In the extremities, the vascular response to sympathetic stimulation is vasoconstriction with blanching and cooling of skin and increased sweating, whereas, blocking of the sympathetic system results in increased blood flow through cutaneous arteriovenous fistulae and cessation of sweating, thereby, resulting in increased dryness, warmth and accentuation of pink color. In the past, sympathetic denervation of the upper extremity was suggested as a treatment of many disorders; bronchial asthma, essential hypertension, peptic ulcer disease, hyperthyroidism, hyperhidrosis, vasospastic syndromes (Raynaud's disease), thoracic outlet syndrome, causalgia, post-traumatic sympathetic dystrophy (Sudeckatrophy), and angina pectoris. The indications for upper thoracic sympathectomy are limited today to hyperhidrosis, causalgia, severe vasospastic disorders, and ischemic changes of the extremities (Buerger's disease).