Nerves of the Thorax: Anatomy, Clinical Signs, and Imaging Findings of Pathological Conditions

Background: Radiological diagnosis of thoracic nerve diseases is difficult because they are rare, and nerves cannot be seen directly on radiological images. The major nerves of the thorax can be listed as the phrenic, vagus, recurrent laryngeal, long thoracic nerve pairs, sympathetic chains, costal nerves, and brachial plexus. Diseases of thoracic nerves have various causes, including traumatic injury, neuromuscular diseases, infection, compression, radiation, drugs, and tumors. Objective: This pictorial review aims to describe the anatomic locations of the major thoracic nerves on radiological images, comprehensively describe the causes of thoracic nerve diseases and define the clinical signs and primary and secondary imaging findings of dysfunction of the thoracic nerves. Methods: This paper was designed to illustrate primary and secondary imaging findings of nerve diseases. Firstly, the normal anatomy of nerves is shown with diagrams. Secondly, we explained primary and secondary imaging features with variable radiological methods, including chest X-Ray, magnetic resonance imaging, and computed tomography. Conclusion: Primary findings of nerve diseases can be detected if radiologists are familiar with the courses of the nerves on radiological images. Knowledge of the normal functions of the nerves can aid in diagnosing thoracic nerve diseases identified from secondary imaging findings such as diaphragmatic elevation, muscular atrophy, and winged scapula. It is essential to know the normal anatomy, function, and possible causes of thoracic nerve diseases to make a correct diagnosis and apply the prompt treatment.