Evaluation through in vivo reflectance confocal microscopy of the cutaneous neurogenic inflammatory reaction induced by capsaicin in human subjects.

We perform an in vivo analysis of the effects of capsaicin on cutaneous microvascularization. A total of 29 healthy subjects are administered a solution of capsaicin (CAP group) or a vehicle solution (nonCAP group) on the dorsal side of the nondominant hand. The evaluation is performed using in vivo reflectance confocal microscopy (RCM). Ten minutes after administration, the area of the section, the perimeter, and the Feret's diameter of the capillaries in the dermal papillae become significantly larger in the CAP group as against the nonCAP group, and this difference is maintained until the conclusion of the experiment. In vivo RCM allows the investigation of cutaneous vascular reactions induced by capsaicin. As such, this method may constitute an useful technique both for research and clinical practice.