07 July 2021

Thoracic Outlet Syndrome

Thoracic Outlet Syndrome

Thoracic Outlet Syndrome (TOS) is characterised by pain, numbness, or pins and needles in the arm and hand. It is caused by the compression of blood vessels or nerves around the chest or shoulder.


The type of TOS caused by an irritated nerves leads symptoms like:

  • pins and needles
  • numbness
  • weakness
  • pain, which might be shooting

These symptoms are typical of an irritated nerve. Sciatica is an example of an irritated nerve affecting the leg, and symptoms of that are the same as those above, just in a different area.

TOS and Rounded Shoulders

The most common major factor in TOS is a hunched posture. This kind of posture is commonly associated with desk work or stress. Ideally, your desk will be ergonomically set up just for you, and you will be able to take frequent breaks and move around. In reality, this is rarely the case. Sitting in front of a computer for hours at a time encourages your muscles to take shortcuts. An example of this is the shoulders slumping forwards. Brief periods of this position are not a problem, but if repeated for hours every day, the body begins to adapt.

The muscles on the front of the chest (the pectoral muscles) are held in a contracted position. For efficiency, they begin to shorten, further encouraging that posture. The muscles between the spine and shoulder blade that do the opposite job become stretched and weak. With these changes, the shoulders stay rounded even when away from the desk.

The problem with this rounding is that it compresses the nerves and vessels involved in TOS. They sit in an already small space in front of the arm: a space that only becomes smaller in this position. The shortening of the pectoral muscles themselves can be a factor too. Similarly, shortening of muscles that raise the shoulder can have the same effect.

Other Causes of Thoracic Outlet Syndrome

Not all cases are due to posture. Sometimes it comes down to anatomy. Normally the first rib comes from the first vertebra in the thorax. Some people are born with a projection that resembles a small rib from the lower neck bones. This may go completely undetected, or it may only show signs when it leads to something like TOS.

Trauma or injury are other possible causes. Whiplash can lead to TOS, as can fractures of upper ribs or the collar bone. If you have symptoms listed above and have recently suffered trauma, you should speak to a doctor before seeing your osteopath.

Signs of Vascular TOS

The vast majority of cases are neurogenic, meaning the nerves cause the symptoms. Rarely, a vein or artery is compressed, in which case there are additional symptoms:

  • Swelling
  • Blue-tinged arm
  • Paleness
  • Cold skin

Not every case will have every symptom, although it is possible if both an artery and vein are compressed. If symptoms developed after a trauma, such as a road traffic accident, seek urgent medical attention. Symptoms that develop slower may be within your osteopath's remit, or they may advise you to see a doctor.

Managing Thoracic Outlet Syndrome

If your symptoms look like they might be related to posture, we can help. Alongside hands-on treatment, we will want to correct the balance between muscles. This might need to occur in two stages, but over time we will aim to loosen the tight muscles and strengthen the weak ones. Both parts of this plan work together, and success in one part makes the other part easier. We might achieve this balance through exercises. Stretches for the tight muscle can be quite straight forward, and strengthening exercises can be adapted to suit you. Some people prefer to use a weight or a machine at the gym. Other people prefer resistance bands. We can support you through your exercises during our clinical sessions.

To fully break the cycle and prevent recurrence, it may also be necessary to change your desk set-up. If your employer does not have the means to support you here, we can give some advice to change it yourself.

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