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Letter to the editor

Editor, I refer to Professor Murtagh's article on the nonpharmacological treatment of back pain (Aust Prescr 1994;17:33-6).

In the relief of pain, including back pain, transcutaneous electrical nerve stimulation (TENS) has a place, provided certain criteria are met. If correctly applied, a central effect does occur (with elevation of the pain threshold), thereby reducing pain and agitation, and minimising any associated narcotic withdrawal effects. The works of Professor J.S. Han have proven that TENS, if applied to certain specific points, e.g. the first interosseus motor point of the thumb, produces a rise in endorphins in both the spinal cord and brain with an elevation of cortisone levels in the blood stream.1 The work of Professor G. Ulett has proven that the effect is not caused by suggestion alone.2

This response is determined not only by the correct placement of the conducting pads, but also by the frequency of the stimulation. Stimulation at two cycles per second (2 Hertz) releases the beta endorphins, 15 Hertz releases the metenkephalins and 100 Hertz releases the dynorphins.

The use of these devices also has the advantage of economy and ease of use, even to the point of supervised self use.

James J. Nichols
Belmont, N.S.W.


Author's comments

Professor J.E. Murtagh, the author of the article, comments:

TENS does have a place in the management of back pain. In 1975, a survey of major pain centres in the U.S.A. showed around 2000 patients with chronic pain of various aetiologies were being treated with TENS. Treating practitioners estimated about one third of these were achieving satisfactory pain control with TENS alone.3 There have been many uncontrolled studies which show in a general way very good to excellent response rates to TENS in low back pain.4

Where intense high frequency TENS has been compared with placebo in double blind crossover studies, TENS has been shown to be more effective in relieving chronic pain.5 Other studies have indicated that intense TENS is no better than placebo applied with strong suggestion, in treating pain.6 This of course does not preclude the use of TENS as a therapeutic modality, especially as it is largely well tolerated and free of adverse effects. A review of randomly selected double blind trials found the placebo effect to be generally around 35%.7 TENS certainly is effective in at least one third of patients treated, but the contribution of the placebo effect to this improvement remains a controversial question. Nevertheless, I think that most practitioners would consider this to be a most satisfactory result in dealing with chronic low back pain.

Acknowledgement: Dr Merilyn Liddell for providing this information.


James J. Nichols

Psychiatrist, Belmont, N.S.W.

John E. Murtagh

Professor of General Practice, Monash University, Melbourne