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Neurophysiological mechanisms leading to chronicity of pruritus are not yet fully understood and it is not known whether these mechanisms diverge between different underlying diseases of chronic pruritus (CP). This study aimed to detect such mechanisms in CP of various origins. A total of 120 patients with CP of inflammatory origin (atopic dermatitis), neuropathic origin (brachioradial pruritus), and chronic prurigo of nodular type, the latter as a model for chronic scratching, as well as 40 matched healthy controls participated in this study. Stimulation with cowhage induced a more intensive itch sensation compared with stimulation with other substances in all patient groups but not in healthy controls, arguing for sensitization of cutaneous mechano- and heat-sensitive C-fibers in CP. All patient groups showed a decreased intraepidermal nerve fiber density compared with controls. A decreased condition pain modulation effect was observed in all patient groups compared with controls, suggesting a reduced descending inhibitory system in CP. In sum, CP of different etiologies showed a mixed peripheral and central pattern of neuronal alterations, which might contribute to the chronicity of pruritus with no differences between pruritus entities. Our findings may contribute to the development of future treatment strategies targeting these pathomechanisms., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)

The aim of this multicentre, randomized, double-blind, placebo-controlled, cross-over, phase-II study was to determine the antipruritic effect of aprepitant vs. placebo in 58 patients with anti-histamine-refractory chronic pruritus in chronic nodular prurigo. Patients were randomized to receive either first oral aprepitant 80 mg/day or placebo for 4 weeks. Following a 2-week wash-out phase, the patients were crossed-over to receive the other treatment for 4 weeks. Primary efficacy criterion was the intra-individual difference between mean itch intensity (visual analogue scale) at baseline compared with the end of treatment period. Prurigo lesions, pruritus course, quality of life, patient benefits, and safety were secondary parameters. No significant differences were found between aprepitant treatment and placebo for any of the parameters investigated. Under the experimental conditions of the study, aprepitant, 80 mg daily for 4 weeks, did not have an antipruritic effect in patients with chronic prurigo. (DRKS00005594; EudraCT Number: 2013-001601-85).

Few studies have validated standard measurement instruments for evaluation of chronic pruritus. The Chronic Pruritus Tools Questionnaire PRURITOOLS assembles a set of instruments for the assessment of pruritus, such as the visual analogue scale (horizontal 100-mm line), numerical rating scale (0-10), verbal rating scale, and information on pruritus quality and improvement during therapy. This study, with 40 subjects, analysed PRURITOOLS regarding convergent validity and test-retest reliability (60 min), followed by a feasibility questionnaire. Test-retest reliability for PRURITOOLS items was excellent (intraclass correlation coefficient 0.84-1). Strong to very strong correlations between the pruritus intensity scales indicated convergent validity. The feasibility questionnaire showed an overall acceptance of PRURITOOLS, and the majority of subjects (82.5%) considered it an appropriate questionnaire to measure pruritus. In conclusion, PRURITOOLS offers validated tools for rapid pruritus assessment in routine care or endpoints of clinical trials. [ABSTRACT FROM AUTHOR]

Impaired sleep due to nocturnal pruritus is a common symptom in patients with chronic pruritus. How ever, there is no standardized, simplified instrument for assessing sleep-related problems in patients with chronic pruritus. After a literature search, we conducted 50 interviews with patients with chronic pruritus and tested 12 items most frequently used in routine sleep questionnaires. Afterwards, 2 sleep assessment questionnaires (Pittsburgh Sleep Quality Index; Regensburg Insomnia Scale) were selected for use in 88 patients with chronic pruritus with sleep impairment due to pruritus. They were completed twice; once before optimizing their individual pruritus therapy and once again after 4 weeks. During the latter survey, 21 patients reported that pruritus no longer negatively affected their sleep. These patients also achieved a significant improvement in their sleeping behaviour in the Regensburg Insomnia Scale. Therefore, the Regensburg Insomnia Scale appears to be well-suited to assessing sleep impairment in patients with chronic pruritus. [ABSTRACT FROM AUTHOR]