Ann Clin Neurophysiol.  2021 Oct;23(2):99-107. 10.14253/acn.2021.23.2.99.

Usefulness of infrared thermography in diagnosing and evaluating severity of carpal tunnel syndrome

• Yang J
• Lee YB
• Sung YH
• Shin DJ
• Kim YJ
• Park HM

• KMID: 2521887
• DOI: http://doi.org/10.14253/acn.2021.23.2.99

Abstract

Background
Pain and autonomic dysfunction are prominent symptoms in some patients with carpal tunnel syndrome (CTS). Infrared thermography (IRT) has been used to evaluate CTS by measuring the cutaneous temperature and sympathetic vasomotor function.
Methods
This study enrolled the 66 hands of 33 subjects, some of which had clinical CTS and the others were healthy. The enrolled patients completed the Boston Carpal Tunnel Questionnaire (BCTQ) and Historical-Objective scale, and underwent nerve conduction studies (NCSs) and IRT. Skin temperature was measured at the fingertips and the thenar and hypothenar regions in each hand. We analyzed (1) the correlations between self-reported severity, physician-assessed severity, and test results, and (2) the sensitivity and specificity of IRT in diagnosing CTS.
Results
No significant correlation was observed between the results of the BCTQ, NCS, and IRT. IRT had a low sensitivity and high specificity in diagnosing CTS.
Conclusions
IRT cannot replace NCS in diagnosing CTS, nor did it provide an advantage in combination with NCS. However, lower temperatures at the median nerve in some hands with moderate-to-severe CTS suggested the involvement of sympathetic nerve fiber function. Follow-up studies with a larger-scale and complementary design are required to elucidate the relationships.

Figure

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  Fig. 1. An example of digital infrared thermographic imaging in a patient with carpal tunnel syndrome. Regions of interest are indicated as squares where the temperature was measured.

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  Fig. 2. (A) The mean and median values of the absolute temperature difference (ΔT) between the thenar (Th) and hypothenar (Ht) regions in the same hand with carpal tunnel syndrome (CTS) were higher for class 2 on the historical-objective (Hi-Ob) scale. (B) The temperature was lower in Th (median nerve distribution) in hands with more-severe CTS. (C) The mean and median values of ΔT between digit 3 (D3) and digit 5 in the same hand with CTS were higher for class 3 on the Padua scale. (D) The temperature was lower for D3 (median nerve distribution) in hands with more-severe CTS.

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  Fig. 3. (A) A positive correlation was observed between ΔT for the thenar (Th) and hypothenar (Ht) regions and the symptomatic severity score (of > 4.0) in a hand with carpal tunnel syndrome (CTS). (B) The temperature was lower in Th (median nerve distribution) in hands with CTS with higher symptomatic severity score (SSS).

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