Vasodilation induced by transcutaneous nerve stimulation in peripheral ischemia (Raynaud's phenomenon and diabetic polyneuropathy).

In four patients with Raynaud's disease and in two with diabetic polyneuropathy, low-frequency transcutaneous nerve stimulation (TNS) of remote sites for 30–45 min caused a dramatic peripheral vasodilation in the cold limbs with a rise in skin temperature of 7–10 °C (from 22–24 to 31–34 °C) for periods of 4–8 h or more. This rise was associated with relief of ischemic pain. The vasodilation is widespread, affecting the skin of all extremities, with slight temperature elevations of 0.5–2 °C in the warm body parts. It also includes the cranial vessels, as judged from the induced migraine-like headaches in some patients. The responses were more easily elicited in sympathectomized patients and in diabetic polyneuropathy, presumably due to reduced vasoconstrictive tone. Placebo effects were ruled out. The vasodilatory effect and ischemic pain were not blocked by conventional doses of the specific opiate antagonist naloxone, suggesting different mechanisms for suppression of non-ischemic pain and vascular effects. TNS may be tried as an alternative treatment in certain patients with peripheral vascular insufficiency.