Cervical Rib and Thoracic Outlet Syndrome (TOS)

Thoracic outlet syndrome (TOS) causes symptoms in the arm from pressure on the structures running between the collarbone and the first rib — the thoracic outlet. It’s easily confused with other conditions that compress nerves and blood vessels in the neck and arm. One cause of TOS is a cervical rib. So what is a cervical rib, what is thoracic outlet syndrome, and how do we treat them?

What is a cervical rib?

The rib cage usually contains 12 ribs. A cervical rib is an extra rib arising from the cervical (neck) spine, sitting above the first rib. These extra ribs grow from the transverse process of the C7 vertebra, and occur in less than 1% of the population.

Most cervical ribs cause no problems at all. But in some people, the extra rib narrows the thoracic outlet and contributes to thoracic outlet syndrome.

What is thoracic outlet syndrome?

A complex set of nerves and blood vessels passes through a gap — the outlet. Its boundaries are the first rib of the chest wall, the collarbone, and the scalene muscles of the neck. Pressure on these structures produces a range of symptoms, from a pinched nerve (pins and needles, numbness, weakness, and pain) to pinched vessels (swelling, discolouration, and temperature changes).

Causes of thoracic outlet syndrome

Pressure in the outlet can come from trauma or overuse:

Trauma — for example, a broken collarbone, where bone pushes into the outlet

Overuse — repetitive overhead movements or sports

A cervical rib, or a prominent first rib, narrowing the outlet

Types of thoracic outlet syndrome

Symptoms depend on which structure is compressed. There are three types:

Neurogenic — pinching of the brachial plexus nerves, causing pins and needles, numbness, and clumsiness or weakness of the hand. Pain sometimes extends to the chest, under the armpit, or into the head. This is by far the most common type.

Arterial — compression of the subclavian artery, causing coldness, numbness, and pain in the fingers.

Venous — compression of the subclavian vein, causing swelling of the arm, enlarged chest veins, and a heavy sensation in the arm.

How is thoracic outlet syndrome diagnosed?

A thorough examination confirms the picture and excludes other causes. We start with a full neck, arm, and wrist assessment — pressing on the compressed structures in the neck or chest can reproduce symptoms. We then use provocation tests (Roos’s and Adson’s tests) to check the wrist pulse in certain arm positions; loss of the pulse suggests TOS. Nerve testing is essential to look for a pinched nerve and other causes.

Further tests usually include an MRI of the neck and outlet, nerve conduction studies, and blood-vessel studies. Sometimes a local anaesthetic injection near the neck helps localise the site of pressure.

A difficult diagnosis

Diagnosis is often difficult, because early symptoms mimic other conditions — most commonly a pinched nerve in the neck from a herniated disc, or carpal tunnel syndrome.

Thoracic outlet syndrome or cervical radiculopathy?

Telling these two apart is hard. People with cervical radiculopathy usually have a painful neck, and neck movement brings on the pain. A herniated disc doesn’t cause vascular problems such as arm discolouration, arm swelling, or fatigue with arm movement — so those features point towards TOS. Even so, separating them can be challenging.

Treatment

Cervical rib syndrome

Where a cervical rib is compressing the outlet, physiotherapy improves neck mobility and reduces muscle tension. Injections — botulinum toxin (Botox) or local anaesthetic into the scalene muscles — can reduce muscle tension too.

Surgical excision is considered if these measures fail to relieve the pressure. Surgeons sometimes also remove the scalene muscles to open the outlet further, and some believe removing both the cervical rib and the first rib gives the best result.

Thoracic outlet syndrome

We try simple treatments first, particularly for the neurogenic type:

Physiotherapy — soft-tissue massage and stretching of the pectoral, trapezius, and scalene muscles; strengthening the shoulder and rotator cuff to improve posture and open the outlet; and nerve-gliding techniques to keep the nerves moving freely.

Medication — nerve-pain medicines such as amitriptyline or duloxetine can ease the pinching symptoms.

Sleeping position — avoid positions that increase pressure on the outlet. Sleeping on your back, or with support on the affected side, helps.

When surgery is needed

Untreated TOS can cause permanent damage to the nerves and vessels, and clots can form in the veins — which can be dangerous. We generally recommend surgery if 3–6 months of physiotherapy fails, or if signs of vessel compression develop.

Frequently asked questions about a cervical rib and TOS

Does a cervical rib always cause symptoms?

No. Most cervical ribs cause no problems and are found by chance on an X-ray. Only a minority narrow the thoracic outlet enough to compress the nerves or vessels and cause symptoms.

What does thoracic outlet syndrome feel like?

Most often, neurogenic symptoms: pins and needles, numbness, and weakness or clumsiness of the hand, sometimes with pain spreading to the chest, armpit, or head. Vascular types cause a cold, discoloured, or swollen arm, and a heavy, tired feeling with arm use.

How is it different from carpal tunnel or a trapped nerve in the neck?

All three cause hand tingling, which is why TOS is easily missed. A trapped neck nerve usually comes with a painful neck that’s worse on movement; carpal tunnel affects the thumb-side fingers and is often worse at night. Vascular features — a cold, swollen, or discoloured arm — point specifically to TOS. Nerve studies and imaging help separate them.

When should I be worried?

Seek prompt assessment for a swollen, discoloured, or cold arm, or arm swelling with prominent chest veins — these suggest vascular compression, which needs urgent attention. Progressive weakness or wasting of the hand also warrants early review.

Can thoracic outlet syndrome be treated without surgery?

Yes, in most cases. The neurogenic type usually responds to physiotherapy, posture work, nerve-gliding, and sometimes scalene injections. Surgery is reserved for cases that fail 3–6 months of treatment, or where the blood vessels are compressed.

Final word from Sport Doctor London on cervical rib and thoracic outlet syndrome

Thoracic outlet syndrome is a complex condition to diagnose, and it’s often confused with a herniated neck disc or carpal tunnel syndrome. A cervical rib is one cause, but not the only one. Early diagnosis matters, because it can prevent permanent damage to the nerves and blood vessels.

If you have arm pain, numbness, or tingling that hasn’t been explained, Dr Masci can assess you in London, including ultrasound in clinic. Contact the team here or call +44 (0) 203 488 0350.