There are gender-specific differences not only in the quality, localization and triggering of CP but also in the underlying disease and scratching behaviour. These facts must be taken into account in the medical care of patients with CP and when conducting any kind of clinical research on itch. Further research is needed to achieve a gender-specific and gender-adapted diagnostics and treatment of CP.

BackgroundExperimental stress has been shown to have analgesic as well as allodynic effect in animals. Despite the obvious negative influence of stress in clinical pain conditions, stress-induced alteration of pain sensitivity has not been tested in humans so far. Therefore, we tested changes of pain sensitivity using an experimental stressor in ten female healthy subjects and 13 female patients with fibromyalgia.MethodsMultiple sensory aspects of pain were evaluated in all participants with the help of the quantitative sensory testing protocol before (60 min) and after (10 and 90 min) inducing psychological stress with a standardized psychosocial stress test (“Trier Social Stress Test”).ResultsBoth healthy subjects and patients with fibromyalgia showed stress-induced enhancement of pain sensitivity in response to thermal stimuli. However, only patients showed increased sensitivity in response to pressure pain.ConclusionsOur results provide evidence for stress-induced allodynia/hyperalgesia in humans for the first time and suggest differential underlying mechanisms determining response to stressors in healthy subjects and patients suffering from chronic pain. Possible mechanisms of the interplay of stress and mediating factors (e.g. cytokines, cortisol) on pain sensitivity are mentioned. Future studies should help understand better how stress impacts on chronic pain conditions.

Chronic pruritus (CP) is a frequent symptom in the general population; in 8% of all patients, it has a neuropathic origin. CP is of neuropathic origin when nerve fiber damage is responsible for the symptom. The damage can be caused by compression or degeneration of the nerve fibers in the skin or extracutaneous in peripheral nerves or the central nervous system. There are significant differences in the pathogenesis and in the clinical presentation of neuropathic CP. Localized neuropathic CP such as brachioradial pruritus or notalgia paresthetica are due to a circumscribed nerve compression and are often limited on the corresponding dermatome. In contrast, generalized neuropathic CP, as in small fiber neuropathies, may be associated with a systemic or metabolic underlying disease. It is not always easy to establish the diagnosis because a variety of diseases can be responsible for this type of CP. The present study shows an overview of possible diseases, diagnostic tools, and the relevant therapy strategies.

The complex nature and difficult-to-establish aetiology of chronic pruritus (CP) makes it challenging to provide medical care for patients with CP. This challenge can only be met with a multidisciplinary approach. The first multidisciplinary Itch Centre in Germany was established at the University of Münster in 2002 to meet the needs of this patient population. More than 2,500 outpatients and 400 inpatients are diagnosed and receive treatment each year. To ensure evidence-based medical care, an electronic system for medical documentation and patient-reported outcomes was established. Automated data transfer to a research database enables comprehensive data analysis. Our translational research has characterized peripheral and central itch mechanisms, provided novel clustering of CP patients, and identified novel target-specific therapies (e.g. neurokinin 1 receptor-antagonist). The multidisciplinary approach, combined with basic, clinical and translational research, enables comprehensive medical care of patients as well as implementation of high-quality experimental and clinical studies.

There are sex-specific differences in the relationship between the psychological symptoms and clinical characteristics of CP; higher anxiety scores were achieved by women. Whether psychological symptoms can be reversed when CP and scratch lesions improve is an issue that needs further exploration.