Physiologic Studies in Atopic Dermatitis (Disseminated Neurodermatitis)

A novel method to assess the potential role of sweating abnormalities in the pathogenesis of atopic dermatitis

“…Indeed, much less attention has been focused on the fact that reduced sweating in AD patients is one of the most important factors, although not enough in itself, that causes the skin dryness: it may contribute more profoundly to skin dryness in AD than the reduction in ceramide and FLG , given the great capacity of sweat to increase skin surface hydration. Reflecting such neglect in previous studies on the role of sweat in AD, previous attempts to evaluate sweating disturbance in AD have yielded conflicting results . One explanation for these conflicting results is that there was no useful quantitative method that allows an accurate assessment of individual sweat glands/ducts actively delivering sweat over a time frame.…”

“…Nevertheless, there have been few studies investigating the role of sweating on the development of AD and such research has been hampered both by the paucity of reproducible and quantitative methods to accurately evaluate the activity of each sweat gland/duct in a well‐defined location and by the lack of sweat glands/ducts in animal skin, in which a variety of analyses have been performed. In addition, conflicting data regarding whether sweating responses are impaired, normal or enhanced in patients with AD would divert the research interest away from investigating the role for sweating responses in the pathogenesis. A consensus has emerged from these studies that sweating responses are impaired and retarded in AD patients .…”

Pharmacological abnormalities in atopic dermatitis

“…While a large number of mediators, hormones and peptide effects have been studied in the skin of patients with AD, most reports relate to cholinergic, adrenergic and histamine responses. Perhaps the best known of these is the delayed blanch response to acetylcholine, first described by Lobitz & Campbell in 1953 (10). Subsequent studies have shown that this reaction, demonstrable in 70% of patients, probably occurs only in areas of inflammation and is not specific for AD (11).…”

“…Adrenergic responses are likewise controversial with reports of increased vascular reactivity and of normal reactivity to intracutaneous injections (10,15,16). In asthmatics, skin vasoconstriction and pupillary responsiveness to phenylephrine were increased (17).…”

Allergy and the Skin

“…Juvenile ocular cataracts are an uncommon, but numerically significant, associate of Besnier's prurigo. 70 per cent of cases of atopic dermatitis also demonstrate paradoxical vasoconstriction (delayed blanching) when acetyl choline is injected into the skin (Lobitz & Campbell 1953). A smaller proportion of patients suffering from other manifestations of atopy also demonstrate delayed blanching (West et al 1962), suggesting that the dermatitis itself is not responsible for the phenomenon.…”