Home > Encyclopedia of Neurological Disorders > Thoracic Outlet Syndrome

Definition

Thoracic outlet syndrome refers to a condition that results in compression of neurovascular anatomical structures at the superior aperture of the chest (thorax).

Description

Thoracic outlet syndrome (TOS) refers to compression of nerves and blood vessels in the upper portion of the thorax. Neurologic symptoms occur in 95% of affected persons. The cause and treatment of TOS is controversial. In 95% of cases the brachial plexus is involved. The lower two nerves (C8 and T1) are most commonly affected in 90% of persons, following the ulnar nerve distribution. Blood vessels can also be affected. The subclavian vein is involved in 40% of cases and the subclavian artery in 1% of cases. The second most common nerve root involvement occurs in brachial plexus nerves C5, C6, and C7, and symptoms, if these nerves are affected, can be referred to upper back, upper chest, ear, neck, and outer arm that follows a...