The distribution of hyperaemia induced by skin burn injury is not correlated with the development of secondary punctate hyperalgesia

Abstract

This study in 20 volunteers examines whether changes in cutaneous blood flow distribution (laser Doppler flow scanning, LDS) and visible flare correlate in time and in distribution with the development of secondary hyperalgesia (SH, punctate stimulation of a 45-g von Frey filament) induced by a superficial skin burn injury. Areas of LDS and flare were at their largest at 5 minutes after the burn injury (58 ± 30 and 20 ± 11 cm 2, respectively), whereas the largest area of SH was seen after 60 minutes (50 ± 45 cm 2). Although the maximum areas of LDS and SH were of the same magnitude, the blood flow response was essentially abolished when the maximal SH area was noticed at 60 minutes. Furthermore, on an individual basis, there was no correlation between the size of maximal LDS area (at 5 minutes) and maximal SH area (at 60 minutes) ( r = 0.27; P = .26). Therefore, peripheral mechanisms associated with the neurogenic inflammation reaction surrounding a skin burn injury are not directly associated with the induction of SH. Perspective Tissue trauma and inflammation-induced sensory abnormalities are important because they are involved in acute nociceptive pain, as well as in chronic pain conditions. This study notes the significance of central sensitization for the development of secondary hyperalgesia, an important phenomenon underlying many clinical pain conditions.