Why are autonomic responses to pressure pain different from those to heat pain and ischaemic pain?

Abstract

[ In this issue of the Scandinavian Journal of Pain, Mohn et al. pubish an experimental human pain study in which they measured utonomic responses to acute pain stimuli and the modulation f pressure pain sensitivity in normotensive, healthy, pain-free omen during the follicular phase of their menstrual cycle [1]. hey measured pressure pain threshold and pressure pain tolernce at the right masseter muscle and on the sternum. They used a isual analogue pain scale (VAS) tomeasure pain intensity and pain iscomfort. They registered continuously mean arterial pressure, eart rate and facial and digital skin blood flux. They found that he pain threshold was higher on the sternum than at themasseter uscle. The degree of pain discomfort was higher at the pressure ain tolerance level at the masseter. Pressure pain stimulation of he masseter muscle caused increases in blood pressure and heart ate, but a decrease in finger skin blood flux. However, there was o correlation between cardiovascular responses andpressure pain ensitivity. Thus, pressurepain stimulationwasassociatedwith sigificant changes in cardiovascular responses, but pressure painwas ot modulated by the cardiovascular responses. This well done study is important because it increases our nowledge of autonomic cardiovascular responses to acute presure pain. Cardiovascular responses to thermal pain stimuli [2] and o elctrocutaneous pain stimuli [3] are different from the present bservations on pressure pain. The technique of continuous skin lood flux measurements seem to be especially sensitive to pain timuli: Skin blood flux may increase in the face while it decreases n a finger, as it does during electrocutaneous pain stimuli.