BackgroundRheumatoid arthritis (RA) is one cause of carpal tunnel syndromes (CTS); due to increased intracarpal pressure in the rheumatoid wrist, synovial enlargement, joint erosions, and ligamentous laxity cause the compression of the median nerve (MN).Materials and methodsA case-control study was conducted to assess the measurement of median nerve areas in RA using high-frequency ultrasound (US) and to correlate the measurement with the disease duration. Forty patients with rheumatoid arthritis (RA) and 40 with non-rheumatoid arthritis (RA) as a control group were referred to the radiology department of Yastabshiron Hospital, Khartoum, Sudan, from June to August 2022. After assessing the wrist joint by ultrasound scans, median nerve (MN) cross-sectional area (CSA) measurements were performed using a Fukuda Denshi ultrasound machine (Tokyo, Japan) with a linear-array high-frequency transducer (10 MHz), after receiving ethical approval from the research committee of the faculty of radiological science at University of Medical Sciences and Technology (UMST) and the study participants.ResultsThe study demonstrated that the mean measurement of MN cross-sectional area (CSA) in RA patients was 13.60 mm2for the right and 13.25 mm2for the left MN. The study found that the MN CSA decreased by increasing the disease duration, with significant differences in the median nerve cross-sectional areas in RA and healthy control (p-value of <0.01).ConclusionThe study concluded that rheumatoid arthritis (RA) had a greater influence on the median nerve cross-sectional areas. MN areas significantly decreased with increasing duration of diseases; the MN cross-sectional areas were more in RA than in the healthy control group.