The earliest recorded human effort at neurostimulation appears to have been that of the Mesopotamian healer Scribonius Largus who used electrical currents to produce transient pain relief. By either the direct application of electrical torpedo fish (eels, of the type shown below) to the human body or by placing painful extremities into a pool of water containing torpedo fish the resulting electrical shocks stunned the nervous system allowing an immediate and residual numbness in the extremity.
In this application electrical torpedo fish were the very first means of achieving transcutaneous electrical nerve stimulation (TENS) for therapeutic purposes. This form of treatment was particularly popular for the treatment of gouty arthritis.
From these early efforts the creation, storage, and delivery of electrical energy then became the challenge. From the works of Volta, Faraday and others batteries were soon developed. In the United States in the 1750s, pioneers such as Benjamin Franklin began to experiment with these new electrical devices and explore their nature. At this phase of development transcutaneous electrical stimulation was more of a mystical event and attraction rather than a true medical device.
Michael Farady was been considered by many to have be one of the most brilliant scientists of all time. His “Law” announced in 1833 pointed out that an electric current can produce a magnetic field and that the reverse was also true. This observation was the key to the development of the inductorium which then served as the basis for neurostimulation.
This illustration, from the 1871 Edition of the Beard and Rockwell publication on the Medical and Surgical Uses of Electricity demonstrates “Faradization” being performed on a subject using a direct current inductorium device. The unit shown is similar to those used previously by Benjamin Franklin as a means of producing pain relief, as well as relief from a myriad of other disorders.
By 1863, Gaiffe, in Paris France, had constructed a transcutaneous electrical nerve stimulating device remarkably similar to those in use today. This device, was the true precursor of the modern TENS unit featuring removable batteries, an inductorium, lead wires and skin electrodes. It’s only limitation was its low electrical output under load (about 3 milliamperes as opposed to modern TENS units with 90 milliampere outputs).
This advertisement from the 1882 Boston Globe appears to be one of the earliest examples of the M2H phenomenon and “media medicine.” It states:“One of the MOST MARVELLOUS (sic)
INVENTIONS OF THE CENTURY!” “All cases of Rheumatism, Diseases of the Liver, Stomach and Kidneys, Lung Complaints, Paralysis, Lost Vitality, Nervous Disability, Female Complaints…are cured with the Electrifier.”
Welcome to the “Electreat”, a TENS device patented by Charles Willie Kent in 1919 and manufactured in Peoria, Illinois. It has been estimated that as many as 250,000 of the Electreats were sold over the following 25 years. The device operated on two “D” cell batteries and a mechanical inductorium. A roller was built in at the top to be applied to the skin and plug-in sponge pad electrodes were supplied.
The Electreat was one of the very first high-output battery operated TENS units manufactured. Touted as the “Artificial Heart” its claims rivaled those of the Faradic Electrifier. Following passage of the Food, Drug and Cosmetic Act in 1938, Kent was the first individual prosecuted by the U.S. government for making unsubstantiated medical claims and the Electreat company was then forced to limit their claims to pain relief alone.
The family of neurosurgeon C. Norman Shealy (who was the first surgeon to actually implant neuroaugmentive devices in humans) had used the Electreat in the past. Based on his personal experience he approached Medtronic, in Minneapolis, and encouraged them to begin to develop solid-state TENS devices. Shown below are some of the early TENS devices which were manufactured in Minneapolis during the 1970s.
The evolution of TENS devices led to more compact units with better patient safety provisions. At the same time there was an associated evolution in the technology of skin electrodes. Despite these advances both TENS units and skin electrodes remain fairly primitive in design in regard to their future potential similar to that of implanted neuroaugmentive devices.
As with most poorly understood, but impressive, physical phenomena the application of TENS in past times often became used as part of mystical and magical performances. By the 1970s the “Barnum & Bailey” phase of TENS began to change. In Minneapolis, Minnesota a number of medical device manufacturing companies (i.e. Medtronic, Stimulation Technologies, Inc., etc.) were among the first to begin to take a serious look at TENS technology and began, for the first time, to apply solid-state technology to these therapeutic applications.
From the efforts of a small group of pioneers at Temple University in Philadelphia and C. Norman Shealy in Boston the new discipline of implanted electronic devices designed to influence the function of the nervous system for therapeutic purposes began in the 1960s. While there is every reason to believe that neurostimulation will continue to progress and become more sophisticated in the future it is clear that we have a long way to go before this science can begin to approach the sophistication of our piscean brethren.