Serra J, Campero M, Ochoa J
Departments of Neurology and Neurosurgery, Good Samaritan Hospital and Oregon Health Sciences University, Portland, Oregon 97210, USA.
J Neurophysiol. 1998 Dec;80(6):2801-10. doi: 10.1152/jn.1998.80.6.2801.
Flare and hyperalgesia after intradermal capsaicin injection in human skin. J. Neurophysiol. 80: 2801-2810, 1998. We investigated the neurovascular mechanisms that determine the flare response to intradermal capsaicin injection in humans and delineated the associated areas of mechanical and heat hyperalgesia. The flare response was monitored both visually and with infrared telethermography. The areas of mechanical and heat hyperalgesia were determined psychophysically. Thermography detected very large areas of flare. As an early event underlying the flare and before onset of the area of rubor of the skin, thermography detected the appearance of multifocal spots of increased temperature caused by dilatation of cutaneous arterioles. Repetition of capsaicin injection days apart into the same forearm induced multifocal spots of temperature elevation identical to the ones obtained in the first session, indicating dilatation of the same arterioles. Reactive hyperemia also consisted in the appearance of multifocal spots of increased temperature, which were identical to the ones reacting during the flare response, suggesting participation of the same arterioles in both events. Strips of local anesthetic placed to block cutaneous nerves prevented the spread of both the thermographic flare and associated hyperalgesia. It is inferred that the cutaneous nerve fibers responsible for the thermographic flare branch, or have coupled axons, over a long distance. The large area of flare coincided with the area of mechanical and heat hyperalgesia. Equivalence of the areas of flare and mechanical and heat hyperalgesia induced by intradermal capsaicin injection suggests that all three phenomena are the consequence of neural factors that operate peripherally.
人体皮肤皮内注射辣椒素后的潮红和痛觉过敏。《神经生理学杂志》80: 2801 - 2810, 1998年。我们研究了决定人体对皮内注射辣椒素潮红反应的神经血管机制，并描绘了相关的机械性和热痛觉过敏区域。通过视觉和红外热成像技术监测潮红反应。通过心理物理学方法确定机械性和热痛觉过敏区域。热成像检测到非常大面积的潮红。作为潮红的早期事件且在皮肤发红区域出现之前，热成像检测到由皮肤小动脉扩张引起的多焦点温度升高斑点的出现。相隔数天对同一只前臂重复注射辣椒素会诱导出与首次注射时相同的多焦点温度升高斑点，表明是同一小动脉扩张。反应性充血也表现为多焦点温度升高斑点的出现，这些斑点与潮红反应期间出现的斑点相同，提示同一小动脉参与了这两种情况。放置局部麻醉剂条带以阻断皮肤神经可防止热成像潮红和相关痛觉过敏的扩散。据推测，负责热成像潮红的皮肤神经纤维会分支，或者具有远距离耦合的轴突。大面积的潮红与机械性和热痛觉过敏区域重合。皮内注射辣椒素诱导的潮红区域与机械性和热痛觉过敏区域的等效性表明，这三种现象都是外周神经因素作用的结果。
