What Is It?

Thoracic outlet syndrome (TOS) is a relatively uncommon combination of signs and symptoms stemming from compression of nervous or vascular structures between the first rib and collar bone. This can be divided into neurogenic TOS (nTOS), where symptoms arise from compression of nerves, and venous or arterial TOS (vTOS or aTOS), where the blood vessels are compressed. nTOS is by far the most common type.

Symptoms/Risks

nTOS typically brings numbness and/or weakness in the arm that is worsened by overhead activity or prolonged use of the arm. vTOS symptoms include forearm fatigue, and arm and/or hand swelling. aTOS can cause pain, pallor of the skin and cold hands. It is possible to have more than one type of structure compressed, in which a combination of symptoms would be present.

In all forms of TOS, there is an increased prevalence of anatomic variants, such as extra ribs or muscles, or variations of neck musculature arrangements. These conditions commonly happen after trauma from a whiplash injury to the neck, such as an automobile crash, or a collarbone injury. This can also be seen after repetitive overhead arm movements, such as swimming.

Sports Medicine Evaluation & Treatment

A sports medicine physician will start evaluating for TOS by asking for a detailed description of your symptoms and which positions make your symptoms worse. A physical examination will include checking the function of your nerves, muscles and blood vessels in your arms. This can involve moving your arm into positions that may compress these structures to evaluate for changes this position may cause.

Other common conditions can have similar symptoms to TOS, so an x-ray and occasionally MRI of the neck could be warranted. For nTOS, an electromyogram (EMG) or nerve conduction study (NCS) can check the function of the nerves in the arm. An injection to the area, also called a scalene block, can temporarily calm a muscle in the neck that is suspected to be compressing nervous tissue and can be used diagnostically to see if it relieves symptoms. For aTOS and vTOS, ultrasound of the vessels or a CT scan of the area with contrast can help identify blockage of vascular structures.

nTOS is first managed with physical therapy for postural exercises and stretching exercises of potentially tight neck muscles. If a scalene block temporarily alleviated symptoms, a botulinum toxin injection into the muscle can provide months of relief.

In many symptomatic cases of TOS that are not adequately relieved by other treatments, surgery can be suggested. This typically involves removal of bones or muscles that may be involved in compressing the nerves or blood vessels.

Injury Prevention

Those that develop TOS due to repetitive motion may consider adjusting their activities to avoid repetitive overhead activity. Otherwise, TOS typically has no known avoidable cause, as it stems from either bone or muscle variants, which are generally present when you are born, or from an injury.

Return to Play

The decision to return to play with TOS can be complicated, and should involve a discussion between the athlete, sports medicine physician, and perhaps a cardiothoracic or neurosurgeon in some cases. For many cases of nTOS, pain is the limiting factor for return to play unless there is weakness that is occurring. For aTOS and vTOS, finding sports that do not place the shoulders in positions that provoke symptoms may be possible while waiting for a treatment.

AMSSM Member Authors
Mark Sederberg, DO, and Daniel M. Cushman, MD

References
Sanders RJ, Hammond SL, Rao NM. Diagnosis of thoracic outlet syndrome. J Vasc Surg 2007; 46:601.
Roos DB. Congenital anomalies associated with thoracic outlet syndrome. Anatomy, symptoms, diagnosis, and treatment. Am J Surg 1976; 132:771.
Sanders RJ, Hammond SL. Management of cervical ribs and anomalous first ribs causing neurogenic thoracic outlet syndrome. J Vasc Surg 2002; 36:51.