Pruritus, pain, and small nerve fiber function in keloids: a controlled study

Abstract

Background: Keloid scars can itch and hurt, but little is known about the characteristics of these symptoms in keloids. Because itch and pain are carried by small nerve fibers, abnormal function of these fibers could be an explanation for such phenomena.

Objective: We sought to assess the characteristics of itch and pain in keloid scars, and to assess the function of small nerve fibers in keloids.

Methods: We studied the location and intensity of itch and pain in keloids that had been present for at least 1 year. We further studied the function of small nerve fibers by assessing allodynia and alloknesis (which are pain and itch, respectively) from innocuous stimuli that do not normally provoke pain and itch, and we used quantitative thermosensory testing (in keloid lesions, perikeloidal skin, and contralateral normal skin as a control). Results In all, 28 patients (13 men and 15 women) with a mean age of 34 years were enrolled and completed the study. Of the patients, 86% experienced itch and 46% experienced keloid-related pain. Of those who experienced itch, 92% felt the itch at the edge of their keloids. Of the patients with pain, 77% felt pain at the center of the keloid. Mechanical allodynia was noted in 43% of the patients, and only 14% experienced alloknesis. Abnormal thermosensory thresholds to warmth, cold, and heat pain were noted in the keloids. Visual analogue scale of itch correlated significantly to warmth ( r = 0.65), heat pain ( r = 0.4), and cold pain ( r = -0.41).

Conclusion: Itch and pain are common presentations in keloids and are associated with abnormalities in small nerve fiber function, suggesting a small nerve fiber neuropathy.