Pruritus - Pathophysiologie, Klinik und Therapie - Eine Ubersicht. Pruritus - pathophysiology, clinical features and therapy - an overview

Aquagenic pruritus in polycythemia vera: characteristics and influence on quality of life in 441 patients

Aquagenic pruritus (AP) is a symptom typical for polycythemia vera, but very little is known about its exact frequency, characteristics, influence on quality of life, and proper treatment. Therefore, we investigated these aspects in a large cohort of German patients with polycythemia vera using a patient directed questionnaire. Our analysis revealed that 301 of 441 analyzed patients suffered from AP. In 64.8%, AP occurred on average 2.9 years prior to diagnosis of polycythemia vera. Only in 15.4% did this lead to a hematological investigation. AP occurs primarily on the trunk and proximal parts of the extremities. Most patients complain about itching (71.8%), the remainder about tickling, stinging, or burning sensations. Forty-four patients (14.6%) classified the pruritus as "unbearable." Patients with AP reported reduced global health status and higher fatigue, pain, and dyspnea. Only 24% of patients received pruritus specific treatment for pruritus consisting mostly of histamine antagonists, which ameliorated symptoms in about half of the patients. In 5.6% of patients, polycythemia vera directed therapy (phlebotomy/cytoreduction) resolved the symptoms. In summary, AP is a serious symptom in patients with polycythemia vera, which until recently was difficult to treat. The advent of the novel JAK2 inhibitors, however, may open new ways for therapy.

Pruritus as reason for encounter in general practice

Background

Pruritus is a common reason for consulting the general practitioner. Data from a primary care setting have seldom been published. The goal of the recent investigation was to characterize the consultation prevalence of pruritus, frequency of diagnostic and therapeutic procedures, accompanying symptoms and results of encounter or diagnoses of patients with pruritus.

Methods

Cross-sectional data were collected from randomly selected patients during the SESAM 2 study and compared with unpublished but publicly available data from the Dutch Transition Project and the published Australian BEACH study data.

Results

Overall 64 of the 8,877 patients from the SESAM 2 study consulted a physician for pruritus. The male to female ratio was 1.0 : 1.3. Pruritus was more frequent in children and people aged over 75 years. Physical examination was performed in all patients. Further diagnostic measures were seldom necessary. Drugs were prescribed in 84% of the cases. Allergic contact eczema and infectious diseases of the skin were the most frequent results of encounter or diagnoses. Medical adverse effects and allergic reactions should be considered as causes of pruritus. We found no significant association to systemic diseases.

Conclusions

In a primary care setting, pruritus occurs regularly. It is associated to (infectious) skin diseases. Acute dangerous courses are rare.

Keywords

Pruritus; Itch; General practice; Primary care; Reason for encounter

Pruritus: an overview of current concepts

Pruritus is an integral part of the patient's symptoms in numerous dermatological and systemic diseases in humans and animals. Comparable to chronic pain, pruritus can have a dramatic impact on the quality of life of the patient. In recent years, pruritus has been defined as an autonomous, pain-independent sensation, and itch-specific neurons, mediators, spinal neurons and cortical areas have been identified. These observations have not only improved our understanding of the neurobiology of itch but will also lead to improved diagnosis and to the development of new and more efficient therapeutic options. This article reviews the role of itch fibres and their response to various mediators of pruritus including histamine, vasoactive intestinal peptide (VIP), calcitonin gene-related peptide (CGRP), and substance P (SP), and opioids. Substances that may be involved in the induction or modulation of itch may be termed pruritogenic mediators and examples discussed include proteases, lipid mediators, neuropeptides, opioids and various cytokines. There is no single, generally accepted clinical classification of chronic pruritus. In the past pruritus has been classified on the basis of the neuroanatomical origin and on the potential underlying disease. Therapeutic options for the management of pruritus are discussed including topical and systemic therapies, assuming that trigger factors have been eliminated where possible. Topical agents may include capsaicin, the calcineurin inhibitors tacrolimus and pimecrolimus, and cannabinoid agonists such as N-palmitoyl ethanolamine. Systemic therapies may include antihistamines, anticonvulsants, opiate receptor antagonist or agonists, antidepressants, ciclosporin, and UV light.

Evaluation of chronic pruritus in older patients

Chronic pruritus, one of the main symptoms in dermatologic diseases, is often intractable and has a high impact on a patient´s quality of life. In addition to dermatologic disorders, chronic pruritus is associated with systemic and neurologic, as well as psychologic, diseases. Aging skin is considered to be more susceptible to pruritic disorders. Thus, owing to demographic changes, pruritus is becoming more prevalent. The elderly are often afflicted with comorbidities and polypharmacy, which can complicate diagnosis and therapy. In this review we present a rational work-up adapted to the special premises and needs of geriatric patients. This may facilitate the choice of suitable therapeutic regimens.

Topical tacrolimus for the treatment of lichen simplex chronicus

Owing to severe itching and scratching, the natural course of lichen simplex chronicus (LSC) is clinically characterized by typical lichenoid lesions. Topical corticosteroids are often used to treat LSC but after withdrawal a relapse will sometimes occur. Therefore, LSC can be difficult to treat over time. We report a 13-year-old boy suffering from LSC on two symmetrical circumscribed areas on the temple, whose lesions healed completely with tacrolimus 0.1% ointment within approximately 9 months. During active treatment no adverse drug reaction was observed. The patient is completely free of symptoms 3 years after cessation of treatment. We conclude that topical tacrolimus can be used as an effective, long-lasting therapeutic modality in treating LSC, especially in sensitive skin areas such as the face.

Mast cell functions in the innate skin immune system

Mast cells are not only potent effector cells in allergy, but are also important players in protective immune responses against pathogens. Most of our knowledge about mast cells in innate immunity is derived from models of sepsis, whereas their role in innate immune responses of the skin has largely been neglected in the past. Their particular pattern of distribution in the skin and their ability to sense and react to pathogens and other danger signals indicate that mast cells can be important sentinels and effector cells in skin immune responses. The recent findings reviewed here have confirmed this hypothesis and have established a prominent role for skin mast cells in innate immunity.

[Topical cannabinoid agonists. An effective new possibility for treating chronic pruritus]

BACKGROUND

Chronic, therapy-resistant pruritus often fails to respond to standard measures so new therapeutic approaches are needed. Recently, the expression of cannabinoid receptors on cutaneous sensory nerve fibers was described, so cannabinoid agonists seem a rational therapeutic option for pruritus.

PATIENTS

In an open application observation 22 patients with prurigo, lichen simplex and pruritus applied an emollient cream containing N-palmitoyl ethanolamine (PEA).

RESULTS

In 14/22 patients a good antipruritic effect could be documented. The average reduction in itch was 86.4%. The therapy was well-tolerated by all patients; neither burning burn nor contact dermatitis was observed.

CONCLUSIONS

Topical cannabinoid agonists represent an new effective and well-tolerated therapy for refractory itching of various origins. Creams with a higher concentration may be even more effective with broader indications.

Brachioradialer Pruritus

We report on a female patient with brachioradial pruritus, in whom the cause could be verified by purposeful diagnostics (e. g., MRI). The clinical symptoms with localized itching result from circumscribed nerve root compression and hyperexcitation of the nerve fibers. Under treatment with gabapentin, an anticonvulsant with a very good analgesic and good antipruritic effect, the itch ceased and the skin changes healed. This case shows that this special form of neuropathic itch requires targeted therapy, which apart from symptomatic treatment should primarily focus on remedying the cause, if feasible.

[Antipruritic therapy with the oral opioid receptor antagonist naltrexone. Open, non-placebo controlled administration in 133 patients]

BACKGROUND AND OBJECTIVES

The perception of pruritus is modified by endogenous and exogenous opioids via central opiate receptors and can be suppressed with opioid receptor antagonists. The aim of this investigation was to describe the efficacy and safety of naltrexone, an orally active opiate antagonist, in the treatment of severe, otherwise intractable pruritus of varying origins.

PATIENTS

A total of 133 patients with pruritus caused by inflammatory skin diseases (asteatotic dermatitis, atopic dermatitis, prurigo, and psoriasis vulgaris), liver- and renal diseases, cutaneous lymphoma, as well as with pruritus of unknown origin were treated with naltrexone (Nemexin) 50 to 150 mg daily.

RESULTS

A therapeutic response was achieved in 86 of the 133 (64.6%) patients. Naltrexone was most effective in prurigo nodularis, cutaneous lymphoma and pruritus of unknown origin. Tachyphylaxis occurred in 13% of the patients, but appeared late, and could be counterbalanced by raising the dosage. Adverse drug effects were restricted to the first two weeks of treatment and included mainly neurological (dizziness, headache, fatigue) and gastrointestinal (nausea, vomiting, diarrhea) symptoms.

CONCLUSIONS

The oral opiate antagonists may well be an effective, well-tolerated therapy for intractable pruritus in many diseases.

Wirksamkeit von Tacrolimus-0,1-%-Salbe bei Prurigoerkrankungen. Efficacy of tacrolimus 0.1 % ointment in prurigo

BACKGROUND

Potent topical corticosteroids are used the intense pruritus in prurigo diseases. Their long-term application leads to local side effects such as atrophy and telangiectasia.

PATIENTS AND METHODS

We treated 6 women (average age 64 years) with chronic prurigo with tacrolimus 0.1 % ointment (Protopic) to evaluate its efficacy in this clinical setting. Tacrolimus 0.1% ointment was applied twice a day for 4 weeks.

RESULTS

After one week, both clinical improvement and reduced pruritus were observed in all patients.

CONCLUSION

Tacrolimus 0.1% ointment represents a therapeutic option for the treatment of prurigo.

[Pruritus in pregnancy. A frequent diagnostic and therapeutic challenge]

Pruritus is the leading dermatological symptom during pregnancy. Besides preexisting or acquired dermatoses, there are a number of pregnancy-specific dermatological diseases such as PEP (polymorphic eruption of pregnancy, previously named PUPPP), pemphigoid (herpes) gestationis, and pruritus gravidarum that are accompanied by severe itching and scratching. Because of potential effects on the fetus, the treatment of pruritus in pregnancy requires prudent consideration. The use of topical and systemic treatments depends on the underlying aetiology of pruritus and the stage and status of the skin. In general, emollients, topical anti-pruritics and topical corticosteroids appear to be the safest options for localised forms of pruritus in pregnancy whereas systemic treatments and/or UV phototherapy are adequate for generalized pruritus. Systemic corticosteroids and a restricted number of antihistamines may be administered in severe cases. This paper highlights the major aetiologies of pruritus during pregnancy and points out the cornerstones of antipruritic therapy in recognition of our own clinical experiences and the current literature.

[Hydroxyethyl starch-(HES)-induced pruritus as secondary complication of an occupational accident]

A 29-year old employee (controller in the textile industry) had an occupational accident leading to a femoral fracture. After surgery, he developed acute respiratory distress syndrome (ARDS) necessitating intensive care treatment. Three weeks after the accident, he developed generalized severe itching on a daily basis unresponsive to systemic and topical treatments. After one year, the itching had decreased to approximately 50% of its initial intensity. Hydroxyethyl starch (HES)-induced pruritus was diagnosed, based on the typical history and clinical features, the proven administration of HES and its cutaneous tissue storage by electron microscopy. Drug-induced pruritus caused by the plasma expander hydroxyethyl starch can be a secondary consequence of an occupational accident and thus an issue in accident compensation claims.

Behandlung von Pruritus als Symptom von Hauterkrankungen mit dem Serotonin-Rezeptorantagonisten Ondansetron. Therapy of pruritus associated with skin diseases with the serotonin receptor antagonist ondansetron

BACKGROUND

Pruritus is often a stressing symptom and a therapeutic challenge. We report our experience with the serotonin receptor antagonist ondansetron in the symptomatic treatment of pruritus accompanying various skin diseases.

PATIENTS AND METHODS

The influence of ondansetron (8-12 mg orally per day) on pruritus was assessed in twelve patients with various skin disorders. The intensity of pruritus was quantitated daily by a visual analogue scale over the time period of one week before, during, and one week after treatment.

RESULTS

Ondansetron decreased pruritus intensity in prurigo simplex (four patients), asteatotic eczema (two patients), parapsoriasis en plaques, and pruritus of unknown origin (one patient each). One of two patients with atopic dermatitis experienced relief, whereas no benefit was observed in urticaria factitia and notalgia paraesthetica (one patient each).

CONCLUSIONS

Ondansetron may ameliorate the concomitant pruritus of some dermatologic diseases.

[Antipruritic effects of pimecrolimus and tacrolimus]

The development of topical calcineurin inhibitors resulted in a significant improvement in the treatment of inflammatory skin diseases such as atopic dermatitis. In addition, an excellent amelioration of pruritus could be observed. Other itchy dermatoses such as chronic irritative hand dermatitis, rosacea, graft-versus-host-disease, renal pruritus, lichen sclerosus, prurigo simplex, prurigo nodularis, scrotal eczema, and inverse psoriasis also have been treated successfully with pimecrolimus and tacrolimus. The antipruritic effect currently is believed to be related to the inhibition of inflammatory cytokines. Furthermore, recent investigations indicate a release of neuropeptides from sensory nerve fibers and degranulation of mast cells mediated by pimecrolimus and tacrolimus. Similar effects have been observed during capsaicin treatment. These findings may provide a possible explanation for initially observed calcineurin inhibitors related side-effects such as burning and pruritus. Moreover, the antipruritic potency may be related to a direct effect on nerve fibers leading to suppression of itch mediated by unknown mechanisms.