Kobayashi Hiromi, Kikuchi Katsuko, Tsubono Yoshitaka, Tagami Hachiro
Department of Dermatology, Tohoku University School of Medicine, Sendai, Japan.
Dermatology. 2003;206(3):204-11. doi: 10.1159/000068892.
Patients with atopic dermatitis (AD) are well known to be sensitive to irritation from the environment due to the impaired function of the stratum corneum (SC). Electrical current perception threshold (CPT) evaluation quantifies the sensory threshold to transcutaneous electrical stimulation of the sensory nerves.
To study the CPT in a noninvasive fashion using Neurometer CPT/C, together with measurements of various functions of the SC.
We measured the CPT on the flexor forearm and cheek of AD patients and normal individuals. Subsequently, we evaluated the CPT and skin sensitivity to a 30% aqueous solution of lactic acid after the infliction of various mildly disruptive measures on the SC on the flexor forearm of healthy individuals by the following three methods: (1) removal of the superficial sebum with acetone/ether, (2) scarification with a needle and (3) tape stripping of the SC. Finally, we examined the effect of topical applications of emollients such as petrolatum or a moisturizing cream to the scratched skin.
AD patients showed a lower barrier function and lower CPT than normal individuals. In subsequent studies conducted in normal individuals, the CPT was found to be inversely correlated with transepidermal water loss (TEWL) levels after tape stripping. However, most of all, the partial superficial scarification with a needle decreased the CPT and increased the lactic acid stinging response. Prolonged removal of lipids from the SC with acetone/ether for 30 min that increased the TEWL levels for only 1 day decreased the high-frequency conductance value for 2 days and the CPT only on the 2nd day after treatment. Topical applications of emollients were effective to prevent the increased sensitivity caused by scratching.
AD patients showed functional abnormalities of the SC and tended to have more sensitive skin on the cheek and flexor forearm than healthy controls. Even focal SC damage caused by superficial cracking may lead to further disruption of the already damaged SC in AD patients, by eliciting scratching and facilitating the permeation of various environmental allergens and also the induction of hypersensitive skin.
由于角质层（SC）功能受损，特应性皮炎（AD）患者对环境刺激敏感是众所周知的。电流感知阈值（CPT）评估可量化感觉神经经皮电刺激的感觉阈值。
使用神经仪CPT/C以非侵入性方式研究CPT，并测量SC的各种功能。
我们测量了AD患者和正常个体屈侧前臂和脸颊的CPT。随后，我们通过以下三种方法对健康个体屈侧前臂的SC采取各种轻度破坏措施后，评估CPT和皮肤对30%乳酸水溶液的敏感性：（1）用丙酮/乙醚去除浅表皮脂，（2）用针划痕，（3）SC胶带剥离。最后，我们检查了凡士林或保湿霜等润肤剂局部应用于抓伤皮肤的效果。
AD患者的屏障功能和CPT低于正常个体。在随后对正常个体进行的研究中，发现CPT与胶带剥离后的经表皮水分流失（TEWL）水平呈负相关。然而，最重要的是，用针进行部分浅表划痕会降低CPT并增加乳酸刺痛反应。用丙酮/乙醚从SC中长时间去除脂质30分钟，仅使TEWL水平在1天内升高，使高频电导值在2天内降低，CPT仅在治疗后第2天降低。局部应用润肤剂可有效预防抓伤引起的敏感性增加。
AD患者表现出SC的功能异常，脸颊和屈侧前臂的皮肤比健康对照更敏感。即使是由浅表裂纹引起的局灶性SC损伤，也可能通过引发搔抓、促进各种环境过敏原的渗透以及诱导皮肤过敏，导致AD患者本已受损的SC进一步破坏。
