Acupuncture for the Treatment of Itch: Peripheral and Central Mechanisms

From Compression to Itch: Exploring the Link Between Nerve Compression and Neuropathic Pruritus

Neuropathic itch is a type of chronic pruritus resulting from neural dysfunction along the afferent pathway. It is often accompanied by abnormal sensations such as paresthesia, hyperesthesia, or hypoesthesia. This condition, which may involve motor or autonomic neural damage, significantly impacts patients' quality of life, causing severe itch and associated comorbidities such as depression, disrupted sleep, and social strain. Neuropathic itch accounts for 8% of chronic pruritus cases, though this may be underestimated. This comprehensive review focuses on nerve impingement as the primary pathophysiological mechanism for various forms of neuropathic itch including brachioradial pruritus (BRP), notalgia paresthetica (NP), and anogenital itch. BRP, often seen in middle-aged white women, manifests as pruritus in the dorsolateral forearms typically exacerbated by ultraviolet (UV) exposure and related to cervical spine pathology. NP, prevalent in middle-aged women, presents as pruritus in the upper back due to thoracic spine nerve compression. Anogenital pruritus, affecting 1-5% of adults, is often linked to lumbosacral spine issues after ruling out dermatologic conditions such as lichen sclerosus or lichen simplex chronicus. The pathophysiology of neuropathic itch involves both peripheral and central mechanisms, with nerve damage being a key factor. Diagnosis requires a thorough history, physical examination, and potentially imaging studies. Topical agents such as menthol, capsaicin, and lidocaine are used for mild cases, while systemic medications such as gabapentin, pregabalin, and antidepressants are prescribed for moderate to severe cases; however, no US Food and Drug Administration (FDA)-approved therapies currently exist specifically for neuropathic itch. Understanding the underlying neural dysfunction and appropriate therapeutic strategies is crucial for managing neuropathic itch effectively.

Chronic Pruritus: A Review

Importance

Chronic pruritus, defined as itch experienced for 6 weeks or longer, affects approximately 22% of people in their lifetime. Approximately 1% of physician visits are for the chief concern of chronic pruritus. Chronic pruritus is associated with adverse outcomes, including impaired sleep and reduced quality of life.

Observations

Chronic pruritus can be categorized by etiology into inflammatory, neuropathic, or a combination of inflammatory and neuropathic pruritus. Chronic pruritus is due to inflammation in approximately 60% of patients and may be caused by eczema, psoriasis, or seborrheic dermatitis. Chronic pruritus is due to a neuropathic or mixed etiology in approximately 25% of patients. Neuropathic causes of chronic pruritus include postherpetic neuralgia and notalgia paresthetica and are typically due to localized or generalized nerve dysregulation. Approximately 15% of people with chronic pruritus have other causes including systemic diseases with secondary itch, such as uremic pruritus and cholestatic pruritus, medication-induced pruritus such as pruritus due to immunotherapy, and infectious etiologies such as tinea corporis and scabies. When few primary changes are present, a thorough history, review of symptoms, and laboratory evaluation should be performed, particularly for people with chronic pruritus lasting less than 1 year. Clinicians should consider the following tests: complete blood cell count, complete metabolic panel, and thyroid function testing to evaluate for hematologic malignancy, liver disease, kidney disease, or thyroid disease. First-line treatment for inflammatory chronic pruritus includes topical anti-inflammatory therapies such as hydrocortisone (2.5%), triamcinolone (0.1%), or tacrolimus ointment. Approximately 10% of patients do not respond to topical therapies. In these patients, referral to dermatology and systemic oral or injectable treatments such as dupilumab or methotrexate may be considered. When no underlying systemic disease associated with pruritus is identified, patients are likely to have neuropathic chronic pruritus or mixed etiology such as chronic pruritus of unknown origin. In these patients, neuropathic topical treatments such as menthol, pramoxine, or lidocaine can be used either alone or in combination with immunomodulatory agents such as topical steroids. Other effective therapies for neuropathic pruritus include gabapentin, antidepressants such as sertraline or doxepin, or opioid receptor agonist/antagonists such as naltrexone or butorphanol.

Conclusions and Relevance

Chronic pruritus can adversely affect quality of life and can be categorized into inflammatory, neuropathic, or a combined etiology. First-line therapies are topical steroids for inflammatory causes, such as hydrocortisone (2.5%) or triamcinolone (0.1%); topical neuropathic agents for neuropathic causes, such as menthol or pramoxine; and combinations of these therapies for mixed etiologies of chronic pruritus.

An Apriori algorithm-based association rule analysis to identify acupoint combinations for treating uremic pruritus

Objective

Uremic pruritus (UP) is a prevalent and troublesome condition affecting individuals with end-stage renal failure, which results in intense pruritus, depression, as well as poor quality of sleep, significantly impacting their quality of life. According to previous studies, acupuncture and acupoint stimulation have been shown to provide additional benefits in treating UP in dialysis patients. In addition, using acupoints combination may yield superior effectiveness compared to utilizing a singular acupoint. To investigate the potential correlations between acupoint combinations, an association-rule analysis was employed.

Materials and Methods

Apriori algorithms stand out as highly potent techniques for identifying associations in databases; this study utilized an association rule mining to examine the association rules of key acupoint groupings that could be employed for treating UP.

Results

The analysis utilized information derived from the meta-analysis encompassing 40 randomized controlled trials that used acupuncture to treat UP. In total, 64 acupoints were analyzed, and 71 association rules were found. The following acupoint combinations: Auricular shenmen (TF4), Quchi (LI11), and Geshu (BL17); Auricular heart (Extra14), Sanyinjiao (SP6), and Auricular lung (CO14); and Auricular heart (Extra14), Xuehai (SP10), and Auricular lung (CO14) showed the strongest associations.

Conclusion

Acupoints involving Auricular shenmen (TF4), Quchi (LI11), Geshu (BL17), Auricular heart (Extra14), Sanyinjiao (SP6), Auricular lung (CO14), and Xuehai (SP10) can be regarded as the core combination of acupuncture points for managing UP.

Comparative efficacy of acupuncture point stimulation treatments for dialysis patients with uremic pruritus: a systematic review and network meta-analysis

Background

Uremic pruritus (UP) is a common complication of chronic kidney disease that causes sleep disturbances and increases all-cause mortality. Currently, the first-line medications for UP exhibit inadequate pruritus control with adverse effects. Various acupuncture point stimulation treatments (APSTs) have been shown to be effective as adjuvant therapies in UP, and a network meta-analysis can offer relative efficacy estimates for treatments for which head-to-head studies have not been performed.

Methods

We conducted a random-effects network meta-analysis on a consistency model to compare the different APSTs for UP. The primary outcomes were the mean visual analog scale (VAS) score and effectiveness rate (ER).

Results

The network meta-analysis retrieved 27 randomized controlled trials involving 1969 patients. Compared with conventional treatment alone, combination treatment with acupuncture (mean difference, -2.63; 95% confidence interval, -3.71 to -1.55) was the most effective intervention in decreasing VAS scores, followed by acupoint injection and massage (mean difference, -2.04; 95% confidence interval, -3.96 to -0.12). In terms of the ER, conventional treatment with acupuncture and hemoperfusion (risk ratio, 14.87; 95% confidence interval, 2.18 to 101.53) was superior to other therapeutic combinations. Considering the VAS score and ER, combination treatment with acupoint injection and massage showed benefits in treating UP.

Conclusion

Our network meta-analysis provided relative efficacy data for choosing the optimal adjuvant treatment for UP. Combined treatment with acupuncture was more effective than conventional treatment only and was the most promising intervention for treating UP.Systematic review registration: PROSPERO (CRD42023425739: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023425739).

Efficacy of Acupuncture for Chronic Spontaneous Urticaria : A Randomized Controlled Trial

BACKGROUND

The effectiveness of acupuncture for patients with chronic spontaneous urticaria (CSU), reported in a few small-scale studies, is not convincing.

OBJECTIVE

To investigate whether acupuncture leads to better effects on CSU than sham acupuncture or waitlist control.

DESIGN

A multicenter, randomized, sham-controlled trial. (Chinese Clinical Trial Registry: ChiCTR1900022994).

SETTING

Three teaching hospitals in China from 27 May 2019 to 30 July 2022.

PARTICIPANTS

330 participants diagnosed with CSU.

INTERVENTION

Participants were randomly assigned in a 1:1:1 ratio to receive acupuncture, sham acupuncture, or waitlist control over an 8-week study period (4 weeks for treatment and another 4 weeks for follow-up).

MEASUREMENTS

The primary outcome was the mean change from baseline in the Weekly Urticaria Activity Score (UAS7) at week 4. Secondary outcomes included itch severity scores, self-rated improvement, and Dermatology Life Quality Index scores.

RESULTS

The mean change in UAS7 (range, 0 to 42) for acupuncture from baseline (mean score, 23.5 [95% CI, 21.8 to 25.2]) to week 4 (mean score, 15.3 [CI, 13.6 to 16.9]) was -8.2 (CI, -9.9 to -6.6). The mean changes in UAS7 for sham acupuncture and waitlist control from baseline (mean scores, 21.9 [CI, 20.2 to 23.6] and 22.1 [CI, 20.4 to 23.8], respectively) to week 4 (mean scores, 17.8 [CI, 16.1 to 19.5] and 20.0 [CI, 18.3 to 21.6], respectively) were -4.1 (CI, -5.8 to -2.4) and -2.2 (CI, -3.8 to -0.5), respectively. The mean differences between acupuncture and sham acupuncture and waitlist control were -4.1 (CI, -6.5 to -1.8) and -6.1 (CI, -8.4 to -3.7), respectively, which did not meet the threshold for minimal clinically important difference. Fifteen participants (13.6%) in the acupuncture group and none in the other groups reported adverse events. Adverse events were mild or transient.

LIMITATION

Lack of complete blinding, self-reported outcomes, limited generalizability because antihistamine use was disallowed, and short follow-up period.

CONCLUSION

Compared with sham acupuncture and waitlist control, acupuncture produced a greater improvement in UAS7, although the difference from control was not clinically significant. Increased adverse events were mild or transient.

PRIMARY FUNDING SOURCE

The National Key R&D Program of China and the Science and Technology Department of Sichuan Province.

Brain network mechanism of acupuncture for chronic spontaneous urticaria: a functional magnetic resonance imaging study protocol

Introduction

Chronic spontaneous urticaria (CSU) is a common skin condition that can significantly impact patients' quality of life. Although studies have demonstrated the efficacy of acupuncture in treating CSU, the underlying mechanisms remain unclear. Dysfunction within the brain's default mode network (DMN) represents a fundamental characteristic of central pathological changes associated with CSU. Therefore, it is hypothesized that improving brain network dysfunction could serve as a key mechanism through which acupuncture exerts its therapeutic effects. This study aims to provide evidence supporting this hypothesis.

Methods and analysis

This study, a parallel, randomized, sham-controlled functional neuroimaging investigation will be conducted in China. We aim to enroll 50 patients with CSU and 25 healthy controls, distributing them evenly between the acupuncture and sham acupuncture groups in a 1:1 ratio. The total observation period will span 6 weeks, including 2 weeks designated for the baseline phase and 4 weeks allocated for the clinical treatment phase. Prior to treatment, all participants will undergo magnetic resonance scanning, clinical index detection, and microbiota collection. Following treatment, the patients with CSU will be retested for these indicators. Using resting-state functional connectivity (rsFC) analysis, dynamic Functional Connection (dFC) analysis, and brain microstate extraction technology combined with correlation analysis of microbiota and clinical indicators, the regulatory mechanism of acupuncture on the brain network of CSU will be evaluated from multiple dimensions.

Ethics and dissemination

This trial was approved by the Biomedical Ethics Review Committee of the West China Hospital, Sichuan University (No. 2022-1255). Each participant will provide written informed consent to publish any potentially identifiable images or data.Clinical trial registrationhttps://www.chictr.org.cn/, identifier: ChiCTR2200064563.

Role of GRPR in Acupuncture Intervention in the "Itch-scratch Vicious Cycle" Spinal Circuit of Chronic Pruritus

Many previous studies have shown the potential antipruritic effect of acupuncture. This paper reviews the antipruritic mechanisms of acupuncture according to these aspects: sample characteristics, detail of intervention, and effects evaluation. The majority of research on acupuncture's antipruritic effect has focused on primary afferents of the peripheral mechanism. Relatively few studies, however, have addressed the central mechanisms. Combination the latest research achievements of chronic itch, gastrin-releasing peptide receptor (GRPR) in the dorsal horn of the spinal cord may represent the first molecule identified that is dedicated to mediating the itch response and may provide an important therapeutic target for the treatment of chronic pruritic conditions. Therefore, GRPR may be a new target for acupuncture to relieve itch in the future and provide new ideas for acupuncture intervention in the mechanisms of the spinal level of the "itch-scratch vicious cycle" of chronic itch.

Acupuncture for gastrointestinal urticaria: A protocol for systematic review and network meta-analysis

Introduction

The purpose of this review is to evaluate the effectiveness and safety of acupuncture in the treatment of patients with gastrointestinal urticaria (GU) and to provide a clinician's guide to GU treatment options.

Methods and analysis

We plan to search multiple databases (i.e., PubMed, EMBASE, Springer, Web of Science, Cochrane Library, China National Knowledge Infrastructure, Chinese Biomedical Literature Database and Wanfang Database) for studies published before September 1, 2022. We will electronically search for all relevant studies concerning clinical acupuncture treatments of GU, including unpublished conference articles and other gray literature. The language limit of this systematic review is Chinese and English. Any reports of clinical randomized controlled trials of acupuncture for the treatment of GU will be included in the study. Two researchers will perform independent data extraction to increase the quality of the data extraction. The primary outcome was the Urticaria Activity Score 7 (UAS7). Abdominal visual analog scale (VAS) for abdominal pain, dermatological life quality index (DLQI), the total effective rate, recurrence rate, and occurrence of adverse events were secondary outcomes. We will use RevMan V.5.3 statistical software for pairwise meta-analysis and ADDIS V.1.16.8 software for Bayesian network meta-analysis. If feasible, meta-regression and subgroup analyses will also be performed to address the potential causes of inconsistency and heterogeneity. We will conduct a GRADE assessment of the quality of evidence for the interventions included in this review.

Discussion

This study may validate acupuncture as an alternative therapy for the effective treatment of GU.

Trial registration number

PROSPERO CRD42022333977.

Efficacy of Acupuncture for Treatment of Atopic Eczema and Chronic Eczema: A Systematic Review and Meta-analysis

Abstract is missing (Short communication)