Chapter 1: What Is Thoracic Outlet Syndrome?

The Human Spring Approach to Thoracic Outlet Syndrome

If you have headaches, neck pain, chronic neck pain, upper back pain, chronic upper back pain, shoulder pain, arm pain, arm numbness, hand numbness, tingling hands, tingling fingers, or weakness in the arm or hand, you might have thoracic outlet syndrome (TOS).

Some people who haven't been to a doctor for a proper thoracic outlet syndrome diagnosis call it by the slang terms office syndrome, computer syndrome, tech neck, text neck, cell phone syndrome, smartphone syndrome, or poor posture syndrome. After thoracic outlet syndrome has taken over their lives, they prefer to call it by its initials, TOS, for short.

The condition can be caused by compression of the brachial plexus nerves, subclavian artery, subclavian vein, or surrounding soft tissues in more than one area of the neck, thoracic outlet, upper back, rib cage, collarbone (clavicle), shoulder, and pectoralis minor region. That is why thoracic outlet syndrome produces such a wide variety of neurological and vascular symptoms.

Key Point

Thoracic outlet syndrome is not a disease—it is a mechanical compression problem. Thoracic outlet syndrome develops when the nerves or blood vessels passing through the thoracic outlet become compressed. As compression increases, symptoms increase. As compression is reduced and normal movement is restored, thoracic outlet syndrome symptoms often improve. Understanding and reversing this compression is the foundation of successful thoracic outlet syndrome treatment.

Why This Matters infographic explaining that thoracic outlet syndrome is a mechanical compression problem caused by muscle contractions triggered by inflammation from abnormal body mechanics.

What Is Thoracic Outlet Syndrome?

Thoracic outlet syndrome (TOS) is a condition that develops when the brachial plexus nerves, subclavian artery, or subclavian vein become compressed as they pass through the thoracic outlet, the narrow passageway connecting the neck and chest to the arm. This thoracic outlet compression interferes with the normal function of these nerves and blood vessels, producing the many symptoms associated with thoracic outlet syndrome, including neck pain, shoulder pain, arm pain, numbness, tingling, weakness, swelling, cold hands, and reduced movement.

Unlike many medical conditions that affect only a single muscle, joint, or nerve, thoracic outlet syndrome is a mechanical compression disorder involving an entire region of the body. The muscles, ribs, collarbone, connective tissues, nerves, and blood vessels must all work together to maintain an open thoracic outlet. When the available space within the thoracic outlet becomes smaller because of muscle tension, poor posture, injury, abnormal biomechanics, or repetitive movements, pressure is placed on the neurovascular bundle, resulting in nerve compression, vascular compression, or both.

The symptoms of thoracic outlet syndrome depend on which structure is being compressed. Brachial plexus compression typically produces numbness, tingling, burning pain, weakness, and loss of hand coordination. Subclavian artery compression reduces blood flow to the arm and hand, causing fatigue, coldness, color changes, and, in severe cases, tissue damage. Subclavian vein compression interferes with blood returning to the heart and may lead to swelling, heaviness, discoloration, or even blood clot formation in advanced cases of vascular thoracic outlet syndrome.

One of the reasons thoracic outlet syndrome is so frequently misunderstood is that its symptoms can resemble many other conditions, including carpal tunnel syndrome, cervical disc problems, rotator cuff injuries, tendon disorders, and other nerve compression syndromes. Because the symptoms vary depending on the location and severity of the thoracic outlet compression, many patients are treated for the wrong condition before the correct diagnosis is made.

Although the symptoms of thoracic outlet syndrome may appear unrelated, they all share the same underlying problem: compression within the thoracic outlet. Throughout this book, you will learn why this compression develops, why traditional treatments often fail to correct it completely, and how restoring the normal biomechanics of the thoracic outlet can reduce compression of the brachial plexus, subclavian artery, and subclavian vein. Once you understand the true mechanical cause of thoracic outlet syndrome, the examination, treatment, and prevention of this condition become far easier to understand and far more logical.

These atypical thoracic outlet syndrome symptoms are the result of persistent compression of the brachial plexus nerves, arteries, and veins traveling through the thoracic outlet and thoracic tunnel, along with abnormal biomechanics, muscle tension, and postural distortion that twist the structures responsible for keeping your neck, shoulders, upper back, and head functioning normally, resulting in chronic pain, nerve compression, reduced circulation, and restricted movement.

The Thoracic Outlet or Tunnel

The thoracic outlet, thoracic inlet, or thoracic compartment is a narrow anatomical passageway or tunnel located under the shoulder and above the first rib and rib cage, where the brachial plexus nerves, subclavian artery, and subclavian vein pass from the neck and chest into the arm and hand. I refer to the thoracic tunnel as the passageway where the brachial plexus, subclavian artery, and subclavian vein travel from the thoracic outlet over the first rib, beneath the collarbone (clavicle), beneath the pectoralis minor muscle, and into the arm.

Thoracic outlet syndrome (TOS) affects approximately 8 percent of the population, with women being approximately four times more likely to develop neurogenic thoracic outlet syndrome (NTOS), the most common type of thoracic outlet syndrome.

It is one of the most underrated, overlooked, underdiagnosed, misdiagnosed, and misunderstood compression disorders in medicine and remains one of the most difficult peripheral nerve compression syndromes to diagnose and manage. Medical professionals recognize that thoracic outlet syndrome is one of the most important peripheral nerve compression disorders of the upper extremity because it can mimic dozens of other conditions and frequently leads to misdiagnosis and inappropriate treatment (1).

Thoracic outlet syndrome (TOS) is one of the most controversial, misunderstood, misdiagnosed, and challenging conditions in medicine, largely because there is still no universal agreement regarding its cause, diagnosis, examination, classification, or optimal treatment. (1).

History

TOS was first described by Sir Ashley Cooper in 1821 (2). Then, in 1861, Richard Holmes Coote at St Bartholomew's Hospital in London, England, performed one of first surgical procedures, the removal (resection) of a cervical rib, for what came to be termed arterial TOS (3).

Thoracic outlet syndrome was coined in 1956 by R. M. Peet et al. to describe the impacts of compression of the blood vessels and nerves, called the neurovascular bundle in the thoracic outlet or tunnel (4).

The compression can be in one area or in a combination of three possible areas within the tunnel. I usually find the compression is in all three areas.

Compression may occur in several thoracic outlet and arm locations, affecting neck pain, back pain, posture, exercises, and recovery.

Unfortunately, this name has been used since then as a catchall to include myriad symptoms relating to compression at any point along the thoracic outlet passageway. Many doctors believe there should be sub names or titles relating to specific areas of compression to better describe the thoracic outlet syndrome patients have (5).

Thoracic outlet syndrome (TOS) has been called many names, as mentioned previously, including office syndrome, computer syndrome, office worker syndrome, tech neck syndrome, cell phone shoulder, text neck, mobile phone syndrome, smartphone syndrome, repetitive strain syndrome, and repetitive stress injury (RSI). Doctors have an even more confusing list of names for thoracic outlet syndrome, such as **thoracic outlet disorder, thoracic outlet compression syndrome, arterial TOS, arterial thoracic outlet syndrome, venous TOS, venous thoracic outlet syndrome (VTOS), neurogenic TOS, neurogenic thoracic outlet syndrome (NTOS), bilateral thoracic outlet syndrome, cervical rib syndrome, cervicobrachial neuralgia, compressive neuropathy, compression neuropathy, costoclavicular syndrome, disputed neurogenic thoracic outlet syndrome, double crush syndrome, triple crush syndrome, effort thrombosis, first rib syndrome, hyperabduction syndrome, inflammation of the brachial plexus, brachial plexus compression, neurogenic pectoralis minor syndrome (NPMS), pectoralis minor syndrome (PMS), neurological thoracic exit syndrome, Paget-Schroetter syndrome, peripheral nerve compression, scalenus anticus syndrome, spontaneous subclavian vein ("effort") thrombosis, subclavian vein compression, subclavian artery compression, subcoracoid brachial plexus compression, superior thoracic outlet syndrome, symptomatic thoracic outlet syndrome, thoracic outlet compression, thoracic outlet entrapment syndrome, vascular thoracic outlet syndrome, venous compression syndrome, and thoracic outlet vascular compression syndrome.

What I Learned from Lecturing to More Than 50,000 Doctors around the World.

I have been invited to give presentations to doctors and scientists about the human spring application to aging, sports, etc., at more than 50 medical conferences. I have lectured on the human spring approach to the earliest detection, intervention, and prevention of thoracic outlet syndrome at these fifteen medical conferences.

2019 – 5th Euro Global Physiotherapy, Physical Rehabilitation and Sports Medicine – Amsterdam, Netherlands – The Integrated Spring-Mass Approach to Thoracic Outlet Syndrome (Keynote Presentation)
2019 – 2nd International Conference on Orthopedics & Advanced Care – Singapore – The Integrated Spring-Mass Approach to Thoracic Outlet Syndrome (Keynote Presentation)
2018 – 2nd Global Congress on Medical & Clinical Case Reports – Dubai, United Arab Emirates – Case Report: A Patient with Thoracic Outlet Syndrome Who Was Misdiagnosed and Mismanaged: What Lessons Can Be Learned? (Keynote Presentation)
2018 – 2nd International Conference on Surgery and Medicine – Dubai, United Arab Emirates – Conservative Care Options for Patients with a Failed Thoracic Outlet Syndrome Surgery (Keynote Presentation)
2018 – 18th Global Neuroscience Conference – Tokyo, Japan – The Integrated Spring-Mass Model Approach to Treating Thoracic Outlet Syndrome (Keynote Presentation)
2018 – 4th International Conference on Sports Medicine – Edinburgh, Scotland – The Integrated Spring-Mass Model Approach to Treating Thoracic Outlet Syndrome (Keynote Presentation)
2018 – World Physical Medicine and Rehabilitation Conference – Istanbul, Turkey – The Integrated Spring-Mass Model Approach to Treating Thoracic Outlet Syndrome (Keynote Presentation)
2017 – 5th World Congress in Sports and Exercise Medicine (1-WCSEM 2017) – Kuala Lumpur, Malaysia – The Integrated Spring-Mass Model for the Earliest Detection, Intervention and Prevention of Thoracic Outlet Syndrome
2017 – 9th Annual A4M Thailand Congress on Anti-Aging and Aesthetic Medicine – Bangkok, Thailand – The Integrated Spring-Mass Model for the Earliest Detection, Intervention and Prevention of Thoracic Outlet Syndrome
2017 – 10th Annual Meeting of Orthopedicians – Kuala Lumpur, Malaysia – The Earliest Detection, Intervention and Prevention of Thoracic Outlet Syndrome (Keynote Presentation)
2016 – Seventh World Congress of Anti-Aging Medicine – Mexico City, Mexico – The Earliest Detection, Intervention and Prevention of Compression Syndromes, Thoracic Outlet Syndrome, Herniated Discs & Degenerative Joint Disease
2016 – Florida Chiropractic Physicians Association Conference – Florida, USA – The Earliest Detection, Intervention and Prevention of Thoracic Outlet Syndrome
2015 – World Congress in Sports and Exercise Medicine (1-WCSEM 2015) – Kuala Lumpur, Malaysia – The Earliest Detection, Intervention and Prevention of Thoracic Outlet Syndrome
2015 – World Congress in Sports and Exercise Medicine (1-WCSEM 2015) – Kuala Lumpur, Malaysia – Workshop: How to Examine and Treat Athletes with Thoracic Outlet Syndrome
2015 – Florida Chiropractic Physicians Association Conference – Florida, USA – The Earliest Detection, Intervention and Prevention of Thoracic Outlet Syndrome
2014 – Florida Chiropractic Physicians Association Conference – Florida, USA – The Earliest Detection, Intervention and Prevention of Thoracic Outlet Syndrome
2013 – Florida Chiropractic Association Continuing Education Seminar – Florida, USA – The Earliest Detection, Intervention and Prevention of Thoracic Outlet Syndrome
2005 – ICA Symposium on Natural Fitness – Arnold Classic – Columbus, Ohio, USA – Thoracic Outlet Syndrome: Diagnosis, Treatment and Prevention in Sports Medicine
2004 – 12th Annual World Congress on Anti-Aging Medicine – Las Vegas, Nevada, USA – The Most Effective Diagnosis, Treatment and Prevention of Thoracic Outlet Syndrome (TOS)

I have taught thousands of doctors the new Human Spring Approach and how it applies to thoracic outlet syndrome (TOS), neurogenic thoracic outlet syndrome, vascular thoracic outlet syndrome, thoracic outlet compression, and brachial plexus compression. I teach them new ways to diagnose thoracic outlet syndrome, perform a thoracic outlet syndrome examination, evaluate thoracic outlet anatomy and biomechanics, and treat it successfully with conservative, non-surgical thoracic outlet syndrome treatment without surgery. I also teach doctors how to prevent thoracic outlet syndrome, repetitive strain injuries, compression syndromes, and chronic musculoskeletal pain. I will never forget the lecture I gave at the Royal College of Surgeons in England.

What you might not realize is that most of these doctors don't understand the basic thoracic outlet anatomy, brachial plexus anatomy, musculoskeletal anatomy, biomechanics, functional biomechanics, or engineering of the thoracic outlet, thoracic tunnel, costoclavicular space, and neurovascular passageway.

You would think that with years of schooling, they would know human anatomy, clinical anatomy, musculoskeletal anatomy, and functional biomechanics down cold. Unfortunately, this is not the case. Multiple published anatomy education studies and medical education research prove it!

According to an article published in the Annals of The Royal College of Surgeons of England, author Ben Turney stated For 30 years, there has been a decrease in the undergraduate knowledge of anatomy in the surgical community (6) (7) (8) (9) (10) (11)

He goes on to say, "These studies report reductions in allocated time, teaching staff and dissection in most anatomy courses. It is very difficult to assess objectively whether this reduction in anatomy teaching has been excessive. However, the few studies that have been conducted suggest that the knowledge of the qualifying doctor is now below an acceptable level". (12–14).

Here is an example of how confusion with basic anatomy and thoracic outlet anatomy can lead to a huge problem for you. The usual thoracic outlet syndrome surgery approach is to remove three muscles: the anterior scalene muscle, the middle scalene muscle, and sometimes the pectoralis minor muscle. Because these muscles are contracting against the first rib, raising it into the thoracic outlet and causing thoracic outlet compression, they cut that too.

Here is an extremely important lesson in thoracic outlet anatomy, functional anatomy, and thoracic outlet syndrome biomechanics you will learn in later chapters:

There are three muscles (anterior scalene muscle, middle scalene muscle, posterior scalene muscle) that directly pull the first and second ribs into the thoracic outlet from the top, contributing to thoracic outlet compression, brachial plexus compression, and compression of the subclavian artery and subclavian vein.
There are six muscles (subclavius muscle, pectoralis minor muscle, biceps short head muscle, coracobrachialis muscle, lower trapezius, and latissimus dorsi muscle) that drag the shoulder girdle down into the thoracic outlet from below, contributing to compression of the thoracic outlet, thoracic tunnel, nerves, and blood vessels.
There is one muscle group (anterior neck muscles) that indirectly contributes to cervical compression, neck muscle tension, and the overall compression of the thoracic outlet.

That makes a total of nine muscles that directly contribute to thoracic outlet compression, brachial plexus compression, and compression of the neurovascular bundle, and one muscle group that indirectly contributes to compression of the thoracic outlet, for a total of 10 muscles that either directly or indirectly contribute to thoracic outlet syndrome, neurogenic thoracic outlet syndrome, and vascular thoracic outlet syndrome.

What if your doctor or therapist only focused on three muscles (the anterior scalene muscle, the middle scalene muscle, and the pectoralis minor muscle), thinking this was all that's needed to decompress the thoracic outlet, reduce brachial plexus compression, and restore normal function? Why do surgeons only surgically remove three muscles when, according to every anatomy book, there are nine muscles that directly compress the thoracic outlet?

Surgeons only remove these three muscles because if they cut out any more, you wouldn't be able to perform the simple activities of everyday life. This thoracic outlet syndrome surgery, including scalenectomy and pectoralis minor release, is limited because these muscles are essential for normal shoulder and neck function.

They know removing only these three muscles cannot completely decompress the thoracic outlet, eliminate nerve compression, restore the normal thoracic outlet anatomy, or fully relieve thoracic outlet syndrome symptoms. Therefore, they know they cannot bring you 100 percent pain relief, and they are not expecting you to become completely pain free after thoracic outlet syndrome surgery either.

You might wonder, If doctors don't understand the engineering and biomechanics of the thoracic outlet, how can I understand it? Don't worry. In Chapter 2, "A Painful Misunderstanding of Human Engineering," I will teach you, in simple terms, exactly how your body's remarkable Human Spring Approach, Integrated Spring-Mass Model, thoracic outlet biomechanics, and spring engineering work to maintain an open thoracic outlet and help prevent thoracic outlet syndrome.

This chapter has full-color, custom illustrations of the anatomy that are well demarcated. When you look at these illustrations, you're going to "get it."

Woman watches a lesson on thoracic outlet compression points in the shoulder, elbow, forearm, wrist, and hand for recovery.

In this book, I am going to teach you self-help massage techniques to self-treat all 10 muscles to ensure you get 100 percent of the pressure off your thoracic outlet. We need to learn about the anatomy and biomechanics in the next three chapters to understand how to do it.

The thoracic outlet is designed with spring engineering to allow for the safe passage of blood vessels and nerves through a series of three passageways, which I refer to as the thoracic tunnel.

Illustration of normal thoracic outlet anatomy for thoracic outlet syndrome according to Dr Stoxen's Human Spring Approach to Thoracic Outlet Syndrome.

The Three Thoracic Outlet Passageways (Thoracic Outlet Spaces)

The three thoracic outlet passageways (thoracic outlet spaces) are named—

Scalene triangle
Costoclavicular space
Subcoracoid space (pectoralis minor space)

Scalene Triangle

The scalene triangle is the first thoracic outlet passageway through which the brachial plexus and subclavian artery travel. It is formed by the anterior scalene muscle, making up the front of the triangle; the middle scalene muscle, making up the back of the triangle; and the first rib, which forms the foundation of the triangle. Compression within the scalene triangle is a common cause of neurogenic thoracic outlet syndrome (NTOS).

Costoclavicular Space

The costoclavicular space is the second thoracic outlet passageway through which the neurovascular bundle travels. It is formed by the first, second, and third ribs at the foundation; the anterior scalene muscle in the front; and the subclavius muscle and clavicle (collarbone) at the roof. Compression in this region may contribute to neurogenic thoracic outlet syndrome, venous thoracic outlet syndrome (VTOS), and arterial thoracic outlet syndrome (ATOS).

Subcoracoid Space (Pectoralis Minor Space)

The subcoracoid space, also called the pectoralis minor space, is the third thoracic outlet passageway through which the brachial plexus, subclavian artery, and subclavian vein must travel before entering the arm. The neurovascular bundle passes beneath the coracoid process at the roof, beneath the pectoralis minor muscle, and in front of the ribs. Compression in this region is commonly associated with pectoralis minor syndrome, a condition that closely mimics thoracic outlet syndrome.

Blood Vessels and Nerves Passing Through the Thoracic Outlet

The neurovascular bundle travels through these three thoracic outlet passageways and consists of the subclavian artery, subclavian vein, and the brachial plexus, a network of nerves that exits the cervical spine between the vertebrae of the neck. The term subclavian means "under the clavicle" or "under the collarbone."

The subclavian artery supplies oxygen-rich blood to the arm, forearm, and hand. If the artery becomes compressed by thoracic outlet syndrome, blood flow to the arm is reduced, limiting the delivery of oxygen and nutrients to the tissues. Symptoms may include arm weakness, arm fatigue, cold hands, pale skin, hand numbness, and, in severe cases, arterial thoracic outlet syndrome, blood clot formation (embolus), or limb-threatening loss of circulation.

The subclavian vein drains blood from the arm back to the heart. If the vein is compressed, blood cannot drain properly from the arm, resulting in arm swelling, hand swelling, venous congestion, and a feeling of heaviness. One arm or hand may appear noticeably larger than the other, and rings may become tight or no longer fit the fingers. Severe venous compression can lead to venous thoracic outlet syndrome, Paget-Schroetter syndrome (effort thrombosis), or a deep vein thrombosis (DVT).

The brachial plexus supplies sensation and muscle control to the shoulder, arm, forearm, and hand. If these nerves are compressed, patients may experience arm numbness, hand numbness, tingling, pins and needles (paresthesia), burning pain, shooting nerve pain, or a deep aching pain throughout the upper extremity. Symptoms commonly begin in the ring finger and little finger, reflecting involvement of the lower portion of the brachial plexus. As the first rib elevates and compression increases, the nerves higher within the plexus become affected, causing radiating numbness, tingling, or pain extending into the middle finger, index finger, and eventually the thumb.

If compression affects the deeper motor fibers of the brachial plexus, weakness of the arm and hand muscles may develop. Patients often report loss of grip strength, dropping objects, difficulty holding utensils or cups, difficulty opening jars, and reduced hand coordination. In advanced cases of neurogenic thoracic outlet syndrome, prolonged nerve compression can lead to muscle atrophy (muscle wasting) of the hand and permanent loss of strength if left untreated.

Woman joins Dr. Stoxen's live video Q&A to ask questions about thoracic outlet syndrome, neck pain, posture, exercises, and recovery.

What Is the Cause of Thoracic Outlet Syndrome?

The Mayo Clinic, the Cleveland Clinic, and the National Institute of Neurological Disorders and Stroke, plus the top-10 ranked hospitals for neurology and neurosurgery tell us that compression is what leads to thoracic outlet syndrome.

Mayo Clinic

Thoracic outlet syndrome is a group of disorders that occur when blood vessels or nerves in the space between your collarbone and your first rib (thoracic outlet) are compressed (15).

Cleveland Clinic

Thoracic outlet syndrome (TOS) is a term used to describe a group of disorders that occur when there is compression, injury, or irritation of the nerves and/or blood vessels (arteries and veins) in the lower neck and upper chest area (16).

National Institute of Neurological Disorders and Stroke (NINDS)

TOS is an umbrella term that encompasses three related syndromes that involve compression of the nerves, arteries, and veins in the lower neck and upper chest area and cause pain in the arm, shoulder, and neck.

Most doctors agree that TOS is caused by compression of the brachial plexus or subclavian vessels as they pass through narrow passageways leading from the base of the neck to the armpit and arm, but there is considerable disagreement about its diagnosis and treatment (17).

In Chapter 5, I agree that thoracic outlet syndrome (TOS) is caused by compression of the brachial plexus nerves, subclavian artery, and subclavian vein as they pass from the chest and neck through the thoracic outlet into the arm.

If your subclavian artery is compressed long enough, reducing blood flow and circulation to the arm and hand, you could end up losing your limb to amputation.

Warning card for swelling, discoloration, coldness, or severe pain that may need prompt medical evaluation for thoracic outlet symptoms.

If you have compression of the subclavian vein for too long or the compression becomes too severe, a blood clot (thrombus) could form and break free as an embolus, causing a pulmonary embolism in your lung. If you think you have a compressed vein or artery causing vascular thoracic outlet syndrome, you should seek prompt evaluation and treatment for your thoracic outlet syndrome.

If the cause of thoracic outlet syndrome is compression, why can't we reverse the compression in the head, neck, shoulder, and thoracic outlet area without surgery? Because most thoracic outlet syndrome treatment approaches used by doctors are ineffective at reducing the underlying cause of the compression. In fact, many healthcare providers still do not fully understand what causes the compression or how to effectively reverse it.

Four Types of Thoracic Outlet Syndrome

There are four types of thoracic outlet syndrome (TOS).

For practical purposes, if the thoracic outlet is compressed, the nerves and blood vessels passing through the neurovascular bundle are usually compressed to some degree. However, distinguishing which structure is most affected is particularly important for diagnosis and surgical decision-making.

Neurogenic thoracic outlet syndrome (Neurogenic TOS) — compression of the brachial plexus nerves within the neurovascular bundle.
Venous thoracic outlet syndrome (Venous TOS) — compression of the subclavian vein within the neurovascular bundle.
Arterial thoracic outlet syndrome (Arterial TOS) — compression of the subclavian artery within the neurovascular bundle.
Disputed thoracic outlet syndrome (Disputed TOS) — a patient has symptoms consistent with thoracic outlet syndrome, but the exact source of the nerve or vascular compression cannot be definitively identified using current diagnostic methods.

Now, what you really want to know is what causes thoracic outlet syndrome, what causes the compression of the brachial plexus, subclavian artery, and subclavian vein, and most importantly, how to reverse that compression naturally so you can find lasting thoracic outlet syndrome pain relief and recovery.

Your Bad Habit Can Predict the Area of Compression of the Thoracic Outlet.

A more useful classification of thoracic outlet syndrome I devised classifies the condition according to the cause of the compression.

Illustration of thoracic outlet syndrome showing the anterior scalene and middle scalene muscles with an elevated first rib in the interscalene triangle.

For example, if you spend a lot of time leaning back on the couch, reclining in the car with the seat back, leaning to the side at your desk, or maintaining poor posture during computer work, you are essentially dangling your 9–12-pound head from your scalene muscles. This sustained muscle tension can contribute to thoracic outlet syndrome (TOS) by increasing compression of the brachial plexus, subclavian artery, and subclavian vein. In this case, you will be more likely to have nerve and blood vessel compression within the interscalene triangle than within the costoclavicular space or subcoracoid (pectoralis minor) space. The illustration above demonstrates what is happening inside your neck and shoulder as these poor postural habits contribute to thoracic outlet compression, chronic neck pain, shoulder pain, arm numbness, hand tingling, and other thoracic outlet syndrome symptoms.

Illustration of the subpectoral space, costoclavicular space, and interscalene triangle in according to Dr Stoxen's Human Spring Approach to Thoracic Outlet Syndrome.

If you spend a lot of time working with your hands above your head, performing repetitive overhead work, working with the mouse and keyboard at the computer, using a computer workstation, and talking, texting, or looking down at your smartphone or other handheld devices, then you are more likely to develop thoracic outlet syndrome due to compression of the costoclavicular space, subcoracoid space, or thoracic outlet. These repetitive activities, poor posture, repetitive strain, and prolonged forward head posture can contribute to brachial plexus compression, subclavian artery compression, subclavian vein compression, nerve compression, blood vessel compression, and the development of neurogenic thoracic outlet syndrome or vascular thoracic outlet syndrome. The illustration above is an example of what would be occurring inside your chest, shoulder, neck, thoracic outlet, and arm as a result of these poor postural habits and repetitive activities.

Illustration of thoracic outlet syndrome showing contracted pectoralis minor, subclavius, coracobrachialis, and biceps short head narrowing the costoclavicular and subpectoral spaces.

If you lean while talking on the phone, texting, typing, browsing, working overhead, or after a motor vehicle accident, work injury, sports injury, whiplash injury, or repetitive strain injury, you might develop thoracic outlet syndrome (TOS) with compression occurring in all three areas, making your thoracic outlet syndrome symptoms, nerve compression, blood vessel compression, neck pain, shoulder pain, upper back pain, arm numbness, hand tingling, and thoracic outlet syndrome treatment more difficult and time-consuming to reverse. The illustration above is an example of what may be occurring inside your chest, thoracic outlet, shoulder, brachial plexus, and arm as a result of these poor posture habits, repetitive movements, and injury mechanisms.

Because I classify thoracic outlet syndrome this way, I know which area of thoracic outlet compression, brachial plexus compression, vascular compression, or musculoskeletal compression to concentrate on during thoracic outlet syndrome treatment, and you will know which poor posture habits, repetitive activities, ergonomic problems, and movement patterns to eliminate to help prevent your thoracic outlet syndrome symptoms from returning.

Other Symptoms of Thoracic Outlet Syndrome in the Surrounding Area

There are many more thoracic outlet syndrome symptoms associated with the syndrome than just those resulting from compression of the neurovascular bundle, brachial plexus compression, and subclavian artery and vein compression.

Because the muscle spasms twist your skull, neck, shoulders, upper back, and rib cage, they can cause headaches, neck pain, chronic neck pain, neck stiffness, stiff neck, upper back pain, shoulder pain, chest tightness, and even shortness of breath in some individuals with thoracic outlet syndrome.

There are also symptoms that result from muscle spasms twisting and compressing your neck and upper back, twisting and locking your ribs, depressing your shoulder girdle, and creating abnormal biomechanics, postural dysfunction, and musculoskeletal compression throughout the upper body.

As muscular compression of the neck, upper back, shoulders, and chest narrows the thoracic outlet and thoracic tunnel, you may initially experience numbness and tingling in the fingertips, hand tingling, arm numbness, and pins and needles sensations. As the compression progresses, you may develop hand weakness, loss of grip strength, difficulty gripping objects, dropping objects, and reduced hand function, which are common thoracic outlet syndrome symptoms, particularly in neurogenic thoracic outlet syndrome.

The symptoms may occur in one arm (unilateral thoracic outlet syndrome) or both arms (bilateral thoracic outlet syndrome). In fact, symptoms affecting both arms may increase the suspicion of thoracic outlet syndrome, making it easier to distinguish from many other conditions. If you experience numbness, tingling, or radiating pain in both upper extremities, bilateral thoracic outlet syndrome may be more likely than many of the less common neurological disorders or compression syndromes that produce symptoms in both arms.

In more advanced cases, you may develop muscle wasting (atrophy) of the hand and forearm, hand discoloration, cold fingers, cold hands, poor circulation, reduced blood flow, arm swelling, hand swelling, venous congestion, vascular thoracic outlet syndrome, blood clots (deep vein thrombosis), or even Paget-Schroetter syndrome (effort thrombosis) caused by severe subclavian vein compression. These advanced vascular thoracic outlet syndrome symptoms require prompt medical evaluation.

Neck Compression Symptoms

These symptoms of neck compression include stiff neck, chronic neck pain, neck stiffness, reduced neck mobility, cervicogenic headaches, tension headaches, and headaches (severe headaches are often misdiagnosed as a migraine headache), and even radiating pain, numbness, tingling, and nerve pain in the cheek, earlobe, shoulder, and outer arm. Patients can also have vertigo, dizziness, lightheadedness, balance problems, and cervical nerve compression symptoms.

Shoulder Compression Symptoms

These shoulder compression symptoms can be similar to rotator cuff syndrome, rotator cuff injury, rotator cuff tendinitis, or shoulder impingement syndrome, consisting of a stiff shoulder, painful shoulder, shoulder stiffness, shoulder weakness, shoulder instability, pain below the collarbone, and sharp, burning pain between the shoulder blades, upper back pain, scapular pain, and shoulder blade pain.

The upper back pain, upper shoulder pain, neck pain, and shoulder pain are most likely caused by an anterior, middle, and posterior scalene muscle spasm, yanking your first and second ribs up, twisting the rib joints where they attach at the breastbone and upper spine, leading to first rib dysfunction, rib joint irritation, thoracic outlet compression, and brachial plexus compression.
The mid-back pain, shoulder pain, pain between the shoulder blades, and scapular pain are most likely caused by a pectoralis minor muscle spasm, yanking the third, fourth, and fifth ribs up, causing pain between the shoulder blades, mid-upper back pain, chest tightness, and thoracic outlet compression.

Upper Back and Chest Compression Symptoms

These upper back and chest compression symptoms are related to the muscle imbalance, rib dysfunction, and postural misalignment caused by the muscles that attach to the ribs, causing compression of the rib cage, chest wall, and thoracic outlet.

The upper back pain, shoulder pain, neck pain, and chest pain are most likely caused by an anterior, middle, and posterior scalene muscle spasm, yanking your first and second ribs up, twisting the rib joints where they attach at the breastbone and upper spine, leading to thoracic outlet compression, nerve compression, and vascular compression.
The mid-back pain, shoulder pain, chest pain, and pain between the shoulder blades are most likely caused by a pectoralis minor muscle spasm, yanking the third, fourth, and fifth ribs up, causing mid-upper back pain, rib cage pain, chest tightness, and thoracic outlet syndrome symptoms. There are many other muscles that can spasm and compress the chest, leading to anything from tightness in the chest, chest pressure, chest discomfort, difficulty taking a deep breath, difficulty getting a full breath, shortness of breath, difficulty breathing, pain with breathing, and even crushing chest pain, making you feel like you are having a heart attack, angina, or cardiac chest pain.

Illustration of inflamed intercostal muscles associated with thoracic outlet syndrome and intercostal neuritis.

Nerve Compression Symptoms

In more advanced cases of neurogenic thoracic outlet syndrome (NTOS), hand weakness, finger weakness, and loss of hand dexterity can occur, along with a numb hand, numb arm, arm tingling, hand tingling, and other thoracic outlet syndrome symptoms caused by brachial plexus compression or nerve compression. As the condition progresses, there can be muscle weakness, muscle atrophy, decreased grip strength, and an inability to use the arm, without any findings in the neck to suggest paralysis.

Vein Compression Signs and Symptoms

If the shoulder, including the collarbone or other structures, compresses the thoracic outlet, causing subclavian vein compression or venous thoracic outlet syndrome (VTOS), you might notice arm swelling, hand swelling, swollen fingers, heaviness, discoloration, and discomfort in the arm and hand related to the swelling. Commonly, people notice their rings no longer fit because of swollen fingers or hand edema, which are classic vascular thoracic outlet syndrome symptoms.

Artery Compression Symptoms

If the shoulder and collarbone compress the artery, causing subclavian artery compression or arterial thoracic outlet syndrome (ATOS), you might experience cold hands, cold fingers, hand weakness, arm weakness, poor circulation, white skin (pallor), bluish discoloration (cyanosis), or pain with exercise. Patients suffering from arterial compression or vascular compression can have pain, numbness, tingling, and weakness distributed across the shoulder, arm, and hand that does not conform to the typical pinched nerve pattern. Your hand may feel cool to the touch and appear pale, white, bluish, or bright red because of reduced blood flow. Arterial thoracic outlet syndrome reduces blood flow to the arm, hand, and fingers, and symptoms often become worse in cold temperatures or during overhead activities.

Why Is Thoracic Outlet Syndrome So Difficult for Doctors to Diagnose and Manage?

Thoracic outlet syndrome (TOS) is notoriously difficult to diagnose, differentiate, and manage, both conservatively and surgically. According to the doctors who authored the Reporting Standards of the Society for Vascular Surgery for Thoracic Outlet Syndrome: Executive Summary, neurogenic thoracic outlet syndrome (NTOS) is particularly difficult to diagnose and manage because of:

Nonspecific thoracic outlet syndrome symptoms that mimic many other disorders.
Poorly understood pathophysiologic mechanisms and an incomplete understanding of the cause of thoracic outlet syndrome.
Limited accuracy and applicability of objective diagnostic tests for thoracic outlet syndrome.
Significant overlap with other musculoskeletal, neurological, and vascular disorders, making the differential diagnosis of thoracic outlet syndrome difficult.
The absence of well-defined, universally accepted, and consistently applied diagnostic criteria and treatment guidelines for thoracic outlet syndrome diagnosis and thoracic outlet syndrome treatment.

1. Thoracic outlet syndrome has nonspecific symptoms because of three reasons.

The muscles that cause thoracic outlet compression attach at the neck, shoulders, rib cage, chest, arms, and head. As a result, thoracic outlet syndrome symptoms can include neck pain, shoulder pain, upper back pain, chest pain, arm pain, headaches, numbness, tingling, weakness, and chronic pain in all of these areas.

Example 1: If there is a lot of tension in the anterior scalene, middle scalene, or posterior scalene muscles, because they attach at the cervical spine (neck) and the first and second ribs, you can have neck pain, cervical pain, upper back pain, shoulder pain, and rib pain from the muscles pulling on these structures. You can also experience arm numbness, hand numbness, tingling in the fingers, arm weakness, reduced grip strength, and neurogenic thoracic outlet syndrome symptoms when the scalene muscles elevate the first rib, causing compression of the brachial plexus, subclavian artery, or subclavian vein within the thoracic outlet.

Example 2: If there is a lot of tension in the pectoralis minor muscle, because it attaches to the coracoid process of the shoulder blade and the third, fourth, and fifth ribs, you can have front shoulder pain, chest pain, lower neck pain, and upper back pain as the shoulder is pulled downward. As the shoulder drops, it can compress the thoracic outlet, placing pressure on the subclavian artery and subclavian vein, leading to vascular thoracic outlet syndrome, arm swelling, hand swelling, blue discoloration (cyanosis), redness, paleness, cold hands, or changes in skin color caused by impaired blood flow. Compression of the brachial plexus may also produce arm numbness, tingling, burning pain, weakness, loss of coordination, and hand weakness. Because the pectoralis minor muscle also pulls on the ribs, it can alter rib cage biomechanics where the ribs attach both in the front and at the spine, contributing to shortness of breath, pain between the shoulder blades, chest pain, rib pain, difficulty taking a deep breath, and symptoms that may mimic angina or a heart attack.

2. Thoracic outlet syndrome has poorly understood pathophysiologic mechanisms (causes) and remains one of the most misunderstood compression disorders in medicine.

The committee of doctors had a difficult time determining the underlying cause of thoracic outlet syndrome (TOS), but what makes this easier to understand is that compression of the brachial plexus, subclavian artery, and/or subclavian vein is the defining cause of thoracic outlet syndrome. The only way these nerves and blood vessels can become compressed is when the surrounding muscles contract and create excessive muscle tension. Therefore, abnormal muscle tension, muscle tightness, and muscle spasm are the underlying causes of thoracic outlet syndrome compression. That is why the usual treatment approach has been scalene muscle surgery (scalenectomy) or first rib resection to surgically remove the muscles or structures believed to be causing the compression.

3. Thoracic outlet syndrome has limited applicability of objective diagnostic testing procedures.

Some doctors believe that if they cannot see a condition on a medical scan, it does not exist. They rely heavily on MRI, CT scans, X-rays, ultrasound imaging, nerve conduction studies (NCS), electromyography (EMG), vascular studies, and other diagnostic tests because imaging can make diagnosis easier. If they order a scan, they often rely less on performing a thorough physical examination for thoracic outlet syndrome, orthopedic testing, functional assessment, and clinical evaluation. I do not order a large number of diagnostic tests because, in most cases, thoracic outlet syndrome can be accurately diagnosed through a comprehensive history, detailed physical examination, and biomechanical assessment. Unless physicians are documenting injuries for legal cases, workers' compensation claims, or personal injury litigation, most patients with neurogenic thoracic outlet syndrome, venous thoracic outlet syndrome, or arterial thoracic outlet syndrome can be diagnosed accurately without extensive objective testing and can begin appropriate non-surgical thoracic outlet syndrome treatment promptly.

4. There is a potential overlap with other clinical disorders and compression syndromes.

It is true that there are often several compression syndromes occurring at the same time with thoracic outlet syndrome (TOS). Common overlapping conditions include carpal tunnel syndrome, cubital tunnel syndrome, cervical radiculopathy, rotator cuff injuries, shoulder impingement syndrome, brachial plexus compression, double crush syndrome, myofascial pain syndrome, cervical disc herniation, and thoracic outlet syndrome. If I suspect carpal tunnel syndrome, a rotator cuff strain, shoulder impingement syndrome, and thoracic outlet syndrome, I work on all of these conditions simultaneously because treating only one compression syndrome may fail to address the true cause of your chronic pain, arm numbness, hand tingling, shoulder pain, and neck pain.

5. There is an absence of well-defined, generally accepted, or consistently applied criteria for the diagnosis and treatment of thoracic outlet syndrome.

There are more than 10 diagnostic tests that doctors may order to help diagnose thoracic outlet syndrome (TOS), including MRI, CT scan, ultrasound, X-rays, electromyography (EMG), nerve conduction studies (NCS), vascular ultrasound, angiography, venography, and provocative orthopedic tests. However, experts acknowledge that no single diagnostic test is considered the gold standard for diagnosing thoracic outlet syndrome. While these tests may help identify nerve compression, blood vessel compression, or rule out other conditions, none of them can determine the underlying cause of thoracic outlet syndrome, explain why the thoracic outlet is compressed, or identify the biomechanical dysfunction responsible for the compression.

There were 16 different nonsurgical treatments for thoracic outlet syndrome discussed in the medical literature for treating thoracic outlet syndrome (TOS). Not one of these thoracic outlet syndrome treatment options, by itself, can effectively reverse the cause of the compression of the thoracic outlet. It takes a specific combination of conservative treatments, rehabilitation techniques, self-care strategies, and lifestyle recommendations to fully address the underlying cause of thoracic outlet syndrome. There are also specific criteria for each thoracic outlet syndrome treatment to ensure the thoracic outlet compression is corrected to maximum medical improvement, reducing the risk that the symptoms will return.

Examination and Treatment Are Based on a Flawed Model of Biomechanics

The success rate for nonsurgical thoracic outlet syndrome treatment, conservative treatment for thoracic outlet syndrome, and many physical therapy approaches for thoracic outlet syndrome is not as good as patients expect. There are many reasons why thoracic outlet syndrome treatment fails, which I will explain throughout this book.

What if I were to tell you that virtually all thoracic outlet syndrome treatments, examinations, rehabilitation programs, and recommendations made by doctors today are based on an outdated medical model of human biomechanics that attempts to explain how the body moves, absorbs impacts, recycles energy, and, most importantly, how it provides the safe passage of the brachial plexus, blood vessels, and nerves through the thoracic outlet?

After reading this book, you will understand why this 340-year-old lever model of biomechanics cannot fully explain thoracic outlet syndrome, compression syndromes, or many forms of chronic neck pain, shoulder pain, upper back pain, and nerve compression because it does not abide by the laws of physics or nature. In my opinion, when patients improve using many of the current standard-of-care treatments for thoracic outlet syndrome, the improvement is often temporary or coincidental rather than a true correction of the underlying cause.

If you do not know why you are suffering from thoracic outlet syndrome symptoms, chronic pain, or nerve compression, and your doctor does not fully understand the underlying cause either, it becomes easy to accept almost any explanation or diagnosis.

Knowing how commonly thoracic outlet syndrome is misdiagnosed, this is not a good strategy. You need to understand thoracic outlet anatomy, human biomechanics, and how your body truly works so you can make informed decisions about the best thoracic outlet syndrome treatment, conservative care, and recovery plan for you.

Don't worry—it's all here. After reading this book, you will understand more about thoracic outlet syndrome, human biomechanics, human movement, compression syndromes, how the body breaks down, and how the thoracic outlet compresses into a chronic state of pain and suffering than most healthcare professionals. You will also learn how to reduce thoracic outlet compression, restore normal movement, reverse these changes, and return to living an active, pain-free, and fully functional life.

Once you have read the next two chapters, I believe you will never allow another doctor to examine or treat your thoracic outlet syndrome, chronic neck pain, or compression-related condition the same way again.

Let's spring into the Human Spring chapter.

Educational graphic about thoracic outlet syndrome compression, posture, muscle tension, neck pain, and the Human Spring Approach to recovery.

Chapter progress 0%

Frequently Asked Questions

What is thoracic outlet syndrome?

Thoracic outlet syndrome (TOS) is a condition that occurs when the nerves, arteries, or veins passing through the thoracic outlet become compressed. The thoracic outlet is the narrow space between your neck and shoulder where the brachial plexus, subclavian artery, and subclavian vein travel from your chest into your arm.

Because thoracic outlet syndrome can compress nerves, blood vessels, or both, it can produce a wide variety of thoracic outlet syndrome symptoms, including neck pain, shoulder pain, upper back pain, arm pain, arm numbness, hand tingling, hand weakness, cold hands, or swelling. The exact symptoms depend on which structures are being compressed and how severe the compression has become.

There are three primary forms of thoracic outlet syndrome: neurogenic thoracic outlet syndrome, which affects the brachial plexus nerves; venous thoracic outlet syndrome, which affects the subclavian vein; and arterial thoracic outlet syndrome, which affects the subclavian artery. Although each type has unique features, they all result from abnormal compression within the thoracic outlet.

Throughout this book, you will learn what thoracic outlet syndrome is, why the compression develops, why it is frequently misdiagnosed, and how understanding the true cause of the compression is the foundation of successful thoracic outlet syndrome treatment and long-term recovery.

What is the thoracic outlet?

The thoracic outlet is the narrow passageway between your neck and shoulder where the major nerves and blood vessels travel from your chest into your arm. Understanding what the thoracic outlet is is essential because it is the area where thoracic outlet syndrome develops. The thoracic outlet contains the brachial plexus, which is the network of nerves supplying the shoulder, arm, and hand, along with the subclavian artery and subclavian vein, which provide blood flow to and from the arm. These important structures pass between the first rib, clavicle (collarbone), and surrounding muscles before entering the upper extremity.

When the space within the thoracic outlet becomes narrowed, the nerves or blood vessels can become compressed. This thoracic outlet compression may lead to thoracic outlet syndrome, causing symptoms such as neck pain, shoulder pain, upper back pain, arm numbness, hand tingling, weakness, cold hands, or swelling.

Throughout this book, you will gain a thorough understanding of thoracic outlet anatomy, why the thoracic outlet becomes compressed, and how restoring the normal mechanics of this region is the key to relieving compression and promoting long-term recovery from thoracic outlet syndrome.

What passes through the thoracic outlet?

The thoracic outlet serves as an important passageway for the major nerves and blood vessels that travel from your chest into your arm. Understanding what passes through the thoracic outlet is essential to understanding thoracic outlet syndrome. The three major structures that pass through the thoracic outlet are the brachial plexus, the subclavian artery, and the subclavian vein. The brachial plexus is a complex network of nerves that controls the muscles of your shoulder, arm, and hand while providing sensation to the skin.

The subclavian artery delivers oxygen-rich blood to the arm, and the subclavian vein returns oxygen-depleted blood back to the heart. When these nerves or blood vessels become compressed within the thoracic outlet, thoracic outlet syndrome may develop. Compression of the brachial plexus can cause neck pain, shoulder pain, arm numbness, hand tingling, weakness, and burning pain. Compression of the subclavian artery or subclavian vein can reduce blood flow, leading to cold hands, swelling, discoloration, or fatigue of the arm.

Throughout this book, you will learn what passes through the thoracic outlet, why these important structures become compressed, and how understanding thoracic outlet anatomy is the first step toward preventing nerve compression, vascular compression, and long-term recovery from thoracic outlet syndrome.

Why is it called thoracic outlet syndrome?

The name thoracic outlet syndrome comes from the location where the problem occurs—the thoracic outlet. The thoracic outlet is the narrow passageway between your neck and shoulder where the brachial plexus, subclavian artery, and subclavian vein travel from your chest into your arm. The word thoracic refers to the thorax, or chest. The word outlet describes the opening where these important nerves and blood vessels leave the chest and pass into the upper extremity.

The word syndrome means a collection of signs and symptoms that occur together. Therefore, thoracic outlet syndrome literally means a group of symptoms caused by compression of the nerves or blood vessels within the thoracic outlet.

When the thoracic outlet becomes narrowed, the brachial plexus, subclavian artery, or subclavian vein can become compressed. This thoracic outlet compression may produce neck pain, shoulder pain, arm numbness, hand tingling, weakness, swelling, or changes in circulation, depending on which structure is affected.

Throughout this book, you will learn why it is called thoracic outlet syndrome, how thoracic outlet anatomy is designed to protect these important structures, why compression develops, and how understanding the true mechanics of the thoracic outlet is the foundation for lasting recovery.

Why is thoracic outlet syndrome considered controversial?

Thoracic outlet syndrome is considered controversial because many healthcare professionals disagree about how it should be diagnosed, what causes it, and which thoracic outlet syndrome treatment is most effective. As a result, patients with thoracic outlet syndrome are frequently misdiagnosed, underdiagnosed, overdiagnosed, or treated for the wrong condition.

One reason thoracic outlet syndrome remains controversial is that its symptoms often resemble many other disorders, including herniated discs, cervical radiculopathy, carpal tunnel syndrome, rotator cuff injuries, and other causes of nerve compression. Because there is no single test that can reliably confirm every case of thoracic outlet syndrome, making an accurate thoracic outlet syndrome diagnosis requires a thorough history, physical examination, and a detailed understanding of thoracic outlet anatomy.

Another reason thoracic outlet syndrome is controversial is that many treatment approaches focus on relieving symptoms rather than identifying and correcting the underlying cause of the compression. This leads to inconsistent results, making some clinicians question the diagnosis while others question the treatment.

Throughout this book, you will learn why thoracic outlet syndrome has become controversial, why so many patients receive conflicting opinions, and why understanding the true biomechanics of the thoracic outlet provides a more logical explanation for the condition and its successful treatment.

Is thoracic outlet syndrome dangerous?

In most patients, thoracic outlet syndrome is not immediately life-threatening, but it should never be ignored. Whether thoracic outlet syndrome is dangerous depends on which nerves or blood vessels are being compressed and how severe the compression has become.

The most common form, neurogenic thoracic outlet syndrome, primarily affects the brachial plexus nerves and may cause chronic neck pain, shoulder pain, arm numbness, hand tingling, weakness, and loss of function. Although these thoracic outlet syndrome symptoms are usually not life-threatening, they can become disabling if left untreated.

The vascular forms of thoracic outlet syndrome can be much more serious. Venous thoracic outlet syndrome may lead to Paget-Schroetter syndrome, a blood clot in the subclavian vein that can become a medical emergency. Arterial thoracic outlet syndrome may reduce blood flow to the arm, increasing the risk of tissue damage, aneurysm formation, or blood clots.

Throughout this book, you will learn when thoracic outlet syndrome is dangerous, how to recognize the warning signs of serious vascular compression, and why early diagnosis and appropriate treatment are essential to preventing long-term complications and achieving lasting recovery.

How common is thoracic outlet syndrome?

The honest answer is that no one knows exactly how common thoracic outlet syndrome really is because it is one of the most underdiagnosed and misdiagnosed conditions in medicine. Many people with thoracic outlet syndrome are mistakenly diagnosed with herniated discs, cervical radiculopathy, carpal tunnel syndrome, rotator cuff injuries, fibromyalgia, or other causes of neck and arm pain.

Although reported estimates vary widely, hundreds of thousands of people are diagnosed with thoracic outlet syndrome each year, and millions more experience thoracic outlet syndrome symptoms without ever receiving the correct diagnosis. In fact, millions of people search online every year for answers about neck pain, shoulder pain, arm numbness, hand tingling, and thoracic outlet syndrome because they have been unable to find lasting relief.

One reason it is difficult to determine how common thoracic outlet syndrome really is is that many healthcare providers disagree on the diagnostic criteria. As a result, some cases are missed entirely, while others are incorrectly labeled as different conditions.

Throughout this book, you will discover why thoracic outlet syndrome is probably much more common than most people realize, why it is so frequently overlooked, and how understanding the true cause of the compression can lead to a more accurate diagnosis and more effective treatment.

What are the four types of thoracic outlet syndrome?

The four types of thoracic outlet syndrome are classified according to which nerves or blood vessels are being compressed. Understanding the four types of thoracic outlet syndrome helps doctors determine the cause of your symptoms and select the most appropriate treatment.

The first and most common type is neurogenic thoracic outlet syndrome (NTOS). This occurs when the brachial plexus nerves become compressed, producing neck pain, shoulder pain, arm numbness, hand tingling, weakness, and loss of function.

The second type is venous thoracic outlet syndrome (VTOS). This develops when the subclavian vein is compressed, reducing blood flow from the arm back to the heart. Symptoms may include arm swelling, heaviness, bluish discoloration, and, in severe cases, blood clot formation known as Paget-Schroetter syndrome.

The third type is arterial thoracic outlet syndrome (ATOS). This occurs when the subclavian artery is compressed, reducing blood flow into the arm. Patients may experience cold hands, decreased circulation, pain with activity, weakness, or changes in skin color.

The fourth type is pectoralis minor syndrome (PMS). In this condition, the nerves and blood vessels are compressed beneath the pectoralis minor muscle rather than higher in the thoracic outlet. Because the symptoms often resemble thoracic outlet syndrome, pectoralis minor syndrome is frequently overlooked or occurs together with one of the other three types.

Throughout this book, you will learn how to recognize the four types of thoracic outlet syndrome, understand why each develops, and discover why identifying the exact location of the compression is essential for successful treatment and long-term recovery.

What are the symptoms of thoracic outlet syndrome?

The symptoms of thoracic outlet syndrome vary from person to person because the condition can compress nerves, arteries, veins, or a combination of these structures. The most common thoracic outlet syndrome symptoms include neck pain, shoulder pain, upper back pain, arm pain, arm numbness, hand tingling, hand weakness, burning pain, aching, fatigue, and loss of grip strength.

When neurogenic thoracic outlet syndrome compresses the brachial plexus nerves, patients commonly experience numbness, tingling, weakness, muscle fatigue, clumsiness, and pain that may travel from the neck into the shoulder, arm, and hand. These thoracic outlet syndrome symptoms often become worse with overhead activities, repetitive arm movements, poor posture, or prolonged sitting.

When vascular thoracic outlet syndrome affects the subclavian artery or subclavian vein, symptoms may include cold hands, swelling, discoloration, heaviness, reduced circulation, or arm fatigue during activity. These vascular thoracic outlet syndrome symptoms are less common but may require prompt medical evaluation.

Throughout this book, you will learn what the symptoms of thoracic outlet syndrome are, why they develop, why they often change from day to day, and how understanding the true cause of the compression is the first step toward an accurate diagnosis and lasting recovery.

Why is thoracic outlet syndrome so difficult to diagnose?

Thoracic outlet syndrome is difficult to diagnose because its symptoms closely resemble many other conditions, including herniated discs, cervical radiculopathy, carpal tunnel syndrome, cubital tunnel syndrome, rotator cuff injuries, and other causes of nerve compression. Many patients with thoracic outlet syndrome receive several different diagnoses before the correct one is finally identified.

Another reason thoracic outlet syndrome is difficult to diagnose is that there is no single MRI, X-ray, blood test, or nerve test that can accurately diagnose every patient. An accurate thoracic outlet syndrome diagnosis depends on a detailed medical history, a thorough thoracic outlet examination, an understanding of thoracic outlet anatomy, and determining exactly what structure is being compressed and why. Many examinations focus on identifying the symptoms rather than identifying the mechanical cause of the compression. Without understanding the biomechanics of the thoracic outlet, it is easy to overlook the true source of the patient's pain, numbness, weakness, or circulation problems.

Throughout this book, you will learn why thoracic outlet syndrome is so difficult to diagnose, why so many patients are misdiagnosed, and how a logical understanding of anatomy, biomechanics, and the Human Spring model can lead to a more accurate diagnosis and a more effective treatment plan.

Is thoracic outlet syndrome a neurological disorder?

The answer depends on which type of thoracic outlet syndrome you have. The most common form, neurogenic thoracic outlet syndrome (NTOS), is considered a neurological disorder because it involves compression of the brachial plexus, the network of nerves that supplies the shoulder, arm, and hand.

When these nerves become compressed within the thoracic outlet, patients may develop thoracic outlet syndrome symptoms such as neck pain, shoulder pain, arm numbness, hand tingling, weakness, burning pain, loss of grip strength, and muscle fatigue. These neurological symptoms occur because the nerves cannot properly transmit signals between the brain and the arm.

However, thoracic outlet syndrome is more than just a neurological disorder. The condition may also involve vascular thoracic outlet syndrome, in which the subclavian artery or subclavian vein becomes compressed, leading to reduced circulation, swelling, cold hands, discoloration, or blood clots. In many patients, both nerve and blood vessel compression occur together. Throughout this book, you will learn why thoracic outlet syndrome is best understood as a compression disorder rather than simply a neurological disorder.

By understanding the anatomy and biomechanics of the thoracic outlet, you will better understand why these neurological and vascular symptoms develop and how addressing the underlying compression is the key to lasting recovery.

What is vascular thoracic outlet syndrome?

Vascular thoracic outlet syndrome is a form of thoracic outlet syndrome in which one or more blood vessels passing through the thoracic outlet become compressed. Unlike neurogenic thoracic outlet syndrome, which affects the nerves of the brachial plexus, vascular thoracic outlet syndrome involves compression of the subclavian artery, the subclavian vein, or both.

There are two main types of vascular thoracic outlet syndrome. Venous thoracic outlet syndrome (VTOS) occurs when the subclavian vein is compressed, which may cause arm swelling, heaviness, bluish discoloration, and, in severe cases, a blood clot known as Paget-Schroetter syndrome. Arterial thoracic outlet syndrome (ATOS) occurs when the subclavian artery is compressed, reducing blood flow to the arm and causing cold hands, pain, weakness, fatigue, or changes in skin color. Although vascular thoracic outlet syndrome is less common than neurogenic thoracic outlet syndrome, it can be more serious because prolonged thoracic outlet compression of the blood vessels may lead to permanent vascular damage or other complications if left untreated.

Throughout this book, you will learn what vascular thoracic outlet syndrome is, why vascular thoracic outlet syndrome develops, how to recognize its warning signs, and why identifying the exact location and cause of the compression is essential for effective treatment and long-term recovery.

Why is thoracic outlet syndrome so painful?

Thoracic outlet syndrome is painful because it can compress sensitive nerves, blood vessels, muscles, and other soft tissues within the thoracic outlet. As the compression increases, the surrounding tissues become irritated and inflamed, producing many of the familiar thoracic outlet syndrome symptoms.

The most common source of pain is compression of the brachial plexus, the network of nerves that supplies the shoulder, arm, and hand. When these nerves are compressed or stretched, they can produce neck pain, shoulder pain, upper back pain, arm pain, burning sensations, numbness, hand tingling, weakness, and pain that may radiate into the fingers. At the same time, the surrounding muscles often tighten in an attempt to protect the injured area, creating muscle spasms that further increase the compression and pain. As the compression continues, reduced circulation and ongoing inflammation may make the tissues even more sensitive.

This is one reason thoracic outlet syndrome often becomes a chronic condition if the underlying cause of the compression is not corrected.

Throughout this book, you will learn why thoracic outlet syndrome is so painful, why simply treating the pain is rarely enough, and how restoring the normal mechanics of the Human Spring can reduce the compression responsible for your thoracic outlet syndrome symptoms and support lasting recovery.

What are the long-term effects of thoracic outlet syndrome?

The long-term effects of thoracic outlet syndrome depend on which nerves or blood vessels are compressed, how severe the compression is, and how long it has been present. When thoracic outlet syndrome is left untreated, the condition may progress from occasional discomfort to chronic pain, weakness, and loss of function. Long-term thoracic outlet syndrome may lead to persistent neck pain, shoulder pain, upper back pain, arm numbness, hand tingling, muscle fatigue, and reduced grip strength. Prolonged brachial plexus compression can result in chronic nerve irritation, muscle weakness, poor coordination, and, in severe cases, muscle wasting (atrophy).

These long-term effects of thoracic outlet syndrome can interfere with work, sports, sleep, and many everyday activities. In patients with vascular thoracic outlet syndrome, prolonged compression of the subclavian artery or subclavian vein may lead to reduced circulation, blood clots, damage to the blood vessels, or other serious vascular complications if not recognized and treated promptly.

Throughout this book, you will learn what the long-term effects of thoracic outlet syndrome are, why these complications develop, and why early diagnosis, correcting the underlying compression, and restoring normal biomechanics provide the best opportunity to prevent permanent damage and achieve lasting recovery.

Can thoracic outlet syndrome cause permanent damage?

The answer is yes. Thoracic outlet syndrome can cause permanent damage if the compression of the nerves or blood vessels is severe or continues for a prolonged period without appropriate treatment. The risk depends on which structures are compressed, how severe the compression is, and how quickly the underlying problem is identified.

When thoracic outlet syndrome compresses the brachial plexus for an extended period, chronic nerve compression may lead to persistent pain, muscle weakness, loss of sensation, poor coordination, and, in severe cases, permanent muscle wasting (atrophy). The longer the nerves remain compressed, the greater the risk that some neurological deficits may not fully recover.

In vascular thoracic outlet syndrome, prolonged compression of the subclavian artery or subclavian vein may reduce blood flow, damage the blood vessels, or lead to blood clots such as Paget-Schroetter syndrome. These complications may become serious if they are not recognized and treated promptly. The encouraging news is that many patients recover well when thoracic outlet syndrome is diagnosed early and the underlying cause of the compression is corrected before permanent injury develops.

Throughout this book, you will learn how early recognition, accurate diagnosis, and restoring normal biomechanics can help reduce the risk of permanent damage and improve your chances for long-term recovery.

What are the complications of thoracic outlet syndrome?

The complications of thoracic outlet syndrome depend on whether the condition compresses the nerves, arteries, veins, or a combination of these structures. When thoracic outlet syndrome is left untreated, the complications may gradually become more serious and more difficult to reverse. Common complications of thoracic outlet syndrome include chronic neck pain, shoulder pain, upper back pain, arm numbness, hand tingling, muscle weakness, loss of grip strength, reduced coordination, and muscle wasting (atrophy) caused by prolonged brachial plexus compression. Persistent nerve compression may also lead to chronic pain and reduced function that interfere with work, sports, and everyday activities.

The vascular complications of thoracic outlet syndrome may be even more serious. Compression of the subclavian vein can lead to blood clots, including Paget-Schroetter syndrome, while compression of the subclavian artery may reduce blood flow to the arm, causing coldness, discoloration, tissue damage, or aneurysm formation. These vascular complications require prompt medical evaluation.

Throughout this book, you will learn what the complications of thoracic outlet syndrome are, why they develop, and how identifying and correcting the underlying compression early offers the best opportunity to prevent permanent damage and achieve lasting recovery.

What nerve root is affected in thoracic outlet syndrome?

Unlike a herniated disc, which usually compresses a single spinal nerve root, thoracic outlet syndrome most commonly compresses the brachial plexus, a network of nerves formed by the C5, C6, C7, C8, and T1 nerve roots. Therefore, thoracic outlet syndrome does not usually involve just one nerve root but rather multiple nerves that have already joined together to form the brachial plexus.

Although any part of the brachial plexus may be affected, the lower trunk, which is primarily formed by the C8 and T1 nerve roots, is most commonly involved in neurogenic thoracic outlet syndrome. Compression of these nerves may produce thoracic outlet syndrome symptoms such as arm numbness, hand tingling, weakness, loss of grip strength, and pain that radiates into the ring finger and little finger. Understanding what nerve root is affected in thoracic outlet syndrome is important because the symptoms can closely resemble cervical radiculopathy, where a single cervical nerve root is compressed by a herniated disc or bone spur. Distinguishing between thoracic outlet syndrome and cervical radiculopathy is one of the most important parts of making an accurate diagnosis.

Throughout this book, you will learn what nerve roots are affected in thoracic outlet syndrome, how the brachial plexus functions, and why identifying the exact location of the compression is essential for choosing the correct treatment.

Which fingers go numb in thoracic outlet syndrome?

The fingers affected by thoracic outlet syndrome depend on which part of the brachial plexus is being compressed. In most patients with neurogenic thoracic outlet syndrome, the ring finger and little finger are most commonly affected because the C8 and T1 nerve fibers are frequently involved.

However, numbness may also spread into the forearm, hand, or even involve all the fingers in some patients. Many people with thoracic outlet syndrome experience more than numbness. Thoracic outlet syndrome symptoms may include hand tingling, burning pain, weakness, loss of grip strength, clumsiness, or the sensation that the entire arm has "fallen asleep." These symptoms often become worse with overhead activities, prolonged computer use, carrying heavy objects, or poor posture.

Although numbness of the ring and little fingers is common in thoracic outlet syndrome, similar symptoms can also occur with cubital tunnel syndrome, ulnar nerve entrapment, or cervical radiculopathy. That is why an accurate examination is essential to determine exactly where the nerve is being compressed.

Throughout this book, you will learn which fingers go numb in thoracic outlet syndrome, why these symptoms develop, and how understanding the anatomy of the brachial plexus helps distinguish thoracic outlet syndrome from other nerve compression disorders.

Can thoracic outlet syndrome affect circulation?

Yes. Thoracic outlet syndrome can affect circulation when the subclavian artery, subclavian vein, or both become compressed as they pass through the thoracic outlet. This form of the condition is known as vascular thoracic outlet syndrome.

When thoracic outlet syndrome affects circulation, blood flow into or out of the arm may become restricted. Reduced arterial blood flow can cause cold hands, pale skin, fatigue, pain with activity, or weakness. Reduced venous blood flow may cause arm swelling, heaviness, bluish discoloration, enlarged surface veins, or, in severe cases, the formation of a blood clot known as Paget-Schroetter syndrome. Even patients with neurogenic thoracic outlet syndrome may notice changes in circulation because muscle tightness and nerve irritation can alter blood vessel function.

However, persistent coldness, discoloration, swelling, or sudden changes in circulation should always be evaluated promptly by a qualified healthcare professional.

Throughout this book, you will learn how thoracic outlet syndrome affects circulation, why vascular thoracic outlet syndrome develops, and how restoring normal biomechanics may help reduce compression of the nerves and blood vessels that pass through the thoracic outlet.

Can thoracic outlet syndrome affect breathing?

Yes. Thoracic outlet syndrome can affect breathing in some patients, although breathing difficulties are usually an indirect result of muscle dysfunction rather than compression of the lungs themselves. The muscles surrounding the thoracic outlet, particularly the scalene muscles and pectoralis minor, play important roles in both posture and breathing.

When these muscles become chronically tight because of thoracic outlet syndrome, they can restrict normal movement of the neck, upper ribs, and chest. As a result, some patients experience chest tightness, difficulty taking a deep breath, or the sensation that they cannot fully expand their lungs. These thoracic outlet syndrome symptoms often become more noticeable during exercise, periods of stress, or prolonged poor posture. In addition, chronic pain, muscle guarding, and altered breathing patterns may cause patients to rely excessively on the neck muscles instead of the diaphragm, making breathing feel more difficult and less efficient.

Although thoracic outlet syndrome does not directly damage the lungs, it can significantly affect normal breathing mechanics.

Throughout this book, you will learn how thoracic outlet syndrome affects breathing, why restoring normal posture and biomechanics improves chest expansion, and how reducing compression within the thoracic outlet may help improve both breathing and overall function.

Can thoracic outlet syndrome affect the heart?

Thoracic outlet syndrome does not directly affect the heart itself. However, thoracic outlet syndrome can produce symptoms that closely resemble a heart problem, including chest pain, chest tightness, shoulder pain, arm pain, and discomfort that radiates into the neck or upper back.

Because these thoracic outlet syndrome symptoms can mimic heart disease, they should never be ignored. In thoracic outlet syndrome, the pain usually results from compression of the brachial plexus, surrounding muscles, or the blood vessels passing through the thoracic outlet, rather than from disease of the heart muscle or coronary arteries. Some patients with vascular thoracic outlet syndrome may also experience changes in circulation affecting the arm because of compression of the subclavian artery or subclavian vein, but this is different from heart disease.

Although thoracic outlet syndrome is not a heart disorder, anyone experiencing new chest pain, severe shortness of breath, pain spreading into the jaw or left arm, dizziness, fainting, or other symptoms suggestive of a heart attack should seek immediate emergency medical evaluation. Heart disease must always be ruled out before attributing chest pain to thoracic outlet syndrome.

Throughout this book, you will learn how thoracic outlet syndrome can mimic heart-related symptoms, why this occurs, and how a thorough examination can help distinguish thoracic outlet syndrome from cardiac conditions.

Can thoracic outlet syndrome affect the brain?

Thoracic outlet syndrome does not directly affect the brain because it primarily involves compression of the nerves and blood vessels passing through the thoracic outlet into the arm. However, many people with thoracic outlet syndrome report headaches, dizziness, difficulty concentrating, memory problems, "brain fog," fatigue, anxiety, and depression. Some of these symptoms develop because chronic pain, poor sleep, muscle tension, altered breathing mechanics, and the emotional stress of living with persistent pain affect how the brain functions. In addition, chronic thoracic outlet syndrome often produces ongoing inflammation.

As inflammatory chemicals such as interleukin-1 (IL-1), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and interferon-gamma (IFN-γ) increase, they activate an enzyme called indoleamine 2,3-dioxygenase (IDO). This enzyme diverts the amino acid tryptophan away from serotonin production and into the kynurenine pathway. As kynurenine and its downstream metabolites increase, serotonin production may decrease while inflammatory compounds affecting the brain increase. Researchers believe this process may contribute to brain fog, fatigue, anxiety, depression, reduced motivation, and the "sickness syndrome" commonly seen in people living with chronic inflammatory conditions.

While thoracic outlet syndrome does not directly damage the brain, the chronic inflammation associated with persistent pain may indirectly influence brain chemistry and emotional well-being. It is important to remember that thoracic outlet syndrome is not a brain disease. Persistent confusion, one-sided weakness, difficulty speaking, sudden vision loss, or symptoms suggestive of a stroke require immediate emergency medical attention and should never be attributed to thoracic outlet syndrome without proper evaluation.

Throughout this book, you will learn how thoracic outlet syndrome can affect the brain indirectly, why chronic inflammation influences the kynurenine pathway, and how reducing inflammation, restoring healthy biomechanics, and relieving compression may improve not only pain but also mental clarity, mood, and overall quality of life.

Can thoracic outlet syndrome cause swollen hands?

Yes. Thoracic outlet syndrome can cause swollen hands when compression within the thoracic outlet interferes with normal blood flow returning from the arm to the heart.

Although not every patient experiences hand swelling, swollen hands are a common symptom of venous thoracic outlet syndrome. When the subclavian vein becomes compressed, blood cannot drain normally from the arm and hand. This reduced venous return may cause swollen hands, swollen fingers, a feeling of heaviness, bluish discoloration, enlarged surface veins, or tightness in the affected arm. In more severe cases, prolonged compression of the subclavian vein may lead to a blood clot known as Paget-Schroetter syndrome, which requires prompt medical evaluation.

Even patients with neurogenic thoracic outlet syndrome occasionally notice mild hand swelling because chronic muscle tension, inflammation, and altered circulation can affect the tissues surrounding the thoracic outlet. However, sudden or severe swollen hands, especially when accompanied by pain, discoloration, or rapid enlargement of the arm, should always be evaluated immediately to rule out a vascular emergency.

Throughout this book, you will learn why thoracic outlet syndrome can cause swollen hands, how vascular thoracic outlet syndrome affects circulation, and why identifying the exact location of the compression is essential for choosing the most effective treatment and achieving long-term recovery.

What is TOS syndrome?

TOS syndrome, short for thoracic outlet syndrome, is a condition in which the brachial plexus nerves, subclavian artery, or subclavian vein become compressed as they pass through the thoracic outlet between the neck and shoulder. Thoracic outlet syndrome can cause neck pain, shoulder pain, arm numbness, hand tingling, weakness, swelling, and other thoracic outlet syndrome symptoms, depending on which structures are compressed.

Throughout this book, you will learn what TOS syndrome is, why it develops, and how understanding the true cause of the compression is the key to accurate diagnosis and lasting recovery.

What is the definition of thoracic outlet syndrome?

Thoracic outlet syndrome (TOS) is a compression disorder in which the brachial plexus nerves, subclavian artery, or subclavian vein become compressed as they pass through the thoracic outlet between the neck and shoulder. This compression can produce thoracic outlet syndrome symptoms such as neck pain, shoulder pain, arm numbness, hand tingling, weakness, swelling, and changes in circulation.

Throughout this book, you will learn why thoracic outlet syndrome develops, how it is diagnosed, and how correcting the underlying compression is the key to long-term recovery.

What is thoracic inlet syndrome?

Thoracic inlet syndrome is another name that some healthcare professionals use for thoracic outlet syndrome (TOS) because the nerves and blood vessels are actually entering the upper extremity through this region rather than leaving the chest. Regardless of the name, thoracic inlet syndrome refers to compression of the brachial plexus, subclavian artery, or subclavian vein as they pass between the neck and shoulder.

Throughout this book, I use the more widely recognized term thoracic outlet syndrome, which is the accepted medical name for this condition.

What is thoracic inlet and outlet syndrome?

Thoracic inlet and outlet syndrome refers to the same condition, more commonly known as thoracic outlet syndrome (TOS), in which the brachial plexus nerves, subclavian artery, or subclavian vein become compressed as they pass between the neck and shoulder. Some experts prefer the term thoracic inlet because these structures are entering the arm from the chest, while others use the traditional term thoracic outlet, which remains the accepted medical terminology.

Throughout this book, I use the term thoracic outlet syndrome because it is the most widely recognized name used in medicine and by patients searching for information.

What is the superior thoracic aperture?

The superior thoracic aperture, also called the thoracic inlet, is the anatomical opening at the top of the chest through which the brachial plexus, subclavian artery, subclavian vein, trachea, and esophagus pass between the neck and thorax. Although anatomists often use the term superior thoracic aperture or thoracic inlet, the condition resulting from compression of the nerves or blood vessels in this region is commonly called thoracic outlet syndrome (TOS).

Throughout this book, you will learn how the anatomy of the superior thoracic aperture and thoracic outlet influences nerve compression, blood flow, and the development of thoracic outlet syndrome.

What are the other names for thoracic outlet syndrome?

Thoracic outlet syndrome (TOS) is known by several other names, including thoracic inlet syndrome, thoracic outlet compression syndrome (TOCS), neurogenic thoracic outlet syndrome (NTOS), venous thoracic outlet syndrome (VTOS), and arterial thoracic outlet syndrome (ATOS). Depending on the exact location of the compression, healthcare professionals may also use terms such as costoclavicular syndrome, scalene syndrome, cervical rib syndrome, or pectoralis minor syndrome.

Throughout this book, I use the term thoracic outlet syndrome because it is the most widely recognized and accepted name for this group of neurovascular compression disorders.

How does Wikipedia define thoracic outlet syndrome?

Wikipedia defines thoracic outlet syndrome (TOS) as a group of disorders caused by compression of the nerves, arteries, or veins as they pass through the thoracic outlet, the space between the lower neck and the armpit. It describes the three primary forms as neurogenic, venous, and arterial thoracic outlet syndrome, and notes that diagnosis can be challenging because symptoms often overlap with many other conditions.

Throughout this book, you will learn why I believe thoracic outlet syndrome is even better understood as a compression disorder caused by abnormal biomechanics and Human Spring dysfunction, providing a more complete explanation of why the condition develops and how it can be treated.

What is the ICD-10 code for thoracic outlet syndrome?

The ICD-10 code for thoracic outlet syndrome is G54.0, which is classified as Brachial Plexus Disorders because the most common form of thoracic outlet syndrome (TOS) involves compression of the brachial plexus nerves. Healthcare providers, hospitals, and insurance companies use the ICD-10 code G54.0 for medical documentation, billing, and diagnosis, although additional codes may be used when vascular complications are present.

Throughout this book, you will learn why thoracic outlet syndrome is much more than a billing code—it is a complex compression disorder that requires an accurate diagnosis and a thorough understanding of human biomechanics.

Is thoracic outlet syndrome rare?

Thoracic outlet syndrome (TOS) is often described as a rare condition, but many experts believe it is actually underdiagnosed and frequently misdiagnosed rather than truly uncommon. Because thoracic outlet syndrome symptoms closely resemble conditions such as herniated discs, cervical radiculopathy, carpal tunnel syndrome, and rotator cuff injuries, many patients never receive the correct thoracic outlet syndrome diagnosis.

Throughout this book, you will learn why thoracic outlet syndrome is probably far more common than most people realize and why a better understanding of its biomechanics and diagnosis may help identify many previously overlooked cases.

References

Atasoy E. Thoracic outlet compression syndrome. Orthop Clin North Am. 1996;27:265–303 http://www.ncbi.nlm.nih.gov/pubmed/8614579.
A. Cooper, B. Travers (Eds.), Surgical essays. Longman, London (1821), p. 128.
Coote H. Pressure on the axillary vessels and nerves by an exostosis from a cervical rib; interference with the circulation of the arm; removal of the rib and exostosis, recovery. Med Times Gaz. 1861;2:108.
Roos DB. Historical perspectives and anatomic considerations. Thoracic outlet syndrome. Semin Thorac Cardiovasc Surg. 1996;8:183–9. http://www.ncbi.nlm.nih.gov/pubmed/8672572.
Ranney D. Thoracic outlet: an anatomical redefinition that makes clinical sense. Clin Anat. 1996;9(1):50–2. http://www.ncbi.nlm.nih.gov/pubmed/8838281.
Turney BW1. Anatomy in a modern medical curriculum. Ann R Coll Surg Engl. 2007 Mar;89(2):104–7. Full Free http://publishing.rcseng.ac.uk/doi/pdf/10.1308/003588407X168244.
Kaufman MH. Anatomy training for surgeons—a personal viewpoint. J R Coll Surg Edinb. 1997 Aug;42(4):215–6. Abstract https://www.ncbi.nlm.nih.gov/pubmed/9276550.
Shaffer K1. Teaching anatomy in the digital world. N Engl J Med. 2004 Sep 23;351(13):1279–81. Abstract https://www.ncbi.nlm.nih.gov/pubmed/15385652.
Older J1. Anatomy: a must for teaching the next generation. Surgeon. 2004 Apr;2(2):79–90. Abstract https://www.ncbi.nlm.nih.gov/pubmed/15568432.
Anon. The rise and fall of anatomy. BMJ Career Focus. 2005;330:255–6.
Heylings DJ1. Anatomy 1999–2000: the curriculum, who teaches it and how? Med Educ. 2002 Aug;36(8):702–10. https://www.ncbi.nlm.nih.gov/pubmed/12191052.
Waterston SW1, Stewart IJ. Survey of clinicians’ attitudes to the anatomical teaching and knowledge of medical students. Clin Anat. 2005 Jul;18(5):380–4. https://www.ncbi.nlm.nih.gov/pubmed/15971223.
McKeown PP1, Heylings DJ, Stevenson M, McKelvey KJ, Nixon JR, McCluskey DR. The impact of curricular change on medical students’ knowledge of anatomy. Med Educ. 2003 Nov;37(11):954–61. https://www.ncbi.nlm.nih.gov/pubmed/14629407.
Prince KJ1, Scherpbier AJ, van Mameren H, Drukker J, van der Vleuten CP. Do students have sufficient knowledge of clinical anatomy? Med Educ. 2005 Mar;39(3):326–32. https://www.ncbi.nlm.nih.gov/pubmed/15733169.
Mayo Clinic Web Site. http://www.mayoclinic.org/diseases-conditions/thoracic-outlet-syndrome/home/ovc-20237878.
Cleveland Clinic. https://my.clevelandclinic.org/health/articles/thoracic-outlet-syndrome.
National Institute of Neurological Disorders and Stroke (NINDS) web site. https://www.ninds.nih.gov/Disorders/All-Disorders/Thoracic-Outlet-Syndrome-Information-Page.

Glossary

Browse terms by letter or search the glossary.

A Abnormal Biomechanics

Abnormal biomechanics refers to movement patterns or body mechanics that place excessive stress on the body's tissues. Poor posture, repetitive movements, muscle imbalance, injury, or prolonged muscle tension can alter normal biomechanics and reduce the space within the thoracic outlet. According to this chapter, abnormal biomechanics is one of the primary mechanical causes of thoracic outlet syndrome, increasing compression of the brachial plexus, subclavian artery, and subclavian vein.

A Anterior Scalene Muscle

The anterior scalene muscle is one of three scalene muscles located along the side of the neck. It attaches to the first rib and helps stabilize the neck while assisting with breathing. Excessive tension or spasm of the anterior scalene muscle can elevate the first rib, narrow the scalene triangle, and compress the brachial plexus and subclavian artery, making it one of the primary muscles involved in thoracic outlet syndrome.

A Arterial Thoracic Outlet Syndrome (ATOS)

Arterial thoracic outlet syndrome (ATOS) is the least common form of thoracic outlet syndrome. It develops when the subclavian artery becomes compressed within the thoracic outlet, reducing blood flow to the shoulder, arm, and hand. Symptoms may include cold hands, weakness, arm fatigue, pale or bluish skin, pain during activity, and, in severe cases, permanent tissue damage or blood clot formation.

A Artery

An artery is a blood vessel that carries oxygen-rich blood away from the heart to the body's tissues. In the upper extremity, the subclavian artery passes through the thoracic outlet before supplying the shoulder, arm, forearm, and hand. Compression of an artery can reduce blood flow, limiting the delivery of oxygen and nutrients needed for healthy tissue function.

A Atrophy (Muscle Atrophy)

Atrophy is the loss of muscle size and strength caused by prolonged disuse or reduced nerve supply. In advanced neurogenic thoracic outlet syndrome, long-term compression of the brachial plexus may reduce nerve signals to the muscles of the hand and forearm, eventually causing permanent muscle wasting if the compression is not relieved.

B Bilateral Thoracic Outlet Syndrome

Bilateral thoracic outlet syndrome means that thoracic outlet syndrome affects both sides of the body rather than only one. Patients may experience neck pain, shoulder pain, arm numbness, hand tingling, weakness, or circulation changes in both upper extremities. Symptoms involving both arms often increase the likelihood that thoracic outlet syndrome is present because many other nerve disorders usually affect only one side.

B Blood Clot (Thrombus)

A blood clot, also called a thrombus, is a collection of blood that changes from a liquid to a solid mass within a blood vessel. In venous thoracic outlet syndrome, prolonged compression of the subclavian vein may slow blood flow enough to allow a clot to form. If part of the clot breaks loose and travels through the bloodstream, it can become a life-threatening pulmonary embolism.

B Blood Flow

Blood flow is the movement of blood through the arteries, capillaries, and veins to deliver oxygen and nutrients to tissues while removing waste products. In thoracic outlet syndrome, compression of the subclavian artery reduces blood flow into the arm, while compression of the subclavian vein interferes with blood returning to the heart. Both types of compression can produce significant symptoms and tissue dysfunction.

B Brachial Plexus

The brachial plexus is a complex network of nerves formed by the C5, C6, C7, C8, and T1 nerve roots. It travels through the thoracic outlet to supply sensation and muscle control to the shoulder, arm, forearm, and hand. Compression of the brachial plexus is the defining feature of neurogenic thoracic outlet syndrome (NTOS) and may cause pain, numbness, tingling, weakness, burning sensations, and loss of hand function.

B Brachial Plexus Compression

Brachial plexus compression occurs when excessive pressure is placed on the brachial plexus as it passes through the thoracic outlet. This compression interferes with normal nerve function and commonly produces neck pain, shoulder pain, arm numbness, hand tingling, burning pain, weakness, reduced grip strength, and poor coordination. It is the primary cause of neurogenic thoracic outlet syndrome.

B Burning Pain

Burning pain is a common symptom of nerve compression in which pain feels hot, burning, stinging, or electrically irritating. In thoracic outlet syndrome, burning pain most often results from compression of the brachial plexus and may radiate from the neck into the shoulder, arm, forearm, and hand. It is one of the characteristic symptoms of neurogenic thoracic outlet syndrome.

C Carpal Tunnel Syndrome

Carpal tunnel syndrome is a condition in which the median nerve becomes compressed as it passes through the carpal tunnel in the wrist. Common symptoms include hand numbness, tingling, pain, and weakness, particularly involving the thumb, index finger, and middle finger. Because these symptoms often resemble thoracic outlet syndrome, many patients are initially diagnosed with carpal tunnel syndrome when the true source of compression is actually higher in the neck or shoulder.

C Cervical Rib

A cervical rib is an extra rib that develops above the first rib in some people. This congenital anatomical variation can reduce the space within the thoracic outlet, increasing the risk of compressing the brachial plexus, subclavian artery, or subclavian vein. Although many people with a cervical rib never develop symptoms, it is a recognized cause of thoracic outlet syndrome.

C Cervical Rib Syndrome

Cervical rib syndrome is a form of thoracic outlet syndrome caused by the presence of a cervical rib. The additional rib can reduce the available space within the thoracic outlet, compressing the brachial plexus or nearby blood vessels. Symptoms may include neck pain, arm numbness, hand tingling, weakness, or changes in circulation.

C Cervical Radiculopathy

Cervical radiculopathy occurs when one or more nerve roots leaving the cervical spine become compressed or irritated, most commonly by a herniated disc or bone spur. Symptoms may include neck pain, arm pain, numbness, tingling, and weakness. Because these symptoms closely resemble thoracic outlet syndrome, distinguishing between cervical radiculopathy and brachial plexus compression is an important part of making an accurate diagnosis.

C Clavicle (Collarbone)

The clavicle, commonly called the collarbone, is the curved bone connecting the breastbone to the shoulder. It forms the roof of the costoclavicular space, one of the three major passageways of the thoracic tunnel. Changes in the position of the clavicle can narrow the thoracic outlet, increasing pressure on the brachial plexus, subclavian artery, and subclavian vein.

C Compression Disorder

A compression disorder is a condition in which excessive pressure is placed on a nerve, blood vessel, or other body structure, interfering with its normal function. Thoracic outlet syndrome, carpal tunnel syndrome, cubital tunnel syndrome, and other entrapment disorders are all compression disorders because symptoms develop when important structures become compressed within narrow anatomical spaces.

C Compression Neuropathy

A compression neuropathy is a nerve disorder caused by prolonged pressure on a peripheral nerve. The pressure interferes with normal nerve function, producing symptoms such as pain, numbness, tingling, burning sensations, and weakness. Neurogenic thoracic outlet syndrome is a type of compression neuropathy involving the brachial plexus.

C Coracobrachialis Muscle

The coracobrachialis muscle is a shoulder muscle that helps move and stabilize the arm. According to this chapter, it is one of the muscles capable of pulling the shoulder girdle downward, contributing to narrowing of the thoracic outlet and increasing pressure on the neurovascular bundle when excessive muscle tension is present.

C Coracoid Process

The coracoid process is a hook-shaped projection of the shoulder blade (scapula) that serves as an attachment site for several muscles, including the pectoralis minor. It forms part of the roof of the subcoracoid (pectoralis minor) space, one of the three major passageways within the thoracic tunnel.

C Costoclavicular Space

The costoclavicular space is the second of the three major passageways within the thoracic tunnel. Located between the clavicle and the upper ribs, it allows the brachial plexus, subclavian artery, and subclavian vein to pass into the arm. Narrowing of this space may contribute to neurogenic, venous, or arterial thoracic outlet syndrome.

C Costoclavicular Syndrome

Costoclavicular syndrome is a form of thoracic outlet syndrome in which compression occurs primarily within the costoclavicular space, between the clavicle and the first rib. Compression at this location may affect the brachial plexus, subclavian artery, or subclavian vein, producing neurological or vascular symptoms depending on the structures involved.

C Cubital Tunnel Syndrome

Cubital tunnel syndrome occurs when the ulnar nerve becomes compressed at the inside of the elbow. It commonly produces numbness, tingling, and weakness involving the ring finger and little finger. Because these symptoms resemble thoracic outlet syndrome, cubital tunnel syndrome is one of the important conditions considered during the differential diagnosis of arm and hand symptoms.

C Cyanosis

Cyanosis is a bluish discoloration of the skin caused by reduced oxygen delivery or poor blood circulation. In arterial thoracic outlet syndrome or venous thoracic outlet syndrome, compression of the subclavian artery or subclavian vein may reduce circulation enough to produce cyanosis of the hand or fingers.

D Deep Vein Thrombosis (DVT)

Deep vein thrombosis (DVT) is the formation of a blood clot within a deep vein. In venous thoracic outlet syndrome, prolonged compression of the subclavian vein may slow blood flow enough to allow a clot to develop. If part of the clot breaks loose and travels to the lungs, it can cause a pulmonary embolism, making early diagnosis and treatment essential.

D Differential Diagnosis

A differential diagnosis is the systematic process doctors use to determine which medical condition is responsible for a patient's symptoms. Because thoracic outlet syndrome shares symptoms with carpal tunnel syndrome, cubital tunnel syndrome, cervical radiculopathy, rotator cuff injuries, herniated discs, and many other disorders, a thorough differential diagnosis is critical to identifying the true cause of pain, numbness, weakness, or circulatory problems.

D Disputed Thoracic Outlet Syndrome

Disputed thoracic outlet syndrome describes patients whose symptoms strongly suggest thoracic outlet syndrome, but whose nerve or blood vessel compression cannot be definitively confirmed using current diagnostic methods. Although controversial, the diagnosis recognizes that many patients experience classic symptoms despite normal imaging or other objective tests.

D Double Crush Syndrome

Double crush syndrome occurs when the same nerve is compressed at two separate locations. For example, a patient may have compression of the brachial plexus within the thoracic outlet together with compression of the median nerve at the wrist or the ulnar nerve at the elbow. Treating only one compression site may leave symptoms unresolved because both areas contribute to the problem.

E Effort Thrombosis

Effort thrombosis is another name for Paget-Schroetter syndrome, a condition in which a blood clot develops within the subclavian vein after prolonged compression or repetitive overhead activity. Symptoms often include sudden arm swelling, heaviness, pain, and bluish discoloration. Because the clot may travel to the lungs, effort thrombosis requires immediate medical evaluation.

E Electromyography (EMG)

Electromyography (EMG) is a diagnostic test that measures the electrical activity of muscles and the nerves controlling them. Doctors use EMG to evaluate nerve injuries and muscle disorders. In thoracic outlet syndrome, EMG may help rule out other neurological conditions, but many patients have normal EMG results because the nerve compression often occurs only during certain positions or movements.

E Embolus

An embolus is a blood clot or other material that travels through the bloodstream after breaking away from its original location. In venous thoracic outlet syndrome, part of a clot formed in the subclavian vein may become an embolus and travel to the lungs, causing a potentially life-threatening pulmonary embolism.

F First Rib

The first rib is the uppermost rib of the rib cage and forms the floor of the scalene triangle and part of the costoclavicular space. The anterior scalene and middle scalene muscles attach to the first rib. When these muscles become tight or go into spasm, they can elevate the first rib, reducing the space within the thoracic outlet and increasing compression of the brachial plexus, subclavian artery, and subclavian vein.

F First Rib Dysfunction

First rib dysfunction is abnormal movement or positioning of the first rib, often caused by excessive muscle tension or poor biomechanics. Elevation or restricted movement of the first rib may narrow the thoracic outlet, increasing pressure on the brachial plexus and nearby blood vessels. According to this chapter, first rib dysfunction is an important contributor to thoracic outlet syndrome.

F Forward Head Posture

Forward head posture is a posture in which the head sits too far in front of the shoulders rather than being balanced over the spine. This position increases the workload on the neck muscles, particularly the scalene muscles, and contributes to thoracic outlet compression. Prolonged computer use, smartphone use, and poor workstation ergonomics commonly lead to forward head posture.

F Functional Anatomy

Functional anatomy is the study of how the structures of the body work together to produce normal movement. Rather than simply identifying muscles, bones, and joints, functional anatomy explains how they interact during everyday activities. In this chapter, understanding functional anatomy is essential because the muscles surrounding the thoracic outlet must work together to maintain open space for the brachial plexus, subclavian artery, and subclavian vein.

G Grip Strength

Grip strength is the amount of force the muscles of the hand can generate when grasping an object. In neurogenic thoracic outlet syndrome, compression of the brachial plexus may weaken the muscles that control the hand, resulting in reduced grip strength, difficulty opening jars, dropping objects, and impaired hand function. Changes in grip strength often indicate progression of nerve compression.

H Hand Weakness

Hand weakness is a reduction in the strength or endurance of the muscles controlling the hand and fingers. In thoracic outlet syndrome, prolonged compression of the brachial plexus may reduce nerve signals to these muscles, making it difficult to grip objects, perform fine motor tasks, or maintain normal hand function. In advanced cases, weakness may progress to muscle atrophy if left untreated.

H Human Spring Approach

The Human Spring Approach is the examination, diagnosis, treatment, rehabilitation, and prevention system presented throughout this book. It is based on the principle that the body functions as an integrated spring system rather than only as a system of rigid levers. According to this approach, restoring normal biomechanics, reducing abnormal muscle tension, and relieving thoracic outlet compression provide the foundation for long-term recovery from thoracic outlet syndrome.

H Human Spring Engineering

Human Spring Engineering is the concept that the body is designed as an integrated spring mechanism that absorbs impacts, stores and recycles energy, preserves joint spaces, and maintains open passageways for the safe movement of nerves and blood vessels. In this chapter, Human Spring Engineering is presented as the biomechanical explanation for how the thoracic outlet normally protects the brachial plexus, subclavian artery, and subclavian vein.

H Human Spring Model

The Human Spring Model is the biomechanical model proposed in this book that describes the body as an integrated spring mechanism rather than solely as a system of rigid levers. The model explains how the body absorbs impacts, recycles energy, maintains healthy joint spaces, and protects nerves and blood vessels. It serves as the scientific foundation for understanding thoracic outlet syndrome and the Human Spring Approach.

I Integrated Spring-Mass Model of Biomechanics

The Integrated Spring-Mass Model of Biomechanics is the comprehensive biomechanical model introduced in this book. It explains that the body's muscles, tendons, ligaments, fascia, and other elastic tissues work together as an interconnected spring system that absorbs shock, stores elastic energy, improves movement efficiency, preserves joint spaces, and protects the brachial plexus, subclavian artery, and subclavian vein. The model is presented as the biomechanical foundation of the Human Spring Approach.

I Interscalene Triangle (Scalene Triangle)

The interscalene triangle, also called the scalene triangle, is the first of the three major passageways within the thoracic tunnel. It is bordered by the anterior scalene muscle, middle scalene muscle, and the first rib. The brachial plexus and subclavian artery pass through this space. Compression within the interscalene triangle is one of the most common causes of neurogenic thoracic outlet syndrome.

L Latissimus Dorsi Muscle

The latissimus dorsi muscle is a large muscle of the back that helps move and stabilize the shoulder. According to this chapter, it is one of the muscles capable of pulling the shoulder girdle downward. Excessive tension in the latissimus dorsi may contribute to narrowing of the thoracic outlet, increasing compression of the neurovascular bundle.

L Lever Model of Biomechanics

The lever model of biomechanics is the traditional theory that explains human movement by describing the body as a system of rigid levers moved by muscles. This chapter argues that the lever model cannot fully explain thoracic outlet syndrome, impact absorption, energy recycling, joint-space preservation, or the protection of nerves and blood vessels. The Human Spring Model is presented as a more complete explanation of human movement and biomechanics.

M Mechanical Compression

Mechanical compression is the physical squeezing or narrowing of a nerve, blood vessel, or other body structure by surrounding muscles, bones, ligaments, or connective tissues. This chapter explains that thoracic outlet syndrome is fundamentally a mechanical compression disorder. As compression increases, symptoms worsen. As the compression is reduced and normal biomechanics are restored, symptoms often improve.

M Middle Scalene Muscle

The middle scalene muscle is one of the three scalene muscles located along the side of the neck. It attaches to the first rib and helps stabilize the neck while assisting with breathing. Together with the anterior scalene muscle, it forms the scalene triangle, the first passageway of the thoracic tunnel. Excessive tension in the middle scalene muscle can elevate the first rib and compress the brachial plexus and subclavian artery.

M Motor Fibers

Motor fibers are nerve fibers that carry signals from the brain and spinal cord to the muscles, allowing voluntary movement. In neurogenic thoracic outlet syndrome, compression of the deeper motor fibers within the brachial plexus may lead to hand weakness, reduced grip strength, poor coordination, difficulty performing fine motor tasks, and eventually muscle atrophy if the compression persists.

M Movement Dysfunction

Movement dysfunction is abnormal or inefficient movement caused by poor biomechanics, muscle imbalance, injury, or abnormal muscle tension. According to this chapter, movement dysfunction contributes to thoracic outlet syndrome by altering the position of the neck, shoulder, ribs, and surrounding muscles, increasing compression within the thoracic outlet.

M Muscle Atrophy

Muscle atrophy is the loss of muscle size and strength caused by reduced nerve supply or prolonged lack of use. In advanced neurogenic thoracic outlet syndrome, persistent compression of the brachial plexus may cause the muscles of the hand and forearm to waste away, resulting in permanent weakness if treatment is delayed.

M Muscle Imbalance

Muscle imbalance occurs when some muscles become excessively tight while others become weak or underactive. These imbalances alter normal biomechanics, change joint alignment, and increase stress on surrounding tissues. This chapter describes muscle imbalance as an important contributor to thoracic outlet compression and abnormal posture.

M Muscle Spasm

A muscle spasm is an involuntary tightening or contraction of a muscle that may cause pain, stiffness, and restricted movement. In thoracic outlet syndrome, spasms of the scalene muscles, pectoralis minor, and other surrounding muscles can narrow the thoracic outlet, increasing compression of the brachial plexus, subclavian artery, and subclavian vein.

N Nerve Compression

Nerve compression occurs when a nerve is squeezed or irritated by surrounding muscles, bones, ligaments, or connective tissues. Pressure on a nerve interferes with normal nerve function and may produce pain, burning, numbness, tingling, weakness, or loss of coordination. In thoracic outlet syndrome, nerve compression most commonly affects the brachial plexus.

N Neurogenic Thoracic Outlet Syndrome (NTOS)

Neurogenic thoracic outlet syndrome (NTOS) is the most common form of thoracic outlet syndrome. It develops when the brachial plexus becomes compressed within the thoracic outlet. Symptoms commonly include neck pain, shoulder pain, arm numbness, hand tingling, burning pain, weakness, reduced grip strength, poor coordination, and, in advanced cases, muscle atrophy.

N Neurological Symptoms

Neurological symptoms are symptoms caused by irritation or dysfunction of the nervous system. In thoracic outlet syndrome, common neurological symptoms include arm numbness, hand tingling, burning pain, weakness, reduced coordination, decreased grip strength, and muscle wasting caused by compression of the brachial plexus.

N Neurovascular Bundle

The neurovascular bundle is the group of structures that travels together through the thoracic outlet. It consists of the brachial plexus, subclavian artery, and subclavian vein. These structures supply movement, sensation, and blood circulation to the shoulder, arm, and hand. Compression of any component of the neurovascular bundle can produce the neurological or vascular symptoms of thoracic outlet syndrome.

O Objective Diagnostic Tests

Objective diagnostic tests are medical tests that provide measurable information about the body, such as MRI, CT scans, X-rays, ultrasound, electromyography (EMG), and nerve conduction studies (NCS). This chapter explains that although these tests can help identify certain abnormalities or rule out other conditions, no single objective diagnostic test can reliably diagnose thoracic outlet syndrome or determine the underlying mechanical cause of the compression.

O Office Syndrome

Office syndrome is a non-medical term often used to describe pain and stiffness associated with prolonged desk work, poor posture, and computer use. According to this chapter, many people who believe they have "office syndrome" may actually have thoracic outlet syndrome, because long hours of sitting and poor workstation ergonomics can increase compression within the thoracic outlet.

O Orthopedic Examination

An orthopedic examination is a physical assessment used to evaluate the bones, joints, muscles, ligaments, tendons, and related structures of the musculoskeletal system. In patients with thoracic outlet syndrome, orthopedic examination techniques are used together with neurological, vascular, and biomechanical evaluations to help determine the location and cause of the compression.

P Paget-Schroetter Syndrome

Paget-Schroetter syndrome, also called effort thrombosis, is a serious complication of venous thoracic outlet syndrome in which a blood clot forms within the subclavian vein because of prolonged compression. Symptoms commonly include sudden arm swelling, heaviness, pain, bluish discoloration, and enlarged veins. Because the clot may travel to the lungs and cause a pulmonary embolism, immediate medical evaluation is essential.

P Pallor

Pallor is an abnormal paleness of the skin caused by reduced blood flow or decreased oxygen delivery. In arterial thoracic outlet syndrome, compression of the subclavian artery may reduce circulation enough to produce pallor of the hand or fingers, particularly during activity or exposure to cold temperatures.

P Paresthesia

Paresthesia is an abnormal sensation such as tingling, pins and needles, burning, crawling, or numbness without an obvious external cause. It commonly occurs when a nerve is irritated or compressed. In thoracic outlet syndrome, paresthesia most often results from compression of the brachial plexus and frequently begins in the ring and little fingers before spreading to other parts of the hand.

P Pectoralis Minor Muscle

The pectoralis minor muscle is a thin muscle located beneath the larger pectoralis major muscle. It attaches to the coracoid process of the shoulder blade and the third, fourth, and fifth ribs. Excessive tension or spasm of the pectoralis minor can pull the shoulder downward, narrowing the subcoracoid (pectoralis minor) space and contributing to thoracic outlet syndrome.

P Pectoralis Minor Syndrome (PMS)

Pectoralis minor syndrome (PMS) develops when the brachial plexus, subclavian artery, or subclavian vein becomes compressed beneath the pectoralis minor muscle. Because its symptoms closely resemble thoracic outlet syndrome, pectoralis minor syndrome is frequently overlooked or occurs together with other sites of thoracic outlet compression. This chapter identifies it as one of the three major areas where compression can occur within the thoracic tunnel.

P Peripheral Nerve Compression

Peripheral nerve compression occurs when a nerve outside the brain and spinal cord becomes squeezed by surrounding muscles, bones, ligaments, or connective tissues. This pressure may produce pain, numbness, tingling, burning sensations, weakness, or muscle wasting. Thoracic outlet syndrome, carpal tunnel syndrome, and cubital tunnel syndrome are all examples of peripheral nerve compression disorders.

P Poor Posture

Poor posture refers to body positions that place excessive stress on the muscles, joints, and connective tissues. According to this chapter, prolonged forward head posture, slouching, repetitive computer work, smartphone use, and other poor posture habits increase muscle tension and narrow the thoracic outlet, contributing to compression of the brachial plexus, subclavian artery, and subclavian vein.

P Posterior Scalene Muscle

The posterior scalene muscle is the third scalene muscle located along the side of the neck. Working together with the anterior and middle scalene muscles, it helps stabilize the neck and assist with breathing. Excessive tension in the posterior scalene contributes to abnormal neck mechanics, elevation of the upper ribs, and increased compression within the thoracic outlet.

P Provocative Test

A provocative test is a physical examination maneuver designed to reproduce a patient's symptoms by placing stress on a specific anatomical structure. In the evaluation of thoracic outlet syndrome, provocative tests may temporarily increase compression of the brachial plexus or nearby blood vessels, helping identify the location and cause of the compression.

R Repetitive Strain Injury (RSI)

A repetitive strain injury (RSI) is an injury caused by performing the same movement repeatedly over time. Activities such as prolonged computer work, typing, smartphone use, assembly-line work, or repetitive overhead activities can overload muscles, tendons, and nerves. According to this chapter, repetitive strain injuries may contribute to thoracic outlet syndrome by increasing muscle tension and narrowing the thoracic outlet.

R Rib Cage

The rib cage is the framework of bones that protects the heart, lungs, and other organs within the chest. The upper ribs also help form the thoracic outlet and provide attachment sites for muscles that influence the position of the neck and shoulders. Abnormal movement or muscle tension affecting the rib cage can alter thoracic outlet biomechanics and contribute to thoracic outlet syndrome.

R Rotator Cuff Injury

A rotator cuff injury involves damage to one or more of the muscles or tendons that stabilize the shoulder joint. Symptoms commonly include shoulder pain, weakness, and difficulty raising the arm. Because these symptoms often resemble thoracic outlet syndrome, rotator cuff injuries are frequently considered during the differential diagnosis of shoulder and arm pain.

S Scalene Muscles

The scalene muscles are a group of three muscles—the anterior scalene, middle scalene, and posterior scalene—located along the side of the neck. They help stabilize the neck and assist with breathing. According to this chapter, excessive tension or spasm of the scalene muscles can elevate the first rib, narrow the scalene triangle, and contribute significantly to thoracic outlet syndrome.

S Scalene Triangle

The scalene triangle is the first of the three major passageways within the thoracic tunnel. It is bordered by the anterior scalene muscle, middle scalene muscle, and the first rib. The brachial plexus and subclavian artery pass through this space. Narrowing of the scalene triangle is one of the most common causes of neurogenic thoracic outlet syndrome.

S Scalenectomy

A scalenectomy is a surgical procedure in which one or more scalene muscles are partially or completely removed to reduce pressure within the thoracic outlet. It is sometimes performed in patients with severe thoracic outlet syndrome. This chapter notes that removing only a few muscles cannot fully correct all of the muscular contributors to thoracic outlet compression.

S Scalenus Anticus Syndrome

Scalenus anticus syndrome is an older name for a form of thoracic outlet syndrome in which compression occurs primarily within the scalene triangle, often because of excessive tension in the anterior scalene muscle. It produces symptoms related to compression of the brachial plexus and nearby blood vessels.

S Sensory Fibers

Sensory fibers are nerve fibers that carry information such as touch, pain, temperature, and vibration from the body to the brain. Compression of the sensory fibers within the brachial plexus can produce arm numbness, hand tingling, burning pain, or altered sensation in patients with neurogenic thoracic outlet syndrome.

S Shoulder Girdle

The shoulder girdle consists primarily of the clavicles, scapulae, and the muscles that support and move them. It connects the upper extremities to the trunk and plays a critical role in maintaining the size and shape of the thoracic outlet. Abnormal positioning or downward movement of the shoulder girdle can contribute to thoracic outlet compression.

S Shoulder Impingement Syndrome

Shoulder impingement syndrome is a condition in which the tendons or soft tissues of the shoulder become pinched during arm movement. It commonly causes shoulder pain, weakness, and difficulty lifting the arm. Because these symptoms resemble thoracic outlet syndrome, shoulder impingement syndrome is an important condition to consider during the differential diagnosis.

S Subclavius Muscle

The subclavius muscle is a small muscle located beneath the clavicle. It helps stabilize the collarbone during shoulder movement. According to this chapter, excessive tension in the subclavius muscle may contribute to narrowing of the costoclavicular space, increasing compression within the thoracic outlet.

S Superior Thoracic Aperture

The superior thoracic aperture, also called the thoracic inlet, is the anatomical opening at the top of the chest through which the brachial plexus, subclavian artery, subclavian vein, trachea, and esophagus pass between the neck and thorax. Although anatomists often use this term, the compression disorder affecting this region is commonly called thoracic outlet syndrome.

T Tech Neck

Tech neck is a non-medical term describing neck and upper back pain caused by prolonged use of computers, smartphones, tablets, and other electronic devices. Looking downward for long periods places increased stress on the neck muscles, particularly the scalene muscles, contributing to poor posture, abnormal biomechanics, and increased compression within the thoracic outlet.

T Text Neck

Text neck is a repetitive strain condition caused by frequently bending the head forward while using a smartphone or other handheld device. This prolonged posture increases muscle tension in the neck and shoulders, contributing to thoracic outlet compression, neck pain, shoulder pain, and other symptoms associated with thoracic outlet syndrome.

T Thoracic Compartment

The thoracic compartment is another term used in this chapter to describe the anatomical region that includes the thoracic outlet and surrounding structures through which the brachial plexus, subclavian artery, and subclavian vein travel from the chest into the upper extremity.

T Thoracic Inlet

The thoracic inlet, also called the superior thoracic aperture, is the anatomical opening at the top of the chest where the brachial plexus, subclavian artery, subclavian vein, trachea, and esophagus pass between the neck and thorax. Although anatomists commonly use the term thoracic inlet, the compression disorder occurring in this region is widely known as thoracic outlet syndrome.

T Thoracic Outlet

The thoracic outlet is the narrow passageway between the neck and shoulder through which the brachial plexus, subclavian artery, and subclavian vein travel from the chest into the arm. It is formed by surrounding bones, muscles, ligaments, and connective tissues. Maintaining adequate space within the thoracic outlet is essential for normal nerve function and blood circulation.

T Thoracic Outlet Compression

Thoracic outlet compression occurs when the space within the thoracic outlet becomes narrowed, placing pressure on the brachial plexus, subclavian artery, subclavian vein, or surrounding tissues. This chapter explains that thoracic outlet compression is the fundamental mechanical problem responsible for thoracic outlet syndrome and that reducing this compression is the goal of treatment.

T Thoracic Outlet Syndrome (TOS)

Thoracic outlet syndrome (TOS) is a mechanical compression disorder that develops when the brachial plexus, subclavian artery, subclavian vein, or a combination of these structures becomes compressed within the thoracic outlet. Depending on which structures are affected, symptoms may include neck pain, shoulder pain, upper back pain, arm numbness, hand tingling, weakness, swelling, reduced circulation, or cold hands. According to this chapter, understanding and reversing the underlying compression is the foundation of successful treatment.

T Thoracic Tunnel

The thoracic tunnel is the term used throughout this book to describe the complete pathway traveled by the brachial plexus, subclavian artery, and subclavian vein from the neck into the arm. It consists of three primary passageways: the scalene triangle, costoclavicular space, and subcoracoid (pectoralis minor) space. Compression may occur in one or more of these regions, contributing to thoracic outlet syndrome.

T Triple Crush Syndrome

Triple crush syndrome occurs when the same nerve is compressed at three separate locations along its course. For example, a patient may simultaneously have compression within the thoracic outlet, at the elbow, and at the wrist. This chapter emphasizes that multiple compression sites may exist at the same time and should all be considered during evaluation and treatment.

T Tingling (Paresthesia)

Tingling, also called paresthesia, is an abnormal sensation often described as "pins and needles." It occurs when a nerve becomes irritated or compressed. In thoracic outlet syndrome, tingling commonly begins in the ring and little fingers because the lower portion of the brachial plexus is frequently affected, although the sensation may spread throughout the hand as compression worsens.

U Upper Extremity

The upper extremity refers to the entire upper limb, including the shoulder, arm, forearm, wrist, and hand. The brachial plexus, subclavian artery, and subclavian vein travel through the thoracic outlet before supplying the upper extremity. As a result, compression within the thoracic outlet can produce pain, numbness, tingling, weakness, swelling, or changes in circulation throughout the upper extremity.

V Vascular Compression

Vascular compression occurs when an artery or vein becomes narrowed or squeezed by surrounding muscles, bones, or connective tissues. Within the thoracic outlet, compression of the subclavian artery or subclavian vein may reduce blood flow, producing symptoms such as cold hands, arm swelling, heaviness, discoloration, fatigue, or blood clot formation.

V Vascular Thoracic Outlet Syndrome

Vascular thoracic outlet syndrome is a form of thoracic outlet syndrome involving compression of the major blood vessels rather than the nerves. It includes arterial thoracic outlet syndrome (ATOS), which affects the subclavian artery, and venous thoracic outlet syndrome (VTOS), which affects the subclavian vein. Although less common than neurogenic thoracic outlet syndrome, vascular thoracic outlet syndrome may lead to serious complications if left untreated.

V Vein

A vein is a blood vessel that returns oxygen-poor blood from the body's tissues back to the heart. In the upper extremity, the subclavian vein carries blood from the arm through the thoracic outlet. Compression of a vein can reduce blood return, producing arm swelling, heaviness, venous congestion, and an increased risk of blood clot formation.

V Venous Congestion

Venous congestion is the buildup of blood within a vein because normal blood flow back to the heart has been restricted. In venous thoracic outlet syndrome, compression of the subclavian vein may produce venous congestion, causing arm swelling, hand swelling, heaviness, bluish discoloration, and enlarged surface veins.

V Venous Thoracic Outlet Syndrome (VTOS)

Venous thoracic outlet syndrome (VTOS) develops when the subclavian vein becomes compressed within the thoracic outlet, restricting blood flow from the arm back to the heart. Symptoms commonly include arm swelling, heaviness, bluish discoloration, visible veins, and aching discomfort. Severe or prolonged compression may result in deep vein thrombosis (DVT) or Paget-Schroetter syndrome.

W Weakness

Weakness is a reduction in normal muscle strength caused by impaired nerve function, muscle injury, or reduced blood supply. In thoracic outlet syndrome, weakness most commonly results from compression of the brachial plexus, making it difficult to grip objects, lift the arm, or perform everyday tasks requiring fine motor control.

W Workstation Ergonomics

Workstation ergonomics is the design and arrangement of a work area to reduce physical stress and improve posture and biomechanics. Proper positioning of the chair, desk, monitor, keyboard, and mouse helps reduce unnecessary muscle tension and may decrease the risk of developing thoracic outlet syndrome, neck pain, shoulder pain, and other repetitive strain injuries.

Previous Chapter Continue Reading

Your cart is empty

Your cart

Estimated total

What Is Thoracic Outlet Syndrome?

Key Point

What Is Thoracic Outlet Syndrome?

The Thoracic Outlet or Tunnel

History

The Three Thoracic Outlet Passageways (Thoracic Outlet Spaces)

Scalene Triangle

Costoclavicular Space

Subcoracoid Space (Pectoralis Minor Space)

Blood Vessels and Nerves Passing Through the Thoracic Outlet

What Is the Cause of Thoracic Outlet Syndrome?

Mayo Clinic

Cleveland Clinic

Four Types of Thoracic Outlet Syndrome

There are four types of thoracic outlet syndrome (TOS).

Other Symptoms of Thoracic Outlet Syndrome in the Surrounding Area

Neck Compression Symptoms

Shoulder Compression Symptoms

Upper Back and Chest Compression Symptoms

Nerve Compression Symptoms

Vein Compression Signs and Symptoms

Artery Compression Symptoms

Why Is Thoracic Outlet Syndrome So Difficult for Doctors to Diagnose and Manage?

1. Thoracic outlet syndrome has nonspecific symptoms because of three reasons.

2. Thoracic outlet syndrome has poorly understood pathophysiologic mechanisms (causes) and remains one of the most misunderstood compression disorders in medicine.

3. Thoracic outlet syndrome has limited applicability of objective diagnostic testing procedures.

4. There is a potential overlap with other clinical disorders and compression syndromes.

5. There is an absence of well-defined, generally accepted, or consistently applied criteria for the diagnosis and treatment of thoracic outlet syndrome.

Examination and Treatment Are Based on a Flawed Model of Biomechanics

Frequently Asked Questions

References

Glossary