Thoracic Outlet Syndrome

The thoracic outlet is the area found between the neck and the armpit. Thoracic outlet syndrome, or TOS, is the term used to describe a condition caused by the compression of nerves or the vein and artery that emerge from the chest in this area. The space available for the nerves, vein and artery to pass through the base of the neck is quite small, as they all must pass between the clavicle and the first rib.


To make things more difficult, what little space is available is split in two by the scalenus muscles that are attached to the first rib. The nerves, which are a bundle of nerves called the brachial plexus and control the arm, subclavian artery pass behind the muscles and the subclavian vein pass in front of them.


Causes and Risk Factors of Thoracic Outlet Syndrome


Thoracic outlet syndrome is often the result of an injury, disease or inherited abnormality. Injuries that can cause the syndrome include whiplash, a neck injury, or repetitive stress injuries associated with work, such as on assembly lines, 10-key pad or keyboard typing, and filing or stocking shelves overhead. While the occurrence itself is rather rare, those that are born with a cervical rib, or an extra rib in the neck, are ten times more likely to develop thoracic outlet syndrome.


Additionally, the syndrome tends to occur more often in women than in men, while obesity and poor posture can often aggravate the condition.


Symptoms of Thoracic Outlet Syndrome


When the nerves are compressed, the most common symptoms are pain and numbness along the shoulder, both the front and back of the upper arm, and a sensation of pins and needles or tingling in the fingers. Also, the hand or arm may be cold.


Sometimes the pain will radiate out to the back of the neck and base of the head. While the symptoms may not be constant, they could get worse with exercise or lifting the shoulder or arm.


If the artery is compressed, symptoms usually include a cold hand and pain in the fingers and arm when the arm is used. If the artery becomes blocked, the symptoms could become severe and permanent. If the vein is compressed, the arm may swell or become puffy and the veins of the upper arm may become prominent.


Diagnosis of Thoracic Outlet Syndrome


Your doctor will be able to diagnose thoracic outlet syndrome by studying your medical history, the presence of the above mentioned symptoms, and a brief physical examination, but a number of different tests may be necessary.


An arteriography is performed by injecting a dye into the artery, which then shows up in a test; the same can be done for the vein with a venogram. A CT scan or an MRI can be useful in a diagnosis as well.


Treatment of Thoracic Outlet Syndrome


Mild cases can be treated with conservative therapy, such as exercises and avoiding certain triggers, such as sleeping on the side with the arm elevated. In cases where the artery or vein is compressed or the nerve compression is severe, surgery may be necessary to widen the opening at the thoracic outlet.