Thoracic Outlet Syndrome


What Is Thoracic Outlet Syndrome?

Thoracic Outlet Syndrome, or T.O.S., is a “group of disorders that result in compression of the brachial plexus and subclavian vessels exiting the thoracic outlet” (Dierks, et al.). While it used to be considered mostly a vascular issue (blood flow based), it is now understood to be classified as either neurogenic T.O.S. (about 90-95% of cases) or vascular T.O.S. (venous T.O.S. or Arterial V.O.S.). Many who have experienced thoracic outlet syndrome understand how limiting it can be, and how difficult a proper diagnosis can be. One contributing factor to the difficult diagnosis is the lack of consensus diagnostic criteria there is. However, by using systematic reviews and the existing literature, we are able to gain a much clearer understanding on what criteria help diagnose this, and which medical interventions are more successful/when. It is also difficult because there are other diagnoses that can have some of these symptoms. One key I tell all my patients is to write down symptoms, how long they last for, what gives you relief and what aggravates them. The key to the correct diagnosis is providing all details and having someone who can help you rule in and out based on subjective and objective findings. 


What T.O.S. boils down from a structural standpoint  is a compression of the brachial plexus and/or the subclavian vessels. The compression from T.O.S. typically occurs in three main “spaces”:

  1.  Scalene Triangle 
  2.  Costoclavicular Space
  3.  Subcoracoid Space

Creator: Amy Zhong – Copyright: © 2015 Amy Zhong


Common symptoms can vary based on the type, location and severity of the thoracic outlet syndrome. Differentiating the signs and symptoms can be helpful as well, as there is neurogenic TOS (compression of the brachial plexus), and vascular TOS (which is divided into arterial and venous and involves compression of the subclavian artery/vein). 

Many with TOS describe feeling of numbness and tingling in the arm down to the hand, feeling of their hand getting cold, muscle atrophy, hand weakness and arm weakness, difficulties with sustaining arms overhead, fingers getting pale when arm is in certain positions, difficulties with certain postures, pain with repetitive movements.


Vascular TOS (Arterial and Venous) is often caused by a cervical rib or spasming in the surrounding musculature, and it makes up about 5% of all cases. Cervical Ribs are congenital in nature, and X-rays would show an extra rib and its compression of the subclavian artery/vein. Arterial TOS is the rarest, but often the most severe. Individuals with arterial T.O.S. would likely present with arm fatigue, delayed capillary refill, and would experience cold and pale fingers. Certain positions too would result in sudden pain in the hands and weakness in the hand and arm. 


Venous TOS is compression at the subclavian vein, and one would often present with upper extremity swelling/edema that occurs pretty acutely, a ‘heavy’ sensation in the arm and hand, cyanosis, and fingers turning while/blue in response to stress or cold (Raynaud’s Phenomenon).


Neurogenic TOS makes up about 90% of all TOS cases, and individuals with this often can have occipital headaches (coming from the base of the neck), radiating nerve pain, numbness, and paresthesias down into the hand, notable muscle weakness, neck/shoulder/arm pain, and even chest pain and discomfort.  It is more often associated with those with a history of neck trauma/whiplash, surgeries, repetitive irritations/stresses or irritating postures that provoke these symptoms. Neurogenic TOS is often seen more with those whose sports/jobs involve repetitive movements, often overhead. 

You can experience vascular symptoms and neurogenic symptoms, as there are combined forms!


Original caption: A superior anterior view of the nerve supply of the shoulder. The surface anatomy of the body is semi-transparent and tinted green. — Image by ©

Causes of Thoracic Outlet Syndrome (TOS)

Acquired Causes: 

  • Whiplash Associated Injuries 
  • Falls 
  • Clavicle Fractures
  • Traumatic Injury
  • FOOSH/Brachial Plexus Injuries
  • Rib injuries
  • Pregnancy
  • Repetitive Stress Injury
  • Postural factors result in irritation


Congenital Factors

  • Anamolous cervical ribs
  • Congenital Soft Tissue injuries
  • Scalene insertional muscle abnormality 
  • Prolonged Transverse Process



Let us not forget that while the biomechanical elements play a strong role, so do the chemical/neurological elements. There are many aspects that can influence pain science, including (but not limited to) environmental and psychological stressors, movement and exercise habits, nutrition, past experiences, alcohol use, and sleep quality. At Perfect Stride, we love the pain science analogy of “What is in your cup?”. If you have too many things in your cup, then it overflows, and we experience pain. And when this pain system continues to go off, it takes less to set that system off, as it is becoming ‘sensitized’. So, even in a complicated condition such as thoracic outlet syndrome, find some ways to decrease what’s in your cup. 

  1.  Find ways to exercise and move without irritating the pain (walking, stationary bike)
  2.  Find some ways to relax from a stressful day at work (such as meditation, board games, restorative yoga). 
  3.  Find ways to get some better quality sleep (nap during the day, doing some deep breathing before bed, etc)

What works for someone else may not work for you. 



A physical therapy evaluation should emphasize learning your history, when the symptoms started and what aggravates and what relieves your symptoms. After this, testing one’s sensation, grip strength, manual muscle testing, positional and postural  tolerance and control, and performing a series of special tests can help us provide a diagnosis. These tests will only be performed as needed, and referrals to other specialists will occur as necessary. The goal will be to understand you and your background, and develop a treatment plan to address this condition from all angles!


Phases of rehab?

There are thousands of exercises out there. What works for YOU may be slightly (or very) different from someone else. But what we know we need to do is initially calm symptoms down. Without getting the symptoms to calm down, it’ll be incredibly painful to stretch and load up those tissues. Once symptoms begin to calm down a bit, we can start to improve mobility, which emphasizes not only flexibility, but your ability to control and move into your available range of motion without pain flare ups. Then, we can expand more into strengthening and resiliency training, aka, make it take more to cause another irritation or injury. Your rehabilitation should be personalized, and constant communication between you and your rehab professional. 



It really doesn’t. While some positions may be less comfortable, irritating a system that is already super sensitive and irritated is unnecessary. There is a fine line and balance between some discomfort that resolves quickly and does not linger and discomfort that flares you up. PT can be incredibly helpful in restoring muscle strength, improving nerve sensitivity, improving symptoms and improving quality of life. “Exercise has shown to be a useful approach in 50 to 90% of all TOS cases (Levine, et al.)”.


TOS can be a very uncomfortable condition, and can really affect one’s quality of life. It is imperative to have a good understanding of your triggers/stressors, and positions and times when you get relief. The right rehabilitation approach will take into account your goals, your stressors and take a full body approach. This is a condition that can be treated, and a detailed assessment will help individuals’ with this have a better understanding of the next best steps!

If you are looking for individuals trained in this condition and able to help rule in/out other diagnosis, our Doctors’ of Physical Therapy here at Perfect Stride are here for you. Reach out to us at to learn more.



Levine NA, Rigby BR. Thoracic Outlet Syndrome: Biomechanical and Exercise Considerations. Healthcare (Basel). 2018 Jun 19;6(2):68. doi: 10.3390/healthcare6020068. PMID: 29921751; PMCID: PMC6023437.

Heneghan NR, Smith R, Tyros I, Falla D, Rushton A. Thoracic dysfunction in whiplash associated disorders: A systematic review. PLoS One. 2018 Mar 23;13(3):e0194235. doi: 10.1371/journal.pone.0194235. PMID: 29570722; PMCID: PMC5865734.

Li N, Dierks G, Vervaeke HE, Jumonville A, Kaye AD, Myrcik D, Paladini A, Varrassi G, Viswanath O, Urits I. Thoracic Outlet Syndrome: A Narrative Review. J Clin Med. 2021 Mar 1;10(5):962. doi: 10.3390/jcm10050962. PMID: 33804565; PMCID: PMC7957681.

Ohman JW, Thompson RW. Thoracic Outlet Syndrome in the Overhead Athlete: Diagnosis and Treatment Recommendations. Curr Rev Musculoskelet Med. 2020 Aug;13(4):457-471. doi: 10.1007/s12178-020-09643-x. PMID: 32514995; PMCID: PMC7340704.

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