Thoracic Outlet Syndrome
Thoracic outlet syndrome is a condition characterized by pain in
the neck and shoulder,/ numbnesstingling of the fingers, and weakening of the grip.
Information about Thoracic Outlet Syndrome
Thoracic outlet syndrome is a rare condition caused by
compression of blood vessels and nerves in the area of the clavicle (collar bone). This
compression is caused by the presence of an extra cervical rib (above the first rib) or an
abnormal tight fibrous band connecting the spinal vertebra to the rib.
People with long necks and droopy shoulders may be predisposed to develop this
condition because of extra pressure on their nerves and blood vessels.
The thoracic outlet is an area at the top of the rib cage, between the neck and the
chest. Several anatomical structures pass through this area, including the esophagus,
trachea, and nerves and blood vessels that lead to the arm and neck region. The area
contains the first rib, collar bone (clavicle), the arteries beneath the collar bone
(subclavian artery), which supply blood to the arms, a network of nerves leading to the
arms (brachial plexus), and the top of the lungs.
Pain and other symptoms occur when the nerves or blood vessels in this area are
compressed. The likelihood of blood vessels or nerves in the thoracic outlet being
compressed increases with increased size of body tissues in this area or with decreased
size of the thoracic outlet. The pain of thoracic outlet syndrome is sometimes confused
with the pain of angina that indicates heart problems. The two conditions can be
distinguished from each other because the pain of thoracic outlet syndrome does not appear
or increase when walking, while the pain of angina does. Also, the pain of thoracic outlet
syndrome usually increases if the affected arm is raised, which does not happen in cases
of angina.
There are three types of thoracic outlet syndrome:
- True neurogenic thoracic outlet syndrome is caused by a compression of the nerves in the
brachial plexus. Abnormal muscle or other tissue causes the problem.
- Arterial thoracic outlet syndrome is caused by compression of the major artery leading
to the arm, usually by a rib.
- Disputed thoracic outlet syndrome describes patients who have chronic pain in the
shoulders and arms and have no other disease or syndrome, but the underlying cause cannot
be accurately determined.
Thoracic outlet syndrome is most common in women who are 35-55 years of age.
Symptoms of Thoracic Outlet Syndrome
The following symptoms may indicate thoracic outlet syndrome:
- Discomfort in the last 3 fingers and inner forearm
- Pain and tingling in the neck and shoulders (may be worsened by carrying something
heavy, such as a suitcase)
- Weakness and wasting of the muscles of the hand
Compression of blood vessels or nerves in the thoracic outlet causes pain and/or
abnormal nerve sensations. Compression usually occurs at the location where the blood
vessels and nerves pass out of the thoracic outlet into the arm.
There are several factors that contribute to a person developing thoracic outlet
syndrome. Poor posture is a major cause and is easy to treat. A person's physical makeup
also can cause thoracic outlet syndrome. For example, abnormalities of certain anatomical
structures can put pressure on blood vessels or nerves. Typical abnormalities that can
cause problems are malformed ribs and too narrow an opening between the collar bone and
the first rib.
The main symptom is pain in the affected area. The patient can also develop weakness in
the arm and hands, tingling nerve sensations, and a condition called Raynaud's syndrome.
In Raynaud's syndrome exposure to cold causes small arteries in the fingers to contract,
cutting off blood flow. This causes the fingers to turn pale. In very severe cases of
blood vessel compression, gangrene can result. Gangrene is the death of tissue caused by
the blood supply being completely cut off.
In the case of arterial thoracic outlet syndrome, the artery beneath the collar bone
leading to the arm is compressed causing the artery to increase in size. Blood clots
(thrombi) may form in the blood vessel. When blood vessels are compressed, the hands,
arms, and shoulders do not receive proper blood supply. They can swell and turn blue from
a lack of blood.
In the case of true neurogenic thoracic outlet syndrome, the nerves most affected are
those of the network of nerves supplying the chest, shoulder, arm, forearm, and hand
(brachial plexus). When a nerve is affected in thoracic outlet syndrome it produces a
tingling sensation (paresthesia). It can also cause weakness in the hand and reduced
sensation in the palm and fingers.
Diagnosis of Thoracic Outlet Syndrome
There are no specific diagnostic tests for thoracic outlet syndromes. The diagnosis is
made by ruling out other diseases and by observing the patient. Two non-specific tests
that can suggest the presence of thoracic outlet syndrome are the Adson's test and the
Allen test. In the Adson test, the patient takes a deep breath and tilts his or her head
back and turns it to one side. The physician tests to see if the strength of the patient's
pulse is reduced in the wrist on the arm on the opposite side of the head turn. In the
Allen test, the arm in which the patient is experiencing symptoms is raised and rotated
while the head is turned to the opposite side. The physician tests to see if the pulse
strength at the wrist is reduced. If the strength of the pulse is reduced in either of
these two tests it indicates compression of the subclavian artery.
Occasionally, examination with a stethoscope may reveal abnormal sounds in affected
blood vessels. X rays can reveal constrictions in blood vessels if a special dye is
injected into the blood stream to make the blood vessels visible (angiography).
Certain tests are available to help with the diagnosis of nerve compression. These
include the nerve conduction velocity test and somatosensory evoked potential test. In the
nerve conduction velocity test, electrodes are placed at various locations on the skin
along a nerve that is being tested. A mild electrical impulse is delivered through an
electrode at one end of the nerve and the electrical activity is recorded by the other
electrodes. The time it takes for the electrical impulse to travel down the nerve from the
stimulating electrodes to the recording electrodes is used to calculate the nerve
conduction velocity. This can be used to determine if any nerve damage exists.
In a somatosensory evoked potential test, electrodes are placed on the skin at the
scalp, neck, shoulder, and wrist. A mild electrical impulse is delivered at the wrist, and
a recording is made of the response by the brain and spinal cord. This test also can
determine the presence of nerve damage.
Treatment of Thoracic Outlet Syndrome
The main treatment for thoracic outlet syndrome is physical therapy. Exercises aimed at
improving the posture of the affected person are also useful. In some cases, surgery can
be performed to remove the cervical rib if this is causing the problem and physical
therapy has failed to work. However, surgery is generally not used to treat thoracic
outlet syndrome. |
