Thoracic outlet syndrome: a controversial clinical condition. Part 1: anatomy, and clinical examination/diagnosis

Abstract

Thoracic outlet syndrome (TOS) is a frequently overlooked peripheral nerve compression or tension event that creates difficulties for the clinician regarding diagnosis and management. Investigators have categorized this condition as vascular versus neurogenic, where vascular TOS can be subcategorized as either arterial or venous and neurogenic TOS can subcategorized as either true or disputed. The thoracic outlet anatomical container presents with several key regional components, each capable of compromising the neurovascular structures coursing within. Bony and soft tissue abnormalities, along with mechanical dysfunctions, may contribute to neurovascular compromise. Diagnosing TOS can be challenging because the symptoms vary greatly amongst patients with the disorder, thus lending to other conditions including a double crush syndrome. A careful history and thorough clinical examination are the most important components in establishing the diagnosis of TOS. Specific clinical tests, whose accuracy has been documented, can be used to support a clinical diagnosis, especially when a cluster of positive tests are witnessed.

Keywords: Diagnosis; Examination; Literature review; Thoracic outlet syndrome.

Figure 1

Diagram showing the thoracic outlet. (A) Clavicle; (B) first rib; (C) coracoid process; (D) middle scalene; (E) posterior scalene; (F) brachial plexus; (G) subclavian artery; (H) pectoralis minor; (I) sternocleidomastoid.