Thoracic outlet syndrome

Also called TOS

Nerves or vessels squeezed between the collarbone and first rib. Difficult to diagnose, easy to dismiss, and the vascular form is dangerous.

What it is

Compression of the nerves or blood vessels in the narrow space between the collarbone and the first rib.

There are three forms and they are very different.

**Neurogenic**, over 90 per cent of cases, compresses the brachial plexus, causing arm pain, numbness, tingling and weakness, typically worse with the arms raised. It is difficult to diagnose objectively, tests are often normal, and people are frequently told nothing is wrong or given a diagnosis of anxiety or fibromyalgia.

**Venous**, sometimes called Paget-Schroetter syndrome, causes a clot in the vein under the collarbone, with a suddenly swollen, blue, heavy arm, often in a young person after repetitive overhead activity. It is a deep vein thrombosis of the arm and needs urgent treatment.

**Arterial** is rarest and most dangerous, causing a cold, pale, painful arm, and can cause clots travelling to the hand.

A cervical rib, an extra rib present from birth, is present in some cases, and posture, previous collarbone fracture and repetitive overhead work all contribute.

First-line treatment for the neurogenic form is physiotherapy focused on posture and the shoulder girdle, over months. Surgery is reserved for the vascular forms and for neurogenic cases that fail.

Signs you might notice

Neurogenic: aching in the neck, shoulder and arm; numbness and tingling, often in the ring and little fingers; weakness and clumsiness; symptoms worse with the arms raised, carrying bags, or overhead work; and worse as the day goes on.

Venous: sudden swelling of the whole arm, a blue or dusky colour, heaviness, and prominent veins over the shoulder and chest. **This is urgent.**

Arterial: a pale, cold, painful arm; weak pulse; and sometimes painful spots in the fingertips. **This is an emergency.**

999 or urgent assessment: a suddenly swollen blue arm, or a cold pale painful arm.

Also assess: progressive weakness or wasting of the hand muscles, which suggests significant nerve compression.

Distinguish from carpal tunnel syndrome, cervical spondylosis and rotator cuff problems, which are far more common.

How it can affect day-to-day life

The neurogenic form is the definition of a contested diagnosis, and people commonly spend years being investigated and disbelieved. Being taken seriously and given a structured rehabilitation programme is what most need.

Daily activities that provoke it are usually identifiable: carrying bags on the shoulder, sleeping with arms overhead, hairdressing, painting, playing instruments, and computer work with poor support.

Practical changes help more than they sound: a rucksack rather than a shoulder bag, arm support at the desk, and avoiding overhead work during flares.

Physiotherapy takes months, and people give up early. Explaining the timescale changes adherence.

For the venous form, treatment is anticoagulation plus, usually, surgery to remove the first rib, and it is generally in young, otherwise healthy people who are shocked by the diagnosis.

Surgery for the neurogenic form has variable results and should follow a proper trial of rehabilitation.

Supporting someone well

Get a suddenly swollen blue arm, or a cold pale arm, assessed urgently.

Ask for a structured physiotherapy programme for posture and the shoulder girdle, and give it months.

Change what provokes it: rucksack instead of shoulder bag, desk and arm support, fewer overhead tasks.

Avoid sleeping with the arms above the head.

Ask about a chest X-ray to look for a cervical rib.

Ask for nerve conduction studies and imaging to exclude the commoner causes rather than as proof of this one.

Be cautious about surgery for the neurogenic form without a full rehabilitation trial.

Ask for the diagnosis to be taken seriously; being disbelieved is the common experience and it is not clinically useful.

Where to get help

A GP practice for assessment and physiotherapy referral.

Urgent vascular assessment for a swollen blue arm or a cold pale arm.

A specialist thoracic outlet or peripheral nerve service for difficult cases.

Chartered Society of Physiotherapy for rehabilitation information.