The term “thoracic outlet syndrome” is used to describe a condition involving compression of the nerves and/or blood vessels in the region around the neck and collarbone, called the thoracic outlet. Thoracic outlet syndrome is controversial in the medical literature. The diagnosis and treatment of patients who have thoracic outlet syndrome have been varied, particularly in those with complaints of tingling, numbness and pain in the arm and hand. Recently, surgeons have recognized that patients with thoracic outlet syndrome can be divided into patients with compression of the blood vessels (subclavian vein and artery) and those with nerve compression (brachial plexus). Symptoms related to nerve compression are more common than those involving compression of the blood vessels. However, most of the controversy surrounds patients with compression of the brachial plexus.
Patients with thoracic outlet syndrome (compression of the brachial plexus) usually complain of a feeling of “pins and needles” and/or numbness in the arm, forearm or hand. Many patients also have complaints of pain and aching in the shoulder neck or shoulder blade region. These symptoms usually are made worse with activities that require the arms positioned overhead. For women, common activities that aggravate the condition include applying makeup or styling their hair. Patients may describe headaches at the back of the head or around the eyes. Occasionally, patients may describe face and chest pain, but these complaints are less common. Pressure on the blood vessels in the region of the thoracic outlet may cause the hand to feel cooler or to be swollen, or the hand may appear white or blue. Early symptoms may only occur with the arms in an overhead position and go away with the arms down by the side. As time goes on, symptoms often occur more frequently and with less time in irritating positions.
What Causes Thoracic Outlet Syndrome?
Thoracic outlet syndrome is thought to be caused by a combination of factors, although exact causes remain uncertain. Nerve compression in other parts of the body, such as carpal tunnel syndrome, is better understood. This information about nerve compression can be related to pressure on the brachial plexus in the thoracic outlet.
There are areas in the extremities where the nerves can be “pinched” and other places where the nerve is not under any risk of pressure. In general, when nerves cross a joint, they are more susceptible to compression or stretching. In some places along the arm, there are tight spaces made by bones, ligaments or muscles, and if the nerve travels through one of these “tunnels,” the nerve may be more at risk of pressure. For example, with carpal tunnel syndrome, there is more pressure on the median nerve when the wrist is bent or extended than when the wrist is in a straight position. Increased pressure in the carpal canal can put increased pressure on the median nerve, causing tingling and numbness of the thumb, index and middle finger.
Nerve compression also can occur as a result of pressure on the ulnar nerve at the elbow. The ulnar nerve runs behind the elbow in the area of the cubital tunnel. When the elbow is bent, there is increased pressure and tension on the nerve. If a person holds the position for a long period of time, he or she will experience a tingling or numbing feeling in the small and ring fingers. With thoracic outlet syndrome, it appears that arm overhead positions and downward pulling (for example, from carrying a heavy bag) increases pressure on the brachial plexus.
Symptoms of nerve compression take many months and, likely, years to progress and worsen. It is easy to hold your wrist or elbow bent for a long time (especially at night) and, therefore, symptoms caused by carpal tunnel or cubital tunnel syndrome are more likely to progress more quickly. Because pressure on the brachial plexus is irritated with arm overhead positions, and these positions often cause significant discomfort, the progression of nerve compression will be much slower – you will be uncomfortable in these positions and quickly learn to avoid them. However, this protective habit may limit your range of movement and make certain muscles very tight.
The onset of thoracic outlet syndrome usually is the result of many factors. Some patients may recall an accident that occurred before their symptoms started; other people may not remember a particular incident when their symptoms began. Patients with an extra cervical rib, tight, soft tissue bands or other unusual anatomy that could press on the brachial plexus are more likely to develop symptoms. People who are overweight or women with large breasts place extra pressure on the nerves and muscles in the thoracic outlet region and also are more likely to have poor posture with associated muscle imbalance.
In general, thoracic outlet syndrome is thought to be caused by a number of factors, including activities at home and work, sleep postures, trauma, anatomy and other diseases.
Double Crush Syndrome
Patients with thoracic outlet syndrome usually have symptoms of tingling and numbness in the hand. These hand symptoms are similar to those of carpal tunnel syndrome and cubital tunnel syndrome. The “double crush” mechanism may play a role in the development of symptoms in patients with thoracic outlet syndrome. The nerve fiber begins in or near the spinal cord and then goes all the way to the hand to give sensation and movement to the arm and hand. If the nerve is pinched at one place, then it is less likely to tolerate any more pressure along the nerve. Therefore, other tight places, such as at the wrist (carpal tunnel) or elbow (cubital tunnel), are more likely to produce symptoms with very little added pressure.
The idea of the “double or multiple crush” is that patients with nerve compression at one site are more likely to develop nerve compression at another site. There are some diseases that can be the first “crush”; for example, patients with diabetes, hypothyroidism, rheumatoid arthritis or alcoholism are more susceptible to developing symptoms from nerve compression. Some people have a hereditary susceptibility to develop nerve compression.
A complete history and physical examination are necessary to identify all sites of nerve compression or other musculoskeletal problems that may be causing your symptoms. The results of nerve conduction studies assessing the thoracic outlet and the brachial plexus usually are normal. However, these studies are useful in identifying associated carpal and cubital tunnel syndrome. An X-ray of the neck and chest may be done to identify a cervical rib or other problems in the neck that are not related to thoracic outlet syndrome, but which may be causing your symptoms. If your symptoms are related more specifically to your cervical spine or shoulder joint, then a consultation by another specialist may be indicated. If you have a shoulder problem, it will be difficult for you to get your brachial plexus nerves to glide or your muscles to stretch out until the shoulder problem is solved. Studies to assess the blood vessels in your neck and hand may be necessary in some patients.
Patients with thoracic outlet syndrome usually have few complaints when their arms are at rest. Therefore, some testing with your arms in an elevated position may be necessary to provoke your symptoms. Because pain often is a significant part of the symptoms of thoracic outlet syndrome, this pain may have an effect on your overall function. You may be asked to take a psychological test to see how much the pain has affected your life.
In the vast majority of patients, non-operative treatment is successful in relieving the symptoms of thoracic outlet syndrome. This begins by modifying your activities to decrease the time that you spend in positions that are irritating your symptoms (usually arm-over-head positions). Physical therapy is recommended to instruct you in exercises to initially stretch soft tissues that are too tight and then to strengthen weak muscles.
Symptoms thought to be from thoracic outlet syndrome may include some symptoms from other problems (such as carpal tunnel syndrome, cubital tunnel syndrome, cervical disc disease, rotator cuff tendinitis, large breasts). If conservative management does not relieve your symptoms, then surgery to address the other problems may be suggested before surgery for thoracic outlet syndrome.
Surgery for thoracic outlet syndrome is controversial and has been associated with many complications. Therefore, if at all possible, surgery should be avoided. However, in some cases, non-operative treatment will not relieve your symptoms, and surgery to release the structures in the thoracic outlet will be discussed. Surgical management may involve release of the scalene muscles and/or removal of the first rib. This operation frequently is done with an incision above the collarbone. However, your surgeon instead may recommend a surgical approach through the armpit. In general, either approach — a first rib resection or release of the scalene muscles alone — produces the same long-term results.
One of the reasons that surgical management of thoracic outlet syndrome is controversial is that complications have been reported after surgery. The most significant complication is injury to the major blood vessels or nerves in the region of the brachial plexus.
Complications can include nerve injury affecting the muscle function in the hand and sensation to the medial border of the forearm and to the ring and small finger, Horner’s syndrome (droopy eyelid and uneven pupil size), “winging” of the shoulder blade, and nerve injury affecting movement of your diaphragm, which may result in shortness of breath. Sensory nerves in the area of the incision also can be injured or irritated, causing decreased sensation or hypersensitivity in the region around the collarbone.
Other complications are related to bleeding and fluid collection, and if these occur, they may require drainage. Blood, fluid or air may collect around the lung and cause temporary breathing problems and may require a chest tube for drainage. Even when great care is taken during this surgery, these known and recognized complications can occur.
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More information on treatment of peripheral nerve injuries is available on the Center for Nerve Injury & Paralysis website.