Background Rheumatoid arthritis (RA) is one of the risk factors associated with carpal tunnel syndrome (CTS). Ultrasonography is a useful tool for the diagnosis of CTS, but the features of ultrasonography in RA patients complicated with CTS are not well known.
Objectives To examine the utility of ultrasonography for the diagnosis of CTS complicated with RA.
Methods Eighteen wrists from the 10 RA patients with CTS (CTS+RA group), 14 wrists from the 8 patients of CTS without RA (CTS group), 42 wrists from the 22 RA patients without CTS (RA group) and 26 wrists from 13 healthy subjects (control group) were assessed by ultrasonography. Diagnosis of CTS was made based on the guideline published from American Academy of Orthopaedic Surgeons (AAOS). Ultrasonography assessment was made according to the methods proposed from OMERACT. We also evaluated the maximum and minimum value of cross-sectional area (CSA) of the median nerves by ultrasonography. We have tried to investigate the characteristics found in ultrasonography of CTS+RA group.
Results CSA of the median nerves were significantly higher in the CTS patients (CTS+RA and CTS groups) compared with the others (RA and control groups). Receiver operating characteristics (ROC) analysis revealed that maximum value of CSA 12mm2 was the most powerful predictor toward CTS (CTS+RA and CTS groups) (AUC=0.93; sensitivity 87%, specificity 90% and accuracy 89%). Furthermore, the presence of PD signals (p<0.001) and tenosynovitis (p<0.001) of flexor tendon were significantly high in CTS+RA group as compared with RA group.
Conclusions CSA measurement of median nerves and the presence of PD signals of median nerves as well as flexor tenosynovitis determined by ultrasonography are considered to be clinically useful indicators to diagnose the patients of CTS complicated with RA.
Disclosure of Interest None declared