Thoracic Outlet Syndrome
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Thoracic Outlet Syndrome


Pronounced: tho-RASS-ik OUT-let SYN-drome

En Español (Spanish Version)


Thoracic outlet syndrome (TOS) is a collective name for disorders that involve compression, injury, or irritation to nerves and blood vessels in the parts of the lower neck and upper chest called the “thoracic outlet.” These disorders are not all well-understood, and have little in common with one another except that they occur in the same part of the body.

Thoracic Outlet Syndrome


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Causes and Symptoms

TOS can be divided into the following five types:

True Neurologic TOS

The only type of TOS that is well-understood. It is caused by birth defects of vessels and nerves in the lower neck and upper chest.

Symptoms occur only on one side of the body, and include hand weakness, numbness, Raynaud’s phenomena (changing of the color of the limb when exposed to cold), and decreased size of hand muscles.

Arterial TOS

Caused by birth defects of blood vessels in the lower neck and upper chest, but does not involve damage or injury to nerves in this area. Thrombi (blood clots) cause blockage of the arteries and in turn cause the symptoms. Symptoms include cold sensitivity in the hands and fingers, numbness, pain or sores of the fingers, and poor blood circulation to the arm, hands, and fingers.

Venous TOS

A rare type of damage to the veins of the lower neck and upper chest. Its exact cause is unknown. It is thought to be due to blockage of the blood flow through the veins draining the arm. Venous TOS usually develops suddenly, often after unusual and tiring exercise of the arms. It is associated with swelling of the limb and cyanosis (skin turning pale and blue) of the limb. There is also sometimes tingling (parasthesias) of the fingers.

Traumatic TOS

Damage to vessels and nerves caused by an injury such as a car accident. Symptoms include pain and tingling and pricking of the neck, chest, and arms. Numbness and weakness can also occur. Certain body positions may worsen these symptoms.

Disputed TOS

Also called common or non-specific TOS, it is the least understood but most common type of TOS. Its cause is unknown but may be related to accident or injury. Common symptoms include pain in the upper extremity, muscle weakness, and fatigue.

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition. The most common risk factors for TOS include sagging muscles related to aging, being obese, or having heavy breasts. Other possible risk factors include sleep disorders, imbalanced blood levels of estrogen and/or thyroid hormone levels, rheumatoid arthritis , fibromyalgia , poor nutrition, anemia, infection, the presence of tumors or large lymph nodes in the upper chest or underarm area, and psychological stress or depression .

TOS may also be caused by work activities such as repetitive injuries from carrying heavy shoulder loads, which may lead to swelling of tendons and muscles in the shoulders and upper arms. This swelling may lead to TOC by compressing and damaging nerves and blood vessels in the neck and shoulders.


Your doctor will ask about your symptoms and medical history, and perform a physical exam. So called "stress tests" are commonly employed in the diagnosis of TOS.

During these tests, your doctor will ask you to hold your arms and head in positions that may cause the TOS symptoms to reappear. The results of these tests will help determine whether you have TOS, and rule out other possible related medical conditions.

Rarely will arteriography be used to evaluate thoracic outlet syndrome. Arteriography is an invasive procedure in which a dye is injected into the arteries to evaluate for any abnormalities. This may be used if a surgery is being planned to correct an arterial TOS.


Treatment varies depending on the type of TOS that occurs. Surgery may successfully treat true neurologic TOS, vascular TOS, and some cases of traumatic TOS. The other types of TOS vary considerably in their response to nonsurgical treatment.

Pain medication, starting with nonsteroidal anti-inflammatory medications (e.g., ibuprofen), is usually the mainstay of therapy. In addition, physical therapy is often prescribed to strengthen the muscles of the neck and shoulders and help patients improve their flexibility.


TOS is not preventable in many cases, though the risk for this problem can be reduced by avoiding 1) repetitive injuries that come with carrying heavy weights, 2) repeatedly reaching overhead, 3) or lifting objects with the arms extended above shoulder level.


National Institute for Neurological Disorders and Stroke

The Nicholas Institute of Sports Medicine and Athletic Trauma (NISMAT)

The Spinal Injury Foundation


Canadian Centre for Occupational Health and Safety (CCOHS)

The Association for Repetitive Motion Syndromes (ARMS)


Crotti FM, Carai A, Carai M, et al. TOS pathophysiology and clinical features. Acta Neurochir Suppl . 2005;92:7-12.

Huang JH, Zager EL. Thoracic outlet syndrome. Neurosurgery . 2004;55:897-902.

Sanders RJ, Hammond SL, Rao NM. Diagnosis of thoracic outlet syndrome. J Vasc. Surg . 2007;46:601-604.

Surgery for thoracic outlet syndrome (TOS). Washington State Department of Labor and Industries website. Available at: Accessed July 26, 2005.

Wehbe M, Leinberry C. Current trends in treatment of thoracic outlet syndrome. Hand Clin . 2004;20:119-121.

Last reviewed January 2008 by Rimas Lukas, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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