Thoracic Outlet Syndrome (TOS)

Picture of thoracic outlet syndrome (TOS) showing symptom areas

Thoracic outlet syndrome (TOS) is a condition whereby symptoms are produced (such as numbness in fingers, and pain in the shoulder, arm, and neck) due to compression of nerves and/or blood vessels in the upper chest. The passageway for these nerves and blood vessels to exit the chest and supply the upper extremities is referred to as the thoracic outlet. Muscle, bone, and other tissues border the thoracic outlet. Any condition that results in enlargement or movement of these tissues of or near the thoracic outlet can cause thoracic outlet syndrome. These conditions include muscle enlargement (such as from weight lifting), injuries, an extra rib extending from the neck (cervical rib), weight gain, and rare tumors at the top of the lung. Often no specific cause is detectable.

Some scientists feel that the evolution of the torso of primates from a four-legged to a two-legged position may predispose humans to the development of thoracic outlet syndrome. The resulting vertical posture produced a flattening of the chest cage and a shift of the shoulder joint backward, both of which narrowed the thoracic outlet.

An inadequate passageway for nerves and blood vessels as they pass through an area (thoracic outlet) between the base of the neck and the armpit causes thoracic outlet syndrome. This can be constant or intermittent. Thoracic outlet syndrome can be caused by weight lifting, obesity, tumors in the chest, and extra ribs extending from the seventh cervical vertebra at the base of the neck.

Risk factors include occupations that involve heavy usage of the upper extremities against resistance, including jackhammer operators and dental hygienists, weight lifting, pregnancy, and obesity. Any condition that causes encroachment of the space for the brachial plexus at the thoracic outlet can lead to thoracic outlet syndrome, including poor posture.

Symptoms include neck, shoulder, and arm pain, numbness in the fingers, or impaired circulation and flushed sensations to the extremities (causing discoloration). The involved upper extremity can feel weak. Often symptoms are reproduced or worsened when the arm is positioned above the shoulder or extended. Patients can have a wide spectrum of symptoms from mild and intermittent to severe and constant. Pains can extend to the fingers and hands, causing weakness.

Doctors who treat thoracic outlet syndrome include general physicians, such as general-medicine doctors, family medicine doctors, and internists, as well as rheumatologists, physical-medicine doctors, and chest surgeons.

The diagnosis of thoracic outlet syndrome is suggested by the symptoms and supported by the findings of the doctor during the examination. Certain maneuvers of the arm and neck can produce symptoms and blood vessel "pinching," causing a loss of pulse. This includes Adson's maneuver, whereby the examiner moves the shoulder joint into positions that can cause pinching of both the nerves and artery to the tested arm.

Further supportive testing can include electrical tests, such as electromyogram (EMG) and somatosensory evoked responses (although these may not be positive in all patients). Some patients can have angiogram X-ray tests that demonstrate the pinched area of the blood vessel involved.

Treatment of thoracic outlet syndrome can usually be successful with conservative measures. Treatments include a variety of exercises that effectively stretch open the tissues of the thoracic outlet. These are done with and without weights in the hands to pull the outlet into a "relaxed" open position. Physical therapists are specially trained in the instruction of exercises for thoracic outlet syndrome, and their evaluation of the patient can be helpful. Shoulder-shrug exercises and others can be done at home or at work to relax the muscles around the thoracic outlet.

A healthcare professional might prescribe medications to help improve the symptoms, such as anti-inflammatory medications (ibuprofen [Advil], naproxen [Aleve]) and muscle relaxants.

Some patients with severe, resistant symptoms can require surgery to open the thoracic outlet. These procedures include interruption of the scalene muscle (scalenotomy) and removal (resection) of the first rib to spare injury to the affected nerve and blood vessels from ongoing compression. Thoracic outlet syndrome that affects the vascular system (veins and arteries) is more likely to require surgery to resolve the symptoms.

Patients should avoid prolonged positions with their arms held out or overhead. For example, it is best to avoid sleeping with the arm extended up behind the head. It is also helpful to have rest periods at work to minimize fatigue. Weight reduction can be helpful for obese patients. Patients should avoid sleeping on their stomachs with their arms above their heads. They should also not repetitively lift heavy objects.

Most people with thoracic outlet syndrome can have complete resolution of symptoms with conservative measures, including exercises specific for thoracic outlet syndrome, physical therapy, and avoiding stressing the tissues of the thoracic outlet. It can be helpful to avoid sleeping with the arms extended above the head. Rarely, surgical intervention can be necessary to take pressure off of involved nerves and blood vessels.

Complications include embolization to the hand and nerve damage to the extremity involved.

It's possible to prevent thoracic outlet syndrome by maintaining relaxed tissues of the upper chest. This can involve prevention exercises, stretches, and therapies designed to loosen the tissues around the shoulders and neck.