Abstract
Both itch and pain are common symptoms and cause morbidities in AD patients. AD patients may show neuronal sensitization to itch and pain. Itch sensitization is associated with alloknesis (phenomena in which normal or non-pruritic stimuli are perceived as itchy) and hyperknesis (excessive itch perception to pruritic stimuli); while pain neuronal sensitization is associated with hyperalgesia (increased pain due to a normal noxious stimuli) and allodynia (a painful response to normally non-noxious mechanical, tactile, or thermal stimuli). The mechanisms underlying these neuronal sensitization phenomena share many similarities. These processes can occur at any level of perception, including peripheral sensitization (in the skin and peripheral sensory neurons) and central sensitization (at neuronal circuits in the spinal cord, descending inhibitory pathways in the spinal cord, and the brain).