Role of the Noninvasive Vascular Laboratory in Thoracic Outlet Syndrome

Abstract

The thoracic outlet is an area encompassing the structures above and below the first rib, which provides passage of the axillary and subclavian artery, vein, and brachial plexus as they travel from the neck and chest down the upper arm. An abnormality anywhere along this pathway results in an impingement of blood flow or neurologic transmission, which results in a condition known as thoracic outlet syndrome (TOS). Clinical symptoms of TOS can vary depending on the type of structure compressed and therefore is subdivided into two categories: neurogenic and vascular. Vascular TOS can be further divided into venous and arterial disease. In the nonacute stage, the majority of the vascular TOS patients present clinically with the same vague symptoms as the neurogenic TOS group, making diagnosis and delineation of subsequent treatment challenging. With vast improvements in ultrasound equipment, there is considerable emphasis placed on the utility of duplex imaging in the upper extremity. A TOS duplex ultrasound protocol and diagnostic interpretation, with a focus on the anatomic relationship of the upper extremity vessels, normal and abnormal color filling, and velocities with and without maneuvers, is described within this chapter. This ever expanding role of the noninvasive vascular examination, in the confirmation, treatment, and follow-up of the TOS patients has proven to have diagnostic usefulness.