Neuromuscular ultrasound of the brachial plexus: know-how, know-when.

Neuromuscular ultrasound has become an integral diagnostic tool for brachial plexopathies, complementing electrodiagnostic studies and MRI. Despite the complex anatomy of the brachial plexus, nearly its entire postganglionic course is accessible by ultrasound, providing real-time, high-resolution structural information at the bedside. Characteristic sonographic findings have been described in traumatic plexopathies, neurogenic thoracic outlet syndrome, neuralgic amyotrophy, immune-mediated polyneuropathies, and neoplastic plexopathies. Evidence of moderate-to-high certainty now supports the use of ultrasound as a diagnostic adjunct in these conditions. Integration into clinical practice requires thorough knowledge of plexus anatomy and sonoanatomy, appropriate scanning techniques, and familiarity with condition-specific sonographic patterns. This review provides a practical framework for brachial plexus ultrasound, covering applied anatomy, systematic scanning approach, sonographic parameters and their interpretation, condition-specific findings, scanning protocols, and an evidence-based summary of its current indications.