Cervical rib and band syndrome.

Thoracic outlet syndrome (TOS) describes a syndrome of compression of the brachial plexus and the subclavian or axillary arteries or veins as they cross the thoracocervical area to the axilla. The classification of TOS is based on vascular or neurologic structures involved in this disorder. The vasculature and brachial plexus may be compromised in the interscalene triangle, the costoclavicular space, and the retro-pectoralis minor space. TOS may be related to congenital or acquired conditions. Congenital causes of TOS include cervical ribs, structural abnormalities of the first rib, or an elongated C7 transverse process. Other causes of TOS include fibrous bands around the neurovascular structures. Acquired TOS may be related to aging, obesity, pendulous breasts, and postural changes. Neurologic TOS is usually unilateral and affects women. Patients typically have some features of both neurologic and vascular involvement. Intermittent...