Yudu - sportEX medicine - 1999-2010

the tendons of anterior and middle scalene and the first rib (12,13) (Fig.3).

SITES OF COMPRESSION There are several potential sites where entrapment/compression or snagging of the neural structure may occur (5,7,14,15,).

Interscalene space This is bordered anteriorly by the anterior scalene and posteriorly by the middle scalene (13,14). The base of the triangle is bordered by the first rib (14) (Fig.4). There are many anatomical variations which can be identified at this site which may be responsible for compression of the neurovascular bundle. One study of 180 patients showed that 30% of patients had narrowing in the interscalene triangle (16).

Costo-clavicular space The second potential site of compromise is the costo-clavicular space. This is the space between the first rib and the clavicle, bordered medially by the costoclavicular ligament (Fig.5) and the costal origin of the subclavius muscle (1) (Fig.6). This has been shown to be the site of most frequent compromise in this syndrome, with 75% of the investigated subjects having compromise at this site (16).

Sub-coracoid space The sub-coracoid space is a further potential area of entrapment. The sub-acromial space (also known as the retropectoralis space (15)) lies inferior to the coracoid process and posterior to the pectoralis minor (Fig.7). Here the neurovascular bundle runs

in its pathway towards the axilla. The anterior deltoid, the pectoralis minor and the coracoid may be potential sources of brachial plexus compression (13). This site has been found to account for the symptoms of 6% of researched subjects (16).

Langers arch The fourth area of compromise is the axillary arch, also known as Langers arch (17) (Fig.8). This is a potential entrapment

site between a fascial extension which exists in some individuals. The fascial extension may pass between latissimus dorsi or teres minor and attaches to the corachobrachialis.

SIGNS AND SYMPTOMS Venous TOS Venous TOS may be as a result of compromise of either the subclavian or the axillary vein. The symptoms are very similar (18).

They include: n Cyanosis of the upper limb (1) n Oedema of the arm, forearm and hand (1) n Pain may or may not be present (4) n Distended superficial veins of the shoulder and chest (19).

Figure 2: The brachial plexus

Arterial TOS Arterial TOS may be a result of compromise of either the subclavian artery or axillary artery. The symptoms include:

THORACIC OUTLET

Figure 3: Thoracic outlet

INTERSCALENE SPACE

n Pain (4,9,19) n Intermittent pallor, cyanosis or erythema (4,9,19) n Paraesthesia (4,9) n Pulselessness (19) n Decreased blood pressure (19) n Coolness/coldness of the upper limb (9,19) n Claudication (4) n Easy fatigue-ability/claudication (20,21) n Unilateral Raynauds phenomenon (9,21) n Numbness (21) n Swelling may be evident but is usually less significant than the larger swelling seen in venous TOS (1) n Unilateral cold hypersensitivity (21) Patients that have venous compromise in the thoracic outlet or sub-coracoid areas may also have signs of neurogenic compromise, likewise a combination of arterial objective signs and subjective neurological symptoms may be evident because the structures in the channels are very closely approximated (7,18).

Figure 4: Interscalene space

Neurogenic TOS-brachial plexus n Pain and paraesthesia - compromise of the superior trunk (C5,6) at the interscalene triangle may lead to pain of the outer aspect of the shoulder and proximal upper limb. The ipsilateral cervical spine and supraclavicular areas may also be sites where pain is described (5). Compromise of the inferior trunk (C8, T1) of the brachial plexus at the interscalene triangle or at the costo-clavicular space or compression of the medial cord (which is the extension of the inferior trunk)

sportEX medicine 2009;44(Apr):13-17