Thoracic Outlet Syndrome: What Causes This Rare Condition

Thoracic outlet syndrome (TOS) occurs when nerves or blood vessels are compressed between your collarbone and first rib. Common symptoms include pain, numbness, tingling, or weakness in your neck, shoulder, arm, or hand.

It's often difficult to diagnose TOS. But once you have a diagnosis, various treatments -- like physical therapy and lifestyle changes -- can help. Learn more about TOS, including the different types, causes, symptoms, and treatment options.

What causes thoracic outlet syndrome?

The thoracic outlet is a narrow passageway between your collarbone and first rib. Important nerves and blood vessels pass through this space near the front of your neck, chest, and shoulder. When this space gets smaller, it compresses nerves or blood vessels. This leads to TOS.

Different things can reduce the space in your thoracic outlet and cause compression. For example:

• Repeated activity, especially overhead arm use, can make certain muscles in the area bigger

• Poor posture can change the shape of structures in the area

• Abnormal anatomy, like the presence of an extra rib (called a cervical rib) or tumor

• Injury from a car accident or direct trauma

There are three types of TOS. These types - and their symptoms - depend on which structure is being compressed:

• Neurogenic: Compression of one or more nerves, making up 90-95% of all TOS cases

• Venous: Compression of the subclavian or axillary veins

• Arterial: Compression of the subclavian or axillary arteries

What does thoracic outlet syndrome feel like?

Symptoms of TOS depend on the type and can occur anywhere in your neck, shoulder, arm, or hand. They tend to get worse with repeated overhead arm movements, which can increase compression within the thoracic outlet. Sometimes, symptoms can be triggered by holding a certain posture, like flexing your neck (moving your chin down to your chest).

Most cases of TOS are neurogenic, affecting the nerves. Typical symptoms include:

• Pain

• Numbness

• Tingling

• Weakness

Symptoms of venous TOS in your affected arm include:

• Swelling

• Pain or heaviness

• Bluish coloration

Arterial TOS can cause:

• Decreased color and/or temperature

• Pain

• Numbness

Venous and arterial TOS can reduce blood flow in your arm. Even subtle changes may be noticeable when comparing your affected arm to the other. These types of TOS can also cause blood clots. So, symptoms of arterial or venous TOS should be evaluated sooner versus later to avoid any complications.

What can be mistaken for TOS?

Other conditions with similar symptoms may be mistaken for TOS. For example:

• Cervical radiculopathy: This is essentially a pinched nerve in your neck. It causes pain, numbness, tingling, and weakness that can radiate down your arm.

• Carpal tunnel syndrome: Caused by nerve compression at your wrist, carpal tunnel syndrome results in numbness, tingling, and pain in your hand and fingers.

• Shoulder impingement: When overhead motions cause tissues in your shoulder to be pinched, shoulder impingement can lead to shoulder and arm pain.

• Raynaud's phenomenon: This condition causes your fingers to become cold, pale, and painful.

How do you treat thoracic outlet syndrome?

First, your primary care provider needs to confirm your diagnosis. But there isn't a single test for TOS. Your symptoms and a physical exam can help a medical professional make a diagnosis. Imaging tests, like X-rays and ultrasounds, along with nerve studies, can help rule out other conditions.

Treatment for TOS depends on the underlying cause. Typically, treatment involves different methods to relieve pain, reduce compression, and improve posture. Fortunately, most people with neurogenic TOS improve with conservative treatment. This may include:

• Physical therapy: A physical therapist can check your posture, strength, and range of motion around your chest, neck, and shoulder. They can also recommend specific exercises and stretches to address muscle imbalances.

• A short course of OTC pain relievers: Pain-relieving or anti-inflammatory medications can help reduce discomfort. But these medications don't cure TOS. So, they should only be taken for a short period.

• Activity modification: Taking a break from aggravating exercises or activities can help reduce symptoms.

• Workstation changes: Your workstation has a big effect on your posture. It may even cause or worsen your thoracic outlet syndrome. Correcting your posture and maintaining good ergonomics can help manage your symptoms. Pay attention to the position of your head, neck, shoulders, and arms as you work to reduce strain.

• Weight management: Excess body fat around your neck, shoulder, and chest can compress nearby structures. If you've been told you're overweight, a balanced diet and regular exercise can help you find a comfortable weight that may help reduce compression.

Venous and arterial TOS can cause your blood vessels to be blocked (occlusion) by clots. In these cases, blood-thinning medications or clot-removing procedures may be necessary. These types of TOS are often due to a cervical rib or other abnormal anatomy. So, removing the abnormality through surgery may create more space in your thoracic outlet.