The thoracic outlet is not just a syndrome, it’s actually a ring-shaped area of the body that sits below the collarbone and is also formed by the top of the cervical rib. Thoracic outlet syndrome (TOS) develops when there is nerve compression (or impingement) that may also impact the blood vessels, nerves, and other structures. There are several structures that can be the source of impingement, including the clavicle (or collarbone), anterior/posterior scalene muscles (located at the front and back of the neck), or the first rib that is below the nerves.

Similarly, TOS can be further categorized by type. Over 85% of cases are neurogenic thoracic outlet syndrome, meaning the compression affects the nerves that run from the neck to the arm. These nerves are called the brachial plexus. The other forms — arterial thoracic outlet syndrome and venous thoracic outlet syndrome — are diagnosed when the compression impacts a person’s blood flow, including arteries and veins. One of the most common arteries impacted by arterial TOS is the subclavian artery, which is a major artery located below the first rib that also connects to the heart via the aorta. Cases of venous TOS can be serious because they place someone at risk for developing a thrombosis, or blood clot, in the upper body or upper chest.

There are a variety of causes that contribute to any type of TOS. Some of these causes include:

• • • Trauma to the shoulder or upper arm, such as whiplash
    • Repetitive activities such as typing, doing overhead work, or playing certain sports (swimming or those that involve pitching a ball)
    • Pregnancy, which often causes joints to loosen and can aggravate this part of the body
    • Congenital deficits, including the presence of an extra rib or abnormally tight arm musculature
    • Any activity or risk factor that places excess pressure on the joints, such as obesity or wearing a heavy backpack

Neurogenic TOS is more common in women and may also be more likely to occur in people with poor posture, since this causes misalignment of bones and muscles.

Diagnosis is the most important first step to getting treatment for thoracic outlet syndrome. An official diagnosis is especially crucial for TOS because there are several different categories of this condition and a range of contributing causes. By addressing any medical causes that are present, such as an extra rib, an individual is more likely to experience symptom relief and a restoration of function.

A doctor usually begins the diagnostic process by assessing someone’s medical history, including past treatments, surgeries, medications, and family history. From there, they will do a physical exam by palpating different spots on the neck and back. This is also called a provocation test, and it involves doctors asking someone to assume certain positions and checking whether they are painful, tender, or result in other discomfort.

During a physical exam, doctors might search for signs such as:

• • • Unusual swelling or skin discoloration of the arm, hand, and/or shoulder
    • An irregular heartbeat
    • Poor range of motion in the shoulder
    • Abnormal divots (also called depressions) in or below the shoulder

These are some external indications of thoracic outlet syndrome that might lead your doctor to do further testing. These may also suggest that someone’s TOS is impacting blood supply to the heart, so their condition should be treated immediately.

Your doctor will also perform an imaging test such as an x-ray, ultrasound, magnetic resonance imaging (MRI) scan, or computed tomography (CT) scan. These allow your doctor to more clearly see muscles, bones, and other structures in the affected area. If you are reporting symptoms that may suggest vascular or arterial TOS, your doctor may also order an angiography, arteriography, or venography. These are also imaging tests, but they focus specifically on nerves and blood vessels, so doctors can use such exams to get a more detailed picture of small structures. The last two procedures can also serve as treatments in some cases. For example, if your doctor finds a clot in your veins or arteries while completing the test, they can inject medication to dissolve it.

Another test that may aid in the diagnosis of thoracic outlet syndrome is a nerve conduction study, which involves sending a very low electrical current through the body to determine how the muscles respond. Similarly, electromyography (also known as EMG) measures the body’s existing electrical activity both at rest and when contracted. This allows doctors to determine if there is any nerve or blood vessel damage and the extent to which they are impaired.

Individuals with thoracic outlet syndrome might display some of the following symptoms:

• • • Muscle shrinkage (also called muscle atrophy) at the base of the thumb
    • Decreased movement in the arm or hand, especially poor grip strength
    • Pain, numbness, and/or tingling in the neck, shoulder, arm and/or hand

In cases of arterial or venous TOS, individuals are likely to have additional symptoms, including:

• • • Swelling of the arm and hand
    • Weak heartbeat in the arm where the compression is
    • Arm fatigue and weakness
    • Blood clots in parts of the upper body
    • Excess coldness in the hand, arm, and fingers
    • Discoloration or lack of color to the skin on the arm and hand

If surgical treatment is needed, doctors will perform a thoracic outlet decompression. Depending on the source of the problem, doctors may take one of three approaches. The transaxillary approach involves removing part of the first rib, if this is what is causing the compression. The supraclavicular approach works to repair compressed and otherwise damaged blood vessels through an incision in the lower neck. However, if blood vessels need extensive repair, doctors may not be to access them appropriately from that angle. So they may take an infraclavicular approach that involves placing an incision under the collarbone.

In most cases of TOS, doctors will refer an individual to physical therapy or a chiropractor. Physical therapy and chiropractic care both work to relieve release the impingement in the affected area, which in turn, will lessen the condition and improve function. Treatments include strengthening exercises, manipulative therapy, mobilization, and myofascial release. Adopting certain lifestyle changes is also key to recovery. Additionally, your doctor may recommend:

• Postural corrective exercises and stretches
• Avoiding placing straps on bags or backpacks over your shoulder
• Losing weight and/or maintaining a healthy weight
• Lessening your participation in repetitive activities (if you must engage in them, take regular stretch breaks)
• Applying heat whenever your shoulders feel stiff or sore
• Massage/mobilization on the affected area

If you are concerned that you might have thoracic outlet syndrome, you should get medical advice from your doctor or other health care professional.