Carpal tunnel syndrome evaluation with ultrasound in rheumatoid arthritis patients

In this study, our primary aim was to compare ultrasound (US) findings of the median nerve between rheumatoid arthritis (RA) with carpal tunnel syndrome (CTS) (RA(+)CTS), RA without CTS (RA(-)CTS) and healthy controls (HC) and to determine the optimal US parameters to detect the presence of CTS in RA patients.

65 RA patients and 25 HC patients were included in this study. The diagnosis of CTS was made according to the clinical history and physical examination of the participants. Median nerve cross-sectional area(CSA) was measured at the carpal tunnel inlet(CTI), outlet(CTO), and forearm level by the US. In addition, anteroposterior(AP) and mediolateral(ML) diameters of the median nerve were measured. After the measurements, wrist-to-forearm ratio, wrist-to-forearm difference, and flattening ratio were calculated. The presence of tenosynovitis was investigated.

CTS was detected in 26(40.0%) of 65 RA patients who participated in the study. CTS was detected in 43(35.2%) of 122 wrists of 65 RA patients. CTI CSA, CTO CSA, forearm CSA, anteroposterior/mediolateral diameter, wrist-to-forearm ratio, wrist-to-forearm difference, and flattening ratio were significantly higher in RA(+)CTS than in RA(-)CTS and HC(p<0.01). In addition, CDAI and CTI CSA(r=0.322, p<0.01), CTO CSA(r=0.301, p<0.01), CTI-to-forearm ratio(r=0.345, p<0.001), CTI-to-forearm difference(r=0.362, p<0.01) and CTO-Forearm difference(r=0.304, p<0.01) moderate correlation was found between. The frequency of tenosynovitis was higher in wrists with CTS than in wrists without CTS (p<0.05).

While the presence of CTS in RA patients is sonographically evaluated, it may be useful to evaluate parameters such as CTI-to-forearm difference, ratio, and CTI ML diameter rather than just sticking to CTI CSA during diagnosis. Correlations of these parameters with disease activity can also be noted.