[Interactions between itch and pain].

The discovery of specific pathways for the processing of itch has greatly enhanced our understanding of the physiology of pruritus. However, the complex interactions between itch and pain are only partly understood. This review focuses on the neurophysiological basis of itch under experimental and clinical conditions. Chronic inflammatory diseases can locally sensitize nerve endings and thereby contribute to itch. In addition, there is increasing evidence that also central processing of itch can be sensitized in pruritus patients. Interestingly, this pattern of peripheral and central sensitization in pruritus has striking similarities to the one observed in chronic pain patients. The presumed similarities in underlying sensitizing mechanisms between itch and pain has major therapeutic consequences as successful therapies for chronic pain might be used also in chronic itch.