New aspects of itch pathophysiology: component analysis of atopic itch using the 'Eppendorf Itch Questionnaire'

Construction and Validation of a Novel "Pruritus Impact Scale" (PIS) for Assessment of Chronic Pruritus

Background

Currently available pruritus assessment tools may not always fulfill the needs of the Indian population and populations who share similar sociocultural backgrounds. To overcome this limitation, a new assessment tool "Pruritus Impact Scale (PIS)" was constructed and validated.

Aims and Objectives

The primary objective is to construct and validate the novel PIS. The secondary objective is to evaluate the responsiveness of PIS to changes in symptoms.

Patients and Methods

This study design was cross-sectional for the primary objective and longitudinal for the secondary objective. The study recruited 435 patients of chronic pruritus of different etiologies for the construction of the PIS scale. Patients were asked to fill out four different pruritus measuring tools i.e., Numerical Rating Scale (NRS), Dermatology Life Quality Index (DLQI), 12-item Pruritus Severity Score (PSS), and newly constructed PIS. The PIS was derived from existing standard assessment tools with certain modifications to keep a balance of psychometric properties of the scale and the sociocultural needs of the population. The validity and reliability of the scale was assessed. For detecting the response of PIS to change in pruritus intensity, 276 patients were followed and were instructed to refill all four scales at 6 weeks from the baseline. The responsiveness was judged by comparing the mean score of all scales at baseline with the mean score at 6 weeks. In addition, the changes in the scores among all 4 scales were correlated and compared.

Results

PIS showed strong internal consistency (Cronbach α = 0.882) and positively correlated with other validated pruritic tools such as NRS (ρ = 0.938, P < 0.0001), DLQI (ρ = 0.914, P < 0.01) and 12- PSS (ρ = 0.913, P < 0.001) at baseline. PIS showed satisfactory reproducibility at 3-hour intervals (Cronbach α = 0.994). Responsiveness to change in pruritus as measured by PIS at 6 weeks reassessment was correlated well with the changes in NRS (ρ = 0.689, P value < 0.0001), DLQI (ρ = 0.586, P value < 0.0001) and 12-PSS (ρ = 0.928, P value <0.0001).

Limitations

A noteworthy limitation of the present study is the lack of comparison of different items (within a construct) comprised in different tools used for comparison.

Conclusions

The newly constructed PIS is a valid tool in the studied population.

Drug Survival, Retention, and Persistence of Dupilumab in Adults and Adolescents with Atopic Dermatitis: A Narrative Literature Review

Atopic dermatitis (AD) is a chronic, relapsing inflammatory skin condition that can have a negative impact on a patient's quality of life. Long-term effectiveness is required to manage the symptoms of AD (skin inflammation, eczematous lesions, and itching). Because some of the systemic immunosuppressants used to treat AD have been associated with serious adverse events (AEs), other safer, more effective options, including dupilumab, have been proven effective long-term for treatment of adult and adolescent patients with moderate-to-severe AD. The long-term safety and effectiveness of a drug are usually confirmed in real-world studies by evaluating its performance over time. Measures such as drug survival, drug retention, drug persistence, or retention rates reflect whether treatment may be considered as satisfactory by both patients and physicians, meeting key clinical needs. This review aimed to describe the survival, retention, or persistence of dupilumab therapy in adults and adolescents with moderate-to-severe AD by conducting a PubMed search in March 2023 and screening for relevant publications. Globally, real-world studies with dupilumab have regularly reported high drug survival rates after 1, 2, and 3 years of observation, being consistently at 80-90%, with low rates of treatment discontinuation due to lack of efficacy or AEs. These findings are notably higher than 1- and 2-year drug survival rates of systemic immunosuppressants (including cyclosporine [37% and 20%, respectively] and methotrexate [41% and 33%, respectively]). Overall, real-world data on drug survival have confirmed that dupilumab provides long-term sustained efficacy and acceptable safety in patients with moderate-to-severe AD.

Translation, Reliability and Validity of the Greek Version of the 5-D Itch Scale in People With Chronic Kidney Disease Receiving Haemodialysis

BACKGROUND

Chronic kidney disease-associated pruritus (CKD-aP) is a condition that causes significant distress to people undergoing haemodialysis (HD). It significantly impacts individuals' sleep habits, everyday activities, social interactions, mental health and overall quality of life. A number of tools have been developed to evaluate the severity of pruritus. The 5-D itch scale is one of the most widely used tools for assessing various aspects of pruritus. In Greece, there is no validated and culturally adapted tool to assess pruritus in individuals with CKD receiving HD. Hence, this study aimed to evaluate the reliability and validity of the Greek version of the 5-D itch scale.

MATERIALS AND METHODS

The English version of the 5-D itch scale was translated into the Greek language according to international guidelines and was cross-culturally adapted in people with CKD on HD (Ν = 120). The intraclass correlation coefficient was used to assess the reliability of the instrument after the test-retest procedure (n = 30). Confirmatory factor analysis was conducted in order to test how well the 5-D itch scale one-factor model fits the data. Internal consistency reliability was determined by the calculation of Cronbach's alpha coefficient (n = 120). Convergent validity was tested through the correlation with the Kidney Disease Quality of Life Instrument Short-Form (KDQOL-SF) scale and the visual analogue scale. Statistical significance was set at p < 0.05. Analyses were conducted using IBM SPSS Statistics for Windows, version 26.0 (released 2019, IBM Corp., Armonk, NY).

RESULTS

The sample consisted of 120 people with CKD receiving HD (60.0% males, n = 72), with a mean age of 65.7 years (SD ±13 years), of whom 80 individuals reported CKD-aP. Regarding confirmatory factor analysis, this solution had a good model fit (χ2/df = 1.93; root mean square error of approximation (RMSEA) = 0.03; comparative fit index (CFI) = 0.92; Tucker Lewis index (TLI) = 0.93 and standardized root mean square residual (SRMR) = 0.05). The intraclass correlation coefficients were significant (p < 0.001) in all items and over 0.85. Cronbach's alpha for the 5-D itch scale total score was 0.75, indicating good reliability. The reliability index had minor changes after removing its items; thus, no item needed to be removed from the scale. The correlation of the 5-D itch scale with the KDQOL-SF (p = 0.002) indicates the good convergent validity of the scale.

CONCLUSION

The Greek version of the 5-D itch scale is an instrument with good reliability and validity, possessing the potential to be utilised by healthcare professionals for the purpose of the assessment of CKD-aP among Greek-speaking people undergoing HD.

[Quality of life and sleep quality in patients with chronic pruritus]

Pruritus is defined as a symptom that leads to scratching. Clinically, a heterogeneous group of clinical pictures of different etiology must be considered. Pruritus is characterized by varying intensity and duration. Many patients and/or their social environment, which is influenced by this, cite the impact on sleep quality as an accompanying main symptom. The patient's quality of life is affected depending on the severity of the pruritus and often leads to comorbidity such as depressive disorders or sleep disorders as well as to an impact on psychosocial well-being if it becomes chronic. To date, in addition to the medical history, the established examination methods have been the determination of the disease burden by assessing disease activity, e.g., with validated disease-specific scores, plus the assessment of quality of life using a dermatological quality of life index (DLQI). The latest studies show that this is by no means sufficient to determine the severity of disease and, as a result, to identify adequate treatment options.

AST-120 improved uremic pruritus by lowering indoxyl sulfate and inflammatory cytokines in hemodialysis patients

BACKGROUND AND HYPOTHESIS

Pruritus is a common and distressing symptom that affects patients with chronic kidney disease. The concentration of protein bounded uremic toxin was associated with the uremic pruritus. The aim is to assess the efficacy of AST-120 for uremic pruritus in hemodialysis patients.

MATERIALS AND METHODS

The participants were enrolled and then divided into the AST-120 treatment group and control group with a ratio of 2:1. All participants underwent pre-observation screenings two weeks before the study with three visits. In the treatment phase (week 1 to week 4), the treatment group added 6g/day of AST-120 along with routine anti-pruritic treatment. Visual analog scale (VAS) and biochemical parameters were measured.

RESULTS

The VAS score began to be lower in the AST-120 treatment group after the 5th visiting (p < 0.05). The reduction in indoxyl sulfate (IS) at 5th week along with TNF-alpha. The reduction ratio of indoxyl sulfate correlated with reduction of parathyroid hormone.

CONCLUSION

This study has demonstrated that the four-week treatment of AST-120 decreased the severity of uremic pruritus in patients with ESRD. The concentration of IS and TNF-alpha decreased in the AST-120 treatment group. The reduction of iPTH correlated with the reduction of IS in the AST-120 treatment.

Atopic Dermatitis: Managing the Itch

Atopic dermatitis has a substantial impact on sleep, appearance, psychological well-being, and other qualities of life. The visual appearance of lichenification, cheilitis, hyperpigmentation, ichthyosis, and erythema can be socially stigmatizing, and treatment of these symptoms is challenging. In managing pruritus in patients, practitioners should assess and document pruritus through questionnaires at each routine visit. Initially, practitioners should advise patients to employ nonpharmaceutical treatments such as emollients with wet wraps, elimination of triggers, changing scratching habits, and psychological interventions. If these methods of treatment are not successful or if the disease presentation is severe, pharmacological therapies should be employed. This chapter describes the therapeutic ladder for pruritus in atopic dermatitis and discusses each treatment modality in further detail for practitioners to advise their patients.First-line topical pharmaceutical agents include topical glucocorticoids and topical calcineurin inhibitors. Second-line topical agents include coal tar, menthol, capsaicin, or doxepin. After the use of topical agents has been exhausted, primary systemic agents can be applied. These include sedating antihistamines, nonsedating antihistamines, oral glucocorticoids, or cyclosporine A. Finally, neuromodulating or immunomodulating agents can be attempted, including SSRI/SNRIs, TCAs, immunosuppressants, neural modulators, and opioid receptor modulators. Outside of pharmacological treatments, phototherapy has been shown to provide a dramatic improvement of pruritus in atopic dermatitis and can be used at any stage of treatment including as a first-line agent.

Spanish translation and cultural adaptation of the 5-D itch scale in burn patients

The objective of this study was to make an equivalent and culturally adapted translation of an already existing scale for itching, the 5-D itch scale (5-D IS), developed as a short questionnaire and designed to measure pruritus, in order to be applied in a Spanish-speaking population. The 5-D IS consists of five sections that evaluate duration, degree, direction, disability and distribution of itching. The adequate translation process was performed according to the guidelines from the World Health Organization (WHO) and the International Society of Pharmacoeconomics and Outcomes Research (ISPOR). Two forward translations, one backwards translation, harmonization by an expert panel, and cognitive interviews with patients were included. The result was a culturally adapted Spanish version of the 5-D IS which was then field-tested in a burn population with an internal reliability of 0,83, considered good. As pruritus and pain are bothersome symptoms present in more that 90% of burned patients during the rehabilitation phase, this culturally adapted scale allows Spanish speakers clinicians to easily objectivize the severity of pruritus and measure the impact of any intervention or treatment.

Mild Skin Heating Evokes Warmth Hyperknesis Selectively for Histaminergic and Serotoninergic Itch in Humans

Chronic itch can severely affect quality of life. Patients report that their chronic itch can be exacerbated by exposure to warm conditions (“warmth hyperknesis”). The aim of this mechanistic study was to investigate the effect of mild heating of the skin in humans on various experimental models of itch. A total of 18 healthy subjects were recruited to the study. Itch was provoked by histamine, serotonin, or cowhage in 3 different sessions. The provoked area was heated with an infrared lamp, and the skin temperature was either not altered, or was increased by 4°C or 7°C. Subsequent to induction of itch, the itch intensity was recorded for 10 min while the skin was heated continuously throughout the entire period of itch induction. Heating the skin resulted in a significant increase in itch intensity when provoked by histamine or serotonin. It is possible that thermoception and pruriception interact and selectively produce a higher itch intensity in histaminergic and serotoninergic itch.

Differences in Psychometric Properties of Clinician- and Patient-Reported Outcome Measures for Atopic Dermatitis by Race and Skin Tone: A Systematic Review

The psychometric validity and reliability of widely used atopic dermatitis (AD) outcome measures across different races and ethnicities are unclear. We describe the rates of reporting race, ethnicity, and skin tone in studies testing the psychometric properties of AD outcome measures and compare the psychometric analyses across race, ethnicity, and skin tone. We systematically reviewed MEDLINE and EMBASE for studies reporting psychometric properties of clinician-reported or patient-reported outcome measures in AD (International Prospective Register of Systematic Reviews: CRD42021239614). Overall, 16,100 nonduplicate articles were screened; 165 met inclusion criteria. Race and/or ethnicity were reported in 55 (33.3%) studies; of those, race was assessed by self-report in 10 studies (6.1%) or was unspecified in 45 (27.3%). A total of 16 studies (9.7%) evaluated psychometric property differences by race, and only five (4.4%) of those did not recognize it as a limitation. Properties assessed across race, ethnicity, or skin tone were differential item functioning, convergent validity feasibility, inter-rater reliability, intrarater reliability, test‒retest reliability, and known-groups validity. Multiple instruments demonstrated performance differences across ethnoracial groups. This review highlights the paucity of race/ethnicity consideration for psychometric property testing in AD outcome measurement instruments. More AD outcomes instruments should be validated in diverse populations.

Development of the Patient- and Observer-Reported PRUCISION Instruments to Assess Pruritus and Sleep Disturbance in Pediatric Patients with Cholestatic Liver Diseases

INTRODUCTION

Understanding how patients experience their disease is a vital step in optimal disease management, and patient- and observer-reported outcome (PRO and ObsRO, respectively) measures can add important details to clinical information that is obtained as novel treatments are developed. Instruments that measure meaningful symptoms and impacts from the perspective of pediatric patients with cholestatic liver disease or their caregivers are needed. This study aimed to identify salient concepts in pediatric cholestatic liver disease, develop novel PRO and ObsRO instruments, and establish the instruments' content validity.

METHODS

Relevant signs, symptoms, and impacts of cholestatic liver disease were identified through a literature review, interviews with expert clinicians, and concept elicitation interviews with children and caregivers of children who had progressive familial intrahepatic cholestasis (PFIC), Alagille syndrome, biliary atresia, or primary sclerosing cholangitis. Additional cognitive debriefing interviews with patients and caregivers were performed to ensure that participants could understand the instructions, questions, and response scales of the PRO and ObsRO instruments, with modifications made as necessary to improve comprehension and/or usability.

RESULTS

A total of 36 interviews with patients and caregivers were conducted. Pruritus and sleep disturbance (e.g., difficulty falling or staying asleep due to itch) were identified as the most problematic symptom and significant impact, respectively, of the pediatric cholestatic liver diseases assessed. The ObsRO and PRO instruments, called PRUCISION, focus on these key disease features in the morning and evening. Several modifications were made to the draft instruments following cognitive interviews. The final PRUCISION PRO and ObsRO measures are designed as an electronic diary to be completed twice daily. The response scales include pictorial, verbal, and numeric scales.

CONCLUSION

Novel PRO and ObsRO PRUCISION instruments were created that evaluate the patient experience of cholestatic pruritus in children with PFIC and other cholestatic liver diseases. The content validity of the PRUCISION instruments is established.

Characterization of Cowhage-induced Pruritus in Sensitive Skin: An Observational Laboratory Study

Sensitive skin is a prevalent syndrome, characterized by discomfort in response to mild stimuli, which impacts on quality of life. Pruritus is one of the major symptoms of sensitive skin. However, the pathomechanism of sensitive skin is insufficiently understood. As an experimental model for pruritus, the cowhage skin prick test might provide insight into the understanding of sensitive skin. This study aimed to specify the characteristics of cowhage-induced pruritus in sensitive skin. Female volunteers, 20 with sensitive skin and 20 controls, were recruited. Self-report questionnaires were distributed and the responses evaluated; moreover, alongside assessments by dermatologists, skin physiology assessments, lactic acid sting test, capsaicin test and cowhage skin challenge were performed. Pruritus in sensitive skin was perceived as more intense and longer-lasting than in normal skin, with different qualities of accompanying sensations. Cowhage skin challenge results showed moderate consistency with clinical assessments. The results suggest that cowhage skin challenge could be a new tool for the assessment of sensitive skin.

Dissecting the precise nature of itch-evoked scratching

Itch is a discrete and irritating sensation tightly coupled to a drive to scratch. Acute scratching developed evolutionarily as an adaptive defense against skin irritants, pathogens, or parasites. In contrast, the itch-scratch cycle in chronic itch is harmful, inducing escalating itch and skin damage. Clinically and preclinically, scratching incidence is currently evaluated as a unidimensional motor parameter and believed to reflect itch severity. We propose that scratching, when appreciated as a complex, multidimensional motor behavior, will yield greater insight into the nature of itch and the organization of neural circuits driving repetitive motor patterns. We outline the limitations of standard measurements of scratching in rodent models and present new approaches to observe and quantify itch-evoked scratching. We argue that accurate quantitative measurements of scratching are critical for dissecting the molecular, cellular, and circuit mechanisms underlying itch and for preclinical development of therapeutic interventions for acute and chronic itch disorders.

Development and preliminary validation of the patient-reported Chronic Itch Burden Scale assessing health-related quality of life in chronic pruritus

BACKGROUND

Chronic pruritus (CP) significantly affects patients' health-related quality of life (HRQoL). Very few self-reported HRQoL questionnaires exploring CP have been developed according to international guidelines, thus limiting their use in preauthorization trials.

OBJECTIVES

To develop a self-reported HRQoL questionnaire in patients with CP owing to psoriasis, atopic dermatitis, seborrhoeic dermatitis of the scalp or idiopathic dermatitis, and to explore the preliminary psychometric properties of the questionnaire.

METHODS

The study was performed in France. A conceptual framework was developed based on a structured literature review and expert insight, and was improved using three focus groups involving 19 participants. A 50-item questionnaire was created and tested with 21 participants using cognitive debriefings; 11 items were removed. A cross-sectional study including 251 participants was performed to explore the preliminary psychometric properties of the 39-item questionnaire. Dimensionality was explored using principal component analysis. Cronbach's alpha and correlation coefficients (interitem, item-total score and item-dimension score) were measured. The number of items was reduced through expert consensus.

RESULTS

In the 39-item version, three main dimensions were identified (Cronbach's alpha = 0·94) and all correlation coefficients were > 0·34. Upon review, 13 items were deleted owing to poor quality and six items were deleted by the team, generating a 20-item version. The questionnaire's factorial structure was best reflected with a two-dimension solution, i.e. (i) social and emotional repercussions and (ii) relation to others, fear of judgement.

CONCLUSIONS

The Chronic Itch Burden Scale patient-reported questionnaire explores broad aspects of HRQoL that are relevant for patients with various skin diseases. Its good cross-sectional validity makes it useful for trials and practitioners.

Acupuncture for the Treatment of Itch: Literature Review and Future Perspectives

Background: Chronic pruritus is a prevalent, multifactorial and debilitating condition that is often underestimated. This article reviews current evidence to evaluate the efficacy of acupuncture for the treatment of itch. Results: Although many researchers have conducted observational studies, clinical trials, and systematic reviews on the subject, the lack of more-robust and well-designed studies to prove the effectiveness of acupuncture in the management of itch is evident. Many published studies are of poor quality, with no clear description of randomization methods, and an absence of control groups and measurable clinical outcomes. In addition, a lack of standardization in methods for assessing pruritus and the acupuncture treatment protocols hinders more-comprehensive and higher-quality pooled data analysis. Conclusions: Current evidence cannot fully support acupuncture for the treatment of itch yet.

Joint AAD-NPF Guidelines of care for the management and treatment of psoriasis with topical therapy and alternative medicine modalities for psoriasis severity measures

Psoriasis is a chronic, inflammatory, multisystem disease that affects up to 3.2% of the United States population. This guideline addresses important clinical questions that arise in psoriasis management and care and provides recommendations based on the available evidence. The treatment of psoriasis with topical agents and with alternative medicine will be reviewed, emphasizing treatment recommendations and the role of dermatologists in monitoring and educating patients regarding benefits as well as risks that may be associated. This guideline will also address the severity assessment methods of psoriasis in adults.

Validity of skin blot examination for albumin and nerve growth factor β to detect itching of the skin in Indonesian older adults

AIM

Itching, a common skin disorder, impacts the quality of life of individuals. Itchy skin occurs more with increasing age and the prediction of itchy skin prognosis is necessary to provide good skincare. This study validated biomarkers in skin blotting to identify and measure itching sensation as well as conventional methods to measure skin barrier function.

MATERIALS AND METHODS

From a cross-sectional study conducted in Long-term Care (LTC) facilities in Indonesia itching symptoms were obtained through a questionnaire. Skin conditions were assessed using photographs, stratum corneum (SC) hydration, skin pH, and skin blotting for biomarkers: albumin, interleukin 2 (IL2), nerve growth factor β (NGFβ), and thymic stromal lymphopoietin (TSLP). Association of skin measurements with the presence of skin blotting and trends analysis were conducted.

RESULTS

Altogether, 564 LTC residents (average age, 70 years) participated. The SC hydration, skin pH, albumin, and NGFβ were associated with the presence of itch (p value= <0.001, <0.001, <0.001, and <0.001, respectively). The signal levels of skin blotting biomarkers were higher in itch group than in the non-itch group. Additionally, the higher quantile of SC hydration was significantly associated with a lower intensity level of NGFβ and TSLP (p value = 0.005, 0.003, respectively). The lower quantile of skin pH (better skin condition) was significantly associated with lower albumin, NGFβ, and TSLP (p value = 0.048, 0.035, and <0.001, respectively).

CONCLUSION

The albumin, NGFβ, and TSLP could be a candidate for measurement of itchy skin among older adult with disrupted skin barrier function and local skin inflammation.

No significant relation of proinflammatory slanDCs with uremic pruritus

The pathogenesis of the pruritus associated with chronic kidney disease-(CKD-aP) is not completely understood. Endocrine, metabolic, neuropathic, and inflammatory disorders were suspected to be the origin of CKD-aP. Based on the hypothesis which suggests that deregulated systemic inflammation may play a crucial role in CKD-a, we investigated the potential relation of an inflammatory monocyte subset (slanDCs) with CKD-aP. Itch questionnaire, visual analogue scale (VAS)-scoring, and Dermatology Life Quality Index (DQLI) were applied for the characterization of itch sensation. VAS-scoring was re-evaluated after 6 months. Monocytes were flow-cytometrically categorized into classical, intermediate, and non-classical subsets. slanDCs are part of the non-classical monocyte subpopulation. Sixty-six hemodialysis patients (CKD5-D) were screened of whom 43 met the study inclusion criteria. In all, 46.5% of patients were scored pruritus-positive (CKD-aP+). CKD-aP severity level of patients was moderate at the start of the study (VAS 5.3 ± 2.5) and remained unchanged after 6 months (VAS: 5.2 ± 1.9, P < 0.757). Thirty percent of patients were affected with mild, 30.0% with moderate, and 35.0% with severe itchiness. In contrast to all other factors tested solely slanDC showed a weak correlation to VAS-score (r = 0.41, P = 0.07). slanDC frequencies between CKD5-D patients with and without itch sensation, however, were not significantly different. Endocrine problems appeared to influence CKD-aP. CKD-aP + patients had significantly higher L-thyroxin supplementation than CKD-aP- (50.0% vs 8.7%, P < 0.005). A binary logistic regression model confirmed the significance of L-thyroxin medication on chronic itch problems of our CKD5-D patients ( P < 0.007). There is no clear evidence that slanDCs are related to uremic pruritus. Therefore, other factors underlie the pathophysiology of CKD-aP.

Clinical validation and utility of Chinese Eppendorf Itch Questionnaire in adults with chronic pruritus symptoms

BACKGROUND

Pruritus, or itch, is a prevalent symptom causing profound health burden in many dermatological and non-dermatological disorders. Several itch questionnaires have been created to assess itch. Particularly, Eppendorf Itch Questionnaire (EIQ) is widely accepted since it encompasses various aspects of itch, including intensity, affects, coping behavior, and motivation to scratch.

METHODS

In a cross-sectional survey, we examined the validity, reliability and clinical utility of Traditional Chinese EIQ.

RESULTS

We administered the consensus version to 128 adults (median: 48.5 years, interquartile range [IQR]: 39-63) with active itch for more than 6 weeks at the Outpatient Clinics of three medical centers in Taiwan. Clinical diagnoses included psoriasis (N = 82), xerosis (N = 34), or other dermatitis (N = 12). Cronbach's alpha for each EIQ scale ranged 0.82-0.98, suggesting good to excellent internal consistency and reliability. Three EIQ scales significantly correlated with visual analogue scale (VAS) for itch intensity (P ≤ 0.001 for median test), supporting for its concurrent validity. None of EIQ scale was statistically correlated with Psoriasis Area Severity Index (PASI) scores in psoriasis patients, confirming its discriminant validity. Moreover, patients of different diagnoses had distinct responses to the multi-scale EIQ index, affording it a better clinical test (area-under-the-ROC curve [AUC]: 0.76, 95% CI: 0.63-0.90) than VAS alone (AUC: 0.42, 95%CI: 0.24-0.59) in distinguishing dermatitis/eczema-related itch from psoriasis or xerosis-related itch.

CONCLUSION

We demonstrated the reliability and validity of Chinese EIQ in adult patients with chronic itch at the outpatient setting. The study also revealed the diversified aspects of itch across patients with various dermatoses.

When life is an itch: What harms, helps, and heals from the patients' perspective? Differences and similarities among skin diseases

Itch is the commonest skin-related symptom, associated with a high psychosocial and economic burden. While the main focus of itch research lies on a few chronic skin diseases, only little is known about the perception of itch, itch-aggravating/-relieving factors and treatment preferences in patients with acute and chronic itch of various etiology. In this cross-sectional study, we assessed these aspects in 126 patients (mean age 61.7 ± 18.4 years, 67 females, median itch duration 3.9 years) using a 78-item questionnaire. The diseases were categorized into 11 diagnostic groups for descriptive analysis; the three most frequent groups ("atopic dermatitis," "nonatopic eczema," "inflammatory dermatoses") were statistically compared. Itch was most often perceived as localized 42.9%, burning (40.5%), and worrying (39.7%) with worsening in the evening (49.2%), due to warmth (42.1%) and sweating (26.2%). While itch perception, itch-aggravating factors and treatment preferences differed broadly among patients, the itch-relieving personal strategies were more uniform ("scratching by hand 70.6%, applying topicals 57.9%). Also, 69.8% of patients suffered from itch-related sleep disturbance, consequently affecting their relatives in 30.0%. Subgroup comparisons revealed significant differences regarding itch-aggravating factors (P = .0012) and itch duration (P = .0082). Patients rated the antipruritic effectiveness of phototherapy, "complementary and alternative medicine" and "other tablets" as high, but oral antihistamines, "cortisone tablets" and any topical as only moderately efficacious. The preferred administration of an ideal itch treatment was "creams/ointments" (51.6%) or "tablets" (35.7%), only few patients preferred "injections" or "patches." Consideration of such differences and similarities in itch characteristics and treatment preferences could help to better tailor treatment in itch patients.

Enhanced Thermal Sensitivity of TRPV3 in Keratinocytes Underlies Heat-Induced Pruritogen Release and Pruritus in Atopic Dermatitis

Itch in atopic dermatitis (AD) is aggravated under warm conditions. Transient receptor potential vanilloid (TRPV) 3, a member of the thermosensitive transient receptor potential channels, is activated by innocuous heat and is abundantly expressed in keratinocytes. The potential role of TRPV3 in itch is illustrated in TRPV3 channelopathies of humans and mice. However, the role of TRPV3 in heat-induced itch in AD and the underlying mechanisms are unclear. Here we showed that keratinocytes isolated from patients with AD exhibit enhanced expression and heat sensitivity with hyperactive channel function of TRPV3. Heat stimulus induced enhanced secretion of thymic stromal lymphopoietin, nerve growth factor, and prostaglandin E₂ by keratinocytes from patients with AD through TRPV3 activation. TRPV3 agonists increased thymic stromal lymphopoietin, nerve growth factor, prostaglandin E₂, and IL-33 production in human keratinocytes and induced scratching behavior upon intradermal injection in mice. TRPV3 was upregulated in the skin of MC903-induced AD mouse model. Heat stimulation to MC903-treated mice increased scratching behavior and produced higher levels of thymic stromal lymphopoietin, nerve growth factor, prostaglandin E₂, and IL-33 from the epidermis, which were attenuated by pharmacologic inhibition of TRPV3. Moreover, neutralization of thymic stromal lymphopoietin reduced heat-evoked scratching in MC903-challenged mice. These results suggest that TRPV3 is a potential therapeutic target for heat-induced itch in AD.

Characterization of cowhage-induced pruritus in inflamed and non-inflamed skin

BACKGROUND AND OBJECTIVE

Pruritus is a major symptom of many inflammatory diseases and impacts greatly the quality of life in patients. We aimed to specify the characteristics of experimentally induced pruritus in normal skin and in experimentally induced inflammatory dermatitis in healthy volunteers.

METHODS

Skin inflammation was induced by the repeated application of sodium lauryl sulphate (SLS 2%) on the volar forearms of 30 healthy volunteers. Inflammatory dermatitis intensity was assessed using the eczema score adapted from Frosch and Kligman. Non-histaminergic pruritus was induced by cowhage spicules rubbed on the volar forearms and recorded for 30 min on a 10-cm visual analogue scale (VAS) in both non-inflamed and inflamed skin.

RESULTS

Induction of inflammatory dermatitis by SLS resulted in a mild inflammatory dermatitis with an inflammation score of 2.3 ± 0.1 within 7 days of treatment. Cowhage-induced pruritus was of markedly higher intensity (P < 0.001), and all but two individuals had higher maximum pruritus intensity in inflamed skin as compared to non-inflamed skin, whereas the kinetics of the pruritus response were similar. The quality of cowhage-induced pruritus was significantly different with more 'burning' and 'painful sensations' in inflamed skin (P < 0.01). Maximum pruritus intensity in inflamed skin strongly correlated with maximum pruritus intensity in non-inflamed skin (r = 0.51, P = 0.004). Skin hydration, skin barrier integrity and dermatitis severity did not correlate with pruritus intensity.

CONCLUSION

Taken together, pruritus in inflamed skin is perceived as more intense, painful and burning. This may explain, in part, why pruritus is a major driver of quality-of-life impairment in patients with chronic inflammatory skin conditions such as atopic dermatitis.

Exploring content and psychometric validity of newly developed assessment tools for itch and skin pain in atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a common skin disorder characterized by chronic inflammation, altered skin barrier function, and inflammatory cell skin infiltration that decreases health-related quality of life (HRQoL). The study objective was to understand the patient perspective of AD burden and determine suitable patient-reported outcome (PRO) measures.

METHODS

This mixed methods study involved the collection of qualitative and quantitative information from adults (≥ 18 years old) and adolescents (12 - 17 years old) with clinician-confirmed AD regarding their experiences of AD symptoms and its impact on HRQoL. The first part of the study included three stages: in-person concept elicitation (CE) interviews, a 2-week daily electronic diary (eDiary) study, and in-person cognitive debriefing (CD) interviews. An Itch numeric rating scale (NRS) (v1.0) and a Skin Pain NRS (v1.0) evaluation during CD interviews required participants to think about their 'worst' itch and 'worst' skin pain in the past 24 h. Other PRO measures allowed for psychometric testing. The second part of the study involved telephone-depth interviews (TDIs) and qualitative feedback from participants who had not participated in the CD interviews. Qualitative data were thematically analyzed. Psychometric evaluation of NRS measures was performed using eDiary data.

RESULTS

In the CE interviews, itch and/or itching and skin pain were the most prevalent symptoms consistently discussed by participants. Both NRS measures demonstrated strong psychometric reliability and were applicable across ages with suitable concurrent validity. During the CD interviews, some participants focused their answers on their 'average' itch/itching in the past 24 h, rather than their 'worst' itch. Some participants answered the Skin Pain NRS thinking about general pain or other types of pain, rather than skin pain specifically. Consequently, modifications to both measures addressed these issues and re-tested as paper-and-pen versions in subsequent TDIs. Itch NRS (v2.0) modifications helped participants focus on their worst itching. Most participants preferred Skin Pain NRS v2.0b, which included skin pain descriptors.

CONCLUSIONS

Itching and skin pain are the most important and relevant AD symptoms. The Itch NRS (v2.0) and Skin Pain NRS (v2.0b) appear to be appropriate endpoints for the assessment of itching and skin pain severity for clinical trials with adults and adolescents with AD.

Effect of adding nalbuphine to intrathecal bupivacaine with morphine on postoperative nausea and vomiting and pruritus after elective cesarean delivery: a randomized double blinded study

BACKGROUND

The use of intrathecal morphine may result in serious side effects in parturients undergoing cesarean delivery. Nalbuphine, is a mu receptor antagonist and a ĸappa receptor agonist. Combinations of opioid agonist and agonist antagonist can decrease the incidence of opioid related side effects. We aimed to investigate the effect of adding nalbuphine, to intrathecal morphine on postoperative nausea and vomiting and pruritus after a cesarean delivery.

METHODS

Eighty parturient undergoing elective cesarean delivery under spinal anesthesia were randomized into two similar groups. Group 1: received 10 mg of 0.5% hyperbaric bupivacaine with 0.2 mg morphine. Group 2: received as a group 1 plus 0.5 mg nalbuphine, with total volume 2.5 mL in both groups. Measurements: Data on the severity of nausea and vomiting were collected using a numerical rating scale and visual analogue scale was used to quantify pruritus. Onset and duration of sensory blockade, Visual Analog Scale for pain, the first time to ask for rescue analgesia and total rescue analgesic consumption were recorded.

RESULTS

Nausea and vomiting and pruritus severity scores and number of patients developed nausea and vomiting and pruritus were significantly lower (P<0.001) in group 2. Onset and duration of sensory block, time to first request for rescue analgesia, Visual Analog Scale for pain and paracetamol consumption showed no statistically differences between both groups (P>0.05).

CONCLUSIONS

We concluded that the addition of nalbuphine to intrathecal bupivacaine plus morphine significantly reduced the incidence and severity of postoperative nausea and vomiting and pruritus without affecting analgesic potency.

Consensus-based European guidelines for treatment of atopic eczema (atopic dermatitis) in adults and children: part I

This guideline was developed as a joint interdisciplinary European project, including physicians from all relevant disciplines as well as patients. It is a consensus-based guideline, taking available evidence from other guidelines, systematic reviews and published studies into account. This first part of the guideline covers methods, patient perspective, general measures and avoidance strategies, basic emollient treatment and bathing, dietary intervention, topical anti-inflammatory therapy, phototherapy and antipruritic therapy, whereas the second part covers antimicrobial therapy, systemic treatment, allergen-specific immunotherapy, complementary medicine, psychosomatic counselling and educational interventions. Management of AE must consider the individual clinical variability of the disease; highly standardized treatment rules are not recommended. Basic therapy is focused on treatment of disturbed barrier function by hydrating and lubricating topical treatment, besides further avoidance of specific and unspecific provocation factors. Topical anti-inflammatory treatment based on glucocorticosteroids and calcineurin inhibitors is used for flare management and for proactive therapy for long-term control. Topical corticosteroids remain the mainstay of therapy, whereas tacrolimus and pimecrolimus are preferred in sensitive skin areas and for long-term use. Topical phosphodiesterase inhibitors may be a treatment alternative when available. Adjuvant therapy includes UV irradiation, preferably with UVB 311 nm or UVA1. Pruritus is targeted with the majority of the recommended therapies, but some patients may need additional antipruritic therapy. Antimicrobial therapy, systemic anti-inflammatory treatment, immunotherapy, complementary medicine and educational intervention will be addressed in part II of the guideline.

A Comprehensive Conceptual Model of the Experience of Chronic Itch in Adults

BACKGROUND

Itch is common and often debilitating. Itch is best assessed by self-report, often using patient-reported outcome measures (PROMs). Current PROMs for itch are limited and may not capture its full impact on quality of life (QOL).

OBJECTIVE

We sought to develop a comprehensive conceptual model of itch to improve the understanding of itch for clinicians and to serve as a framework for development of efficient and valid PROMs of itch.

METHODS

Using mixed methods, including systematic review (n = 491 articles), semi-structured interviews (n = 33 adults with chronic itch with multiple etiologies), and grounded theory using a constant comparative approach, we developed a conceptual model of itch.

RESULTS

We found the Wilson and Cleary model to be a reasonable framework for organizing our findings. It includes five primary components: biological and physiological variables, symptom status, functional status, general health perceptions, and QOL. We propose a causal relationship beginning with the biological and physiological driving factors, with direct and indirect impacts of itch and its sequelae, including pain and sleep disturbance. These can impair function, lead to task avoidance, stigma, social life and relationship problems, emotional disturbances, and treatment burden. Together, these sequelae alter one's perceptions of health, QOL, and treatment response.

CONCLUSIONS

Our conceptual model demonstrates the profound patient-burden of itch and identifies unmet needs in the evaluation and management of itch.

[Terms for the feeling of itching in the Bavarian dialect]

BACKGROUND

Pruritus can have many different causes and is a very subjective sensation. As dialects show a greater diversity of linguistic expressions than standard languages, the description of the sensation of pruritus in a dialect might carry additional information about the quality of pruritus.

METHOD

This cross-sectional study was carried out in Q1/2016 in the rural Bavarian Forest region in Bavaria, Germany. Participants were recruited in the waiting rooms of local doctors. They were asked to complete four sentences composed in the Bavarian dialect in which one word per sentence that signified the sensation of pruritus had been replaced by a blank space.

RESULTS

In total, the 1,007 participants (mean age 49.97 years, SD = 15.76; 58.2% female) named 2,870 expressions, 144 excluding duplicates. 98.7% of the expressions could be matched to 13 underlying terms. The most frequent ones were "jucken" ('to itch'', 59.5%), "brennen" ('to burn', 26.5%), "kribbeln" (no English equivalent, 1.1%), "kratzen" ('to scratch', 0.7%) and "beißen" ('to bite', 0.6%). The use of the different expressions was strongly situational: In 75% of the cases "brennen" ('to burn') was used in the context of contact to a stinging nettle (in German 'Brennnessel'). Two of the 13 expressions ("kribbeln" and "bitzeln", no English equivalents) were even used only in this scenario.

DISCUSSION

In the Bavarian dialect several different expressions for the sensation of pruritus exist. Although "jucken" ('to itch') is the most common expression for the sensation of pruritus, the German medical terms "Pruritus" ('pruritus') and "Juckreiz" ('itch') don't do justice to the situational use of expressions in the dialect.

Translation of the 5D Itching Scale from English to Malay, and Its Validation among Patients with Chronic Kidney Disease in Malaysia

Introduction

Several tools have been developed to assess the severity of pruritus. In Malaysia, no tool has been validated to assess pruritus in patients with chronic kidney disease (CKD). Therefore, the aim of our study was to validate the Malay 5D itching scale (M5D-IS) among patients with CKD in Malaysia.

Method

The English version of the 5D-IS was translated into Malay according to International Guidelines. Face and content validity was determined by an expert panel and pilot tested in patients with end-stage renal disease (ESRD). The M5D-IS was then validated in a tertiary hospital in Malaysia from May to June 2016. We recruited patients with (i.e., patients with ESRD) and without pruritus (i.e., patients with stage 1–3 CKD) (to determine if the M5D-IS could discriminate between the two groups), and administered the M5D-IS at baseline and 2 weeks later. Exploratory factor analysis was used to examine the construct validity. Internal consistency was assessed using Cronbach’s alpha and intraclass correlation coefficient was calculated to assess the reliability of the instrument.

Results

A total of 70 participants were recruited (response rate = 100%). The majority were males (51.4%) and Malay (67.1%). Exploratory factor analysis revealed that the 5D-IS had 2-factor loadings: “daily routine activity” and “pattern of itching,” which explained 77.7% of the variance. The overall score of the M5D-IS, as well as for each domain, was significantly worse in participants with pruritus (9.83 ± 0.35), compared to those without pruritus (5.51 ± 0.93, p < 0.001). The overall Cronbach’s alpha for the M5D-IS was (0.861), indicating adequate internal consistency. At test–retest, the intraclass correlation coefficient was significantly correlated.

Conclusion

The M5D-IS was found to be a valid and reliable instrument to assess pruritus among patients with CKD in Malaysia.

12-Item Pruritus Severity Scale: Development and Validation of New Itch Severity Questionnaire

Introduction

A validated assessment of pruritus intensity is an important but still difficult clinical problem due to a subjective nature of this sensation.

Objective

The aim of this study was the creation and validation of new itch severity questionnaire assessing pruritus intensity.

Material and Methods

A total of 148 patients with pruritic dermatoses were asked to assess pruritus intensity using 12-Item Pruritus Severity Score (12-PSS) and Visual Analogue Scale (VAS). Patients were also asked to complete the Dermatology Life Quality Index (DLQI) and Hospitality Anxiety and Depression Scale (HADS). Test-retest comparison of 12-PSS was conducted in 102 subjects who completed the itch questionnaire twice with the 3- to 5-day interval.

Results

We have created the 12-PSS assessing pruritus intensity (two questions), pruritus extent (one question) and duration (one question), influence of pruritus on concentration and patient psyche (four questions), and scratching as a response to pruritus stimuli (four questions). A maximum scoring was 22 points. The results showed strong consistency (Cronbach α coefficient 0.81). A significant correlation was observed with VAS (r = 0.58, p < 0.001) and quality of life level according to DLQI (r = 0.53, p < 0.001). Test-retest comparison in 102 subjects revealed a satisfactory reproducibility of achieved results (ICC = 0,72).

Conclusions

The newly developed pruritus severity questionnaire may be used in daily clinical practice in the future.

Evaluation of the measurement properties of symptom measurement instruments for atopic eczema: a systematic review

BACKGROUND

Symptoms have been identified as a core outcome domain for atopic eczema (AE) trials. Various instruments exist to measure symptoms in AE, but they vary in quality and there is a lack of standardization between clinical trials. Our objective was to systematically evaluate the quality of the evidence on the measurement properties of AE symptom instruments, thereby informing consensus discussions within the Harmonising Outcome Measures for Eczema (HOME) initiative regarding the most appropriate instruments for the core outcome domain symptoms.

METHODS

Using the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) checklist and predefined criteria for good measurement properties on identified development and validation studies of AE symptom instruments, a best evidence synthesis was performed to draw an overall conclusion on quality of the instruments and to provide recommendations.

RESULTS

Eighteen instruments were identified and evaluated. When the quality and results of the studies were considered, only five of these instruments had sufficient validation data to consider them for the core outcome set for the core outcome domain symptoms. These were the paediatric Itch Severity Scale (ISS), Patient-Oriented Eczema Measure (POEM), Patient-Oriented SCOring Atopic Dermatitis (PO-SCORAD), Self-Administered Eczema Area and Severity Index (SA-EASI) and adapted SA-EASI.

CONCLUSIONS

ISS (paediatric version), POEM, PO-SCORAD, SA-EASI and adapted SA-EASI are currently the most appropriate instruments and therefore have the potential to be recommended as core symptom instrument in future clinical trials. These findings will be utilized for the development of a core outcome set for AE.

Skin provocation tests may help to diagnose atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a common skin disorder. Its diagnosis relies on clinical judgment. Mild and untypical manifestations may cause diagnostic difficulties. Biomarkers for the differential diagnostic workup of AD are needed.

OBJECTIVE

To test whether the results of skin provocation with cowhage, an established model of histamine-independent pruritus, and histamine are different in AD patients and healthy subjects and whether these tests may be used as diagnostic markers of AD.

METHODS

Twenty-two AD patients and 18 healthy controls were subjected to topical cowhage provocation and skin prick testing with histamine and assessed for differences in the quality, intensity, and persistence of itch, for wheal diameter, volume, and flare size and intensity.

RESULTS

Patients with AD, compared with healthy controls, exhibited significantly smaller histamine-induced flares (P < 0.01) and markedly longer itch persistence after provocation with cowhage (P < 0.01). Both parameters showed good diagnostic properties for AD (area under the receiver operating characteristic (ROC) curve 0.78 and 0.80, respectively). The persistence of cowhage-induced itch for at least 30 min and a histamine-induced flare of less than 2 cm in diameter were reliable thresholds for the diagnosis of AD. If combinations of the results of both tests were used, their sensitivity and specificity of diagnosing AD were up to 91% and 94%, respectively.

CONCLUSION

The clinical benefit of cowhage and histamine skin provocation tests should be investigated in further studies. Long persistence of cowhage-induced itch and diminished histamine-induced flare in nonlesional skin may support diagnosis of AD.

Reliability and validity of the Psoriasis Itch Visual Analog Scale in psoriasis vulgaris

INTRODUCTION

The single-item Psoriasis Itch VAS was developed to measure itch intensity within the last 24 hours in psoriasis vulgaris to assess treatment benefit. Its psychometric properties were explored in two trials.

METHODS

Data from two randomized, parallel-group phase 3 trials with subjects suffering from psoriasis vulgaris on the body (n = 426, 463) were analyzed. Cross-sectional distributional properties and construct validity of the Psoriasis Itch VAS as well as longitudinal test-retest reliability and sensitivity to change of the Psoriasis Itch VAS were investigated. All statistical tests were two-tailed.

RESULTS

Across both trials, acceptable distributional properties were observed. Convergent-validity correlations between the Psoriasis Itch VAS and other patient-reported and clinician-reported outcomes provided strong endorsement for construct validity as did tests of known-groups validity. Longitudinal measurement properties, involving test-retest reliability and sensitivity to change, also offered evidence for the measurement integrity of the Psoriasis Itch VAS.

DISCUSSION

Results from the assessment of validity, reliability, and sensitivity to change support the use of the Psoriasis Itch VAS to measure itch intensity in psoriasis vulgaris. Data from two trials provided evidence that the Psoriasis Itch VAS is well-defined and reliable for measuring itch in psoriasis vulgaris to assess treatment benefit (i.e. therapeutic response).

Assessment of pruritus in patients with psoriasis and atopic dermatitis: subjective and objective tools

Pruritus is a major symptom of skin disease. The quest to identify a valid and reliable method to assess this important symptom has led to the development of a myriad of measurement tools. Some clinical trials using subjective measurements of itch intensity have reported itch intensity levels in psoriasis that are close to severity levels found in atopic dermatitis. Although it is possible that we have previously underestimated the severity of pruritus in psoriasis, these unexpected findings prompted us to review and evaluate these subjective methodologies. We provide an overview of the current tools available to measure itch severity, including subjective rating scales and questionnaires and objective measures of scratch activity through videotape observation and wrist actigraphy. We discuss the advantages and limitations of these methods and encourage consideration of a novel objective method of evaluation.

Jaundice associated pruritis: A review of pathophysiology and treatment

To review the underlying pathophysiology and currently available treatments for pruritis associated with jaundice. English language literature was reviewed using MEDLINE, PubMed, EMBASE and clinicaltrials.gov for papers and trails addressing the pathophysiology and potential treatments for pruritis associated with jaundice. Recent advances in the understanding of the peripheral anatomy of itch transmission have defined a histamine stimulated pathway and a cowhage stimulated pathway with sensation conveyed centrally via the contralateral spinothalamic tract. Centrally, cowhage and histamine stimulated neurons terminate widely within the thalamus and sensorimotor cortex. The causative factors for itch in jaundice have not been clarified although endogenous opioids, serotonin, steroid and lysophosphatidic acid all play a role. Current guidelines for the treatment of itching in jaundice recommend initial management with biliary drainage where possible and medical management with ursodeoxycholic acid, followed by cholestyramine, rifampicin, naltrexone and sertraline. Other than biliary drainage no single treatment has proved universally effective. Pruritis associated with jaundice is a common but poorly understood condition for which biliary drainage is the most effective therapy. Pharmacological therapy has advanced but remains variably effective.

Chronic pruritus associated with dermatologic disease in infancy and childhood: update from an interdisciplinary group of dermatologists and pediatricians

An effective treatment strategy for chronic pruritus in children with dermatologic disorders should consider the multidimensional aspects of pruritus, the unique challenges associated with treating pruritic skin disorders in the pediatric population, and evidence-based therapies with demonstrated antipruritic benefits and clinically relevant effects on patient/family quality of life (QoL). The Course of Advanced Learning for the Management of ITch (CALM-IT) Task Force is an interdisciplinary group of experts specializing in core aspects of pruritus treatment, integrating pediatrics, dermatology, psychotherapy, pruritus management, and sleep. CALM-IT recently convened to provide updated guidance on managing chronic pruritus associated with dermatologic diseases in pediatric patients, with a special focus on atopic dermatitis (AD) and chronic spontaneous urticaria (csU). This review highlights the updated concepts and best practices, which were built upon international PRACTALL consensus and modified for children and infants with AD and csU. CALM-IT supports the routine use of basic skin therapy and the escalation of topical medications, according to severity and focused on rapid itch control. Anti-inflammatory agents should be appropriate for infants and children (i.e., with an optimized therapeutic index) and have proven antipruritic properties, such as those demonstrated by methylprednisolone aceponate. New experimental findings do not support the use of non-sedating oral antihistamines as adjuvant antipruritic therapy for AD. In csU, oral H1 -antihistamine use is justified, consistent with the distinct pathophysiologic mechanisms of itch underlying AD and csU. All encompassing QoL assessments should consider the burden of both patient and caregiver and should address outstanding unmet clinical needs of pediatric patients. Future research areas include integrated QoL assessments and multidisciplinary treatment programs with pediatric-targeted pruritic therapies providing rapid itch control.

Recent progress in unraveling central nervous system processing of itch sensation

Itch is the major symptom of many allergic or inflammatory skin diseases, yet it is still difficult to measure objectively. This article shows and updates the development and approaches of central nervous system investigation of itch.

Human neuroimaging studies on the physiology and pathophysiology of itch sensation have been hampered by the lack of a reproducible "on-off" stimulus. Short-term alternating temperature modulation of histamine-induced itch has recently been shown to provide on-off characteristics.

Recent studies with functional magnetic resonance imaging demonstrate that itch sensation in healthy volunteers is processed by a network of brain regions contributing to the encoding of sensory, emotional, attentional, evaluative, and motivational aspects of itch.