Thoracic outlet syndrome (TOS) is a condition caused by the compression of one or more neurovascular structures as they cross the thoracic outlet. There are three types of thoracic outlet syndrome—neurogenic, venous, and arterial—each with its own clinical features and treatment algorithm. Neurogenic TOS (nTOS) is by far the most common type of TOS, with upwards of 90% of all TOS cases accounted for by nTOS in large single-institution series.1,2 Arterial TOS is the least common TOS, accounting for about 1% of cases, and venous TOS makes up the difference.3 These three types of TOS are not mutually exclusive and can coexist, potentially complicating the diagnostic workup. In addition, the compression of the neurovascular bundle can occur in three distinct anatomic levels: the interscalene triangle, the costoclavicular space, and the pectoralis minor triangle or subcoracoid space.4,5 This chapter addresses the supraclavicular approach to first rib resection and scalenectomy, which is well suited for the management of nTOS, especially in the case of a cervical rib.
The thoracic outlet is the body region that extends from the supraclavicular fossa to the axilla.5 As discussed above, there are three distinct spaces that should be noted: the interscalene triangle, costoclavicular space, and subcoracoid space. The interscalene triangle is demarcated by the anterior and middle scalene muscles that constitute the sides and the first rib forming the base. The subclavian artery, vein, and brachial plexus pass through this narrow space. The costoclavicular space is bordered by the first rib and clavicle and contains the subclavius muscle, brachial plexus, subclavian artery, and vein. The subcoracoid space is the region beneath the pectoralis minor tendon where the brachial plexus, axillary artery, and vein course through (Figs. 144-1 and 144-2). The interscalene triangle and subcoracoid space are the most common sites of compression.6
Anatomy relevant to thoracic outlet obstruction.
The three anatomic spaces that are implicated in brachial plexus compression are the costoclavicular space, the subcoracoid space, and the scalene triangle.
A combination of congenital anatomic variations and acquired compressive factors can predispose the patient to TOS.3 Cervical ribs, typically arising from the seventh cervical vertebra transverse process, have an incidence of 0.5% to 2.0% and can cause a predilection to all forms of TOS.5 Trauma and repetitive motion such as swimming, pitching, and weightlifting also play a role in the development of TOS.3
PREOPERATIVE ASSESSMENT and PATIENT SELECTION
Chapter 143 presents the key elements of preoperative assessment and patient selection for first rib resection among those with nTOS. Physical therapy should serve as the initial treatment for most ...