Use of a New Argon Laser Technique to Evaluate Changes in Sensory and Pain Thresholds in Human Skin following Topical Capsaicin Treatment

Abstract

A new argon laser technique was introduced to evaluate the excitability of the free nerve endings in the skin following topical application of capsaicin. Short argon laser pulses can be perceived as distinct, painful pin pricks and the pain threshold can be determined. This gives the possibility to follow changes in sensory and pain thresholds after topical application of various substances. In the present study the long-term effect of topically applied capsaicin on the pain threshold was monitored. Capsaicin was applied to human skin once daily for 21 days, and the pain threshold was significantly increased after 10 days of application, and after 21 days the increase was found to be 260%. After termination of capsaicin treatment the thresholds were monitored for 21 days, and normalization occurred after 7 days. Argon laser stimulation is a reliable method to evaluate sensory and pain thresholds in human skin.