Functional anatomy of hypnotic analgesia: a PET study of patients with fibromyalgia.

Hypnosis is a powerful tool in pain therapy. Attempting to elucidate cerebral mechanisms behind hypnotic analgesia, we measured regional cerebral blood flow with positron emission tomography in patients with fibromyalgia, during hypnotically-induced analgesia and resting wakefulness. The patients experienced less pain during hypnosis than at rest. The cerebral blood-flow was bilaterally increased in the orbitofrontal and subcallosial cingulate cortices, the right thalamus, and the left inferior parietal cortex, and was decreased bilaterally in the cingulate cortex. The observed blood-flow pattern supports notions of a multifactorial nature of hypnotic analgesia, with an interplay between cortical and subcortical brain dynamics. Copyright 1999 European Federation of Chapters of the International Association for the Study of Pain.