and Disattention (Hypnotic Analgesia) to Pain
Helen J. Crawford, Ph.D. Department of Psychology Virginia Polytechnic Institute and State University Blacksburg, VA 24061
Data are reviewed from regional cerebral blood flow, EEG, and somatosensory event-related potential (SERP; both scalp and intracranial) studies of attention to and disattention (hypnotic analgesia) of painful stimuli to provide further evidence for two neurophysiological systems of pain involving the cortex: (1) the epicritic, sensory system of pain associated with the parietal, posterior region, and (2) the protocritic, distress, comfort- discomfort system of pain associated with the far fronto-limbic region. Studies of neurophysiological changes accompanying suggested hypnotic analgesia support the hypothesis that the executive controller of the far frontal cortex, via the far fronto-limbic attentional system, acts as a gate against the ascent of painful stimuli into conscious awareness by "directing" downward the inhibition of incoming somatosensory information coming from the thalamic region. In hypnotically responsive individuals who could eliminate the perception of pain, reviewed studies demonstrated increased regional cerebral blood in the frontal and somatosensory regions, shifts in hemispheric dominance of EEG theta power, differential surface SERP topographical patterns in the anterior and posterior regions of the brain, and reduction of the intracranial SERP P160 waveform in the gyrus cingulus.
Pain is an alerter to us: it tells us that something biologically harmful may be happening to us. It can be a friend to us, but it also can be considered our enemy when it is overwhelming and prolonged. Unless we are one of the few misfortunate individuals who have been born with congenital insensitivity to pain ( Sternbach, 1968), it has probably enveloped us all at some time or another in our lives, and led to decreased cognitive functioning, increased irritability, sleeplessness, and withdrawal from social interactions. Over 70 million people have chronic pain ( Brena & Chapman, 1983), the most frequent symptom presented to the primary care physician. In the United States alone, an estimated 700 million work days are lost per year ( Bonica, 1985), and the total cost of health care associated with pain is estimated to be 60 to 90 billion dollars annually.
In the United States, the most common treatment strategies for chronic pain are medications, surgery, or supportive talk -- yet, often they fail ( Margolis, Zimny, Miller, & Taylor, 1964). Somewhat surprising to the medical community are recent findings from a national survey ( Eisenberg, Kessler, Foster, Norlock, Calkins, & Delbanco, 1993): 34% of Americans reported seeking out unconventional medical therapies in the prior year, often for enduring, debilitating pain. While relaxation (including hypnosis) techniques have been shown to be effective for pain control (e.g., Hilgard & Hilgard, 1983) and are commonly sought out as possible alternative treatments, they are not consistently incorporated into mainstream medical treatments. Many recent advances have been made in understanding the basic mechanisms of pain (e.g., for review, see Price, 1988), yet we are far from understanding the neuropsychophysiology of pain and how these alternative treatments reduce or eliminate pain perception.