Thoratic
Outlet Syndrome

Have you been told you have thoracic outlet syndrome and you have no idea what it is? Here is a quick guide on what thoracic outlet syndrome is and what causes it.

Thoracic outlet syndrome (TOS) is group of disorders that occurs when blood vessels or nerves in the space between the collar bone (clavicle) and first rib are compressed. The cause of compression varies between each type of TOS. These groups of disorders are called different names and they present with differing symptoms:

Neurological thoracic outlet syndrome

This is the most common type of TOS. It occurs when the brachial plexus, which a network of nerves that supply sensation and movement to the shoulder, arm and hand, is compressed between the space of the clavicle and first rib.

Compression can be due to the following:

• Trauma such as fractures or whiplash from motor vehicle accidents
• Anatomical abnormalities such as an extra rib
• Over-use or repetitive movements causing soft tissue changes in the neck. Most commonly the scalene muscle can become enlarged leading to reduced space between the clavicle and rib.
• Sports-related injuries that require repetitive overhead movements such as swimming and volleyball
• Pregnancy

Common symptoms of neurogenic TOS include: numbness or tingling of the arm and hand, pain or achy sensations in neck, shoulder or hand, weakness of the upper limb, reduced grip strength and frequent headaches.

Vascular thoracic outlet syndrome:

Vascular TOS is term where either the subclavian artery (arterial TOS) or the subclavian vein (venous TOS) gets compressed.

Arterial TOS:

For arterial TOS the subclavian artery gets compressed. The subclavian artery originates from the aorta and travels between two muscles within the neck called the middle and anterior scalene muscles, over the first rib and under the clavicle. The subclavian artery provides blood to arm and hand, as well as to other vessels such as the carotid artery and the vertebral arteries. These arteries supply blood to the neck, brain and face.

When the subclavian artery gets compressed it results in the first symptom of migraines due to the lack of blood flow to the brain. Other symptoms of arterial TOS include:

• Upper limb weakness and fatigue
• Weak pulse in affected arm
• Cold hands and fingers
• Numbness
• Pain
• Loss of blood flow to fingers
• Stroke

Generally, the cause of arterial TOS is a bony abnormality that causes compression with overhead activities. Arterial TOS is a sudden onset type of syndrome.

Venous TOS

Venous TOS also known as Paget-Schroetter syndrome is where the subclavian vein gets compressed at the TOS region. The subclavian vein passes over the first rib and in front of the anterior scalene muscle and into a space called the costoclavicular space. This space is located between the clavicle and another muscle within the neck called the subclavius muscle. Venous TOS results in compression of the subclavian vein due to external compression of the costoclavicular space or enlargement of the muscles located near the vein (anterior scalene or subclavius).

Symptoms of venous TOS include:

• Arm swelling
• Arm heaviness
• Aching
• Prominent veins within the arm
• Cyanosis which is blue fingers

It is crucial that TOS is diagnosed and treated correctly to prevent further harm and reduce permanent damage to either the nerves or blood vessels that supply the arm and other parts of the body.

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