Heat-detection has played a significant role in chiropractic’s search for its elusive “subluxation.” A 1990 chiropractic monograph on thermography states that D.D. Palmer used the back of his hand to locate “hot boxes” along the spinal column in an effort to detect differences in surface temperature from one side to the other. The authors observed that “this technique, although subjective and unreliable owing to the variable sensitivity of the diagnosing physician, has been taught to chiropractic students since the birth of the profession.” 
Chiropractic’s developer B.J. Palmer became enamored with the “neurocalometer,” a device developed by one of his students. In the 1920s, he became convinced that it could identify the existence, location, and extent of vertebral subluxations. The hand-held device consisted of two probes connected to a meter that registered whether points on either side of the spine had different temperatures. B.J. espoused (and insisted upon leasing) the device so vigorously that many of his supporters became alienated .
The Nervo-Scope, a neurocalometer descendant, was marketed during the 1970s by a leading chiropractic supply house. It contained two thermocouples, a battery, and a meter. Its findings could be recorded by connecting the device to a strip chart recorder. The supplier’s catalog said that the device was “taking its place alongside the x-ray in importance” . However, “unreliability and lack of scientific documentation” have prevented widespread use of heat detectors in chiropractic practice .
A 1993 Canadian chiropractic consensus conference concluded that paraspinal measurement with thermocouple devices “has not been shown to have good discriminability, and both their validity and reliability of measurement are highly doubtful.”  This is a politically correct way of saying that the devices are clinically worthless. Yet two models of the device are still marketed, so it is safe to assume that some chiropractors still use them .
In 1973, as part of an investigation I supervised, a woman took her healthy four-year-old daughter to five chiropractors for a general check-up. The woman reported that one of the chiropractors used a Nervo-Scope, which he moved up and down the girl’s spine. Based on deflections of the needle, he stated that the child had spinal problems in the areas containing the nerves that controlled the functioning of her stomach and gallbladder. These problems, of course, were figments of his imagination. A chiropractor who responded to this article said he had experimented with a nervoscope and discovered that the reading was determined by how hard he pressed one probe or the other against the patient’s skin.
Despite their uselessness, these thermocouple devices remain popular among subluxation-based chiropractors. A recently published chiropractic pediatrics textbook even advises that the device is useful for examining newborns. The book states:
The purpose of skin temperature analysis (e.g. Temp-o-scope, Nervoscope) is to obtain objective neruological evidence of a vertebral subluxaiton complex [VSC]. . . .
The method for conducting the exam is dynamic scanning. A bilateral skin temperature difference is depicted as meter needle movement to one side or the other. The “reading” . . . is considered significant if an abrupt “over and back” nedle movement is seen over a one spinal segment distance. The amount of the temperature differential is thought to be directly proportional to the amount of neurophysiolgic involvement due to the presence of VSC. The spinal subluxationin the acute stage often reveals a large variation in temperature. . . . Monitoring the intersegmental heat differential is one of several parameters of assessing and gauging patient progress in response to specific spinal adjusting .
- Christiansen J, Gerow G. Thermography. Baltimore: Williams & Wilkins, 1990.
- Wardwell WI. Chiropractic: History and Evolution of a New Profession. St. Louis: Mosby Year Book, 1992.
- The Complete Catalog of Chiropractic Literature and Supplies. Austell, GA: Si-Nel Publishing & Sales Co., 1971.
- Henderson D and others. Clinical Guidelines for Chiropractic Practice in Canada. Toronto: Canadian Chiropractic Association, 1994.
- Chiropractic Equipment and Supply Catalog. Mt. Horeb, WI: Gonstead Seminar of Chiropractic, 1997.
- Anrig CA. Spinal examination and specific spinal and pelvic adjustments. In Anrig CA, Plaugher G editors. Pediatric Chiropractic. Baltimore: Williams & Wilkins, 1998, pp 323-423.
This article was posted on January 20, 1999.