Reliability of Side-to-Side Sonographic Cross-sectional Area Measurements of Upper Extremity Nerves in Healthy Volunteers

OBJECTIVES: In sonographic evaluations of peripheral nerves, the healthy, contralateral side may be used as an internal control for the pathologic one. Therefore, the inherent side-to-side differences must be minimal. The goal of this study was to determine the reliability of side-to-side measurements of upper extremity nerves in healthy volunteers. METHODS: Forty participants with no upper extremity abnormalities were included. Upper limb nerves were evaluated bilaterally at the usual pathologic sites by 3 musculo-skeletal radiologists in separate sessions. To assess intraobserver and interobserver agreement, sonographic examinations were repeated 2 months after the first evaluations. The median nerve, ulnar nerve, musculocutaneous nerve, and radial nerve were considered. Nonparametric tests were used for statistical analysis. RESULTS: Minimum detectable differences with relative 95% confidence intervals were reported. Intraobserver and interobserver agreements were good (0.73 < κ < 0.85). When the combined influence of the observer and the repeated measurement was evaluated, the reliability was 80% to 87%. CONCLUSIONS: In general, the healthy contralateral side can be used as an internal control considering that changes in minimum detectable differences are related to the anatomic site considered.