Thoracic Outlet Syndrome
What is thoracic outlet syndrome (TOS)?
Thoracic outlet syndrome is a condition that results from narrowing of the space where the blood vessels and nerves run from the trunk of the body (thorax) to the arm. It can cause pain and numbness in the shoulder, arm, and hand. Testing for TOS is difficult. There is no one test to accurately diagnose TOS, and other conditions can have similar symptoms. You will need to go through several tests to find out if TOS is actually the cause of your pain. Making the right diagnosis often takes time and can be a cause of frustration, both for you and your doctor.
What is the thoracic outlet?
The nerves and blood vessels that go into the arm and hand start at the side of the neck. Nerves come out of the spine through small openings along the side of each vertebra. These openings are called neural foramina. The nerves and vessels travel between muscles in the neck called the scalene muscles and over the top of the rib cage. The thoracic outlet is this opening between the scalene muscles and the rib cage. The nerves and blood vessels then go under the collarbone (also known as the clavicle), through the armpit (the axilla), and down the arm to the hand.
What causes TOS problems?
The main cause of TOS is that the nerves and blood vessels going to the arm and hand get squeezed near the thoracic outlet. This can occur for many reasons. Pressure on nerves and vessels can happen in people who have fractured their clavicle. It can also happen in people who have an extra first rib, although this doesn't always result in TOS. Extra muscle or scar tissues in the scalene muscles can put extra pressure on the nerves and arteries. Heavy lifting and carrying can bulk up the scalene muscles to the point where the nerve and arteries get squeezed. Neck and arm positions used at work and home may contribute to TOS. People who have to hold their neck and shoulders in awkward alignment sometimes develop TOS symptoms. TOS symptoms are also reported by people who have to hold their arms up or out for long periods of time.
People with TOS often slouch their shoulders, giving them a drooped appearance. The poor body alignment of slouching can compress the nerves and arteries near the thoracic outlet. Being overweight can cause problems with posture, and women who have very large breasts may also have a droopy posture. For some reason, TOS affects three times as many women as men.
What are the symptoms?
TOS causes pain along the top of the clavicle and shoulder. The pain may spread along the inside edge of the arm. Occasionally pain spreads into the hand, mostly into the ring and pinky fingers. Numbness and tingling, called paraesthesia, may accompany the pain, especially in the early hours of the morning before it's time to wake up. Symptoms tend to get worse when driving, lifting, carrying, and writing. The arms may also feel tired when held overhead, as when using a blow dryer. It may be harder to hold and grip things, and the hand may feel clumsy. Symptoms related to the blood vessels are less common. If the blood vessels are causing symptoms, the arm and shoulder may feel heavy and cold. The arm may become somewhat blue (cyanotic), and the constriction of vessels can cause the arm and hand to swell. TOS symptoms are similar to the symptoms of many other conditions. A herniated disc in the neck, carpal tunnel syndrome in the hand, and bursitis of the shoulder can all cause symptoms very much like those of TOS.
How is it diagnosed?
TOS can be diificult to diagnose because TOS doesn't have any unique symptoms. The diagnosis of TOS involves getting as much information as possible to eliminate other possible causes of your pain. First, your doctor will take your medical history and do a thorough physical examination. Because TOS is so difficult to diagnose, your doctor will rely heavily on what you report about your symptoms and medical history. You may need to get an X-ray. The X-ray could show an extra cervical rib or other problems with the bones and joints, such as arthritis. Your doctor may also ask you to get a magnetic resonance imaging (MRI) scan or other imaging tests. Your doctor may recommend electrical tests, called electromyography, of the nerves in the arm. These tests are used to find out if the nerves between the neck and hand are being pinched. To confirm the diagnosis, doctors may do special tests of the blood vessels that run along the nerves. These tests are frequently negative, but it is important that your doctor rule out other causes of your pain.
What is the treatment?
Doctors begin treating your pain conservatively, without surgery or other invasive procedures. Your doctor can prescribe some types of medicine to ease your discomfort. Nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin and ibuprofen, can relieve pain and inflammation, and muscle relaxants can relieve muscle spasm. Some patients who experience chronic pain, such as the pain of TOS, end up battling depression. In these cases, anti-depressants can be very helpful. Your doctor may recommend some simple ways to help you combat TOS. For example, decrease the tension of the shoulder strap of your seat belt. Take rest periods to avoid fatigue. Overweight patients should seek help with weight loss. Avoid heavy lifting, pulling, or pushing. Rapid breathing and stress can worsen symptoms. Avoid looking up, bending the neck back, or holding your arms up for long periods of time. You may be referred for physiotherapy. In most cases therapy can be very effective.
Surgery for TOS is usually a last resort. The surgery is directed at removing the source of compression on the nerves of the brachial plexus. The brachial plexus is the network of nerves that go to the hand and forearm. If there is an extra rib, it is usually removed. Otherwise, surgery consists of simply releasing the constricting elements and scar tissue around the nerves.