Neuroimaging

Itch is a complex and unpleasant sensory experience that induces the urge to scratch.¹ It is the most prevalent symptom of inflammatory skin diseases²,³ and difficult to be measured objectively. With its well-known psychophysiological aspects it has substantial impact on the quality of life of the patients.⁴ Its pathophysiology remains poorly understood in spite of numerous studies.² Quantity and quality of perceived itch show specific characteristics in different pruritic skin diseases. Clinical observations point to differences in the processing of pruritus by the central nervoussystem. The multidimensional Eppendorf Itch Questionnaire (EIQ)⁵ was used in hospitalized patients suffering from atopic eczema (AE, n = 62) and chronic urticaria (CU, n = 58). Total scores (127 items), emotional and sensory ratings, reactive behavior and visual analogue scale (VAS) ratings for itch intensity were evaluated. The mean VAS ratings of itch intensity showed no significant difference between the two diseases. In contrast, the total EIQ score was significantly higher in the AE group with 231.6 ± 11.5 vs. 175.2 ± 9.4. In 34 of 127 items, a significantly different rating was obtained, mostly with a higher load for the affective and some sensory items in AE. Significant differences were also seen in the description of the scratch response. Thus, itch perception in AE and CU differs on a qualitative level, influencing items relevant for quality of life. Similar findings were perceived in a study investigating the preventive effect of acupuncture on experimental itch - showing a preventive point-specific effect on emotional items of the EIQ.⁶ These findings accentuate the emotional component of the itch sensation; with possibly differences in Central Nervous System (CNS) processing.