Thoracic Outlet Syndrome

What Is Thoracic Outlet Syndrome?

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Thoracic Outlet Syndrome (TOS) is an umbrella term that is used to describe a range of symptoms in the upper extremity due to the compression of nerves and/or blood vessels around the neck area.

There are three main areas where this can occur

  1. The interscalene triangle (scalenes are muscles on the side of your neck)
  2. The Costoclavicular triangle (the space between the clavicle and the first rib)
  3. The Sub-coracoid space (a small space under the pec minor muscle where it attaches to the front of the shoulder blade)

The symptoms you may experience vary greatly in severity and frequency. Some people find intermittent pain due to postural positions, while other people may get symptoms with repetitive overhead actions (overhead workers, throwing athletes etc).

Thoracic Outlet Syndrome

The Thoracic Outlet with boxes showing 

1) Interscalene triangle
2) Costoclavicular triangle
3) Subcoracoid space

Nerves are yellow, arteries are shown as red, and veins are shown as blue. 

The symptoms of TOS are diverse and can depend on what structure is being compressed – nerve, artery or vein. Some common symptoms include

  • Pain in the arm or hand
  • Pins and needles or skin crawling
  • Numbness in the arm or hand
  • Coolness of the skin
  • Fullness or swelling in the arm and hand
  • Distended veins and swelling
  • Muscle weakness

There are three classifications of TOS that are commonly used:

1) Vascular TOS

This type of TOS accounts for ~5% of all presentations and includes all conditions that are related to the occlusion of veins or arteries. This can be diagnosed by monitoring blood flow through your subclavian artery when placing you arm in overhead positions.

2) True Neurological TOS

This group is very rare and is due to bony structures compressing the nerves around your neck or collarbone.

3) Symptomatic TOS

This is by far the most common presentation and accounts for ~80% of suspected cases. Patients in this category have no clear findings on medical investigations but have symptoms common to this syndrome. This is therefore often a diagnosis of exclusion.

Accurate diagnosis can be difficult and depends on your physiotherapist completing a thorough assessment of your symptoms and provocative actions. If you think you may have some of these symptoms, please get in contact with our physiotherapy team.

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