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

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.

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).

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).

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