ABSTRACT
The skin is the frontier between self and non-self and the site of impact of extraneous perturbations of environment. There is a clear benefit obtained from “protective reflexes” designed to reduce potential damage, a term coined by Sherrington at the turn of the century [Sherrington, 1906, referenced in (1)]. However, visceral pain comes from within and is more related to disease processes. There is no obvious protective countermeasure that one can make in response to the perception of visceral pain. Indeed, effective stimuli to evoke visceral pain are not always damaging nor necessarily potentially harmful. The assumption has been to infer that the cutaneous and visceral systems share comparable pain mechanisms. However, it is becoming evident that the incongruent clinical features of somatic and visceral pain reflect differences in the neurobiology of these nociceptive systems (1,2).
