Thoracic Outlet Syndrome
In this article:
- What is Thoracic Outlet Syndrome?
- Symptoms of Thoracic Outlet Syndrome?
- Causes of Thoracic Outlet Syndrome
- Diagnosing Thoracic Outlet Syndrome
- Treating Thoracic Outlet Syndrome
- Surgical Treatment
Thoracic outlet syndrome involves compression of certain nerves and blood vessels that travel from the thorax to the arm. The outlet is called the superior thoracic outlet and it is created by the anterior scalene and the middle scalene muscles. The nerves and blood vessels include the brachial plexus, the subclavian artery and the subclavian vein.
In fact, there are three main types of thoracic outlet syndrome, including the following:
- Neurogenic Thoracic Outlet Syndrome, which involves compression of the brachial plexus. This involves 95 percent of all cases of the syndrome.
- Arterial Thoracic Outlet Syndrome, which results in the compression of the subclavian artery. It is the second most common form of the syndrome.
- Venous Thoracic Outlet Syndrome, which leads to compression of the subclavian vein. This the rarest form of the condition.
The condition may simply be positional and occurs by movement of the clavicle and shoulder girdle. This is a non-static form of the condition. There are multiple static forms of the condition, usually caused by a muscle spasm of the surrounding muscles, fixation of a first rib, the presence of a cervical rib, enlargement of muscles near the structures or abnormalities of the muscles.
A Pancoast tumor is a type of lung cancer near the top of the lung that can cause thoracic outlet syndrome. However, the most common cause of a thoracic outlet syndrome is physical injury from an auto accident. Another cause is a repetitive strain from using a keyboard the wrong way, sports injuries and being born with an extra rib. Some people can get thoracic outlet syndrome from pregnancy, especially if a previously narrow thoracic outlet existed.Symptoms of Thoracic Outlet Syndrome
Thoracic outlet syndrome affects the arms and is usually unilateral. There is usually pain that can be burning, sharp or aching that can involve the fourth or fifth finger, the entire hand, or the inside aspect of the forearm and the upper arm. There can also be pain in the area of the armpit, on the side of the neck, or overlying the pectoral muscles. The upper back can be painful. One hand is pale, colder than the other hand and weaker than the other hand. In fact, there is a weakness of the entire arm. Tingling in the hand and arm is a common symptom.
Thoracic outlet syndrome can ultimately cause symptoms of carpal tunnel and a frozen shoulder on the affected side. When this happens, the secondary conditions of carpal tunnel and frozen shoulder are often resistant to the standard treatment protocols.
Thoracic outlet syndrome can be associated with cerebrovascular arterial injury, especially when the subclavian artery is part of the problem. The vertebral artery can also be affected, resulting in a case of transient blindness. With a vertebral arterial injury, there can also be cases of embolic cerebral infarction.
If the arm becomes painful, blue, and swollen, especially after exercise, it is likely due to compression of the subclavian vein. It can cause thrombosis of the arm and cause a condition known as Paget-Schroetter syndrome.
The symptoms differ widely depending on the type of thoracic outlet syndrome the patient has. For example, in neurogenic thoracic outlet syndrome, the main symptoms are:
- Wasting of the thenar eminence of the thumb.
- Numbness or tingling of the fingers.
- Back and shoulder pain
- Aching of the hand or arm
- Weak grip strength
Signs and symptoms of vascular thoracic outlet syndrome (vein or artery) include:
- Bluish discoloration of the hand
- A subclavian blood clot (thrombosis)
- Arm pain and swelling secondary to blood clots
- Throbbing lump near the collarbone
- Extreme paleness of at least one finger on your hand
- No or weak pulse in the arm
- Tiny black spots (infarcts) on the fingers
The basic cause of thoracic outlet syndrome is compression of the various blood vessels and nerves in the thoracic outlet, located beneath the collarbone. The causes of this type of compression vary and involved:
- Inherited defects. This can include birth defects like having an extra rib called a cervical rib. It is located just above your first rib. You can also be born with an abnormally stiff and tight band connecting the spine to the first rib.
- Bad posture. If you droop your shoulders or hold your head down, this can result in compression in the thoracic outlet.
- Automobile trauma. This can cause internal injuries that compress the nerves traveling through the thoracic outlet. It can also result in a delayed-onset of vascular compression.
- Repetitive motion. Repetitive activities can cause thoracic outlet syndrome. Some repetitive movements include typing on a computer for a long time, pitching baseball, swimming for long periods of time, or working on an assembly line for many hours on end.
- Pregnancy. Joints tend to loosen in pregnancy causing a narrowing of the thoracic outlet.
- Joint pressure. Obesity can stress out the joints and carry around an oversized backpack or bag can do damage to the thoracic outlet.
This can be a difficult diagnosis because the symptoms vary from person to person and much of it depends on whether the nerves, the blood vessels or both are affected.
The doctor starts with a physical examination, looking for depression in the shoulder or looking for discoloration and a limited range of motion of the arm or hand. The doctor will ask about your past medical history, your physical activities, and your occupation.
The doctor can do provocation tests. These are specially designed to reproduce the symptoms. The tests can point toward thoracic outlet syndrome and can rule out those disorders that have similar types of symptoms. These are the most common provocation tests:
- Wright test. You sit in a seated position and hold your arm up and back, rotating it outward. Your doctor will check the pulses in the arm to see if they are present. The doctor will ask if your symptoms are reproduced by the test.
- Adson’s Maneuver. In this test, you turn your head toward the affected shoulder while you extend your arm, shoulder, and neck away from the body. Inhale while the doctor checks for a wrist pulse. You will also be asked whether or not your symptoms are repeated during the maneuver. There can be false positives with this test, necessitating repeating the test on the opposite side of your body.
- Roos Stress Test. You sit in a chair and hold both elbows at shoulder height, pushing the shoulders back. Repeatedly open and close the hands for several minutes to see if your symptoms are repeated on your affected side.
The doctor can also order nerve and imaging studies that might confirm the diagnosis of thoracic outlet syndrome. These include:
- Plain film x-ray. A plain film x-ray is effective in locating an extra cervical rib which could be causing the symptoms.
- MRI Scan. This is a good test that uses a large magnet and radio waves to create
- cross-sectional images of the body. It can help find the exact location and the cause of the outlet syndrome. It can show where the brachial plexus and blood vessels are located. This is a scan that will also show the presence of a cervical rib and other congenital anomalies contributing to thoracic outlet syndrome.
- Electromyography or EMG. This is a test to see whether or not the muscles are receiving enough nerve input. Electrodes are inserted into the muscles near where you’re having your symptoms. The electrical activity in the muscles can be determined.
- Nerve conduction study. This test is also known as a nerve conduction velocity study. It measures how fast nerve impulses pass through a nerve. This is a test that can show the possibility of nerve damage in thoracic outlet syndrome. Electrodes are placed before and after the thoracic outlet to look for a slowing of the nerve conduction.
The video below discusses thoracic outlet syndrome, including its diagnosis and treatment.Treating Thoracic Outlet Syndrome
In many cases, a conservative approach is used effectively to treat thoracic outlet syndrome, especially if it is diagnosed early in the course of the disorder.
Conservative treatment includes the following practices:
- Relaxation therapy. The techniques used are deep breathing, meditation, guided imagery, and other similar techniques. These can keep you from tensing your shoulders and will remind you to maintain excellent posture.
- Physical therapy. You’ll work with a physical therapist, doing exercises that strengthen the shoulder muscles so they open up the thoracic outlet. Your posture will also be improved by these exercises and eventually, you will effectively be able to take the pressure off the nerves and blood vessels in the thoracic outlet.
- Medications. These medications include anti-inflammatory medications like ibuprofen and naproxen as well as muscle relaxants that take the inflammation and tension off the muscle putting pressure on the nerves and blood vessels.
Sometimes conservative measures do not work. You can have evidence of worsening nerve damage or worsening weakness of the affected arm muscles. Your doctor might also suggest surgery if you have confirmed neurogenic thoracic outlet syndrome. This is because only surgery seems to be the best option in such cases. If the artery has formed an aneurysm because of backpressure at the level of the thoracic outlet, it can be treated surgically.Surgical Treatment
Surgery seems to be able to handle much of the pain associated with thoracic outlet syndrome but unfortunately cannot always fix the muscle atrophy and weakness seen in the disorder. This is especially true when the disorder was not treated for a long time.
It will be a thoracic surgeon or vascular surgeon who performs this procedure. There is a great risk of injury to the brachial plexus in this type of procedure so the doctor needs to be careful not to damage the delicate nerves.
One approach to the procedure is called the anterior supraclavicular approach. In this approach, the incision is made just beneath the neck. It then exposes the brachial plexus area. The doctor then looks for fibrous bands that might be causing the problem. The doctor can also fix any blood vessels that have been compromised.
The other approach is called the transaxillary approach. The surgeon makes an incision in the chest and gets access to the first rib. A portion of the first rib is then removed in order to relieve compression on the nerves. This has the added advantage of being able to access the rib without getting into the nerves or blood vessels. It has the disadvantage of not being able to gain access to the blood vessels to correct any complications.
Photo by jasminnagdy on slideshare.net
Editor’s Note: This page has been updated for accuracy and relevancy [cha 11.2.20]