Skin wrinkling for the assessment of sympathetic function in the limbs

Background: Wrinkling of the skin of the palm and sole is considered to be dependent on the presence of intact sympathetic nervous activity. Loss of s ympathetic integrity could be simply and usefully assessed by the absence o f wrinkling. To test this hypothesis, the skin wrinkle test was compared wi th the starch-iodine sweat test and sympathetic skin response (SSR) in pati ents with abnormal sym pathetic function. Methods: The three tests were carried out in 34 patients (68 limbs) undergo ing temporary or permanent disruption of the sympathetic chain to upper or lower limbs. Included in this group were six diabetics undergoing chemical or surgical sympathectomy, lumbar epidural infusions following vascular sur gery, and patients for whom sympathectomy was being considered. Sensitivity and specificity analysis and predictive values of the wrinkling response a nd the starch-iodine test were related to the SSR as the standard. Results: The wrinkle test showed a sensitivity of 97% and specificity of 95 %, and bore good correlation to the SSR. The starch-iodine test showed sens itivity of 55% and specificity of 93%. A hypothesis for the mechanism of wr inkling based on the observations of the present study is proposed. Conclusion: The wrinkle test is a reliable test of sympathetic function, is inexpensive and is easy to perform at the bedside. The sweat gland myo-epi thelial cells and absence of sebum could play an important role in the wrin kling response. It can be used to select patients who will benefit from sym pathectomy, and can adequately evaluate sympathetic blockade.