Asymmetry and time-course of cutaneous sympathetic reflex responses following sustained excitation of chemosensitive nociceptors in humans

摘要: Sympathetic reflex responses were elicited in human volunteers by sustained selective excitation of nociceptors noxious chemicals, namely topical application mustard oil which burning pain, or histamine induced itching a skin area 5 cm2 on the volar aspect one forearm. Stimulus-related sympathetic studied means computer-assisted infrared thermography palmar aspects both hands. Nociceptive stimulation decrease surface temperature hands interpreted as vasoconstriction. The magnitude cooling was correlated with sensation (r = 0.49), but independent quality (itch pain). reduction maintained for more than 30 min and its time-course matched time-courses pain itch sensations. It is concluded that elicits response, adapts very slowly. reflexes suggests these are not arousal responses, may be indicators nociceptive processing conscious humans. Contralateral decreases consistently smaller ipsilateral ones. Thus, nociceptive-specific vasoconstrictor somatotopically organised an emphasis areas close to painful stimulus (homotopic), has so far only been shown animals. study thus demonstrates first time humans presence asymmetry, specific afferent input.