Localization of the brachial plexus: Sonography versus anatomic landmarks

PURPOSE: Interscalene brachial plexus blocks are performed for perioperative management of surgeries involving the shoulder. Historically, these procedures employed anatomic landmarks (AL) to determine the location of the brachial plexus as it passes between the anterior and middle scalene muscles in the neck. In this study, we compared the actual location of the brachial plexus as found with sonography (US) to the anticipated location using AL. METHODS: The location of the brachial plexus was evaluated using US and AL in 96 subjects. The distance between the two locations was measured. A multivariate analysis of variance was used to determine the significance of the difference and a 2 × 2 analysis of variance was used to compare differences in gender, height, and body mass index. RESULTS: The brachial plexus was located on average 1.8 cm inferior (p = 0.0001) and 0.2 cm lateral (p = 0.09) to the location determined with AL. A significant difference was also associated with gender (p = 0.03), but not with height or body mass index. CONCLUSIONS: US is a reliable method that accurately pinpoints the roots of the brachial plexus. The brachial plexus is often located inferior to the location anticipated using AL.