University of Iowa, Iowa City, IA
2Departments of Anesthesia, Technical University of Aachen (RWTH), Aachen, Germany
3Department of Neuroradiology, Technical University of Aachen (RWTH), Aachen, Germany
4Department of Neurology, Technical University of Aachen (RWTH), Aachen, Germany.
Accepted for publication September 7, 2004
The thermal pain stimulation device TSA 2001 (Medoc, Israel) was provided by Medizin-Elektronik von Petersdorff, München, Germany.
Presented in part in abstract form at the ASA Meeting, Orlando, FL, 2002, and the EURO-NEURO Meeting, Munich, Germany, 2002.
Reprint requests: Sebastian Schulz-Stübner, M.D., Ph.D., Department of Anesthesia, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, 6 JCP, Iowa City, IA 52242-1079. E-mail: Sebastianemail@example.com