Sonographic evaluation of median nerve cross-sectional area in a normal Iranian population: A cross-sectional study

Introduction: Considering disagreements on the normal range of median nerve cross-sectional area (MNCSA) and insufficient data in the Iranian population, this study aimed to measure normal MNCSA.

Methods: In this cross-sectional study, bilateral upper limbs of 99 subjects were assessed by sonography, and MNCSA was measured at three levels: forearm, carpal tunnel inlet (CTI), and carpal tunnel outlet (CTO). The association between MNCSA and demographic factors was assessed.

Results: Mean MNCSA was 6.33 mm² at the forearm, 9.41 mm² at CTI, and 10.67 mm² at CTO. MNCSA was significantly higher in males (6.78 vs. 5.94 mm² at the forearm, 9.98 vs. 8.92 mm² at CTI, and 11.24 vs. 10.84 mm² at CTO in males and females, respectively) and taller (>170 cm) subjects in all three levels (6.69 vs. 6.03 mm² at the forearm, 9.80 vs. 9.02 mm² at CTI, and 11.27 vs. 10.12 mm² at CTO in taller and shorter subjects, respectively). MNCSA was not significantly associated with wrist ratio (WR) or body mass index (BMI).

Conclusion: The normal MNCSA range in the Iranian population is 6.31 mm² (forearm) to 10.74 mm² (CTO). MNCSA is significantly higher in males and taller subjects but is not associated with BMI and WR.