Reference Values for the Cross Sectional Area of Normal Tibial Nerve on High-resolution Ultrasonography.

Aim: The aim of the study was to establish reference values for the cross-sectional area of the tibial nerve on high-resolution ultrasonography and to investigate the relationship between the cross-sectional area of the tibial nerve and subject's age, gender, height (in cm), weight (in kg) and body mass index.

Methods: Two hundred subjects of either gender and over 18 years of age with no history of peripheral neuropathy or trauma to the lower limb were evaluated with high-resolution ultrasonography. Mean cross-sectional areas of tibial nerves were measured at two different levels in both lower limbs, first at 1 cm below the bifurcation of the sciatic nerve into tibial and common peroneal nerves (level I) and the second at 1 cm superior and posterior to the medial malleolus (level II).

Results: The mean cross-sectional area measured at level I (0.196 + 0.014 cm²) was larger than the one measured at level II (0.111 ± 0.011 cm²). A positive correlation was found between the mean cross-sectional area and height, weight, and body mass index (p <0.05). Women had smaller cross-sectional areas of the tibial nerves than men at both sites. In addition, no significant relationship was found with the age of the subjects (p >0.05).

Conclusion: The established reference values of the cross-sectional area of the tibial nerve will aid in early diagnosis of peripheral neuropathy.