Thermography as a Diagnostic Aid in Sciatica

Abstract

Thermography has been proposed as a diagnostic aid in patients with sciatica. Supporters of thermography state that: (a) normal patients have normal thermograms of their lower extremities, and (b) abnormal patients (with disk ruptures causing sciatica) have abnormal thermograms. To test these two hypotheses, 56 patients with clinically documented acute sciatica, with a supporting diagnostic study [computed tomography (CT), CT/myelography, and/or magnetic resonance imaging] showing a ruptured disk, had presurgical thermograms. One year after surgical intervention, they had to have had a documented success to surgical treatment intervention to stay in the study. These 56 patients were then matched with 56 control (normal) patients who had electronic thermograms. The 112 thermograms were then interpreted blindly by two thermographers. The sensitivity and specificity of thermography as a diagnostic aid in sciatica were statistically analyzed. The sensitivity of thermography (its ability to be positive when sciatica was clinically obvious) was 60% and 50% for the two thermographic readers. The specificity of thermography (its ability to be negative in asymptomatic patients) was 45% and 48% for the two thermographers. Our conclusions are no different than those published in 1985: thermography is not useful as a diagnostic aid in sciatica.