Transcutaneous sympathetic stimulation: effects of autonomic nervous function.

In recent years the use of transcutaneous electrical nerve stimulation (TENS) for the treatment of painful disorders has been widely adopted. Minor side effects such as skin irritation are recognised but with appropriate safeguards the technique is considered free from permanent sequelae. This study examines the effects of TENS on hand skin temperature in 6 normal volunteers and 3 patients with alcoholic peripheral neuropathy. Changes of skin temperature were registered using thermocouples and a thermovision camera. Digital artery pulsation was recorded using the Doppler ultrasound technique. Stimulation at 5 to 10 per second of the ulnar nerve at the elbow and digital nerves in the fingers was maintained for 1 to 4 minutes. Profound cooling of the skin and decrease in arterial pulsation was observed and usually persisted for several minutes after cessation of stimulation. Digital arterial changes were not seen in the 3 patients with neuropathy. The possible physiological basis of the observations is discussed and the implications for TENS therapy considered.