What is thoracic outlet syndrome?

Thoracic outlet syndrome is a condition that occurs when the blood vessels or nerves in the space between your collarbone and your first rib (thoracic outlet) are compressed. This can cause pain in your shoulders and neck and numbness in your fingers.

Risk Factors

There are several factors that appear to increase the risk of thoracic outlet syndrome, including

  • gender. Women are much more likely to be diagnosed with thoracic outlet syndrome than males.
  • age. Thoracic outlet syndrome is most common in young adults, aged 20-40 years.


Types of thoracic outlet syndrome

There are a number of types of thoracic outlet syndrome, including:

neurogenic (neurological) thoracic outlet syndrome. 

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

thoracic outlet vascular syndrome. 

This type of thoracic outlet syndrome occurs when one or more veins (venous thoracic outlet syndrome) or arteries (arterial thoracic outlet syndrome) below the collarbone (clavicle) are compressed.

Non-specific type thoracic outlet syndrome. 

This type is also known as disputed thoracic outlet syndrome. Some doctors do not believe it exists, while others say it is a common disorder. People with the non-specific type of thoracic outlet syndrome have chronic pain in the thoracic outlet area that worsens with activity, but a specific cause of the pain cannot be determined.


Causes of thoracic outlet syndrome

In general, the cause of thoracic outlet syndrome is compression of nerves or blood vessels in the thoracic outlet, just below your collarbone (clavicle). The cause of the compression varies and may include:

  • Anatomical defects. Inherited abnormalities that are present at birth (congenital) may include an extra rib above the first rib (cervical rib) or an abnormally tight fibrous band connecting your spine to your rib.
  • Poor posture. Slumping your shoulders or holding your head in a forward position can cause compression in the thoracic outlet area.
  • trauma. A traumatic event, such as a car accident, can cause internal changes which then compress the nerves in the thoracic outlet. The onset of symptoms related to a traumatic accident is often delayed.
  • Repetitive activity. Doing the same thing over and over again can, over time, take its toll on your body tissues. You may notice symptoms of thoracic outlet syndrome if your job requires you to repeat a continuous movement, such as typing on a computer, working on an assembly line, or lifting things over your head, as you would if you were stocking shelves. Athletes, such as baseball pitchers and swimmers, can also develop thoracic outlet syndrome from years of repetitive movements.
  • Pressure on your joints. Being overweight can put an excessive amount of stress on your joints, as can carrying an oversized bag or backpack.
  • pregnancy. Because the joints loosen during pregnancy, signs of thoracic outlet syndrome may first appear while you are pregnant.


Symptoms of the thoracic outlet

The symptoms of thoracic outlet syndrome can vary, depending on which structures are compressed. When nerves are compressed, the signs and symptoms of neurological thoracic outlet syndrome include

  • Muscle atrophy in the thumb base (Gilliatt-Sumner Hand)
  • Numbness or tingling in your arm or fingers
  • Pain or soreness in the neck, shoulder or hand
  • Weaknesses of the hand

Signs and symptoms of thoracic outlet syndrome may include

  • Discolouration of your hand (bluish colour)
  • Pain and swelling in the arms, possibly due to blood clots
  • Blood clots in the veins or arteries in the upper part of your body
  • Lack of colour (pale appearance) in one or more of your fingers or in your whole hand
  • Weak or no pulse in the affected arm
  • Cold fingers, hands or arms
  • Arm fatigue with activity
  • Numbness or tingling in your fingers
  • Weakness in the arm or neck

Stabbing bump near your collarbone


Possible complications

If your symptoms are not treated early, you may experience progressive nerve damage and may need surgery. Doctors recommend surgery to treat thoracic outlet syndrome only when other treatments have not been effective. Surgery carries higher risks than other treatments and does not always treat your symptoms.


When should a doctor be consulted?

Consult your doctor if you consistently experience any of the signs and symptoms of thoracic outlet syndrome.

effective. Surgery carries higher risks than other treatments and does not always treat your symptoms.


How to diagnose thoracic outlet syndrome :

Diagnosing thoracic outlet syndrome can be difficult because symptoms and their severity can vary widely among people with the disorder. To diagnose thoracic outlet syndrome, your doctor may examine your symptoms and medical history and perform a physical examination.

Physical examination

Your doctor will carry out a physical examination to look for external signs of thoracic outlet syndrome, such as a depression in your shoulder, swelling or pale discolouration in your arm, abnormal pulses or limited range of movement.

Medical history 

Your doctor will probably ask you about your medical history and symptoms, as well as your occupation and physical activities.

Provocative tests

Challenge tests are designed to try to reproduce your symptoms. The tests can help your doctor determine the cause of your condition and help rule out other causes that may have similar symptoms.

During these tests, your doctor may ask you to move your arms, neck or shoulders in various positions. Your doctor will check your symptoms and examine you in different positions.

Image and Nerve Study Tests

To confirm the diagnosis of thoracic outlet syndrome, your doctor may order one or more of the following tests:

  • X-ray. Your doctor may ask you to have an X-ray of the affected area, which may reveal an extra rib (cervical rib). X-rays can also rule out other conditions that may be causing your symptoms.
  • ultrasound. Ultrasound uses sound waves to create images of your body. Doctors can use this test to see if you have thoracic outlet syndrome or other vascular problems.
  • Computed tomography (CT). A CT scan uses X-rays to obtain cross-sectional images of your body. A dye can be injected into a vein to see the blood vessels in more detail (ct angiography). A CT scan can identify the location and cause of compression of the blood (vascular) vessels.
  • Magnetic resonance imaging (MRI). An MRI uses powerful radio waves and magnets to create a detailed view of your body. Your doctor may use an MRI to determine the location and cause of blood vessel (vascular) compression. An MRI may reveal congenital abnormalities, such as a fibrous band connecting your spine to your rib or a cervical rib, which may be the cause of your symptoms.
  • angiography. In some cases, you may be given an intravenous dye before a CT or MRI scan. The dye helps to make the blood vessels more visible on the images.
  • Arteriography and venography. In these tests, your doctor inserts a thin, flexible tube (catheter) through a small incision, usually in your groin. The catheter is moved through your main arteries in arteriography, or through your veins in venography, to the affected blood vessels. Your doctor then injects a dye through the catheter to show X-ray images of your arteries or veins.

Doctors can check if you have a compressed vein or artery. If a vein or artery has a clot, doctors may administer medication through the catheter to dissolve the clot.

  • Electromyography (EMG). During an EMG, your doctor inserts a needle electrode through your skin into various muscles. The test assesses the electrical activity of your muscles when they contract and when they are at rest.
  • Nerve conduction study. These tests use a small amount of electrical current to test and measure the ability of your nerves to send impulses to muscles in different areas of your body. This test can determine whether you have nerve damage.



  • Thoracic outlet syndrome left untreated for years can cause permanent neurological damage, so it is important that your symptoms are assessed and treated early, or that you take steps to prevent the disorder.
  • If you are sensitive to thoracic outlet compression, avoid repetitive movements and lifting heavy objects. If you are overweight, you can prevent or relieve the symptoms associated with thoracic outlet syndrome by losing weight.
  • Even if you do not have symptoms of thoracic outlet syndrome, avoid carrying heavy bags on your shoulder as this can increase pressure on the thoracic outlet. Stretch daily and do exercises that keep your shoulder muscles strong.
  • Daily stretches focusing on the chest, neck and shoulders can help improve shoulder muscle strength and prevent thoracic outlet syndrome.