Electrically evoked itch in humans
Electrically evoked itch in humans
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DOI：
10.1016/j.pain.2004.10.003
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发表时间：
2005-01-01
期刊：
影响因子：
7.4
通讯作者：
Schmelz, M
中科院分区：
文献类型：
--
作者：
Ikoma, A;Handwerker, H;Schmelz, M
我们比较了经皮电刺激（0.08-8 ms，2-200 Hz）和化学刺激（组胺离子导入; 100 μ C）引起的瘙痒感觉和轴突反射。刺激施加到20名健康人受试者和10名特应性皮炎患者的非病变掌侧手腕皮肤。诱发的瘙痒和疼痛感觉的强度在0（无感觉）至10（可想象的最大感觉）的数字评定量表（NRS）上进行评定。通过激光多普勒成像仪测量轴突反射性红斑，并对感觉异常（由轻刷引起的瘙痒）和感觉过敏（由针刺引起的瘙痒）的区域进行精神病学评估。电刺激是最有效的刺激持续时间大于或等于2毫秒和频率大于或等于50赫兹。在80%的受试者中，它引起了纯粹的瘙痒作为阈值感觉，延迟约1秒。高达7/10的瘙痒强度不伴有轴突反射闪光。相比之下，组胺引起轴突反射红斑和最大瘙痒等级3.1 +/- 0.2的大量增加。电刺激诱发的感觉异常区的延伸（2.3 ± 0.5 cm）明显超过组胺诱发的感觉异常区的延伸（0.7 ± 0.3 cm）。健康受试者和特应性皮炎患者对两种刺激的反应没有显著差异。我们的结论是C-纤维激活的基础上的电诱发瘙痒的感觉。低的电阈值和轴突反射耀斑的情况下，这些纤维是不相同的与先前描述的机械不敏感组胺反应性C纤维，但代表一个单独的外周神经元系统诱导瘙痒。(C)2004年国际疼痛研究协会。Elsevier B. V.出版，保留所有权利。
We compared itch sensations and axon reflex flare induced by transcutaneous electrical (0.08-8 ms, 2-200 Hz) and chemical (histamine iontophoresis; 100 muC) stimulation. Stimuli were applied to non-lesional volar wrist skin in 20 healthy human subjects and 10 patients with atopic dermatitis. Intensity of evoked itch and pain sensations were rated on a numerical rating scale (NRS) of 0 (no sensation) to 10 (the maximum sensation imaginable). The axon reflex erythema was measured by laser Doppler imager and areas of alloknesis (itch evoked by light brushing) and hyperknesis (itch evoked by pricking) were assessed psychophysically. Electrical stimulation was most effective for stimulus durations greater than or equal to 2 ms and frequencies greater than or equal to 50 Hz. It evoked pure itch as threshold sensation in 80% of the subjects that was perceived with a delay of approximately 1s. Itch intensities of up to 7/10 were not accompanied by an axon reflex flare. In contrast, histamine provoked a massive increase of axon reflex erythema and maximum itch ratings of 3.1 +/- 0.2. The extention of alloknesis areas (2.3 +/- 0.5 cm) evoked by electrical stimulation clearly exceeded those induced by histamine (0.7 +/- 0.3 cm). Healthy subjects and patients with atopic dermatitis did not differ significantly in their response to either stimulation. We conclude that C-fiber activation underlies the electrically evoked itch sensation. The low electrical thresholds and the absence of an axon reflex flare suggest that these fibers are not identical with the previously described mechano-insensitive histamine responsive C fibers, but represent a separate peripheral neuronal system for the induction of itch. (C) 2004 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.