Brachial Plexus and Thoracic Outlet Syndrome

Anatomy

The brachial plexus consists of the C5-T1 nerve roots; it emerges from the neck and extends to the armpit, providing innervation to the entire upper extremity.

Injury Types

Supraclavicular (upper type — Erb-Duchenne): C5-C6 involvement. Loss of shoulder abduction and external rotation, weakness in elbow flexion. Most commonly seen in motorcycle accidents.^1,2

Infraclavicular (lower type — Klumpke): C8-T1 involvement. Weakness in the intrinsic muscles of the hand, may be accompanied by Horner syndrome.

Total plexus injury: Loss of all arm functions. Root avulsion (preganglionic) has the worst prognosis.^3,4

Treatment

If there is no improvement, surgical exploration + nerve graft/transfer. In avulsion: nerve transfers (e.g., intercostal nerves → musculocutaneous nerve). In the late stage: tendon transfers, arthrodesis.

Thoracic Outlet Syndrome (TOS)

What is it?

It is a symptom complex that develops as a result of compression on the brachial plexus and/or subclavian vessels in the narrow passage between the neck and the armpit (thoracic outlet).

Types

Neurogenic TOS (95%): Nerve compression, pain in the arm, numbness, weakness.⁵ Generally seen in young women and people with long necks. Common after whiplash.

Venous TOS (3%): Subclavian vein thrombosis (Paget-Schroetter syndrome). Swelling and bruising in the arm.

Arterial TOS (2%): Subclavian artery compression. Coldness in the arm, loss of pulse, risk of embolisation.

Treatment

In neurogenic TOS, primarily physical therapy (posture correction, shoulder strengthening, scalene stretching).

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