About 1 in 200 people are born with an extra rib called a cervical rib. About 1 in 10 people who have a cervical rib develop thoracic outlet syndrome. Your thoracic outlet is a space, or passageway, that lies just above your first rib and behind your clavicle (your collarbone). It runs from the base of your neck to your armpit. Your brachial plexus (a group of nerves that pass from your neck to your arm) and your subclavian artery and vein pass through your thoracic outlet. Thoracic outlet syndrome can occur when one or more of these structures is compressed (squashed) in your thoracic outlet. A cervical rib can sometimes cause this compression. Compression of your brachial plexus nerves is most common. This can cause pain and pins and needles in your arm on the affected side. Treatment can include painkillers, physiotherapy and sometimes surgery to relieve the compression caused by, for example, a cervical rib.
Understanding your ribs and your ribcage
Your ribs are curved bones that help to protect your heart and lungs. You have twelve pairs of ribs altogether. Together, these twelve pairs of ribs form your ribcage.
At the back, the head of each rib articulates (makes contact with) one of your thoracic vertebrae. Your vertebrae are your back bones. Your thoracic vertebrae are your vertebrae in your thorax (chest area). You have twelve thoracic vertebrae. Your cervical vertebrae are your vertebrae in your neck. You have seven cervical vertebrae.
For your first seven pairs of ribs, at the front, the other end of each rib is attached to some cartilage called costal cartilage. (Cartilage is a type of special connective tissue.) Your costal cartilage connects each rib to your sternum (your breastbone). Your next three pairs of ribs are joined by their costal cartilage to the rib above them. Your last two pairs of ribs are often called floating ribs because they are just joined to your vertebrae at the back and don't have a connection at the front.
What is a cervical rib?
About 1 in 200 people are born with an extra rib called a cervical rib. Because this is something that you are born with, it is known as a congenital condition. At the back, this rib connects to your seventh cervical vertebra in your neck. At the front, in some people a cervical rib can be 'floating' and have no connection. In other people it can be connected to your first rib by a band of tough, fibrous tissue. In some others there may be an articulation (like in a joint) with their first rib.
A cervical rib can be present just on your right side, just on your left side, or on both sides.
What is your thoracic outlet?
Your thoracic outlet is a space, or passageway, that lies just above your first rib and behind your clavicle (your collarbone). There are also some muscles that surround the thoracic outlet. The thoracic outlet runs from the base of your neck to your armpit. You have a thoracic outlet on the left and the right side of your body.
A number of structures pass through your thoracic outlet, including some important blood vessels and nerves. The brachial plexus, a group of nerves that pass from your neck to your arm, passes through your thoracic outlet. The subclavian artery and subclavian vein are blood vessels that pass through your thoracic outlet as they connect between your chest and your arm.
What is thoracic outlet syndrome and what causes it?
If you have thoracic outlet syndrome, the nerves and/or blood vessels in your thoracic outlet are compressed or squashed for some reason. In most cases, it is nerves that are compressed. This compression causes the typical symptoms (see below). In some people, the subclavian artery or subclavian vein may be compressed. Sometimes, a combination of both nerves and blood vessels may be compressed.
Thoracic outlet syndrome usually only affects one side of your body. However, rarely, compression can occur in the thoracic outlet on both sides and so symptoms then occur on both sides. There are a number of different things that can cause compression of the nerves or blood vessels in thoracic outlet syndrome.
Having a cervical rib
About 1 in 10 people who have a cervical rib develop thoracic outlet syndrome. So, most people with a cervical rib do not develop any symptoms. Having a cervical rib can cause narrowing of your thoracic outlet, making compression of the structures that pass through it more likely.
Other congenital causes
Some people are born with an extra band of tissue underneath their skin around the thoracic outlet area called a fibrous band. This can act a bit like an extra rib and cause compression of the thoracic outlet in some people. Anomalous (or extra) muscles around the thoracic outlet that you may be born with can also cause narrowing and compression. Also, some people are born with an enlarged or elongated part of a vertebra in their neck which can cause compression in their thoracic outlet.
A recent accident
It is quite common for people with thoracic outlet syndrome to have a history of some kind of recent trauma to their neck. For example, whiplash following a car accident. Trauma during an accident can cause structures in your neck and chest wall to move slightly and narrow your thoracic outlet. If you fracture (break) your clavicle (collarbone), broken bone fragments or bleeding due to the fracture can also cause narrowing of the thoracic outlet.
A job that involves repetitive movements
Thoracic outlet syndrome can be more common in someone who has a job that involves very repetitive movements or a lot of overhead work. These movements can lead to 'wear and tear' of the nerves of their brachial plexus. Also, people who play a lot of sport, particularly sports that involve lots of arm movement are also more likely to develop thoracic outlet syndrome. For example, swimmers, javelin throwers and shot putters.
People with a poor posture and 'droopy' shoulders may be more likely to develop thoracic outlet syndrome. Sitting in front of a computer for long hours with a poor posture, an incorrect desk position, and an inadequate chair may be a cause. This poor posture can cause narrowing of your thoracic outlet.
Also, thoracic outlet syndrome can be a problem for women who have large breasts. Their breasts pull the muscles of their chest wall forwards and can cause narrowing of their thoracic outlet and lead to the typical symptoms.
Artery and vein problems
Narrowing and blockage of your subclavian artery or vein is another cause of thoracic outlet syndrome. Some people can have a congenital narrowing of one of these blood vessels. In these people, a blood clot can form if there is a period where the arm is overused. For example, weight lifting or working for long periods with your arms raised above your head.
In other people, the blood vessel narrowing may be caused by, for example, a cervical rib. Because of this narrowing, a blood clot is more likely to form in the subclavian artery or vein, which can lead to the typical symptoms of blood vessel compression (see below).
Who gets thoracic outlet syndrome?
Overall, thoracic outlet syndrome is more common in women than men. It usually affects people between the ages of 20 to 50 years. As mentioned above, people with thoracic outlet syndrome have often had a recent injury to their neck. It is more common in people whose jobs involve repetitive movements or in some athletes whose sport involves a lot of arm movement.
What are the symptoms of thoracic outlet syndrome?
The symptoms of thoracic outlet syndrome depend on what is being compressed (or squashed) in your thoracic outlet. As mentioned above, in most cases it is the nerves of the brachial plexus rather than blood vessels that are compressed. Therefore, symptoms are more likely to be due to nerve compression. However, sometimes a combination of nerves and blood vessels may be compressed at the same time. This can give rise to a mixture of symptoms.
Symptoms are usually just felt on one side of the body. Rarely, symptoms can occur on both sides.
Symptoms due to nerve compression
The symptoms depend on which nerves of the brachial plexus are compressed. Most commonly you will develop pain and pins and needles in your hand and arm. You may particularly feel these along the inside of your arm and into your ring and little finger. Pins and needles are usually worse at night time and can sometimes wake you from your sleep.
If different brachial plexus nerves are compressed, you may have neck, ear, upper back, upper chest and outer arm pain on the affected side. Some people also have headaches.
Your affected arm may feel weak. You may also notice that your affected hand gets very cold, especially in cold weather.
Symptoms due to blood vessel compression or blockage
In rare cases when your subclavian vein is compressed, your arm may become swollen and may sometimes appear a blue colour. The swelling may lead to pins and needles in your affected arm. Some people also develop pain in their arm. The symptoms tend to come and go and may be brought on at times when you are using your arms a lot. If you have a blood clot in your subclavian vein causing blockage of the vein, these symptoms will become constant and urgent treatment is needed.
In rare cases, when your subclavian artery is compressed, this means that blood is unable to get through to your arm and hand on the affected side as readily as it should do. Again this can lead to pain and pins and needles. Your arm and/or hand can appear pale white in colour and it can also feel cold. Like with the vein-related symptoms, the symptoms may be brought on by using your arms a lot.
How is thoracic outlet syndrome diagnosed?
Your doctor will usually start by asking you questions about your symptoms and examining you. If they suspect that you may have thoracic outlet syndrome, they may ask you to move your arms and shoulders into certain positions when they examine you. This is to try to induce, or bring on, your symptoms. They may then suggest certain tests to look for the underlying cause. Usually, thoracic outlet syndrome is diagnosed after other conditions that can cause pain or pins and needles in one of your arms have been excluded. You may also be referred to a specialist.
A chest X-ray and X-ray of your neck can show if you have a cervical rib. Other tests including an MRI or CT scan of your neck and upper chest area may help to rule out other causes for your symptoms, such as arthritis in your neck causing compression of the nerves in your neck. Special tests called nerve conduction studies may sometimes be suggested. These look at the electrical activity of your nerves and can help to show which nerves are being compressed.
If your doctor suspects that you have compression of your subclavian artery or vein, other tests may be carried out to look for this. A test call angiography looks at your arteries and venography looks at your veins. Special tests known as Doppler studies can also look at blood flow through your arteries and veins.
What is the treatment for thoracic outlet syndrome?
Treatment depends on the underlying cause.
Blood vessel compression or blockage
In the rare case that you have blockage of one of your blood vessels by a blood clot, drug treatment is needed urgently to break down the clot. This drug treatment may then be continued for a period of time to prevent further clots. Surgery may also be needed to relieve any compression on your blood vessels. For example, removal of a cervical rib that may be squashing a blood vessel.
There is not currently a consensus about what treatment is best for this type of thoracic outlet syndrome. More trials are needed to determine the best treatment. However, in general, treatment is aimed at relieving your symptoms.
Physiotherapy may be helpful for some people and may include stretching exercises, exercises to improve posture and exercises to increase muscle strength and endurance. These exercises may all help to open up the thoracic outlet and relieve the compression.
You may also need to modify or change your work or sport activities. This may involve looking at the way that you sit in a chair or at your desk.
Drugs such as non-steroidal anti-inflammatory drugs (NSAIDs) - for example, ibuprofen - may be helpful in relieving pain in some people. Paracetamol or stronger painkillers may sometimes be needed. A drug from a group called tricyclic antidepressants may also be suggested. They are not used here to treat depression. Tricyclic antidepressants can ease nerve pain in some people separate to their action on depression. It is thought that they work by interfering with the way nerve impulses are transmitted.
In some cases, surgery to relieve the cause of the compression may be advised. For example, to ease pressure from a cervical rib, or from an extra muscle or fibrous band in your neck, or to repair a broken collarbone that is pressing on nerves (or blood vessels). However, in many cases, surgery is not a good option and may even be harmful. This is because there are many important structures in your thoracic outlet and there is a small risk of damage to these with surgery. Your specialist will be able to advise if surgery is an option.
What is the prognosis (outlook) for thoracic outlet syndrome?
In most people with thoracic outlet syndrome, the outlook is generally good and symptoms often improve over time.
If compression or blockage of the subclavian artery or vein is diagnosed quickly and treated, a good recovery is possible. However, nerve compression symptoms can be difficult to treat in a few people. Chronic (persistent) pain and weakness with some loss of ability to use the affected arm may be experienced by some. This can sometimes be severe enough to affect your quality of life.
Further reading & references
- Chang AK; Thoracic Outlet Syndrome, eMedicine, Jan 2010
- Singh MK; Thoracic Outlet Syndrome, eMedicine, Feb 2010
- Leffert RD; Thoracic outlet syndromes. Hand Clin. 1992 May;8(2):285-97.
- Brewin J, Hill M, Ellis H; The prevalence of cervical ribs in a London population. Clin Anat. 2009 Apr;22(3):331-6.
- Richardson AB; Thoracic outlet syndrome in aquatic athletes. Clin Sports Med. 1999 Apr;18(2):361-78.
- Dugas JR, Weiland AJ; Vascular pathology in the throwing athlete. Hand Clin. 2000 Aug;16(3):477-85, x.
- de Leon RA, Chang DC, Hassoun HT, et al; Multiple treatment algorithms for successful outcomes in venous thoracic outlet Surgery. 2009 May;145(5):500-7. Epub 2009 Mar 21.
- Povlsen B, Belzberg A, Hansson T, et al; Treatment for thoracic outlet syndrome. Cochrane Database Syst Rev. 2010 Jan 20;(1):CD007218.
|Original Author: Dr Tim Kenny||Current Version: Dr Michelle Wright|
|Last Checked: 27/07/2010||Document ID: 13155 Version: 1||© EMIS|
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