Anomalous Course of the Brachial Plexus Identified During Ultrasound-Guided Brachial Plexus Nerve Block.

Knowledge of brachial plexus anatomy is essential when performing upper-extremity regional anaesthesia. Anomalous brachial plexus anatomy has been reported in up to 35% of patients. Variants include anomalous course of the roots anterior to, or within, the scalene musculature and abnormal separation of the cords around the subclavian artery. These anomalies have been detected with ultrasound, a valuable tool for delineating anatomy and providing imaging guidance during regional anaesthesia. We report a previously undescribed course of the brachial plexus relative to the subclavian artery within the supraclavicular fossa identified by ultrasound prior to peripheral nerve blockade.