What is thoracic outlet syndrome?
Thoracic outlet syndrome (TOS) is a rare disorder that can occur when there is compression of the nerves, arteries and veins in the lower neck and upper chest area (the thoracic outlet).
What causes thoracic outlet syndrome?
TOS is often difficult to diagnose, but typically it pertains to the first rib and anterior scalene muscle (see Figure 1). However, it can be caused by a ‘cervical rib’, an extra rib connected to the cervical spine. When the blood vessels and/or nerves in the passageway of the thoracic outlet are abnormally compressed due to this they become irritated, resulting in TOS. Thoracic outlet syndrome can also be the result of past trauma or injury such as a collarbone fracture, which compresses nerves or blood vessels due to extra bone formation. Whiplash from a car accident can also be a cause, as it can lead to spasms of the anterior scalene muscle which narrow the thoracic outlet. Competing in sports that require repetitive use of the neck and shoulder muscles also poses a risk.
Some of the causes of TOS are:
- History of trauma to the thoracic outlet area.
- Competing in sports that involve repetitive arm or shoulder movement, such as baseball (especially pitching), swimming, rowing, weightlifting, and others that involve the muscles in the shoulder and neck.
- Repetitive injuries from carrying heavy shoulder loads.
- Whiplash injury to the neck or back.
- Tumors or large lymph nodes in the upper chest or underarm area that press on nerves.
- Poor posture that causes nerve compression.
- Pregnancy.
What are the symptoms of TOS?
The signs and symptoms of TOS include neck, shoulder and arm pain or numbness, burning and tingling in your arm, hand and fingers.
The pain of TOS is sometimes confused with the pain of angina (chest pain due to an inadequate supply of oxygen to the heart muscle). However, TOS pain does not occur when walking, while the pain of angina usually does. Also, TOS pain typically increases when raising the affected arm, which does not occur with angina.
There are three types of TOS: neurogenic, venous and arterial. Signs and symptoms of TOS help determine the type of disorder a patient has. Thoracic outlet syndrome disorders differ depending on the part of the body they affect. The nerves are the most common area affected, but TOS can also affect the veins and arteries. In all types of TOS, the thoracic outlet space is narrowed and there is scarring around the structures.
Types of thoracic outlet syndrome disorders and related symptoms
- Neurogenic thoracic outlet syndrome: This is the most common type of TOS and the hardest to diagnose. It is related to abnormalities of bony and soft tissue in the lower neck region (which may include the cervical rib area) that compress and irritate the nerves of the brachial plexus, the complex of nerves that supply motor and sensory function to the arm and hand. Symptoms include weakness or numbness of the arm, decreased size of hand muscles on one side of the body, and/or pain, tingling, numbness and weakness of the neck, chest and arms. Swelling is uncommon.
- Venous thoracic outlet syndrome: This condition is caused by damage to the major veins in the lower neck and upper chest over time. Scar tissue can form, decreasing blood flow. This can result in a blood clot forming in the vein, a condition known as deep vein thrombosis (DVT). It can develop suddenly, often after unusual and tiring exercise of the arms, and often requires going to the emergency room. Symptoms include swelling of the hands, fingers and arms, as well as heaviness and weakness of the neck and arms. The veins in the anterior (front) chest wall may appear dilated.
- Arterial thoracic outlet syndrome: This is the least common, but most serious, type of TOS. It is caused by bony abnormalities such as a cervical rib (extra rib) present at birth. This can cause compression on the subclavian artery, which causes dilation and can result in an aneurysm or blood clot. Symptoms include coolness, paleness, numbness or soreness in the arm, hands or fingers due to decreased blood flow. A pulse above the collarbone may be found if an aneurysm is present.
Who is affected by thoracic outlet syndrome?
Thoracic outlet syndrome usually affects men and women between the ages of 20-50. The condition can affect athletes who participate in sports that require repetitive motions of the arm and shoulder or people whose work requires repetitive or strenuous arm movement. Traumatic injury to the area can also be a risk factor.
Neurogenic TOS is the most common form of the disorder (95 percent of people with TOS have this form) and it generally affects middle-aged women.
Venous TOS is more common in men, and arterial TOS affects both men and women.
How is thoracic outlet syndrome diagnosed?
Making a proper diagnosis is the most important step in treating TOS. Doctors who treat this condition include vascular surgeons, chest (thoracic) surgeons and vascular medicine physicians.
To diagnose your condition, your doctor will perform a physical examination using special tests such as the elevated arm stress test (EAST). They will review your patient history and the results of previous imaging tests. They may recommend further ultrasound testing.
In some cases, a thorough evaluation by a skilled neurologist may be recommended to rule out cervical spine disease or other neurological conditions that may be mimicking or causing your symptoms.
Tests performed to diagnose thoracic outlet syndrome include:
- Nerve conduction studies (NCS).
- Ultrasounds.
- Vascular studies (of the arteries or veins).
- Chest X-ray to rule out cervical rib abnormalities.
- Cervical spine X-rays to rule out a cervical rib (extra rib) or cervical (neck) spine abnormalities.
- Computed tomography (CT) scan and magnetic resonance imaging (MRI) of the chest.
- CT scan or MRI of the spine to rule out cervical spine impingement (pressure), which can mimic neurogenic thoracic outlet syndrome.
- Magnetic resonance imaging with angiography (MRA) to view blood vessels.
- Arteriogram/venogram (X-ray that uses dye to look at blood flow).
- Electromyography (EMG).
- Blood tests.
Is thoracic outlet syndrome serious?
Although many cases of thoracic outlet syndrome (TOS) can’t be prevented, the condition is treatable. If left untreated, TOS can cause complications such as:
- Permanent arm swelling and pain (especially in patients with venous TOS).
- Ischemic ulcer of the fingers (open sore caused by reduced blood flow).
- Gangrene (the death of body tissue, often caused by a loss of blood flow).
- Blood clot.
- Pulmonary embolism (obstruction in a blood vessel due to a blood clot).
- Neurogenic complications, such as permanent nerve damage.
How is thoracic outlet syndrome treated?
Early identification of TOS can help improve the success of treatment, which varies depending on the type of TOS you have. The goals of treatment are to reduce symptoms and pain. Physical therapy, medications, botulinum toxin A (BOTOX®) injections and surgical procedures are all treatment options; your doctor will evaluate what is best for you.
Treatment of neurogenic thoracic outlet syndrome
- Physical therapy: The most common initial treatment for neurogenic TOS is physical therapy. Physical therapy increases the range of motion of the neck and shoulders, strengthens muscles and promotes better posture. Most patients experience an improvement in symptoms after undergoing physical therapy. Botulinum toxin A (BOTOX®) injections may be used in conjunction with physical therapy if symptoms do not improve with physical therapy alone.
- Medications: For pain relief, over-the-counter pain medications such as aspirin, acetaminophen (Tylenol), or ibuprofen (Motrin) may be recommended. Your doctor also may prescribe a muscle relaxant for additional pain relief.
- Surgery: In some cases, surgery may be needed to treat neurogenic TOS if symptoms continue despite an optimal course of physical.
Treatment of venous thoracic outlet syndrome
To reduce the risk of blood clots and pulmonary embolism, treatment for venous TOS may include thrombolytic (clot-busting) or anticoagulant (blood thinning) medications to dissolve the thrombosis. Surgery may then be used to relieve the compression that caused the DVT (deep vein thrombosis).
- Thrombolytic medications are given to dissolve blood clots. This type of medication is given to the patient in the hospital so they can be closely monitored. The medication(s) may be injected directly into the vein or delivered via a catheter which is guided through the vein to the area where the blood clot is located. The clot-dissolving drug is sent through the catheter into the clot. The clot usually dissolves in a matter of hours to a few days. In some cases, the narrowed area of the vein will need to be treated with angioplasty (opening the vein using a balloon) to keep more clots from forming.
- Anticoagulant medications decrease the blood’s ability to clot. They include warfarin (Coumadin), heparin, low-molecular-weight heparin and fondaparinux (Arixtra). You will receive information about how to take the anticoagulant medication that is prescribed for you.
- Surgery may be necessary along with medications to manage your symptoms. Decompression surgery is often recommended following clot-busting medication and blood thinners. This corrects the narrowing that is causing problems with the vein and may be recommended after the clot in the vein has been effectively treated/dissolved with medications. Although it is uncommon, open surgical venous reconstruction may be necessary.
Treatment of arterial thoracic outlet syndrome
- Surgery: Patients with arterial TOS often require surgical treatment. Surgery may be performed to remove the first rib and/or scalene muscles in order to make more room for the vessels and nerves. Reconstructive surgery may also be performed to repair any structural problems of the artery such as an aneurysm or blood clot.
When is surgery necessary?
Although only 10 to 20 percent of patients with TOS need surgical treatment, most patients with venous or arterial TOS will need some form of surgical treatment.
Surgery for venous and arterial TOS is very effective. Among patients with venous TOS, elective surgery corrects symptoms in 90 to 95 percent of cases; in patients with arterial TOS, elective surgery resolves symptoms in more than 95 percent.
Some patients with neurogenic TOS will need surgery. The primary goal of surgery for these patients is to remove the source of compression on the brachial plexus. This is typically accomplished by removing the first rib, abnormal muscles or fibrous bands. If there is an extra rib causing compression, it may also be removed.
Known as “decompression surgery,” the procedure is typically completed by making an incision in the underarm area on the affected side. It can also be performed through an incision made above the clavicle (collarbone). An alternative surgical approach known as video-assisted thoracoscopic surgery (VATS), which is performed through several small incisions, may be used in some cases.
Surgical risks
Like all extensive surgical procedures, there are risks associated with decompression surgery. One significant risk is the failure to respond to surgery. In experienced centers, approximately 50 to 70 percent of patients will have improvement in their symptoms after decompression surgery. Surgery to treat neurogenic TOS is reserved for those patients who remain debilitated despite appropriate noninvasive therapy, including supervised physical therapy, and pain relief. Other complications are rare, occurring in only 2 to 3 percent of cases, but include:
- Nerve injury.
- Bleeding.
- Pneumothorax (collapsed lung).
- Lymphatic fluid leakage.
What can I do to prevent TOS?
Minimizing repetitive arm movement, improving posture and avoiding injury can help prevent TOS. However, some causes, such as anatomical defects at birth like a cervical rib or previous trauma cannot be reversed and will likely require treatment.
How does TOS affect my life?
The compression of nerves and blood vessels due to TOS can cause pain, burning and weakness in the neck, shoulder and arm. Prognosis is good for all three types of TOS. With medication, physical therapy, and/or surgery most people respond well and recover.
