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.

中文翻译：

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周围过敏和下降抑制的丧失是慢性瘙痒症的标志。

导致瘙痒症慢性的神经生理机制尚未完全了解，并且尚不清楚这些机制是否在慢性瘙痒症（CP）的不同基础疾病之间有所区别。这项研究旨在检测各种起源的CP中的这种机制。共有120例具有炎症起源（特应性皮炎），神经性起源（腕radi神经性瘙痒）和结节型慢性瘙痒的CP患者（后者是慢性抓挠的模型），以及40位相匹配的健康对照者参加了这项研究。在所有患者组中，与其他物质刺激相比，用牛皮纸刺激引起更强烈的瘙痒感，但在健康对照组中则不然，这表明CP中皮肤机械和热敏C纤维敏化。与对照组相比，所有患者组均显示表皮内神经纤维密度降低。与对照组相比，在所有患者组中均观察到病痛调节作用降低，表明CP的下降抑制系统降低。总之，不同病因的CP显示出神经元改变的周围和中央混合模式，这可能有助于瘙痒的慢性，而瘙痒实体之间没有差异。我们的发现可能有助于针对这些致病机理的未来治疗策略的发展。不同病因的CP显示神经元改变的周围和中央混合模式，这可能有助于瘙痒的慢性，而瘙痒实体之间没有差异。我们的发现可能有助于针对这些致病机理的未来治疗策略的发展。不同病因的CP显示神经元改变的周围和中央混合模式，这可能有助于瘙痒的慢性，而瘙痒实体之间没有差异。我们的发现可能有助于针对这些致病机理的未来治疗策略的发展。