The Rheumatologist
COVID-19 News
  • Connect with us:
  • Facebook
  • Twitter
  • LinkedIn
  • YouTube
  • Feed
  • Home
  • Conditions
    • Rheumatoid Arthritis
    • SLE (Lupus)
    • Crystal Arthritis
      • Gout Resource Center
    • Spondyloarthritis
    • Osteoarthritis
    • Soft Tissue Pain
    • Scleroderma
    • Vasculitis
    • Systemic Inflammatory Syndromes
    • Guidelines
  • Resource Centers
    • Ankylosing Spondylitis Resource Center
    • Gout Resource Center
    • Rheumatoid Arthritis Resource Center
    • Systemic Lupus Erythematosus Resource Center
  • Drug Updates
    • Biologics & Biosimilars
    • DMARDs & Immunosuppressives
    • Topical Drugs
    • Analgesics
    • Safety
    • Pharma Co. News
  • Professional Topics
    • Ethics
    • Legal
    • Legislation & Advocacy
    • Career Development
      • Certification
      • Education & Training
    • Awards
    • Profiles
    • President’s Perspective
    • Rheuminations
  • Practice Management
    • Billing/Coding
    • Quality Assurance/Improvement
    • Workforce
    • Facility
    • Patient Perspective
    • Electronic Health Records
    • Apps
    • Information Technology
    • From the College
    • Multimedia
      • Audio
      • Video
  • Resources
    • Issue Archives
    • ACR Convergence
      • Systemic Lupus Erythematosus Resource Center
      • Rheumatoid Arthritis Resource Center
      • Gout Resource Center
      • Abstracts
      • Meeting Reports
      • ACR Convergence Home
    • American College of Rheumatology
    • ACR ExamRheum
    • Research Reviews
    • ACR Journals
      • Arthritis & Rheumatology
      • Arthritis Care & Research
      • ACR Open Rheumatology
    • Rheumatology Image Library
    • Treatment Guidelines
    • Rheumatology Research Foundation
    • Events
  • About Us
    • Mission/Vision
    • Meet the Authors
    • Meet the Editors
    • Contribute to The Rheumatologist
    • Subscription
    • Contact
  • Advertise
  • Search
You are here: Home / Articles / The Science of Chronic Itch

The Science of Chronic Itch

December 1, 2014 • By Shivani V. Tripathi, MD, & Brian S. Kim, MD, MTR

  • Tweet
  • Email
Print-Friendly Version / Save PDF

The definition of pruritus, more commonly known as itch, was introduced by a German physician named Samuel Hafenreffer in 1660 as an “unpleasant sensation that elicits the desire or reflex to scratch.”1 Chronic pruritus affects approximately 15–20% of the U.S. population and accounts for more than 7 million outpatient visits per year in the U.S.2 In addition to its high prevalence, chronic pruritus affects multiple quality of life (QoL) parameters, including mood, concentration, eating habits, sexual function and sleep.3-5 Indeed, QoL studies have shown equivalence in terms of impact of chronic pain and chronic itch on QoL measures.6

You Might Also Like
  • Psoriasis May Itch as Intensely as Atopic Dermatitis
  • A History of the Science, Treatment of Rheumatologic Illnesses from Gold to Gene Therapy
  • Science from our Sisters
Explore This Issue
December 2014

Despite the high burden of itch-associated conditions on both society and the individual, itch as a medical problem remains an overlooked epidemic because the etiology of itch remains poorly understood. Even 354 years after Hafenreffer initially defined pruritus, treatments remain limited, with no FDA-approved medications for use in humans.

ad goes here:advert-1
ADVERTISEMENT
SCROLL TO CONTINUE

It’s widely appreciated that chronic pruritus underlies multiple dermatologic conditions, such as atopic dermatitis (AD), contact dermatitis and psoriasis. Beyond the skin, pruritus is associated with a variety of systemic medical conditions, including, but not limited to, chronic kidney disease (CKD), liver dysfunction, malignancy, various infections and even psychiatric disease (see Table 1). Recent scientific advances have revealed previously unrecognized itch-specific pathways that are regulated by particular mediators, including neurotransmitters, pharmacologic agents and inflammatory cytokines (see Figure 1).7,8 Although off-label treatments can be employed, more investigation is needed to develop definitive therapeutics to appropriately target chronic pruritus. Recent scientific discoveries have led to a greater understanding of the mechanisms underlying the sensation of itch, which will invariably inform the design of novel treatments in the future.

Pathophysiology of Itch

Classically, itch was viewed as a mild form of pain. As a result, the prevailing wisdom was that the same neurologic pathways mediated both pain and itch. The identification of histamine-responsive neurons in the periphery revealed for the first time that distinct itch-sensitive, pain-independent pathways were present.9,10 However, it was widely appreciated that antihistamines, although effective in certain forms of itch (e.g., urticaria-associated itch), were ineffective in the treatment of many forms of chronic pruritus. These clinical observations provoked the hypothesis that perhaps histamine-independent pathways were present.

ad goes here:advert-2
ADVERTISEMENT
SCROLL TO CONTINUE

Acute itch, as seen in response to arthropod bites & poison ivy, is transient in nature. In contrast, chronic itch is highly debilitating & its etiology is often difficult to define.

Indeed, in 2009 Liu et al identified the Mas-related G protein-coupled receptor (Mrgpr) as a novel family of histamine-independent itch receptors expressed in the dorsal root ganglia (DRG).11 Subtypes of Mrgprs have been identified in both mice and humans.12 Further, MrgprA3 is activated by the drug chloroquine, which has been associated with the development of itch in patients.11 Beyond the peripheral nervous system (PNS), Sun et al identified the first receptor that mediates itch in the central nervous system (CNS), namely gastrin-releasing peptide receptor (GRPR).13 This seminal discovery identified that itch can be regulated both in the periphery, where exogenous pruritogenic stimuli may be encountered, as well as centrally in the spinal cord itself.

Pages: 1 2 3 4 5 6 7 | Single Page

Filed Under: Education & Training, Professional Topics Tagged With: chronic pruritus, itch, Kim, myositis, pathophysiology, patient care, Research, rheumatology, TripathiIssue: December 2014

You Might Also Like:
  • Psoriasis May Itch as Intensely as Atopic Dermatitis
  • A History of the Science, Treatment of Rheumatologic Illnesses from Gold to Gene Therapy
  • Science from our Sisters
  • ACR/ARHP Annual Meeting Offers Basic Science Track

American College of Rheumatology

Visit the official website for the American College of Rheumatology.

Visit the ACR »

ACR Convergence

Don’t miss rheumatology’s premier scientific meeting for anyone involved in research or the delivery of rheumatologic care or services.

Visit the ACR Convergence site »

Simple Tasks

Learn more about the ACR’s public awareness campaign and how you can get involved. Help increase visibility of rheumatic diseases and decrease the number of people left untreated.

Visit the Simple Tasks site »

The Rheumatologist newsmagazine reports on issues and trends in the management and treatment of rheumatic diseases. The Rheumatologist reaches 11,500 rheumatologists, internists, orthopedic surgeons, nurse practitioners, physician assistants, nurses, and other healthcare professionals who practice, research, or teach in the field of rheumatology.

About Us / Contact Us / Advertise / Privacy Policy / Terms of Use

  • Connect with us:
  • Facebook
  • Twitter
  • LinkedIn
  • YouTube
  • Feed

Copyright © 2006–2021 American College of Rheumatology. All rights reserved.

ISSN 1931-3268 (print)
ISSN 1931-3209 (online)

loading Cancel
Post was not sent - check your email addresses!
Email check failed, please try again
Sorry, your blog cannot share posts by email.
This site uses cookies: Find out more.