Usefulness of Infrared Thermography in Diagnosis of Unilateral Carpal Tunnel Syndrome

Objective: To evaluate the usefulness of infrared thermography in the diagnosis of unilateral carpal tunnel syndrome (CTS). Method: Thirty six patients confirmed electrodiagnostically as CTS and fifteen adults with normal electrodiagnostic study were included in this study. For the thermographic diagnosis, we measured the skin temperature of the palmar area of all 5 fingers, thenar area, hypothenar area and volar area of forearm bilaterally. We compared the interside peak temperature difference between median nerve innervated area and noninnervated area in three different groups (normal control, mild CTS and moderate to severe CTS groups). Results: Thermography of the CTS patients showed significant temperature differences in more than one area of the median vasomotor nerve territory, and no significant temperature difference in all the areas that were not innervated by the median vasomotor nerve. When we considered interside temperature differences of more than 0.3 degrees C as abnormal findings, the sensitivity of thermography was 2.7% and the specificity was 86.6%. With more than 0.6 degrees C as abnormal, the sensitivity was 25% and the specificity was 66.6%. With more than 1.0 degrees C, the sensitivity was 8.3% and the specificity was 73.3%. There was no significant interside peak temperature difference in all groups. Conclusion: This study suggests that infrared thermography has low sensitivity and specificity, which implies that it is not useful for the diagnosis of CTS.