Is Infrared Thermography Reliable to Assess Pain in the Trapezius Muscle Region?

The aim of this study was to evaluate the inter- and intra-examiner reliability of infrared thermography (IT) in skin temperature analysis of people with pain complaints in the upper trapezius muscle.

A total of 82 subjects (24.8 ± 6.9 years; 63.8 ± 13.1 kg) of both genders who had moderate (VAS-3) or severe pain in the upper trapezius muscle were evaluated. Skin temperatures of four areas (ROIs) were analyzed by IT using a FLIR camera (model T640SC - Sweden). Each evaluator performed two area analyses at different times.

The evaluation of the four areas indicated a very strong overall intraclass correlation coefficient (ICC) for both intra-examiner (Examiner 1: ICC = 0.936; 95% CI = 0.905–0.959; P < 0.001; Examiner 2: ICC = 0.979; 95% CI = 0.968–0.987; P < 0.001) and inter-examiner (Measurement 1: ICC = 0.933; 95% CI = 0.902–0.958; P < 0.001; Measurement 2: ICC = 0.979; 95% CI = 0.968–0.987; P < 0.001). The ICC was regular on ROI 3 in the measurement 1 inter-exam test, and the ROI 1, ROI 2, and ROI 4 values were strong; all points were very strong in measurement 2. The ICC was rated from strong to very strong for both examiners in the intra-examiner test at all points.

IT was reproducible in measuring the upper trapezius muscle skin temperature, and the intra and inter-examiner agreement levels can be used as a reliable tool in clinical practice.