Chiropractic History Assignment: Current trends and the history of TENS

Steve Zoltai
June 18, 2008
Written by Steve Zoltai
In the May edition of CHA, we gave you a quick sketch of the history of electricity, its effect on popular culture and its impact on the philosophies of thinkers like Bergson, Mesmer and D.D. Palmer. Mary Shelley’s Frankenstein tale and D.D. Palmer’s theoretical framework for modern chiropractic shared common roots with the belief in electricity as a primal source of animation and regeneration. The McIntosh No. 2 Polysine Generator was one practical manifestation of this fascination with the seemingly boundless potential of electricity in a landscape populated with often fanciful claims to health improvement. The challenge for us became to divine what the polysine’s makers intended the machine to do, whether it had any real therapeutic effect and if there are any modern analogies.

Dr. Rick Ruegg is the associate dean of Clinical Education at CMCC and our resident modalities expert. I put those questions to him. Dr. Ruegg says:

“If asked to label this interesting device in modern terms, I’d likely describe it as one of the original ‘mult-stim devices.’ Today, multi-stim devices typically provide programs for interferential current (IFC) therapy, bi-polar (pulsed or pre-modulated), Russian (muscle) stimulation, bi-phasic and micro-current. This particular device appears to provide two of these functions. Both channels can develop alternating current (AC) and are able to generate a sinusoidal wave form which is the basis for all IFC units. With one channel “fixed” and the other “variable,” the interference between the two channels would produce a therapeutic frequency within the tissues – a principle which is still used today in modern IFC devices. The channels are also capable of creating direct current (DC) which can be applied directly to the tissues in a low volt or bi-phasic fashion. The patient’s experience would include a gentle buzzing sensation (high frequency stimulation), a sharp, prickling sensation (low frequency stimulation) or muscle twitching/contraction. While early therapeutic devices were attributed with a variety of effects – from pain relief or anti-inflammatory effects to preventing hair loss – current research provides support for temporary pain relief and muscle rehabilitation only.”

Electricity has been used in medicine since Roman times. In 46 CE, the physician and pharmacologist Scribonius Largus noted the pain-relieving properties of the discharge of the electric torpedo ray and recommended it for the treatment of headache and gout (1):

“Headache even if it is chronic and unbearable is taken away and remedied forever by a live black torpedo placed on the spot which is in pain, until the pain ceases. As soon as the numbness has been felt the remedy should be removed lest the ability to feel be taken from the part. (2)”

An early form of electroanalgesia, this therapy is still in use 2,000 years later with a small Transcutaneous Electrical Nerve Stimulator (TENS) pulse generator replacing the ray.

Dr. Calin Lucaciu in our anatomy department sees the parallel.

“Although the first modern, wearable TENS was patented in 1974, the basic components are similar to our polysine generator even though our instrument was manufactured sometime early in the 20th century,” says Dr. Lucaciu. “This suggests that chiropractors even in those days possessed a surprisingly high level of clinical understanding in the field of applied neuro-physiology.”

What does this renowned showcase for musical talent have in common with this portable medical instrument?  Hint: Who debuted at this location on a very different type of instrument at age 13?
He goes on to explain the theoretical rationale for the use of TENS: “proprioception and general sensations are transmitted to the spinal cord via highly myelinated nerve fibres while nerve impulses related to pain sensation are transmitted via low myelinated fibres. The highly myelinated fibres will stimulate interneurons that suppress the projection of the low myelinated fibres onto tract cells in the cerebral cortex. Consequently the “pain gate” is closed and no pain is felt. Alternately, the continuous stimulation of low myelinated fibres will suppress the activity of these interneurons, which causes the gate to open and pain is experienced. This is where electrical stimulation by TENS finds its therapeutic application along with other procedures such as mild exercise, massage and ice application. Any of these procedures, including chiropractic manipulation, promote the activity of the highly myelinated fibres that eventually reduce pain or stop it entirely.” In other words, activation of nerves that do not transmit pain signals by modalities such as TENS can disrupt signals from pain fibres and may inhibit pain perception. “This is essentially the Gate Control Theory of Pain that was originally proposed by Melzack and Wall in 1962,” Dr. Lucaciu concludes. Although since revised many times, the concept of modulation of pain perception within the nervous system remains key to pain studies.

Surprisingly, it was not until Melzack and Wall’s mid-twentieth century postulation that a theoretical rationale was laid out for the therapeutic effects observed by Scribonius Largus with his torpedo rays two millennia ago. 

1. Encyclopaedia Romana, James Grout,
2. Cabinet of Wonders, Heather McGougal,
3. The Marvellous Toy, Tom Paxton.

Steve Zoltai is the collections development librarian and archivist for CMCC and was previously the Assistant Executive Director of the Health Sciences Information Consortium of Toronto. He has worked for several public and private libraries and with the University of Toronto Archives. Steve comes by his interest in things historical honestly – he worked as a field archeologist for the Province of Manitoba. He can be contacted at This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

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