Thoracic outlet syndrome caused by a cervical rib: case report

The thoracic outlet syndromes (TOSs) are a group of etiologically and clinically distinct disorders characterized by compression of one or more neurovascular elements as they pass through the thoracic outlet. These syndromes are classified into neurogenic, arterial, and venous types based on the compressed anatomic structure: brachial plexus branches, subclavian artery, or vein, respectively. TOS may be caused by multiple etiologies, encompassing congenital anomalies, such as cervical ribs or fibrous bands, acquired musculoskeletal deformities, traumatic injuries, or, less commonly, neoplastic processes. The cervical rib is a recognized anatomical variant that is typically asymptomatic, but has been documented as a potential etiology of thoracic outlet syndrome. We present a case of neurogenic thoracic outlet syndrome (NTOS) in a 17-year-old female patient with no significant medical history, attributed to bilateral cervical ribs. The clinical manifestation included progressive neck, left shoulder, and upper limb pain with paresthesia over six months. Electromyography (EMG) identified nerve conduction abnormalities in the dermatomes of the left ulnar and median nerves. Magnetic resonance imaging (MRI) revealed focal narrowing of the lower trunk of the left brachial plexus and adjacent vascular structures due to a cervical rib, a finding corroborated by chest X-ray and computed tomography (CT) scan. The patient underwent medical and physical rehabilitation therapy, with curative surgical intervention recommended and discussed; however, she declined the procedure. Diagnosing and managing TOS remains challenging and often controversial. In addition to a thorough clinical examination and electrophysiological assessments, diverse imaging modalities provide complementary insights, aiding in the identification of TOS subtypes, sites of involvement, underlying etiology, and optimal management strategies. This article aims to review the anatomical, clinical, and electrophysiological features of TOS while emphasizing the pivotal role of imaging in its management. Keywords: Thoracic outlet syndrome, Cervical rib, Brachial plexus, Nerve conduction abnormalities, MRI, CT.