Objectives: Ultrasonography (US) has shown increased cross-sectional area of the median nerve in carpal tunnel syndrome (CTS). Knowledge of the normal distribution of the areas is a prerequisite to be able to evaluate pathology. Presently, the distribution of cross-sectional areas of the median nerve was explored in rheumatoid arthritis (RA) patients.
Methods: RA patients with no symptoms or signs of CTS were examined with bilateral US of the median nerve at the entrance of the carpal tunnel.
Results: A total of 154 RA patients were included. The median nerve was divided in 11.7% of the hands. The mean (SD) cross-sectional areas of the not divided median nerves were not significantly different on the two sides (8.3 (1.5) mm2 right side and 8.3 (1.4) mm2 left side). The areas of the examined 308 median nerves ranged from 5.0 to 12.8 mm2, with the 97.5 percentile being 11.1 mm2. Areas > 10.0 mm2 was found in 10% of the patients.
Conclusions: The mean cross-sectional area of the median nerve in RA patients was similar to values reported in healthy persons. However, 10% of the patients had values that are overlapping with areas commonly reported in patients with mild idiopathic CTS.
- carpal tunnel syndrome
- median nerve
- rheumatoid arthritis