Thoracic Outlet Syndrome


Thoracic Outlet Syndrome (TOS) is a condition in which the nerves and/or the blood supply to or from the arm becomes entrapped in the neck and shoulder area. Neurological symptoms include numbness, shooting pains, weakness, or tingling in the arm or hand. Vascular symptoms involve altered sensations caused by diminished blood flow to the arm, including swelling and discoloration. The many symptoms of TOS can also be caused by several other factors, making TOS diagnosis into a daunting detective game! The thoracic outlet is the area under the collarbone where space is provided for the brachial plexus to pass through. The brachial plexus is a bundle of spinal nerves, which originate from the lower cervical vertebrae and the first thoracic vertebrae. These nerves “splice” together and meander through a complicated path to provide sensation and motor control for the arm and hand. As with any nerve bundle, the brachial plexus is accompanied by arterial and venous blood vessels. The tricky part of true TOS diagnosis lies in the fact that there can be so many structural issues along this path, which may cause compression to this neuro-vascular bundle.

The typical sufferer of TOS tends to have a vague and mild onset of symptoms, which they may control by changing the arm position or taking anti-inflammatory medication. Symptoms tend to get worse at night, when the person is tired, or when the person begins to exercise the arm. Pain from TOS usually involves the neck and shoulder area, and can move down the arm to involve the whole limb. Pain will usually be increased with elevation of the arm.

Causes for TOS can include skeletal misalignments or abnormalities, muscular tightness, or pathological conditions.

In terms of bony abnormalities, a person may be born with a small, rib-like projection in the lower cervical vertebrae (usually C7) that generally occurs on one side of the neck. This may cause crowding to the thoracic outlet space.

There may be a rib that is too high or angled too close to the collarbone, which closes the thoracic outlet space.

Pathological conditions that may lead to TOS are less commonly seen, but should be mentioned. Invasive tumors in the lung or upper pleural cavity may impinge the thoracic outlet area.

A frequent cause of TOS include muscular imbalances in the neck, shoulder, and chest. The trauma of a whiplash injury involves the rapid hyperextension of the head and neck. This strains the muscles that normally provide stability to the neck, and puts much strain on the lower cervical spine, where the brachial plexus emerges. Frequently, TOS results from a whiplash type injury, especially for the person who is already compromised with poor posture, or an occupation that involves repetitive movements. Such occupations include computer work, heavy lifting, carpentry work, musicians, or any job which requires the arms to be held up for prolonged periods.

One cannot underestimate the connection of TOS with poor posture.