Ultrasound Characteristics of Carpal Tunnel Syndrome in the Spanish Population

The aim of this study was to determine the cross-sectional area (CSA) (cm²) of the median nerve and its relationship with patient age and sex, together with the frequency of other qualitative ultrasound patterns in patients with carpal tunnel syndrome (CTS) in the Spanish population.

An observational, cross-sectional, prospective, descriptive study was conducted among 79 patients diagnosed with CTS. The CSA of the median nerve was measured at the carpal tunnel inlet (CTI) and outlet (CTO) by ultrasound examination. In addition, qualitative variables such as hyperechoic enhancement, thickening, and loss of ultrasound pattern of the median nerve were measured. The images were analyzed using Image J software.

The sample comprised 73.4% women and 26.6% men. In 68.4% of the cases, the dominant hand was involved. Professional cleaners and domestic staff were the most affected (22.8%). The CSA of the median nerve in patients with CTS was 0.16 cm² (95% CI 0.15-0.18) at the CTI and 0.17 cm² (95% CI 0.16-0.18) at CTO. At the CTI and CTO, the CSA showed significant differences in men under 50 years. As for the qualitative variables at the CTI and CTO, the most notable finding was the alteration in the ultrasound pattern, which was present in 87.3% and 91.1% of subjects, respectively.

The median nerve CSA has a homogeneous value at the CTI and CTO in the Spanish population with CTS. These values show differences in terms of patient age and sex. The alteration in the ultrasound pattern of the nerve and the presence of hyperechoic reinforcement are the most frequent qualitative findings.