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Thoracic outlet syndrome (TOS) consists of a group of distinct disorders that affect the nerves in the brachial plexus (nerves that pass into the arms from the neck) and various nerves and blood vessels between the base of the neck and axilla (armpit). For the most part, these disorders are produced by positional compression of the subclavian artery and vein, the vertebral artery, and the nerve cords of the brachial plexus. The disorders are complex, somewhat confusing, and poorly defined, each with various signs and symptoms not only arising from the upper extremity but also from the chest, neck and head. The chest pain can mimick anginal pain.
Categorization by system
True neurologic TOS is the only type with a clear definition that most scientists agree upon. The disorder is rare, because most of the patients with thoracic outlet syndrome undergo treatement before wasting of the muscles occurs. It is caused by congenital anomalies (unusual anatomic features present at birth). It generally occurs in middle-aged women and almost always on one side of the body. Symptoms include weakness and wasting of hand muscles, and numbness in the hand. Although wasting of the muscles of the hand reveals a late diagnosis with a long period of undiagnosed thoracic outlet syndrome.
Disputed TOS, also called common or non-specific TOS, is a highly controversial disorder. Some doctors do not believe it exists while others say it is very common. Because of this controversy, the disorder is referred to as "disputed TOS." Many scientists believe disputed TOS is caused by injury to the nerves in the brachial plexus. The most prominent symptom of the disorder is pain. Other symptoms include weakness and fatigue.
Arterial TOS occurs on one side of the body. It affects patients of both genders and at any age but often occurs in young people. Like true neurologic TOS, arterial TOS is rare and is caused by a congenital anomaly. Symptoms can include sensitivity to cold in the hands and fingers, numbness or pain in the fingers, and finger ulcers (sores) or severe limb ischemia (inadequate blood circulation).
Venous TOS is also a rare disorder that affects men and women equally. The exact cause of this type of TOS is positinal compresion of the subclavian vein at the thoracic outlet. It often develops suddenly, frequently following unusual, prolonged limb exertion.
Traumatic TOS may be caused by traumatic or repetitive activities such as a motor vehicle accident or hyperextension injury (for example, after a person overextends an arm during exercise or while reaching for an object). Pain is the most common symptom of this TOS, and often occurs with tenderness. Paresthesias (an abnormal burning or prickling sensation generally felt in the hands, arms, legs, or feet), sensory loss, and weakness also occur. Certain body postures may exacerbate symptoms of the disorder.
Categorization by region
An alternate taxonomy of TOS is used in ICD-9-CM and other sources:
- Scalenus anticus syndrome (compression on brachial plexus and/or subclavian artery caused by muscle growth) - diagnosed by using Adson's sign with patient's head turned outward
- Cervical rib syndrome (compression on brachial plexus and/or subclavian artery caused by bone growth) - diagnosed by using Adson's sign with patient's head turned inward
- Costoclavicular syndrome (narrowing between the clavicle and the first rib) -- diagnosed with costoclavicular maneuver (*)
This article is based on information from the NINDS subdivision of the NIH.
Anatomy Diagrams
See also
External links
"Thoracic outlet syndrome"