Aδ and not C fibers mediate thermal hyperalgesia to short laser stimuli after burn injury in man

TY - JOUR

T1 - Aδ and not C fibers mediate thermal hyperalgesia to short laser stimuli after burn injury in man

AU - Slimani, Hocine

AU - Plaghki, Leon

AU - Valenti, Paola

AU - Werner, Mads U.

AU - Kehlet, Henrik

AU - Kupers, Ron

PY - 2018/11

Y1 - 2018/11

N2 - It remains unclear which nerve fibers are responsible for mediating hyperalgesia after skin injury. Here, we examined the role of Ad and C fibers in inflammatory hyperalgesia after a first-degree burn injury. A CO2 laser delivered ultrafast short constant-temperature heat pulses to the upper part of the lower leg to stimulate selectively the relatively fast-conducting thinly myelinated Ad and the slowly conducting unmyelinated C fibers. Participants were asked to respond as fast as possible whenever they detected a thermal stimulus. Thresholds and reaction times to selective Ad and C fiber activations were measured in the conditioned and the surrounding intact skin, at pre-injury, and 1 hour and 24 hours after injury. First-degree burn injury caused a significant decrease in Ad fiber detection thresholds and a significant increase in the proportion of Ad-fiber-mediated responses in the inflamed area 24 hours, but not 1 hour, after burn injury. No changes in heat perception were observed in the intact skin surrounding the injury. No group differences in C-fiber-mediated sensations were observed. Our findings indicate that quickly adapting Ad fibers but not quickly adapting C fibers are sensitized when activated by short and ultrafast heat stimuli after skin burn injury. Our results further show that this change occurs between 1 hour and 24 hours after injury and that it does not extend to the skin surrounding the injury.

AB - It remains unclear which nerve fibers are responsible for mediating hyperalgesia after skin injury. Here, we examined the role of Ad and C fibers in inflammatory hyperalgesia after a first-degree burn injury. A CO2 laser delivered ultrafast short constant-temperature heat pulses to the upper part of the lower leg to stimulate selectively the relatively fast-conducting thinly myelinated Ad and the slowly conducting unmyelinated C fibers. Participants were asked to respond as fast as possible whenever they detected a thermal stimulus. Thresholds and reaction times to selective Ad and C fiber activations were measured in the conditioned and the surrounding intact skin, at pre-injury, and 1 hour and 24 hours after injury. First-degree burn injury caused a significant decrease in Ad fiber detection thresholds and a significant increase in the proportion of Ad-fiber-mediated responses in the inflamed area 24 hours, but not 1 hour, after burn injury. No changes in heat perception were observed in the intact skin surrounding the injury. No group differences in C-fiber-mediated sensations were observed. Our findings indicate that quickly adapting Ad fibers but not quickly adapting C fibers are sensitized when activated by short and ultrafast heat stimuli after skin burn injury. Our results further show that this change occurs between 1 hour and 24 hours after injury and that it does not extend to the skin surrounding the injury.

KW - Inflammation

KW - CO2 laser

KW - Nociception

KW - Thermal hyperalgesia

KW - Pain

KW - Burn injury

U2 - 10.1097/j.pain.0000000000001339

DO - 10.1097/j.pain.0000000000001339

M3 - Journal article

C2 - 29994994

AN - SCOPUS:85055080473

SN - 0304-3959

VL - 159

SP - 2331

EP - 2338

JO - Pain

JF - Pain

IS - 11

ER -