Abstract

Sixty patients, with chronic pain of diverse etiologies, were treated with a modified TENS technique using a relatively inexpensive, low-frequency electro stimulator. The method and results of treatment are described, and possible explanations for the effectiveness of TENS therapy are examined. In summary, clinical experience indicates a relief rate of 88% in those cases studied, with observed pain relief varying both in duration and degree. Analgesic and anti-inflammatory effects were also noted. The ongoing home use of TENS patients is encouraged.

January 1986

Robert D. Milne, M.D. and Fuller Royal, M.D.
The Nevada Clinic
6105 West Tropicana Avenue
Las Vegas, Nevada 89103
(702) 871-2700

Introduction

Clinical interest is heightening in the use of transcutaneous electrical nerve stimulation (TENS) for control of pain syndromes of diverse etiologies (13, 4, 12). Recent studies have demonstrated the efficacy of TENS for the treatment of acute postoperative incision pain, and it has become an accepted alternative to conventional methods of treatment (6). Rheumatoid arthritis pain has been successfully treated with TENS (1).

This study, which is part of a continuing attempt to assess the practical uses of TENS, was designed to test the hypothesis that specific low-frequency electrostimulation provides effective reduction of relatively non-severe pain and that it can be a useful adjunct for the overall approach to pain control.

Methods

Sixty patients with chronic pain consented for treatment. Each patient reported continuous or intermittent pain and had been previously seen by orthopedic and/or neurology physicians. Within this group of 60, 44 patients were considered to be suffering from mild to moderate pain; 6 other patients were classified as severe.

Previous studies have indicated the effectiveness of wrist and ankle stimulation for treatment of pain syndrome (7). Low-frequency stimulation has also been used with good success (8).

We felt that many of our patients had difficulty in understanding the proper application of TENS electrodes and we sought to find a simple, more universal approach for this study. The method ultimately selected for use is known under the appellation “REBUILDER^® Footbath System.”¹ Using this method, the patient receives low-frequency electrostimulation (within a range of 7-to-8 Hz.) from a portable, single-channel, battery-operated device (REBUILDER^®) while appropriate portions of the body are immersed in water.

Patients were first directed to fill ankle-deep with warm water a special twin-compartment plastic bucket. The patient then placed one foot or hand, along with one electrode lead connected to the electro-stimulator device, into the water on each side of the bucket.

The device’s power dial was then turned on until a “tingling” sensation was felt in the submerged portions of the body. Once the “tingling” was felt, low-frequency electrostimulation was continued for a period of ten minutes for both the feet and hands. Treatments were self-administered once daily for periods of two weeks or longer. If no response was noted after two weeks, the treatment was termed a failure.

Results

Data accumulated from 60 patients using the REBUILDER^® Footbath System are summarized below in Table I.

Since pain is a subjective phenomenon, the reduction of which it is difficult to a subjective scale. Responses were verbally elicited, along a scale ranging from 0-to-10, whereby a rating of 10 equated to “most severe pain” while a rating of 0/1 equated to “least pain. (11)

Responses were then grouped and classified into one of three categories: “no relief”; significant relief (i.e., greater than 50% less pain), but lasting only through the “initial” treatments; and “long-term” or continued relief lasting throughout an additional three-to-six months of use.

As documented in Table 1, the most gratifying results were obtained in elderly patients with osteoarthritis, whereby 15 out of 18 patients reported long-term relief. This finding is similar to that reported in a previously published study. Only one patient of the 18 we tested in this category was unaffected by treatment, and she had a severe deformity. Most other patients in this category noted decreased joint swelling in addition to continued pain relief.

Six out of the 13 patients tested with migraine/headache syndrome achieved long-term relief using low-frequency, electrostimulation therapy. However, TENS therapy proved most helpful for the prodromal stage; for acute-phase sufferers, it was minimally effective and more invasive acupuncture/medication techniques were necessary.

An interesting use was noted by Dr. Corson of a man with severe debilitating knee pain who had been recommended for knee-replacement surgery. He had such complete relief that he went out and worked in the yard all day and called in saying the knees were okay but he now had the cramps in his calves. His medication and vitamins were adjusted and he had improved.

Discussion

The long-term pain reduction noted in 63% of the patients with mild to moderate pain suggests that TENS stimulation, employing low- frequency electrical current, is effective in relieving moderate pain. Further, the anti-inflammatory effects of such electrostimulation techniques are encouraging. This has been noted by other investigators (8), while prior studies have also documented the significant healing of osteoarthritic joints, as demonstrated by x-ray examination. By way of explanation, Becker and his co-workers have suggested that this noted augmentation of normal healing results from amplification of a neural control signal that is more primitive than the discrete action potential. (2, 3) In particular, Becker et al feel that the perineural cells compose a DC control system and that the Schwann cells transmit the current of injury, which is interpreted consciously as pain.

Other theories of action include the various “gate” theories summarized briefly below:

1. Supranuclear or Psychic Gate Theory — argues that pain is blocked at the supranuclear/psychic level by suggestion, hypnosis, or placebo;
2. Thalamic Gate Theory — argues that vibratory sensations activate the large A-beta fibers which, on reaching the thalamus, cause the reticular formation and limbic system to shut the “gate” on pain ascending through the spinothalamic and bulfothalamic tracts;
3. Spinal Gate Theory (by Melzack and Wall (10)) — argues that large, more rapidly conducting A-beta fibers transmit the vibratory sensation of TENS, which enters the dorsal horn of the spinal chord and activates cells of the substantia gelatinosa, in turn, causing blockage of pain sensations arriving via the slower-conducting unmyelinated C-fibers at the segmental level; and
4. Peripheral Gate Theory {by Campbell and Taub (5)) — argues that the pain and touch threshold is increased in the distal portion of extremities by percutaneous electrical nerve stimulation as a result of the blockage of peripheral sensory fibers.

However, none of these “gate” theories is able to explain the fact that in most instances TENS affords pain relief of prolonged duration. We suggest that there is evidence that alteration of the cellular metabolism at the site of origin of focal pain can result in significant relief of varying duration and degree. We further propose that as Western physicians become increasingly adept at comprehending the true nature of the Yin and Yang balance of Chinese medical theory, and as further investigations of quantum physics dynamics on the subcellular energetic systems yield new information, it will become possible to formulate a more definitive theory of explanation.

The use of a simple, effective, inexpensive, and portable TENS device achieves clinical significance in light of the burgeoning cost of medical care. The use of such low-frequency electrostimulation techniques enables patients to obtain ongoing home treatment, at a reasonable cost, in between visits to their physicians.

Further studies are currently in progress to help better delineate the long-term effects of these devices.

References

1. Abelson, K., et al. “Transcutaneous Electrical Nerve Stimulation in Rheumatoid Arthritis.”· New Zealand Medical Journal March 9, 1983; 96:156-158.
2. Becker, R.O. “The Significance of Bioelectric Potentials.” Bioelectrochemistry and Bioenergetics.1974; 1:187-199.
3. Becker, R.O.; Reichmanis, M.; A.A.; and Spadero, J.A. “A Possible Biological Basis for Acupuncture.” Psychoenergetic Systems.
4. Burton, c.v. “Pain Suppression through Peripheral Nerve Stimulation.” In Neural Organization and Its Relevance to Prosthetics. Monograph of Houston Neurological Symposium, 1972. : Intercontinental Book Corporation, 1973, pp. 241-251.
5. Campbell, J.N. and Taub, A. “Local Analgesia from Percutaneo.us Electrical Stimulation: A Peripheral Mechanism.” Archives of Neurology May 1973; 28:347-350.
6. Cotter, Dennis J. “Overview of Transcutaneous Electrical Nerve Stimulation for Treatment of Acute Postoperative Pain.” Medical Instrumentation July – Aug us_t 1983; 17.4:289-291.
7. Hwang, Paul. “Wrist-Ankle Acupuncture: A New Technique.” American Journal of Acupuncture April-June 1977; 5.2:129.
8. Ledergerber, Charles P. “Transcutaneous Electroacupuncture and Electroanalgesia.” American Journal. Acupuncture April-June 1979; 7.2:127.
9. Man, P.L. and Chen, C.H. “Mechanism of Acupunctural Anesthesia.” Diseases of the Nervous System November 1972; 33:730-735.
10. Melzack, R. and Wall, P.D. “Pain Mechanism: A New Theory.” Science November 19, 1965; 150:971-979.
11. Rice, M.C. Electricity. Gynecology• Laing Co., 1909. Chicago, Illinois: L. I.
12. Shealy, C.N. “Six Years Experience with Electrical Stimulation for Control of Pain.” Advances in Neurology 1974; 4:775-783.
13. Sweet, W.H. and Wepsic, J.G. “Electrical Stimulation for Suppression of Pain in Man.” In Neural Organization and Its Relevance to Prosthetics. Monograph of Houston Neurological Symposium,1972. [Place of Publication]: Intercontinental Book Corporation, 1973, pp. 219-240.
14. Wall, P.D. and Gutnik, M. “Properties of Afferent Nerve Impulses Originating from a Neuroma.” Nature April 1974; 248:740-743.