Transdermal transcutaneous electric nerve stimulation for pain: the search for an optimal waveform.

A search has been made for an optimal wave form for transcutaneous nerve stimulation for pain. The effect of electrical stimulation of sympathetic nerves was studied as a model because (1) this system has small diameter axons, as do nociceptive fibers, and (2) alteration of activity in sympathetic fibers may be evaluated objectively by observing the effects upon circulation. A transcutaneously applied waveform was found which influenced circulation maximally, suggesting that sympathetic nerves were affected by the transdermal stimulation. The hypothesis that these stimulation parameters might be optimal for pain relief was tested. Relief of 40% or more was obtained in 68% of 2,800 patients suffering from chronic pain of diverse origin, utilizing this waveform.