Abstract

The use of thermography in evaluating nerve injury is based on the presence of temperature asymmetry between the involved area of innervation and the corresponding area of the opposite side of the body. However, interpretation of the thermographic image has been troubled by subjectivity. This paper describes a computer-calculated method of collecting data that eliminates subjective biases. Comprehensive normative data are presented on the degree of thermal asymmetry in the human body. The degree of thermal asymmetry between opposite sides of the body (delta T) is very small. For example, the value of delta T for the forehead (mean +-Standard deviation) was 0.18 degrees centigrade, for the leg it was 0.27 degrees +- 0.2 degrees centigrade, and for the foot was 0.38 degrees plus or minus 0.31 degrees centigrade. The values were reproducible in both short-and long-term follow-up measurements over a period of 5 years. The delta T's reported here were obtained from 40 matched regions of the body surface and of 90 asymptomatic normal individuals. These values can be used as a standard in assessment of sympathetic nerve function, and the degree of asymmetry is a quantifiable indicator of dysfunction.

The system is governed by autonomic nerve impulses generated from the hypothalamus and the brain as a whole. The system is both anatomically and physiologically symmetrical. For this reason, localized, asymmetric temperature changes at the body surface have interested physicians as far back as Hippocrates. Each scan last 3.7 seconds.

As may be expected, while the absolute temperature may vary with time, between nonhomologous regions, and between individuals, the delta T's obtained from anatomically matched homologous regions are extremely stable and reproducible. It is our belief that the delta T's we obtained for normal subjects may be used as a reference standard for comparison to delta T's obtained in most medical examinations. Deviations from the normal values will allow suspicion of neurological pathology to be quantitated and therefore can improve assessment and lead to proper clinical management.

EditorialComment

The "break analysis" appears to be consistent with the findings from this study. Symmetry appears to be the rule when examining paraspinal thermography. It is niceto see medical literature indicate that thermometry is a way of checking sympathetic nerve function.