Itch and scratch
Blog Author: George Szasz, CM, MDPosted: Thursday, April 20, 2017 - 09:40
Itch (from Middle English icchen) and scratch (from Middle English cracchen) are notorious twins annoying people and most other mammals since the word go. The word pruritus, meaning “unpleasant sensation,” was introduced in 1660 by Samuel Hafenreffer (1587–1660), a German physician and the author of the first textbook in German-speaking countries on the subject of dermatology. The secrets of pruritus still bedevil contemporary medical professionals.
I became preoccupied by itch and scratch because my dear wife, suffering from advanced dementia of the Alzheimer type, suffers from recurrent, severe rubbing and scratching episodes. First came the rubbing of the eyelids. The opthalmologist’s opinion was that it was due to “dry eye” secondary to meibomian gland insufficiency. However, artificial tears and eye drops of various complexity offered no relief—nor did various antihistamines. Steroids applied to the eyelids did help up to a point, as did gentle application of a warm moist cloth to the eye region, and also acetaminophen. In the last few months the pruritus, if that is what it is, became extended to the chest, and more recently, to the abdominal skin. A recent episode rapidly became a violent rubbing of the abdomen with both hands, fingers digging in, accompanied by heartbreaking cries of “help me,” “I cannot bear it,” “I’d rather die.” These clear exclamations came from a person whose speech is usually incoherent. This episode stopped suddenly after about half an hour and she fell into a light sleep as if nothing had happened.
Chronic itch in the elderly is currently attributed to several causes, including skin diseases, systemic conditions such as end-stage renal disease and diabetes, as well as psychogenic conditions such as depression and anxiety, and as a the side effects of various medications. Neuropathic pruritus, which I believe might be the basis of my wife’s itch and scratch syndrome, is thought to be caused by neuronal or glial damage and does not always originate on the skin’s surface. Recent studies suggest that there may be toll-like receptors (TLRs) that are characterized as pattern-recognition receptors that initiate innate immune responses via recognition of pathogen associated molecular patterns. Activation of TLR signaling in the central nervous system also results in the production of various inflammatory mediators both in microbial infection and in noninfective disorders such as stroke, multiple sclerosis, chronic pain, and Alzheimer disease.
Regrettably, the etiology of pruritus is poorly understood 357 years after Herr Doctor Haffenbreffer’s introduction of the term. We still itch and scratch our head, why?
—George Szasz, CM, MD
Oaklander AL. Neuropathic itch. Semin Cutan Med Surg 2011;30:87-92.
Rapim RP, Bolognia JL, Jorizzo JL. Dermatology. St. Louis, MO: Mosby; 2007.
Valdes-Rodrigues R, Stull C, Yosipovitch G. Chronic pruritus in the elderly: Pathophysiology, diagnosis and management. Drugs Aging 2015;32:201-215.
This posting has not been peer reviewed by the BCMJ Editorial Board.