Experimental elicitation of itch: Evoking and evaluation techniques

Itch is a very common symptom of many skin diseases. Chronic itch may be very troublesome and may strongly impact on work ability, sleep and on the quality of life. Many studies have been conducted to define peripheral and central itch pathways, and to test the anti-pruritic effect of drugs, in which pruritus was experimentally evoked by chemical mediators and by physical stimuli. However, no objective methods to reproduce and to evaluate itch has been standardized. In this review we summarize the experimental techniques used to induce pruritus and to quantify it both in animal models and in humans.