Ultrasonography of traumatic injuries to limb peripheral nerves: technical aspects and spectrum of features.

Traumatic injury to limb peripheral nerves represents an important cause of morbidity and disability. Timely diagnosis and treatment are crucial to optimizing outcomes. The initial evaluation requires a careful history, a thorough physical examination, and electrodiagnostic tests, which lead in most cases to a diagnostic suspicion, but fail to provide an extensive qualitative and quantitative assessment of the nerve damage. Ultrasonography (US) is a low-cost, non-invasive technique which allows for direct visualization of nerve internal structure. It enables performing dynamic examinations and nerves can be followed over long distances in a limb in relatively short times, adding paramount information to extensively characterize the specific type of lesion, and to plan the appropriate treatment. Magnetic resonance imaging (MRI) is complementary to US, especially in examining deep-seated and proximal nerve segments, but is expensive, not available in all institutions and less accepted by patients. The purpose of this review is to describe the role of ultrasonography in the setting of traumatic injury to peripheral nerves, analyzing the main US features in specific types of trauma. Technical aspects with key considerations for optimization are discussed. A brief comparative evaluation between US and MRI is also provided.