Unilateral vocal cord paralysis: A comprehensive guide for general radiologists

Unilateral vocal cord paralysis (UVCP) is characterized by the immobility of a hemilarynx resulting from neurological dysfunction. The laryngeal intrinsic muscles are innervated by the recurrent laryngeal nerve (RLN), a branch of the vagus nerve (VN). Pathological processes affecting the motor nucleus of the VN (nucleus ambiguus), the VN itself, or the RLN can result in UVCP. Crucially, UVCP must be distinguished from mechanical vocal cord hypomobility caused by local laryngeal factors.

This review aims to provide a structured radiological guide for the evaluation of UVCP, focusing on the relevant clinical assessment, optimized imaging protocols, laryngeal anatomy, radiological signs of UVCP, and the anatomical pathways of the vagus and recurrent laryngeal nerves.

A comprehensive review of current literature and clinical imaging standards was performed to synthetize a diagnostic approach for identifying UVCP ant its underlying causes from the brainstem to the neck and mediastinum.

Condition causing UVCP may occur anywhere from the brainstem to the mediastinum and include inflammatory, vascular, and neoplastic diseases. By utilizing a structured anatomical approach, radiologists can systematically evaluate the nerve's entire course. However, while imaging is highly effective at detecting organic lesions, a significant number of cases remains idiopathic.

Imaging is critical for identifying the site and nature of damage causing UVCP. A structured diagnostic approach ensures accurate evaluation of all potential causative lesions from the central nervous system to the chest, significantly impacting patient management.