Pain Forum最新文献

Human brain imaging studies have identified multiple brain regions activated during the experience of pain. Do these complex activation patterns lead to confusion and an “explanatory gap” between classical neurophysiology, psychology, and brain imaging? We propose the contrary, that human functional brain imaging studies can provide a bridge between neurophysiological research and the psychological concept of “pain.” Modern brain imaging techniques allow analysis of the relationship between brain activation patterns and various psychological percepts. However, an essential element in interpreting functional brain imaging observations is a robust psychophysical paradigm that permits the selective manipulation and measurement of individual perceptual features of pain. Functional brain imaging provides a new tool to facilitate our understanding of the complex cognitive, emotional, and sensory experience of pain. Nevertheless, this tool will add little to our knowledge if it is not used wisely.

Although a constructivist view of consciousness is not an obvious one, consciousness theorists since William James have stressed the importance of selectivity and personal history for the creation of conscious experience. The conscious experience of pain is subject to the same processes. The nonlinear dynamic systems model approach introduced to the pain field by Chapman and Nakamura provides a promising overarching framework for multidisciplinary pain research, but does not directly deal with the problem of drawing strong inferences from functional brain imaging studies.

Interstitial cystitis (IC) shares many features with other chronic nonmalignant visceral pain syndromes. In clinical practice, much emphasis has been placed on finding a specific etiology and specific pathological markers for the disease and on identifying specific events that precipitated IC. This conceptualization has influenced clinical treatment approaches for IC and has not resulted in significant progress in this area so far. An additional approach is suggested, based on the conceptualization of three hypotheses: (1) a spectrum of different insults can lead to chronic visceral pain in patients suffering from IC, (2) different underlying pathogenic pain mechanisms may require different pain treatment strategies for patients diagnosed with IC, and (3) multiple different pathogenic pain mechanisms may coexist in the same patient requiring several different pain treatment strategies (perhaps concomitantly) to successfully treat chronic visceral pain associated with IC. This concept is likely to lead to new insights into the pathophysiological mechanisms of IC and to novel treatment avenues for patients suffering from IC and—in a broader view—also for patients with other chronic visceral pain syndromes.

Although pain requires consciousness, the relationship between the two is variable. Some patients with impaired consciousness may have pain or aversive experiences that closely resemble pain. The variable relationship between pain and consciousness suggests that these phenomena are mediated by significantly different neural mechanisms. Consequently, the methods and theories that apply to consciousness research may have limited utility when applied to pain research.

When we exposed the inapplicability of the current definition of pain to neonatal experiences [8], objections to our viewpoint hinged on the absence of consciousness in such nonlinguistic beings [37]. The evidence reviewed in this focus article demonstrates the occurrence and manifestations of consciousness during evolution and human development. Consciousness is described in the full-term newborn, the premature neonate, and the developing human fetus. The clinical implications of ignoring its existence excludes these patients from the benefit of pain relief, promotes more lenient criteria for their participation as research subjects, and produces marked changes in professional attitudes and analgesic practices. We conclude that the definition of pain imposes more stringent standards for acknowledging the presence of pain in nonlinguistic beings and should be changed to include sources of evidence other than verbal self-report.

The recent International Association for the Study of Pain's (IASP) definition of pain apparently minimizes pain suffered by nonverbal individuals. This tendency is also reflected in recent studies about the care of patients and in social policies such as the so-called Baby Doe federal regulations for treatment of infants. It is important to counter this tendency to minimize pain by such means as giving clinicians a better education about (1) pain management; (2) decision-making standards such as the best interest, and moral issues about how to rank important medical goals; (3) research and practice guidelines relating to pain; and (4) encouraging health care, legal, and other institutions to adopt goals and means to address pain adequately.