Transcutaneous electrical nerve stimulation: its role in the control of chronic pain.

An assessment was made of the effectiveness of long-term transcutaneous electrical nerve stimulation (TENS) in the treatment of chronic posttraumatic pain. Compensation Board files showed that 846 patients received TENS from 1975 to 1979, with more than 70% having intractable back pain. Of this group using TENS, 44.6% were free of disability, and an additional 36.2% were capable of modified work. Questionnaire responses were obtained from 563 of 637 patients receiving TENS in 1978 or 1979. At the six-month follow-up, most respondents (472, 83.8%) reported continuing benefit from TENS, including a reduction of pain (418, 74.2%), less need for medication (322, 57.2%), and improved sleep patterns (331, 58.8%). Only 13.6% of those who had returned to work reported no benefit from TENS, while 18.4% of those still unemployed reported no benefit. Among those who had returned to work (264 cases, 46.9% of respondents), benefit was reported equally by those with back injuries and by those with other injuries. The responses observed in this trial seem larger and more long-lasting than could be obtained by a placebo effect, and further attempts at a controlled trial may be warranted. However, there are major practical difficulties to such an investigation, and the resulting controversy could reduce the therapeutic effectiveness of TENS in conditions where alternative treatments are either ineffective or undesirable.