Introduction
Thoracic outlet syndrome represents a spectrum of signs and symptoms that result from compression of the blood vessels and nerves of the arm. This compression can occur at several locations in an area of the neck and upper chest called the thoracic outlet. This includes the area between the clavicle (collarbone) and the first rib. Compression of either the blood vessels or nerves, or both, may produce a variety of different symptoms.
- Compression of the nerves to the arm is called neurogenic thoracic outlet syndrome.
- Compression of the vein or artery would be vascular thoracic outlet syndrome.
The diagnosis of this syndrome can be difficult, and requires a careful evaluation. There are a variety of treatment options, and many patients do not require surgery.
What are some of the signs and symptoms of thoracic outlet syndrome?
Neurogenic thoracic outlet syndrome is the most common form, but often the most difficult to diagnose. The symptoms that these patients notice are related to which nerves are being compressed and the severity of that compression.
Patients can feel pain anywhere along the neck, shoulder or arm. This pain can be sharp or more of an ache. They may feel a sensation of “pins and needles” called paresthesia along part of the arm. Their arm or hand muscles may feel weak or clumsy.
Vascular thoracic outlet syndrome can result from compression of either the artery or vein of the arm. Because the pressure is lower, and the blood flow is slower, compression of the vein can result in clot formation that can completely obstruct the vessel. This is known as the Paget-Schroetter syndrome. The arm can become swollen and discolored. Patients usually feel pain or heaviness in the arm. Compression of the artery in the thoracic outlet can cause numbness and paresthesia of the arm that may also become pale.
What causes thoracic outlet syndrome?
The thoracic outlet is a narrow space behind the collarbone and in front of the ribcage, particularly the first rib. There are several muscles and ligaments in this area as well. The nerves that control arm and hand movements exit the spinal cord in the neck and travel through the thoracic outlet to the arm.
The subclavian artery, which carries blood to the arm, originates in the chest and crosses over the top of the first rib passing through the thoracic outlet down to the arm. The subclavian vein also passes through this area in front of the artery as it returns blood back to the heart.
There are several locations within the thoracic outlet where compression of the blood vessels and nerves may occur. There are also several reasons that can cause this compression.
One of the more common causes is the performance of repetitive motion, particularly if this motion occurs with the arms above shoulder-level. People who have an abnormal posture or who perform a repeated activity with poor posture can develop thoracic outlet syndrome.
A previous injury to this region, such as a broken collarbone, can cause narrowing of the thoracic outlet.
A small percentage of the population is born with abnormal anatomy, such as an additional rib in their neck that can compress these structures. There are other congenital structural abnormalities within the thoracic outlet that can contribute to the development of symptoms.
How is thoracic outlet syndrome diagnosed?
The diagnosis of thoracic outlet syndrome can be challenging. This is because there is more than one cause and a variety of different symptoms that patients may experience.
The initial evaluation will involve a discussion with one of the MGH Thoracic Surgeons about the details of the symptoms.
After this, a physical examination is performed to identify any signs of thoracic outlet syndrome. There are additional tests that may be scheduled depending upon the results of that examination.
Plain X-rays, a CT scan or an MRI can provide useful information regarding the anatomy of the thoracic outlet. This is particularly helpful in patients with congenital abnormalities or with a history of trauma to this area. They are also helpful in evaluating a patient for disorders of the cervical spine, which can mimic the symptoms of thoracic outlet syndrome.
For patients with symptoms and signs of compression of the blood vessels, a non-invasive ultrasound study may be scheduled. Magnetic resonance angiography (MRA) or traditional angiogram may be necessary to evaluate the extent of vascular compression.
Patients with symptoms suggestive of compression of the nerves to the arm may undergo neurophysiological studies such as an electromyography (EMG) or nerve conduction studies.
What is the treatment of thoracic outlet syndrome?
Many patients with thoracic outlet syndrome do not require surgery, especially if the condition is diagnosed early.
Physical therapy is often the initial treatment for patients, particularly those with neurogenic thoracic outlet syndrome. Simple changes in posture may result in opening the thoracic outlet and relieve the pressure placed on the nerves or blood vessels. Physical therapy often involves strengthening the muscles that support this improved posture. There are other muscles within the thoracic outlet that may become abnormally strong as a result of repeated use. These thicker muscles can also compress the structures in the thoracic outlet producing symptoms. Certain physical therapy techniques are designed to weaken these muscles to create more space within the thoracic outlet.
Surgical treatment for thoracic outlet syndrome is typically reserved for some patients whose symptoms persist after aggressive physical therapy.
The goal of surgery is to relieve the compression of the nerves and vessels. This involves removing any abnormal structures, such as a cervical rib or tissue band.
Frequently, the first thoracic rib is removed to decompress this space. There are several approaches that may be used depending upon an individual patients underlying abnormality.
(photos courtesy
Dean Donahue, MD)
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