Reliability of side-to-side ultrasound cross-sectional area measurements of lower extremity nerves in healthy subjects

Introduction: In peripheral nerve ultrasound, the healthy contralateral side may be used as internal control. Therefore, inherent side-to-side differences must be minimal. The goal of this study was to assess intrastudy, intraobserver, and interobserver reproducibility of ultrasound in comparative side-to-side evaluation of lower limb nerves. Methods: Lower limb nerves of 60 normal subjects were evaluated by 3 radiologists. Bilateral sciatic, tibial, common fibular, sural, lateral femoral cutaneous, femoral, obturator, and saphenous nerves were evaluated. Results: Overall, side-to-side differences were not statistically significant at any level. In the lower limb nerves, in a between-limb comparison, the minimum detectable difference of cross-sectional area ranged from 16.4 mm2 (sciatic nerve at the level of piriformis muscle) to 0.4 mm2 (saphenous nerve). Conclusion: In general, the healthy contralateral side can be used as an internal control.