What is TOS?2019-03-20T14:54:24+00:00

What is thoracic outlet syndrome?

What is TOS?

What is TOS?

TOS stands for Thoracic Outlet Syndrome. You can feel the thoracic outlet on each side of your neck. Specifically, the thoracic outlet is the hollow space above your collarbone, between your shoulder and your neck. Slide your hand down either side of your neck to find your thoracic outlets.

Three vital structures pass through the thoracic outlet: an artery, a vein, and a network of nerves. If compression of one or more of these structures causes symptoms, thoracic outlet syndrome is present.

What are the three types of TOS?

Costoclavicular Interval Brachial Plexus

Neurogenic TOS

A large network of nerves, the brachial plexus, passes through each thoracic outlet. When compression causes pain or tingling, neurogenic TOS occurs. Neurogenic TOS is the most common type of TOS, 95 to 98% of all TOS cases. Patients with neurogenic TOS suffer from pain, abnormal sensations, coldness and weakness.

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Venous TOS Retropectoralis Space

Venous TOS

A single, large subclavian vein passes through each thoracic outlet. When compression of the vein causes a blood clot, venous TOS occurs. Venous TOS is very uncommon, accounting for 2 to 5 % of TOS cases. Patients with venous TOS often present with swelling and cyanosis (blue color) of the arm and upper chest.

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Arterial TOS Scalene Triangle

Arterial TOS

A single, large subclavian artery passes through each thoracic outlet. If compression of the subclavian artery causes a blood clot or aneurysm, arterial TOS occurs. Arterial TOS is rare, 1% of TOS cases. Arterial TOS patients may have a pulsatile neck mass, with weakness, pale color, coldness or gangrene of the arm.

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Anatomy of the Thoracic Outlet

The anatomy of the thoracic outlet appears incredibly complex. Besides the native anatomy, a number of anatomic variants and anomalies create more complexity. These variants can compress the nerves, artery or veins, resulting in TOS. Moreover, motion of the arms causes complex changes in the anatomic tunnels of the thoracic outlet. When you understand the anatomy of the thoracic outlet, you have taken the first step in understanding thoracic outlet syndrome.

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What causes TOS?

Laptop Causes TOS Pain

The nerves, artery and vein must be free to pass through the thoracic outlet. However, anatomic variants, acquired abnormalities, and abnormal dynamics of arm motion may cause compression of these vital structures. In that case, patients experience the symptoms of thoracic outlet syndrome. People with neck injuries, occupational injuries or overuse, and overhead athletes are all at risk for developing thoracic outlet syndrome.

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History of TOS

Like many other scientific pursuits, the history of TOS takes many twists and turns. In essence, The history revolves around human nature, curiosity and discovery. Here you can enjoy a wild and fascinating ride of dead ends and discoveries, egos and errors, personalities and politics. Learn about the history of TOS, starting from a simple English housemaid to modern robotic surgeons.

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