Thoracic Outlet Syndrome

Thoracic outlet syndrome (TOS) is a rare medical condition that happens when the nerves or blood vessels between the neck and shoulder are compressed.

When these nerves and vessels are pinched, it can cause symptoms in the neck, shoulder, arm, and hand. These symptoms may include pain, numbness and tingling, and weakness in the affected area.

The area at the top of the chest, between the collarbone and the first rib, is called the thoracic outlet. Nerves, veins, and arteries pass through the thoracic outlet to the neck, shoulder, and arm. There is a thoracic outlet on both sides of the body.

When the thoracic outlet functions normally, the nerves and blood vessels aren’t damaged by being squeezed when you use your arms or turn your head. With TOS, these types of regular movements cause nerves or blood vessels in the thoracic outlet to become pinched or squeezed and damaged.

What is thoracic outlet syndrome?

Thoracic outlet syndrome (sometimes called TOS) is an umbrella term for a group of disorders that occur when blood vessels or nerves in the space between your collarbone and your first rib (the thoracic outlet) are compressed. This compression can cause pain in your shoulders and neck, and numbness in your fingers.

TOS is a rare condition. Experts estimate that between 2-80 people have TOS per 1,000 people. The exact number is unknown, because some symptoms of TOS are vague and not everyone with the condition receives an accurate diagnosis right away.

Several important nerves and blood vessels pass through the thoracic outlet. When these are pinched, they can affect the neck, arms, and hands. Some of the important structures that pass through the thoracic outlet include:

• Brachial plexus: Neves that control movement and sensation in the shoulder, arms, forearms, and hands
• Subclavian artery: An artery that delivers oxygenated blood to the arm
• Subclavian vein: A vein that passes below the collarbone and drains blood from the arm

Types of TOS

There are three main types of TOS.

The type of TOS depends on which structure is affected (the brachial plexus, subclavian artery, or subclavian vein). Each type of TOS can have some differences in its causes, symptoms, diagnosis, and treatment.

The types of TOS are:

• Neurogenic thoracic outlet syndrome: Neurogenic TOS occurs when a brachial plexus nerve is pinched. This causes issues with sensation and/or movement in the shoulder, arm, hand, or fingers. More than 90% of thoracic outlet syndrome cases are neurogenic TOS.
• Venous thoracic outlet syndrome: Venous TOS occurs when the subclavian vein is compressed. This prevents blood from draining efficiently from the arm, causing swelling and pain. About 3-5% of TOS cases are venous thoracic outlet syndrome.
• Arterial thoracic outlet syndrome: Arterial TOS occurs when the subclavian artery is compressed. This reduces the amount of blood that flows to the arm, causing pain and numbness. Arterial TOS is less common than neurogenic and venous TOS. About 1-2% of thoracic outlet syndrome cases are arterial TOS.

Causes of TOS

TOS can be caused by congenital abnormalities or acquired because of trauma or functional use.

Congenital causes of TOS include:

• Cervical rib: A cervical rib is an extra rib that grows from the cervical spine, above the top of the rib cage. Having an extra rib increases the chance of nerves or blood vessels becoming compressed.
• Bony or muscular anomalies: Some people have a short segment of extra bone in their first rib, an abnormal collarbone, or variations in the muscle and tissue of their thoracic outlet, which can increase the chance of developing TOS.

More often, TOS is caused by injury or activity. These common types of causes for TOS can include:

• Trauma: Injuries from car accidents, falls, and other common types of traumas can damage the thoracic outlet, causing compression of the blood vessels or nerves.
• Repeated overhead motions: Performing repeated overhead motions can lead to compression in the thoracic outlet. People who swim, play baseball, or have jobs that require raising their arms over their head may develop TOS.
• Bodybuilding: Large muscles in the neck may compress the nerves or vessels in the thoracic outlet.
• Tumor in or around the neck: Tumors near the thoracic outlet can press against other structures in the area, causing TOS.

TOS symptoms

Symptoms of thoracic outlet syndrome can vary depending on the type, but common symptoms include:

• Pain the neck, shoulder, or arm
• Numbness or tingling in the fingers
• Weakness in grip
• Swelling or discoloration of the arm
• A feeling of heaviness in the arm

TOS diagnosis

Diagnosing thoracic outlet syndrome can be difficult, because some symptoms of TOS are vague and might resemble symptoms of other conditions, such as carpal tunnel syndrome, cubital tunnel syndrome, cervical spine disease, and other diseases. Detecting TOS early is important. Delays in care can lead to worse symptoms and outcomes.

Vascular surgeons are specially trained to diagnose and treat TOS.

Evaluation for TOS may include:

• Medical history to review symptoms
• Physical movements to try to reproduce symptoms
• Imaging tests, including X-rays, MRIs, MRAs, CT scans, or ultrasounds to produce images of the thoracic outlet and areas of the neck, shoulder, and chest
• Electromyography (EMG) to measure electrical activity of a muscle, using a small needle
• Nerve conduction studies to measure the speed of electrical impulses in nerves
• Brachial plexus block to test for neurogenic TOS by injecting local anesthetic into the scalene muscles of the neck

Treatment for TOS

There are several treatment options available for thoracic outlet syndrome. Treatment depends on the type of TOS.

Typically, a combination of physical therapy and medical treatment can achieve results for many people with TOS.

In some cases, surgery may be necessary.

Treatment options can include:

• Physical therapy: Exercises and stretches can strengthen the muscles around the thoracic outlet and reduce the compression of blood vessels or nerves.
• Lifestyle changes: Avoiding certain activities, practicing good posture, and losing excess weight can all help to reduce symptoms.
• Medication: Several types of medications can help relieve symptoms. Muscle injections, including local anesthetic, steroids, or botulinum toxin, may also reduce symptoms.
• Surgery: For TOS caused by congenital problems or other structural problems in the thoracic outlet, surgery may be necessary. Surgery can also help people whose symptoms have not improved with other treatments.

Expert care for thoracic outlet syndrome

Finding a specialist who understands TOS and has the expertise to care for your symptoms is essential.

Most people with TOS see improvements through physical therapy, lifestyle changes, and medication.

The Center for Thoracic Outlet Syndrome at WashU Medicine offers comprehensive diagnosis, surgical and nonsurgical treatment, and team-based care for people with TOS.

We see a high volume of TOS cases each year, meaning our WashU Medicine physicians have the experience to care for people with even the most challenging cases of TOS. Our center has become a destination for people with TOS, with patients coming to us from the St. Louis area, the Midwest region, and from all across the U.S.