HISTAMINE-INDUCED ITCH AND ALLOKNESIS (ITCHY SKIN) IN ATOPIC ECZEMA PATIENTS AND CONTROLS

Alloknesis (''itchy skin'') after histamine iontophoresis was studied together with itch sensations and skin reactions in 19 atopic eczema p atients and 20 controls at the forearm and at the scapular area. Compa red to controls, atopic eczema patients showed significantly reduced a lloknesis or total lack of it in the area around a skin site to which histamine had been iontophoretically applied, although histamine elici ted itching in most patients. As previously demonstrated, patients wit h atopic eczema also developed significantly smaller flares. However, covariance analysis revealed that the smaller alloknesis areas in atop ic patients were not statistically related to the smaller flares. Our results suggest that in atopic eczema a diminished responsiveness of p rimary afferent nerves to histamine is not compensated by a higher cen tral nervous sensitivity reflected in more vivid alloknesis responses to histamine, Therefore, we conclude that histamine is probably not th e key factor of the spontaneous itch experienced by patients with atop ic eczema.