Thoracic outlet syndrome

What is thoracic outlet syndrome?

Thoracic outlet syndrome (TOS) happens when the nerves or blood vessels running from your neck to your arm get squashed in the narrow space near the top of your ribs. This squeezing, called compression, can cause pain, numbness and other symptoms in your neck, shoulder, arm or hand.

What are the symptoms of thoracic outlet syndrome?

Thoracic outlet syndrome usually affects one arm and hand, and symptoms can vary depending on whether a nerve or a blood vessel is being squashed. You may notice:

• pain along the top of your collarbone and shoulder, which can spread down the inside of your arm, sometimes into your ring and little fingers
• pins and needles or numbness, which can be worse at night and wake you up
• your arm getting tired easily, especially when held overhead
• a weakening grip, or your hand feeling clumsy
• swelling and pain in the affected arm
• your hand or arm feeling cold, or looking blue, grey or pale (this can be harder to see on brown or black skin).

Symptoms caused by a squashed blood vessel are less common than nerve symptoms, but tend to include heaviness, swelling and colour changes in the arm.

What causes thoracic outlet syndrome, and who is at risk?

Thoracic outlet syndrome happens when the space that nerves and blood vessels pass through, between your collarbone and first rib, becomes too narrow. Things that can lead to this include:

• being born with an extra rib (a cervical rib) or other differences in your bones or muscles
• poor posture, such as slouched or rounded shoulders
• an injury to your chest, neck or ribs, such as whiplash from a car accident, or a fractured collarbone
• jobs or activities with lots of repetitive arm movements, such as swimming, or occupations like building work
• gaining a lot of muscle, for example from weightlifting
• having large breasts, or being overweight, both of which can affect your posture.

Thoracic outlet syndrome affects women about three times as often as men.

Are there different types of thoracic outlet syndrome?

Yes. Doctors group thoracic outlet syndrome by which structure is being squashed:

• Neurogenic TOS, which affects the nerves; this is by far the most common type, making up about 95% of cases, and usually starts with repetitive strain or a sudden neck injury such as whiplash.
• Venous TOS, which affects the vein carrying blood away from your arm; this is more common in men in their 20s or 30s and can lead to blood clots.
• Arterial TOS, which affects the artery carrying blood to your arm; this is the rarest type, but is more likely to be linked to a cervical rib and is more common in women.

How is thoracic outlet syndrome diagnosed?

Thoracic outlet syndrome can be difficult to diagnose, since there's no single test for it and other conditions, such as a slipped disc in the neck or carpal tunnel syndrome, can cause similar symptoms.

Your doctor will ask about your symptoms and medical history, and examine your arms, chest and neck. They may ask you to lift your arms or move your head into certain positions to see if this brings on your symptoms. You may also be referred for:

• an X-ray, to look for an extra rib or other bone problems
• a CT or MRI scan, for more detailed images
• electromyography (EMG), which checks how well the nerves and muscles in your arm are working
• an ultrasound or other tests of your blood vessels, if a vein or artery is suspected.

How is thoracic outlet syndrome treated?

Treatment depends on which type of thoracic outlet syndrome you have and how severe your symptoms are.

Non-surgical treatment

• physiotherapy, which teaches you stretching and strengthening exercises to reduce pressure on the nerves and blood vessels; this is usually tried first, and most people with nerve-related TOS see an improvement
• medicines such as anti-inflammatory painkillers, muscle relaxants, or medicines that improve circulation and reduce the risk of blood clots
• practical changes, such as taking rest breaks, avoiding heavy lifting, adjusting your seatbelt strap, and losing weight if you're overweight
• for a blood clot, medicine given through a drip to dissolve the clot and help prevent new ones forming

For nerve-related TOS, physiotherapy and other non-surgical treatment is usually tried for at least four to six months before surgery is considered.

Surgical treatment

Surgery is usually a last resort for nerve-related TOS, but is often needed when a blood vessel is affected. Depending on the cause, your surgeon may:

• remove an extra rib (cervical rib), if this is causing the compression
• remove part of your first rib and a neck muscle (the scalene muscle), to create more space
• release scar tissue or tight muscle around the compressed nerve
• repair or replace a damaged section of a blood vessel.

Most people who have surgery for TOS stay in hospital overnight and need two months or more of physiotherapy afterwards to rebuild strength in the shoulder.

When should I see a doctor?

See a GP if you think you have thoracic outlet syndrome.

Ask for an urgent GP appointment, or call 111, if you have throbbing or cramping pain, swelling, redness and warmth in one arm. These could be signs of a blood clot, which can be life-threatening if not treated quickly.

Call 999 if you have sudden breathlessness, sharp chest pain that's worse when you breathe in, and a cough or coughing up blood.