What Is Thoracic Outlet Syndrome (TOS)?
Thoracic outlet syndrome (TOS) is a group of disorders that puts pressure on the arteries, veins, or nerves in the upper chest.
TOS may cause symptoms in the:
- Upper back.
- Neck.
- Arm.
- Hand.
Types of thoracic outlet syndrome
There are three types of TOS. Symptoms help doctors determine the type of TOS you have.
Arterial thoracic outlet syndrome (ATOS)
In ATOS, an artery in the thoracic outlet compresses, narrows, or dilates.
An extra rib at the top of the rib cage or an abnormal first rib may cause this type of TOS.
Complications of ATOS can include:
Venous thoracic outlet syndrome (VTOS)
In VTOS, a vein in the thoracic outlet becomes compressed and damaged. The most common cause is repetitive, strenuous shoulder and arm use.
Complications of VTOS can include:
Neurogenic thoracic outlet syndrome (NTOS)
In NTOS, the brachial plexus — the bundle of nerves in the thoracic outlet — compresses, often from:
- A prior injury.
- Trauma.
- Repetitive forces from exertional movements.
NTOS complications can include:
- Neck, arm, shoulder, or back pain that disrupts sleep, work, and daily activities.
- Neck, arm, or shoulder weakness.
- Nerve damage.
Thoracic outlet syndrome causes
Compressed blood vessels or nerves in the tight corridor of the thoracic outlet get irritated and can cause TOS.
Causes of compression may be:
- Bony and soft tissue abnormalities, such as an extra rib or an old collarbone injury.
- Tumors or enlarged lymph nodes in the upper chest or armpit.
- Playing sports that involve repetitive arm or shoulder movement, such as golf, baseball, swimming, volleyball, tennis, etc.
- Repetition injuries from carrying heavy shoulder loads.
- Injury to the neck or back, such as whiplash.
- Poor posture.
- Heavy weightlifting.
Complications of thoracic outlet syndrome
TOS can occur on either side of the body but most often affects your dominant hand's side because of constant use.
Complications vary depending on the type of TOS you have.
A blood clot may break apart, and smaller pieces — called emboli — can move down the arm.
A blood clot can block blood flow to the hand, causing:
- Pain.
- Coolness.
- Numbness.
- Discoloration.
It's vital to restore blood flow to the hand quickly.
Thoracic outlet syndrome risks
TOS happens to people of all ages and genders, but it is more common in young women.
Factors that can increase your risk of TOS include:
- Stress from repetitive tasks.
- Playing a sport with repetitive arm motion — like baseball, volleyball, swimming, or tennis.
- Having poor thoracic posture.
- Prior cervical spine or neck trauma.
Our TOS experts