Some methods for evaluating clinical itch and their application for studying pathophysiological mechanisms.

Research on itch has been hampered by difficulties in measuring the itch sensation. A microcomputer-based system, where the patients themselves record their symptoms on portable data loggers can be used for quantitative measurements of clinical itch and for the detection of antipruritic effects of drugs. By using this system we have found that itch in atopic dermatitis is not inhibited by antihistamines but by cyclosporin A, a drug inhibiting cytokine production. Thus histamine is not a major pruritogen in atopic dermatitis. A hypothesis is proposed that cytokines are involved in itch in atopic dermatitis.