Anatomy of the normal brachial plexus revealed by sonography and the role of sonographic guidance in anesthesia of the brachial plexus

OBJECTIVE. The purpose of this study is to describe the sonographic appearance of the normal brachial plexus and to evaluate the use of imaging guidance for brachial plexus anesthesia. SUBJECTS AND METHODS. Twenty adults requiring upper limb surgery underwent sonography with a high-frequency transducer to identify the brachial plexus at the interscalene (n = 16) and supraclavicular (n = 4) regions. Catheters for brachial plexus anesthesia were placed using sonographic guidance and evaluated using radiography and CT after injection of contrast material. The success of the neural blockade and surgical anesthesia was assessed. General anesthesia was chosen preoperatively or used for supplementation if blockade was incomplete. RESULTS. The brachial plexus appeared as three discrete rounded hypoechoic nodules between the scalenus anterior and medius muscles on transverse sonography at the lower cervical (C6) region, representing the trunks in sagittal oblique section. A cluster of hypoechoic nodules corresponding to the divisions was seen cephalad to the subclavian artery on sagittal scans of the supraclavicular region. Radiography was used to verify correct catheter placement; the brachial plexus sheath appeared as a tubular area of contrast material in the neck that was well circumscribed in patients who had supraclavicular injections of contrast material and corrugated in those who bad interscalene injections. CT scans showed contrast material spread around the scalenus muscles in most patients with interscalene injections. Successful neural blockade at 20 min and postoperative analgesia were achieved in all patients. Surgical anesthesia was achieved in nine of 15 patients. Five patients chose general anesthesia before surgery and therefore did not have surgical anesthesia assessed. CONCLUSION. High-resolution sonography can show normal brachial plexus anatomy and facilitate catheter- based brachial plexus anesthesia without complications.