Chapter 23: Brachial Plexopathies

Objectives

On completion of this chapter, the student/practitioner will be able to:

• From a historical perspective, discuss the origin of the various terms related to thoracic outlet syndrome and the surgical and conservative interventions used to treat this condition.

• Explain the relationship of the structures within the thoracic outlet to the etiology of the various types of thoracic outlet syndrome.

• Relate the signs and symptoms to the etiological anatomical structures.

• Differentiate between arterial, venous, and neurological thoracic outlet syndrome.

Key Terms

• Scalene muscle

• Subclavian vessels

• Thoracic outlet syndrome

Introduction

Brachial plexopathy can be divided into the same variety of nerve pathologies as other nerve “syndromes.” These pathologies may be caused by acute or chronic compression, stretch injury, ischemic injury, electrical injury, radiation injury, and various direct injuries. The management of brachial plexopathies theoretically does not differ from management of other nerve injuries. However, brachial plexopathy is more difficult to understand and treat. This difficulty is largely due to the variation in manifestations caused by the more complex anatomy of the plexus than, for instance, the median nerve at the wrist; the extensive range of motion of the shoulder; and the complex anatomy of the other associated structures intimately related to the brachial plexus. Most patients presenting with brachial plexopathy fit the entity known as thoracic outlet syndrome (TOS).

The term thoracic outlet syndrome encompasses various clinical entities involving structures around the shoulder girdle. Symptoms can include pain, numbness, paresthesias, headaches, weakness of the arm and hand, ischemia, and arm swelling. The term engenders a great deal of controversy in the literature, especially neurology, because of the difficulty in defining it. TOS may be viewed as a clinical complex that includes four parts: neuropathy of the brachial plexus, compression vasculopathy of the subclavian vessels, complex regional pain syndrome (CRPS) or reflex sympathetic dystrophy (RSD), and cervicothoracic and brachial myofasciitis. Conversely, some authors would choose to limit the use of the term TOS to problems involving only the lower portions of the plexus—the C8 and T1 nerve roots, lower trunk, and medial cord.

Manifestations of compromise of the neurological elements associated with the thoracic outlet differ from the manifestations seen in compromise of the vascular elements of the thoracic outlet. However, because the term TOS is so well entrenched in the literature, this chapter attempts to broaden the understanding of the various manifestations of TOS rather than use an entirely new nomenclature. This broader understanding should improve the diagnosis and treatment of this difficult entity.

The variability in presentation of TOS, which causes great debate and misunderstanding, can be explained rationally if time is taken to comprehend ...