Overview of Thoracic Outlet Syndrome

Thoracic outlet syndrome (TOS) is a condition that causes upper extremity symptoms of pain, numbness, and tingling (not always together, and not the same symptoms in every person). TOS can be difficult to diagnose, is relatively uncommon, and therefore may take a long time to discover it is the cause of your symptoms. Many patients with TOS visit a number of doctors of different specialties and have many tests before being definitively diagnosed with TOS.

Woman with aching shoulder
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Thoracic outlet syndrome refers to a group of conditions caused by compression of the nerves or the blood vessels in the area around the collarbone. The most common type of TOS occurs when the nerves (specifically part of the brachial plexus) are pinched between the collarbone and the first rib. This type of TOS is called neurogenic TOS. There can also be compression of the large blood vessels (subclavian vein or artery), which is less common. This is called vascular TOS.

TOS tends to occur after either a traumatic injury (although the symptoms may not start until weeks after an injury) or repetitive stress. The nerve or blood vessel may become pinched either by the bone or the soft tissues between the clavicle and the first rib.


Typical symptoms of TOS occur in patients who are young, active, and otherwise healthy. Whereas some of the conditions confused with this condition occur in less healthy patients, TOS often seems to come up out of nowhere in otherwise healthy individuals. The less common vascular type of TOS may cause swelling of the arm (venous TOS) or paleness and cold intolerance of the extremity (arterial TOS). However, the most common symptoms for neurogenic TOS, according to John Hopkins include:

  • Tingling in discomfort in the fingers
  • Weakness and pain in shoulder and arm
  • Arm that feels heavy and tires quickly
  • Atrophy of the pad of the thumb

Many tests can be performed, however abnormal test results may or may not be evident. The most important step in diagnosis is a careful history and physical examination by a physician familiar with this condition. Tests often done include x-rays, MRIs, nerve conduction studies, and vascular studies. One of the most useful tests is selective injections to determine the location of the compression of the nerve.

Difficult Diagnosis

The most challenging aspect of thoracic outlet syndrome is that it is a difficult condition to diagnose. Most patients with TOS have been diagnosed with another, if not several other, conditions along the way. Often many tests have been performed and treatments have been attempted without success.

Some of the common problems that may produce symptoms similar to TOS include:

Some patients have been told they have a psychosomatic illness or fibromyalgia. Other patients, who have not found relief from their symptoms of arm or shoulder pain, may find this diagnosis yet not have the condition. My best advice is to find a physician who understands this condition and is willing to work with them as seldom is the management of TOS quick and easy.

Treatment Recommendations

Most patients can find relief with non-surgical treatment. The common steps include resting (especially after trauma-induced TOS), avoiding specific physical activities that cause symptoms, and physical therapy. Injections into the muscles around the clavicle may relieve symptoms if the muscle is the cause of the TOS. 

Surgery is generally reserved for those with persistent symptoms, or in cases of vascular TOS which can be more of an emergency situation. Fortunately, most patients can find relief without having to take that step.

5 Sources
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  1. Masocatto NO, Da-Matta T, Prozzo TG, Couto WJ, Porfirio G. Thoracic outlet syndrome: a narrative review. Rev Col Bras Cir. 2019;46(5):e20192243. PMID.31859722. Published December, 2019.

  2. Kuhn JE, Lebus GF, Bible JE. Thoracic outlet syndrome: Journal of the American Academy of Orthopaedic Surgeons. 2015;23(4):222-232. doi. 10.5435/jaaos-d-13-00215. Published April, 2015.

  3. Hussain MA, Aljabri B, Al-Omran M. Vascular thoracic outlet syndrome. Seminars in Thoracic and Cardiovascular Surgery. 2016;28(1):151-157. doi. 10.1053/j.semtcvs.2015.10.008. Published September, 2016.

  4. Freischlag J, Orion K. Understanding thoracic outlet syndrome. Scientifica. 2014;2014:1-6. doi.10.1155/2014/248163. Published March, 2014.

  5. Povlsen S, Povlsen B. Diagnosing thoracic outlet syndrome: current approaches and future directions. Diagnostics (Basel). 2018;8(1):E21. PMID.  29558408. Published March, 2018.

Additional Reading
  • Kuhn JE, et al. "Thoracic Outlet Syndrome" J Am Acad Orthop Surg April 2015 vol. 23 no. 4 222-232.

By Jonathan Cluett, MD
Jonathan Cluett, MD, is board-certified in orthopedic surgery. He served as assistant team physician to Chivas USA (Major League Soccer) and the United States men's and women's national soccer teams.