Edward F. Owens,
Steven B. Schram
Ronald S. Hosek

Life Chiropractic College, Marietta, Georgia



To better study the effects of adjustment on the skin temperature an inexpensive device was developed, for use under dynamic conditions, with sensors that could remain in place on the spine during manipulation. Thermistors, which transduce temperature changes into resistance changes, were chosen for their quick, repeatable and linear response in the range from 30 to 37 degrees Celsius. An array of fifty-six thermistors with matched responses was constructed to provide temperature monitoring at twenty-eight spots, approximately one centimeter apart, on each side of the spine.

With a series of electronic switches the thermistors are sequentially connected into signal amplification circuitry. Control of the switching is via an Apple II+ computer with an AIO Parallel/Serial Interface, which allows the Apple to send and receive binary signals. Sampling of the entire array occurs under program control approximately once every second, which effectively provides a continuous monitoring of temperature changes. A variable offset voltage is added to the amplified voltage across each thermistor. This conditioned signal is then sent to the Apple via an Analog to Digital Converter. The Apple is programmed to calculate and display the numerical temperature values on a video monitor as a bilateral temperature histogram. Temperature differences between each side of the spine, at each of the twenty-eight levels, is also calculated and displayed as a point plot overlying the histogram.

The variable offset voltage and gain of the conditioning circuitry increases the sensitivity of the system but makes calibration difficult. To circumvent this difficulty, calibration resistors which mimic the response of the thermistors at 33, 34 and 35 degrees Celsius, were incorporated into the conditioning circuitry. The responses of these resistors are conditioned and displayed as temperature references along with the actual temperature values arising from the thermistors array.

In use the thermistor array is properly positioned an then taped in place on the subject's back. For most subjects, the array as constructed will permit sampling from C1 through L5. Once attached, a temperature profile baseline is established for several minutes and then the values saved and the histogram plotted. At this time, an adjustment may be delivered to a previously established level of subluxation with the array in place and the program running. Dynamic changes in the temperature profile with adjustment may be cleared observed and plotted.

Preliminary findings suggest that the thermal profile will change with adjustments. Such changes may involve either increases or decreases in regional temperatures, not necessarily at the adjusted level. Sham and specific adjustments do not appear to give comparable results. Additionally, observed results are not explainable by the adjustor's hand contacting the thermistor array.

The FCER is gratefully acknowledged for funding this work.