Background/Purpose: Rheumatoid arthritis (RA) is an autoimmune joint disease with systemic involvement which can affect the nerves through either compressive pathology due to intra-articular synovitis and tenosynovitis or vasculitis of the vasa vasorum. Carpal tunnel syndrome (CTS) is a compression neuropathy caused by entrapment of the median nerve within the carpal tunnel. This study aimed to evaluate morphological and elasticity-related changes of the median nerve using B-mode ultrasonography (US) and shear wave elastography (SWE) in RA patients without signs of median nerve involvement and to examine the relationship between these changes, disease activity, and hand functions.

Methods: This cross-sectional study included 55 RA patients without CTS symptoms fulfilling the 2010 ACR/EULAR Classification criteria and 55 age- and sex-matched healthy controls. Exclusion criteria were having diagnosis of CTS, pregnancy, endocrine disorders such as diabetes and hypothyroidism, and trauma or surgery history of the upper limbs. Demographic characteristics, disease activity score (DAS28-CRP), medications, hand grip strength (Jamar dynamometer), lateral pinch strength (pinch meter), and hand function (Duruöz Hand Index) were recorded. An experienced physician blinded to patients’ data performed bilateral US evaluations to assess median nerve cross-sectional area (CSA, mm2) and presence of flexor digitorum tenosynovitis by B-mode, inflammatory activity via Power Doppler US, and nerve stiffness using SWE (median and mean velocity values, m/s) using a high frequency linear probe (Siemens S2000 Acuson, Mountain View, CA). The Outcome Measures in Rheumatology (OMERACT) US grading system was used for US evaluations. IBM SPSS Statistics 26 and Python were used for statistical analyses.

Results: The mean age of the RA patients was 58.6 ± 9.1 years and the mean disease duration was 14.3±8.9 years. Sixty nine percent of the cohort was RF positive. RA patients had significantly lower grip strength and worse hand function compared to controls (p< 0.001). The mean median nerve CSA (13.79±4.41 mm2) and the presence of flexor digitorum tenosynovitis and Power Doppler signal were significantly higher in the RA group compared to controls (p< 0.001) (Table 1). The mean SWE velocity of the meadian nerve was significantly higher in the RA group (2.58±0.38 m/s vs 1.76±0.45 m/s; p< 0.001) and RA patients with flexor tenosynovitis (p=0.012). While the median nerve CSA did not show significant relationship with clinical parameters, median nerve SWE velocity showed significant positive correlations with height (p=0.012, r=0.346) and grip strength (p=0.018, r=0,326) and significant negative correlations with CRP and ESR (p=0.046, r=-0.278; p=0.001, r=-0.460 respectively).

Conclusion: The median nerve CSA and SWE-measured stiffness were significantly higher in RA patients without CTS symptoms compared to healthy individuals. The association between tenosynovitis and increased SWE values suggests that local subclinical inflammation may affect biomechanical properties of the median nerve. Therefore, SWE appears to be a promising tool for the early detection of subclinical nerve changes in RA.

Table 1. Clinicodemographic characteristics and handgrip strength, hand function, and ultrasonographic parameters in RA and control groups

Table 1. Clinicodemographic characteristics and handgrip strength, hand function, and ultrasonographic parameters in RA and control groups

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/relationship-between-ultrasonographic-and-elastographic-findings-of-the-median-nerve-and-disease-activity-and-hand-function-in-patients-with-rheumatoid-arthritis/