Diagnostic Capability of Ultrasonography in Evaluating Peripheral Nerve Injuries of the Brachial Plexus

The purpose of this study is to determine the diagnostic capability of ultrasonography (US) in patients with suspected brachial plexus injury (BPI) to the terminal nerves by comparing physical examination (PE) findings with US, electromyography (EMG), and magnetic resonance imaging (MRI) reports.

All patients at a single institution who underwent US for peripheral nerve injury of the brachial plexus and terminal nerves resulting in sensory-motor deficits from October 1, 2017 to October 31, 2023 were identified. A retrospective chart review was performed. Each PE, US, EMG, and MRI reports were given an overall rating: "normal" or "abnormal." Terminal nerves (musculocutaneous, axillary, radial, ulnar, medial) were individually assessed as "normal" or "abnormal." The interobserver agreement between reports was calculated using Cohen kappa. Specificity and sensitivity analyses were performed to determine diagnostic accuracy and were reported with 95% confidence intervals (CI).

A total of 120 patients were included. Most injuries were traumatic in nature (78.8%) and were low-energy (53.8%). When each imaging modality was compared with the PE findings, EMG had the highest interobserver agreement (Cohen kappa = 0.18), followed by US (Cohen kappa = 0.10), and last MRI (Cohen kappa = 0.07). The US had the highest sensitivity (0.92, CI = 0.85, 0.96) among the 3 imaging modalities (Table 2). On US, the ulnar nerve was most commonly abnormal (n = 84, 70.0%).

Ultrasonography serves as a useful adjunct in the workup of patients with suspected peripheral BPI and is reliable in localizing the pathology of injured terminal nerves in the brachial plexus.