Thoracic Outlet Syndrome Overview

Thoracic Outlet Syndrome (TOS) occurs when nerves or blood vessels in the thoracic outlet—the space between the collarbone and first rib—become compressed. This can lead to pain, numbness, tingling, and weakness in the arms, hands, neck, or shoulders.

TOS can be frustrating, but with the right treatment approach, many patients find relief and regain function. If you suspect you have TOS, consulting with a healthcare provider is the first step toward recovery. With proper care, you can manage symptoms and return to your daily activities with less pain and discomfort.

What Causes TOS?

TOS can develop due to various reasons, including:

• Poor posture – Slouching or forward head posture can put pressure on the nerves and blood vessels.
• Repetitive movements – Activities like typing, lifting weights, or playing certain sports (e.g., swimming or baseball) can lead to overuse injuries.
• Trauma or injury – A car accident, fall, or direct blow to the shoulder can cause inflammation and compression.
• Anatomical variations – Some people are born with an extra rib (called a cervical rib) or have tight muscles that can contribute to TOS.

Symptoms of TOS

Depending on whether nerves or blood vessels are affected and how, TOS types and symptoms may vary:

There are three types of thoracic outlet syndrome:

• Neurogenic TOS. This is the most common type of thoracic outlet syndrome. In this type, a group of nerves called the brachial plexus is compressed. The nerves of the brachial plexus come from the spinal cord. The nerves control muscle movements and feeling in the shoulder, arm and hand.
• Venous TOS. This type of thoracic outlet syndrome occurs when one or more of the veins under the collarbone are compressed and damaged. This can result in blood clots.
• Arterial TOS. This is the least common type of TOS. It occurs when one of the arteries under the collarbone is compressed. The compression may cause injury to the artery resulting in a bulge, known as an aneurysm, or blood clot formation.

TOS symptoms can vary between the types listed above. When nerves are compressed, symptoms of neurogenic thoracic outlet syndrome include:

• Numbness or tingling in the arm or fingers.
• Pain or aches in the neck, shoulder, arm or hand.
• Arm fatigue with activity.
• A weakening grip.

Symptoms of Venous TOS can include:

• A change in the color of the hand or one or more fingers.
• Hand or arm pain and swelling.

Symptoms of Arterial TOS can include:

• A pulsating lump near the collarbone.
• Cold fingers, hands or arms.
• Hand and arm pain.
• A change in color in one or more of the fingers or the entire hand.
• Weak or no pulse in the affected arm. 1

How Is TOS Diagnosed?

A healthcare provider will assess your symptoms, medical history, and posture. They may also perform physical exams, imaging tests (such as X-rays or MRIs), or nerve studies to confirm the diagnosis.

Treatment Options for TOS

Manual Therapy – Hands-on manipulation using osteopathic principles to realign the body and relieve pressure on nerves and blood vessels.

Physical therapy – Exercises to improve posture, strengthen muscles, and reduce compression.

Lifestyle changes – Improving posture, adjusting workstation ergonomics, and modifying activities that worsen symptoms.

Medication – Anti-inflammatory drugs or pain relievers may help manage symptoms.

Surgery (in severe cases) – If conservative treatments don’t work, surgery may be considered to relieve compression.

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1. Mayo Clinic. Thoracic Outlet Syndrome Overview. June 2025. Thoracic outlet syndrome – Symptoms and causes – Mayo Clinic

 

To discuss this or any other health concern you have, book an appointment with Jeffrey Russell at Abacus Chinese Medicine.