Detection thresholds of capsaicin: a new test to assess facial skin neurosensitivity.
The goal of this study was to assess the accuracy/reliability of a new test designed to measure cutaneous neurosensitivity. The test was carried out on a random population of 150 healthy adult women and was based on the determination of individual detection thresholds of topically applied capsaicin. Five capsaicin concentrations were used in 10% ethanol aqueous solution (3.16 x 10(-5)%; 1 x 10(-4)%; 3.16 x 10(-4)%; 1 x 10(-3)%; 3.16 x 10(-3)%). The methodology used to attain the detection threshold was capsaicin application in increasing concentration on the nasolabial folds. The vehicle was simultaneously applied following a split-face, single-blind plan. The test was stopped as soon as the subject reported a specific sensation lasting more than 30 seconds on the capsaicin side. The safety of the test was judged as excellent by the panelists since all the reported sensations were considered as slightly or moderately perceptible. The test allowed the classification of the test population according to six threshold levels corresponding to the sensitive reaction to one of the five capsaicin concentrations and to the absence of sensitivity to the highest concentration. Surprisingly, the distribution of the population was not unimodal and seemed to reveal the existence of two different sub-groups: individuals with a low capsaicin detection threshold and those with a high threshold. These two sub-populations strongly differed in their respective self-perception of sensitive skin. The higher the self-declared sensitive skin incidence was, the lower the detection threshold was. This new test of skin neurosensitivity is easy, quick, and truly painless. It appears to be a promising tool for the cosmetic diagnosis of sensitive skin.
Jourdain
Roland
R
L'Oréal Recherche, 90 Rue du Général Roguet, 92583 Clichy, France.
Bastien
Philippe
P
de Lacharrière
Olivier
O
Rubinstenn
Gilles
G
D000279:Administration, Cutaneous; D000293:Adolescent; D000328:Adult; D002211:Capsaicin / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005145:Face; D005260:Female; D006801:Humans; D006930:Hyperalgesia / Q000139:chemically induced / Q000503:physiopathology; D007509:Irritants / Q000494:pharmacology*; D008875:Middle Aged; D009619:Nociceptors / Q000187:drug effects / Q000502:physiology; D012684:Sensory Thresholds / Q000502:physiology*; D012867:Skin / Q000187:drug effects* / Q000294:innervation; D011795:Surveys and Questionnaires
D007509:Irritants; D002211:Capsaicin