Thoracic outlet syndrome (TOS) is a group of disorders that occur when blood vessels or nerves in the space between your collarbone and your first rib (thoracic outlet) are compressed. This can cause shoulder and neck pain and numbness in your fingers.

Common causes of thoracic outlet syndrome include physical trauma from a car accident, repetitive injuries from job- or sports-related activities, certain anatomical defects (such as having an extra rib), and pregnancy. Sometimes doctors don’t know the cause of thoracic outlet syndrome.

There are three general types of thoracic outlet syndrome:

Neurogenic (neurologic) thoracic outlet syndrome

This most common type of thoracic outlet syndrome is characterized by compression of the brachial plexus. The brachial plexus is a network of nerves that come from your spinal cord and control muscle movements and sensation in your shoulder, arm and hand.

Venous thoracic outlet syndrome

This type of thoracic outlet syndrome occurs when one or more of the veins under the collarbone (clavicle) are compressed, resulting in blood clots.

Arterial thoracic outlet syndrome

This is the least common type of TOS. It occurs when one of the arteries under the collarbone is compressed, resulting in bulging of the artery, also known as an aneurysm. It’s possible to have a mix of the three different types of thoracic outlet syndrome, with multiple parts of the thoracic outlet being compressed. Thoracic outlet syndrome symptoms can vary depending on the type. When nerves are compressed, signs and symptoms of neurogenic thoracic outlet syndrome include:

Numbness or tingling in your arm or fingers
Pain or aches in your neck, shoulder, arm or hand
Weakening grip
Signs and symptoms of venous thoracic outlet syndrome can include:
Discoloration of your hand (bluish colour)
Arm pain and swelling
Blood clots in veins in the upper area of your body
Arm fatigue with activity
Paleness or abnormal colour in one or more fingers or your hand
Throbbing lump near your collarbone
Signs and symptoms of arterial thoracic outlet syndrome can include:
Cold fingers, hands or arms
Hand and arm pain
Lack of colour (pallor) or bluish discoloration (cyanosis) in one or more of your fingers or your entire hand
Weak or no pulse in the affected arm

The following events may cause thoracic outlet syndrome, especially in people with the above bone or muscle abnormalities in the neck:

Whiplash: Arm and hand symptoms that persist long after a whiplash injury may be a sign of thoracic outlet syndrome.
Bodybuilding: Built-up muscles in the neck may grow too large and compress nerves or the subclavian vessels.
Repeated overhead motions: People who take up swimming, baseball or painting, or who work as hairstylists, auto mechanics or other jobs that require raised arms may develop thoracic outlet syndrome.
Weight gain: As with extra muscle mass, extra fat in the neck may compress nerves or subclavian vessels.
Tumour in the neck: On rare occasions, a tumour may be the cause of the compression.

General massage therapy, deep tissue massage, cranial sacral therapy, acupuncture and osteopathy are good options to treat thoracic outlet syndrome.