Peripheral nerve ultrasound imaging shows enlargement of peripheral nerves outside the brachial plexus in neuralgic amyotrophy

Purpose: Neuralgic amyotrophy is characterized by acute or subacute onset of shoulder and arm pain, followed by muscle atrophy and weakness, and variable sensory abnormalities. Historically, the site of inflammation has been localized to the brachial plexus, although the involvement of individual nerve branches has been well recognized. Methods: We describe ultrasound findings in two cases with a clinical presentation suggestive of neuralgic amyotrophy, involving individual peripheral nerves, correlating with clinical and electrophysiological findings. Results: In the first case, selective fusiform enlargement of the left radial nerve in the proximal forearm is shown, whereas in the second case, fusiform enlargement of the left median nerve in the antecubital fossa is shown. Discussion: These cases confirm that the site of nerve inflammation may lie outside the brachial plexus, keeping with previous reports, and suggests that peripheral nerve ultrasound imaging might aid in the diagnosis of neuralgic amyotrophy and exclude mimicking conditions.