Pain, tingling, heaviness or weakness travelling from the neck or shoulder into the arm can affect everyday activities more than people expect. You may notice it while working at a computer, driving, carrying groceries, reaching for a high shelf, exercising at the gym, or even brushing your teeth.
One possible cause is thoracic outlet syndrome (TOS). However, symptoms in the neck, shoulder, armpit, arm and hand can also come from the neck, shoulder joint, or nerves around the elbow and wrist. That is why a thorough assessment is more useful than trying to self-diagnose from a list of symptoms online.
What is thoracic outlet syndrome?
Thoracic outlet syndrome is a group of conditions involving irritation or compression of nerves and/or blood vessels as they travel from the lower neck into the arm.
The “thoracic outlet” is not one single hole. It is a region around the neck, first rib, collarbone and upper chest. The main structures passing through this area include:
- The brachial plexus: a network of nerves supplying movement and sensation to the shoulder, arm and hand
- The subclavian artery: a major artery supplying blood to the arm
- The subclavian vein: a major vein returning blood from the arm
The most common type is thought to be neurogenic thoracic outlet syndrome, where the nerves of the brachial plexus are irritated. Vascular forms of TOS—involving a vein or artery—are less common but need prompt medical assessment because they can affect circulation.
Thoracic outlet syndrome symptoms
Symptoms vary between people and may come and go. They are often affected by arm position, repeated activity and how long the arm remains in one posture.
Possible neurogenic thoracic outlet syndrome symptoms include:
- Pain, tightness or pulling around the neck, collarbone, shoulder, upper chest or armpit
- Tingling, pins and needles, numbness or burning down the arm and into the hand
- Arm heaviness, fatigue or a “dead arm” sensation
- Symptoms made worse by repeated overhead movement, carrying, gym training, driving, desk work or certain sleep positions
- Reduced confidence using the arm or hand because of pain, fatigue or weakness
- Symptoms that improve when the arm is supported on a pillow, armrest or lap
Some people have mainly shoulder and neck pain. Others notice discomfort or tingling in the forearm and hand. The location of symptoms alone does not confirm TOS because cervical nerve irritation, shoulder conditions and local nerve compression can produce similar symptoms.
What causes thoracic outlet syndrome?
For many people, there is no single identifiable cause. Symptoms may start after the nerves or blood vessels around the shoulder and neck become more sensitive to load, sustained positions or a sudden increase in activity.
Potential contributors include:
- A rapid increase in gym training, manual work or overhead sport
- Repetitive reaching, lifting or work above shoulder height
- Long periods at a computer, laptop or phone without changing position
- Carrying a heavy bag, backpack or equipment on one side
- Neck, collarbone or shoulder injury
- Reduced shoulder-blade and rotator-cuff endurance after injury or inactivity
- Less commonly, an anatomical variation such as a cervical rib
Posture can influence symptoms, but it is rarely the only explanation. There is no single “perfect posture” that prevents TOS. It is often more helpful to look at how long you remain in one position, how much load your arm is handling, your recent activity changes, recovery and sleep.
How is thoracic outlet syndrome diagnosed?
There is no single scan, blood test or physiotherapy test that proves thoracic outlet syndrome in every person. TOS is assessed by considering the full clinical picture.
A physiotherapist or doctor may assess:
- The exact symptom pattern: where symptoms begin, where they travel and what triggers them
- Whether symptoms change with neck movement, arm elevation, carrying, reaching or arm support
- Neck, upper-back and shoulder movement
- Shoulder-blade, rotator-cuff, arm and grip strength
- Sensation, reflexes and nerve sensitivity
- Arm swelling, colour change, temperature difference or circulation concerns
- Potential alternative explanations, including cervical radiculopathy, shoulder tendon conditions, carpal tunnel syndrome and ulnar nerve compression
Some arm-elevation and pulse-based tests are commonly used in TOS assessment. However, these tests can be positive in people without TOS, so they should not be used alone to make the diagnosis. The most useful assessment relates findings to your own familiar symptoms and daily activities.
Can physiotherapy help thoracic outlet syndrome?
For suspected neurogenic thoracic outlet syndrome, conservative treatment is usually the first step. Physiotherapy aims to settle sensitive symptoms and progressively restore your confidence and tolerance for work, exercise and everyday life.
Treatment may include:
- Load modification: temporarily reducing activities that strongly reproduce symptoms, such as repeated overhead work, prolonged arm-hanging, heavy carrying or high-volume upper-body training
- Positioning strategies: using a pillow under the arm when side-lying; supporting the forearm while using a mouse, phone or laptop; changing bag-carrying habits
- Comfortable movement: maintaining gentle neck, upper-back and shoulder movement within a tolerable range
- Strength and endurance training: improving shoulder-blade control, rotator-cuff capacity and general upper-body conditioning
- Nerve mobility exercises: carefully chosen nerve-gliding exercises when appropriate; these should not create strong or lasting symptoms
- Graded return to activity: building tolerance gradually, rather than avoiding all triggering movements indefinitely
A good programme is individualised. Someone whose symptoms occur during laptop work needs a different plan from someone who develops symptoms during pull-ups, swimming, or overhead lifting.
In clinic, a common early priority is finding a comfortable way to support the arm while symptoms settle, then gradually rebuilding capacity for positions that had become painful. The goal is not to avoid movement forever. It is to return safely to normal work, exercise and daily tasks.
When should I seek medical attention urgently?
Seek prompt medical assessment if you have any of the following:
- Sudden swelling in one arm, a blue/purple colour, prominent veins, a cold hand or pale fingers
- New, worsening or persistent arm/hand weakness; frequent dropping of objects; visible muscle wasting; or loss of hand control
- Numbness that is worsening, persistent or no longer changes with position
- Severe, unrelenting pain; fever; unexplained weight loss; or a significant injury
- New problems with balance, walking, symptoms affecting both arms, or changes in bowel or bladder control
These symptoms may indicate a vascular, spinal, or neurological problem that requires medical investigation rather than self-management.
The key message
Thoracic outlet syndrome is one possible cause of neck, shoulder and arm symptoms, but it is not the only one. The right diagnosis comes from understanding your symptom behaviour, examining the neck, shoulder, nerves and circulation, and ruling out other causes.
Many people with nerve-related arm symptoms improve through education, sensible activity modification, targeted strengthening and a gradual return to the activities that matter to them. The most effective plan is usually practical and personalised—not simply “sit up straight” or stop using your arm.
References
- Hock G, et al. Current Clinical Concepts: Rehabilitation of Thoracic Outlet Syndrome. Journal of Athletic Training. 2024.
- Dessureault-Dober I, Bronchti G, Bussières A. Diagnostic Accuracy of Clinical Tests for Neurogenic and Vascular Thoracic Outlet Syndrome: A Systematic Review. Journal of Manipulative and Physiological Therapeutics. 2018;41(9):789–799.
- Cohen C, et al. Physical assessment and rehabilitation for neurogenic thoracic outlet syndrome (NTOS): A scoping review. Hand Therapy. 2026.