Infrared Thermographic Changes after Decompression Surgery in Patients with Carpal Tunnel Syndrome

Background: Digital infrared thermal imaging (DITI) is a useful tool for assessing carpal tunnel syndrome (CTS). Notably, this can demonstrate autonomic vasomotor activity in the nerve-innervated area. In this study, we compared DITI findings before and after carpal tunnel release (CTR) surgery in patients with unilateral CTS to investigate the corresponding neurophysiological changes. Methods DITI parameters such as the temperature differences between the median and ulnar nerve territories and median nerve-innervated digital anisometry were measured. Subjective symptom duration, pain scale, and ultrasonographic findings were also compared before and after CTR. Patients were evaluated before and six weeks after CTR, respectively. Results A total of 27 patients aged 59.0 ± 11.2 years were finally included. After CTR, median nerve-innervated thermal anisometry was improved (2.55 ± 0.96 ℃ to 1.64 ± 1.34 ℃; p = 0.003). The temperature differences between the median and ulnar nerve territories were not significantly changed. Subjective pain, the Simovic Weinberg Clinical Scale, and palmar bowing of the flexor retinaculum were also significantly improved (p < 0.001 for all comparisons). Conclusions Our results demonstrated that DITI findings could reflect an improvement in autonomic function after CTR. Therefore, DITI can be an objective method to assess pre- and post-operative neurophysiologic changes in CTS.