The presence of nerve interference in the cervical spine is determined by the observation of both a persistent differential parasipinal dermothermographic pattern in the cervical region and a functional leg length deficiency. A dual-probe instrument is used for detecting and recording continuous heat differentials in the cervical paraspinal area, with the instrument glide proceeding superiorly from about TI spinous process to about the superior nuchal line. At least two, and preferably three, consecutive readings, taken on separate days, a-re required to determine the patient's individual, characteristic heat pattern indicative of nerve interference. The individual's pattern is defined by those unilateral heat deflections ("breaks") which are invariantly present on each of the pre-adjustive readings. Except in the case of a new injury changing the misalignment, the patient is not readjusted subsequent to the initial adjustment until the original dermothermographic pattern has returned, in the presence of a functional leg length deficiency. (Dr. Blair required these findings on two separate occasions not more than seven days apart before re-adjusting the patient, as do some contemporary practitioners.)
The functional leg length deficiency has traditionally been assessed in the prone position without further elaboration. However, many current practitioners add the Thompson-Derfeid procedures of modified Prill procedures, or both, and some practitioners use the supine spinal balance test, either instead of the prone testing or in conjunction with it. (See Appendix A for further discussion of the applications of dermothermographic and spinal balance testing.)
A concise summary of the Blair Cervical spinographic analysis has been published previously and is included as Appendix B, to which the reader is here referred.