An evaluation of the sensitivity and specificity of medical thermography for the documentation of myofascial trigger points

• Published in: Pain (Amsterdam) Vol. 48; no. 2; pp. 205 - 213
• Main Authors: Swerdlow, Bernard, Dieter, John Nathan I.
• Format: Journal Article
• Language: English
• Published: United States Elsevier B.V 01.02.1992
• Subjects: Chi-Square Distribution; Humans; Myofascial Pain Syndromes - diagnosis; Myofascial Pain Syndromes - physiopathology; Myofascial syndromes; Sensitivity and Specificity; Thermography; Trigger points; Trigger points; Myofascial syndromes; Thermography
• ISSN: 0304-3959; 1872-6623
• DOI: 10.1016/0304-3959(92)90060-O

This investigation evaluated the diagnostic value of medical thermology for the documentation of myofascial trigger points. Previous investigators have suggested that circumscribed ‘hot spots’ reflect the thermal activity of trigger points. A total of 365 patients participated in the four separate experiments. Upper back trigger points were isolated via palpation. A separate thermographic examination, specific to that experiment, was conducted by a technologist who was blind to the presence or absence of trigger points. The first experiment examined the Swerdlow-Dieter protocol. Fifty percent of the subjects with trigger points demonstrated hot spots. Over 60% of patients without trigger points exhibited hot spots. Chi-square analysis determined that there was no significant difference between these two groups. The majority of hot spots were unrelated to trigger point location. The second experiment evaluated the protocol suggested by Fisher. Hot spots were evident in the majority of subjects, regardless of whether they possessed trigger points. The third experiment investigated hot spot persistence by adapting the Weinstein-Weinstein alcohol spray protocol. Chi-square analysis found no significant difference between the effect which spray had on the hot spots of patients with or without trigger points. Following a post-spray machine adjustment, the majority of pre-spray hot spots could be reproduced. The final experiment used a pressure threshold meter (PTM) to evaluate the number of kilograms pressure a patient's hot spot could comfortably sustain in comparison to the opposite location on the back. Using the t test, no significant difference was found between the kilograms pressure withstood by hot spot and non-hot spot regions. The results of this investigation suggest that thermographic hot spots, observed on the upper back, are unassociated with active trigger points. Efforts should be taken to determine the physiology responsible for these common and persistent thermal phenomena.