What is thoracic outlet syndrome?

Thoracic outlet syndrome, often called TOS, happens when nerves or blood vessels become squeezed in the space between the collarbone and first rib. This pressure can affect the shoulder, arm, and hand, leading to pain, numbness, or weakness.

The condition can develop gradually or after an injury. Some people notice symptoms only during certain activities, especially movements that involve raising the arms overhead.

Several factors can increase the risk of thoracic outlet syndrome, including:

• Repetitive overhead movements from work or sports
• Injuries involving the neck, shoulder, or collarbone
• Poor posture
• Extra rib or muscle differences present at birth
• Excess body weight

In more serious cases, reduced blood flow or blood clots may develop and require prompt medical care.

Symptoms

Thoracic outlet syndrome can affect nerves, veins, or arteries. Symptoms may come and go and often get worse with repeated arm motion or poor posture.

Common symptoms include:

• Pain in the neck, shoulder, arm, or hand
• Tingling or numbness in the fingers
• Weakness in the hand or arm
• Swelling or heaviness in the arm
• Limited arm movement
• Coldness or color changes in the hand
• Aching that worsens during overhead activities

How is it diagnosed?

Diagnosing thoracic outlet syndrome can take time because symptoms may resemble other shoulder, neck, or nerve conditions. Your healthcare provider will review your symptoms, medical history, and daily activities before performing a physical exam.

Testing may include:

• Movement-based exams to reproduce symptoms
• Nerve conduction studies or electromyography (EMG)
• Ultrasound to evaluate blood flow
• Chest X-rays to look for structural differences
• CT scans or vascular imaging for a closer view of nerves and blood vessels

These tests help determine the type of thoracic outlet syndrome and guide treatment planning.

How is it treated?

Treatment usually begins with conservative care focused on reducing pressure in the thoracic outlet area. Many people improve without surgery.

Common treatment options include:

• Physical therapy to improve posture, flexibility, and strength
• Changes to daily activities that trigger symptoms
• Anti-inflammatory medicines to reduce discomfort
• Weight management and ergonomic adjustments

If blood vessels are affected or symptoms do not improve, surgery may be recommended to relieve compression. Some patients with blood clots may also need blood-thinning medicine or procedures to restore blood flow.

Recovery depends on the severity of the condition and the type of treatment needed. Many people experience gradual improvement with therapy and ongoing lifestyle changes.