Thoracic Outlet Syndrome (TOS)

Overview

The thoracic outlet is the narrow space between the base of the neck and the armpit, bordered by the collarbone, the first rib and the scalene muscles at the side of the neck. The bundle of nerves that supplies the arm (the brachial plexus) and the main artery and vein to the arm all pass through it. Thoracic outlet syndrome (TOS) describes symptoms caused when these structures are squeezed or irritated in that space.

By far the most common form is neurogenic TOS, where the nerves are irritated. It typically causes tingling, pins and needles, aching or a heavy, tired feeling in the arm and hand — often towards the ring and little fingers — together with aching in the neck, above the collarbone or around the shoulder blade. Symptoms are usually worse with the arms raised overhead, when carrying bags or a rucksack on the shoulder, or at the end of a long day at a desk, and ease when the arms are rested and supported.

Vascular forms of TOS, where the vein or artery is compressed, are rare. They can cause arm swelling, a bluish, pale or cold hand, or a sudden heavy, painful arm, and need prompt medical care rather than physiotherapy. Because neurogenic TOS can look like a trapped nerve in the neck, carpal tunnel syndrome or an elbow nerve problem, a careful assessment matters. Many people with neurogenic TOS improve with posture, breathing and strengthening work over a period of months, although outcomes vary.

Causes and risk factors

• A drooping, rounded-shoulder posture with the head held forward
• Tight scalene and chest muscles that narrow the space
• Repetitive overhead work or sport such as swimming, volleyball, tennis and overhead lifting
• Carrying heavy bags or a rucksack on one shoulder
• A previous neck injury such as whiplash, or a collarbone fracture
• Anatomical differences such as an extra rib in the neck (cervical rib)
• Shallow upper-chest breathing that keeps the neck muscles working all day

How we may be able to help

Assessment comes first. We examine the neck, shoulder and shoulder blade, test the nerves along the arm, and use specific arm positions to see whether they reproduce your symptoms. We also look for other causes, such as a trapped nerve in the neck or nerve compression at the elbow or wrist, and check the colour, temperature and pulses of the arm. If anything suggests a vascular problem, we direct you to urgent medical care. If the diagnosis is unclear, or there is weakness or muscle wasting, we can arrange an online private GP consultation for nerve conduction studies, imaging or a specialist opinion.

For neurogenic TOS, physiotherapy aims to open up and calm the thoracic outlet. This usually combines strengthening of the muscles that lift and support the shoulder blade, gentle stretching of the scalene and chest muscles, nerve gliding exercises, breathing retraining, and practical advice on your workstation, sleeping position and how you carry bags. Manual therapy for the upper back and first rib may help ease stiffness, and dry needling can be used for tight, tender muscles across the shoulders and upper back.

Our chiropractor can mobilise or manipulate a stiff neck, upper back or first rib where assessment shows it is suitable, which many people find eases the load on the area. A 3D posture scan can show how your head, shoulders and shoulder blades sit, which helps target your exercise programme.

What you can do at home

• Carry bags in your hand or use both rucksack straps, and lighten the load where possible
• Avoid sleeping with your arms above your head; rest the arm on a pillow instead
• Set up your desk so your forearms are supported and your shoulders can relax
• Practise gentle shoulder blade setting and shoulder rolls through the day
• Try slow breathing into the lower ribs and tummy for a few minutes, twice a day
• Break up overhead tasks and lower your arms to rest between sets