Part 1 - Patho-Physiology of Pruritus

Hi. With this video [Part 1], we will discuss the physiology of the Itch-Scratch cycle, and the involved mediators and receptors. A good understanding of the itching process is essential to manage this common and troublesome symptom. This video is directed towards dermatologists and is not at all advisory for non-medical personnel.
Introduction - 05:10
Sensory Nerves - 09:50
Stimulus - 11:32
Histamine - 18:31
Other Mediators - 21:23
TRPV1 Receptors - 23:00
H4 Histamine Receptors - 27:48
PAR Receptors - 29:59
Neurokinin Receptors - 32:37
Opioid Receptors - 35:46
Other Receptors - 39:09
Sensory Nerves - 42:24
Cortical Processing of Itch - 47:44
Negative Feedback Mechanisms- 51:00
Definitions - 55:16
Further Reading - 01:00:15
End - 01:00:43
Further Reading:
1. Garibyan L, Rheingold CG, Lerner EA. Understanding the pathophysiology of itch. Dermatol Ther. 2013 Mar-Apr;26(2):84-91. doi: 10.1111/dth.12025. PMID: 23551365; PMCID: PMC3696473.
2. Cevikbas F, Lerner EA. Physiology and Pathophysiology of Itch. Physiol Rev. 2020 Jul 1;100(3):945-982. doi: 10.1152/physrev.00017.2019. Epub 2019 Dec 23. PMID: 31869278; PMCID: PMC7474262.
3. Herndon JH Jr. Itching: the pathophysiology of pruritus. Int J Dermatol. 1975 Sep;14(7):465-84. doi: 10.1111/j.1365-4362.1975.tb04281.x. PMID: 1099034.
4. Martins MS, Almeida IF, Cruz MT, Sousa E. Chronic pruritus: From pathophysiology to drug design. Biochem Pharmacol. 2023 Jun;212:115568. doi: 10.1016/j.bcp.2023.115568. Epub 2023 Apr 26. PMID: 37116666.
5. Fitzpatrick’s textbook of Dermatology. 9ed. Part 2 - Chapter 21: Neurobiology of the Skin, pg - 351
6. Bolognia 4ed, chapter 5: Cutaneous Neurophysiology. Pg - 101

[@pratibhajp2171]

Thanks a lot for this detailed video, it's means alot to dermatologist

[@sabhderma]

My pleasure 😊 glad you found it helpful 😁

[@roshanisk5189]

Sir is there any classes for dermat pg students?

[@jinishajain3829]

I had a doubt sir, why does dermarophytoses cause itch where as p. Versicolour is usually non itchy.

[@sabhderma]

That is a very interesting insight. I don't know. But I may suggest that m furfur is a commensal, so maybe the immune cells do not elicit a stronger response to the fungi. While dermatophyte is an exogenous organism with greater immune mediated defense reaction, hence a strong itch response. Itching as a response evolved to rid the body of the pathogens. M furfur is a commensal. So maybe the itch response is not that strong. I hope this makes sense. Thank you for your comments ☺️☺️

[@drjaleena9918]

Thank u

[@sabhderma]

Thanks and keep watching 😀