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Understanding Thoracic Outlet Syndrome: Causes, Symptoms, Diagnosis, and Treatment

A physical therapist assists a male patient with his shoulder exercises in a clinic. The therapist holds the patient's elbow to guide his arm movement. The background shows fitness equipment, colorful charts of feet, and foam rollers.

Thoracic Outlet Syndrome (TOS) is a multifaceted and often misunderstood medical condition that affects the nerves and blood vessels in the region between the neck and upper chest. Despite being relatively rare, TOS can cause significant discomfort and impairment in daily activities for those affected by it. There are different types of TOS:

  1. Neurogenic thoracic outlet syndrome is the most common of the three types and occurs when nerves that extend from the neck to the arm become compressed. 
  2. Venous thoracic outlet syndrome occurs when a vein is compressed, which can result in blood clots.
  3. Arterial thoracic outlet syndrome is the least common type of TOS and occurs when an artery becomes compressed.

Anatomy and Physiology of the Thoracic Outlet

To understand Thoracic Outlet Syndrome, it’s essential to grasp the anatomy of the thoracic outlet. The thoracic outlet is a critical anatomical region located between the base of the neck and the upper part of the chest. It is defined by a number of structures, both skeletal and soft tissue, that create a passageway for vital nerves and blood vessels. The structures passing through this space include the brachial plexus (a network of nerves), subclavian artery, and subclavian vein. Any compression or irritation of these structures within the thoracic outlet can lead to the development of Thoracic Outlet Syndrome. More in depth anatomy of the thoracic outlet can be understood in terms of its boundaries and the structures that pass through it:

  1. Interscalene Triangle: Bounded by the anterior and middle scalene muscles and the first rib. The brachial plexus and subclavian artery pass through this space.
  2. Costoclavicular Space: Between the clavicle and the first rib. Both the subclavian vein and artery, along with parts of the brachial plexus, pass through here.
  3. Subcoracoid Space (Pectoralis Minor Space): Under the coracoid process and the pectoralis minor muscle, through which the neurovascular bundle passes.

Thoracic Outlet Syndrome can arise from various factors, including:

1. Anatomical Variations: Some individuals may have anatomical abnormalities such as an extra rib (cervical rib), an enlarged first rib, or variations in muscle structure around the thoracic outlet. These variations can predispose individuals to compression of the nerves and blood vessels in the region.

2. Poor Posture: Activities that involve prolonged periods of holding the shoulders in a forward position, such as working on a computer, carrying heavy bags, or engaging in activities that strain the shoulder and neck muscles, can contribute to Thoracic Outlet Syndrome. Poor posture can lead to muscle imbalances and compression within the thoracic outlet.

3. Trauma: Injuries such as whiplash from motor vehicle accidents, falls, or fractures in the clavicle or first rib can cause inflammation and compression of the nerves and blood vessels in the thoracic outlet.

4. Repetitive Motion: Jobs or hobbies that involve repetitive movements of the arms or shoulders, such as typing, assembly line work, or playing certain sports, can increase the risk of developing Thoracic Outlet Syndrome. Repetitive motion can lead to muscle fatigue, inflammation, and compression of structures within the thoracic outlet.

5. Muscular Imbalances: Weakness or tightness in certain muscles, particularly those in the neck, shoulder, and chest region, can alter the position of the structures in the thoracic outlet, leading to compression. Imbalances in muscle strength and flexibility can result from poor posture, overuse injuries, or inadequate conditioning.

Symptoms of Thoracic Outlet Syndrome

The symptoms of Thoracic Outlet Syndrome can vary depending on which structures are being compressed, but commonly include:

1. Pain: Individuals with TOS may experience pain in the neck, shoulder, arm, or hand. The pain may be dull, aching, or sharp and may worsen with certain movements or activities.

2. Numbness and Tingling: Compression of nerves in the thoracic outlet can lead to sensations of numbness, tingling, or “pins and needles” in the affected arm, hand, or fingers. These sensations may occur intermittently or persistently.

3. Weakness: Some individuals with TOS may experience weakness or fatigue in the affected arm or hand, making it difficult to perform everyday tasks such as lifting objects or gripping items.

4. Coldness and Color Changes: Reduced blood flow to the arm and hand due to compression of blood vessels in the thoracic outlet can cause the affected limb to feel cold to the touch. Some individuals may also notice changes in skin color, such as pallor or blueness, particularly when the arm is elevated.

5. Swelling: In some cases, individuals with TOS may experience swelling or puffiness in the affected arm, hand, or fingers. Swelling may be more pronounced after activities that aggravate the condition or when the arm is held in certain positions.

Diagnosing Thoracic Outlet Syndrome can be challenging due to the diverse range of symptoms and potential contributing factors. A thorough medical history, physical examination, and diagnostic tests are typically required to confirm the diagnosis and identify the underlying cause of compression. These may include:

1. Medical History: Your healthcare provider will ask about your symptoms, medical history, occupation, hobbies, and any previous injuries or trauma to the neck, shoulder, or chest.

2. Physical Examination: A comprehensive physical examination will be conducted to assess your range of motion, muscle strength, sensation, and signs of compression in the thoracic outlet region. Specialized maneuvers such as Adson’s test, Wright’s test, and Roos test may be performed to reproduce symptoms and assess for nerve or vascular compression.

3. Imaging Studies: Imaging tests such as X-rays, magnetic resonance imaging (MRI), computed tomography (CT) scans, or ultrasound may be ordered to visualize the structures within the thoracic outlet and identify any anatomical abnormalities, bone spurs, or soft tissue masses that may be contributing to compression.

4. Nerve Conduction Studies (NCS) and Electromyography (EMG): These tests measure the electrical activity of nerves and muscles to evaluate nerve function and identify areas of nerve compression or damage. NCS and EMG can help differentiate between neurogenic (nerve-related) and vascular (blood vessel-related) forms of Thoracic Outlet Syndrome.

5. Vascular Studies: Doppler ultrasound or angiography may be performed to assess blood flow through the arteries and veins in the affected arm and identify any obstructions or abnormalities that may be causing symptoms.

Treatment of Thoracic Outlet Syndrome

A physical therapist assists a man with shoulder exercises in a well-lit, modern rehabilitation clinic. The man is seated and holding his shoulder, while the therapist gently supports his arm. Other patients and therapists are seen working in the background.

Treatment for Thoracic Outlet Syndrome aims to alleviate symptoms, improve function, and address the underlying cause of compression. Depending on the severity of symptoms and the underlying cause, treatment options may include:

1. Conservative Therapies:

Physical Therapy: A structured physical therapy program tailored to your individual needs can help improve posture, strengthen muscles, improve range of motion, and reduce compression on nerves and blood vessels in the thoracic outlet. Exercises may focus on stretching tight muscles, strengthening weak muscles, improving posture and body mechanics, and enhancing flexibility and coordination.

Manual Therapy: Hands-on techniques such as massage, myofascial release, joint mobilization, and soft tissue manipulation may be used to reduce muscle tension, improve circulation, and alleviate pain and stiffness in the neck, shoulder, and chest region.

Postural Training: Education on proper body mechanics, ergonomic principles, and techniques to maintain good posture during daily activities can help reduce strain on the muscles and joints in the thoracic outlet and prevent exacerbation of symptoms.

Activity Modification: Avoiding activities that aggravate symptoms or increase compression on the nerves and blood vessels in the thoracic outlet, such as carrying heavy bags on one shoulder, lifting heavy objects overhead, or engaging in repetitive motions, can help prevent further injury and promote healing.

Modalities: Modalities such as heat therapy, cold therapy, transcutaneous electrical nerve stimulation (TENS), ultrasound, or acupuncture may be used to relieve pain, reduce inflammation, improve circulation, and promote relaxation in the affected muscles and soft tissues.

Bracing or Taping: External supports such as braces, splints, or kinesiology tape may be used to provide stability, support, and alignment to the shoulder, neck, and chest region and reduce strain on the muscles and joints in the thoracic outlet.

2. Medications:

Medications may be prescribed aimed to reduce pain, inflammation, and swelling in the affected muscles and soft tissues, or to assist in alleviating muscle spasms, tension, and stiffness in the neck, shoulder, and chest region.

3. Minimally Invasive Procedures:

Corticosteroid Injections: Injections of corticosteroids such as cortisone into the affected muscles or soft tissues may be used to reduce inflammation, alleviate pain, and provide temporary relief of symptoms in individuals with Thoracic Outlet Syndrome.

Botulinum Toxin Injections: Injections of botulinum toxin (Botox) into specific muscles or trigger points may be used to relax overactive or hypertonic muscles in the neck, shoulder, and chest region and reduce compression on nerves and blood vessels in the thoracic outlet.

4. Surgical Intervention:

Thoracic Outlet Decompression Surgery: In severe cases of Thoracic Outlet Syndrome where conservative therapies fail to provide adequate relief of symptoms, surgical intervention may be considered to decompress the nerves and blood vessels in the thoracic outlet. During this procedure, the structures causing compression, such as an extra rib, fibrous bands, or abnormal muscles, may be removed or repositioned to relieve pressure and restore normal function.


Thoracic Outlet Syndrome is a complex medical condition that can manifest with a wide range of symptoms and affect individuals of all ages and backgrounds. Understanding the underlying causes, recognizing the signs and symptoms, and implementing appropriate treatment strategies are essential for effectively managing TOS and improving quality of life for those affected by it. If you experience persistent pain, numbness, weakness, or other symptoms in your neck, shoulder, arm, or hand, it’s important to seek prompt medical attention and evaluation by a healthcare professional experienced in the diagnosis and management of Thoracic Outlet Syndrome. With comprehensive treatment and rehabilitation, individuals with TOS can often achieve significant relief of symptoms, regain function, and return to their usual activities with improved comfort and mobility.

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Dr. John DeVries

Freedom Physical Therapy and Wellness

We help those frustrated with their current physical status get back to doing the things they enjoy.