Thoracic Outlet Syndrome (TOS) is a group of conditions where nerves and/or blood vessels get compressed as they travel from the neck into the arm through a narrow space called the thoracic outlet. This space sits between your collarbone (clavicle) and first rib, and it is also bordered by muscles such as the scalene muscles in the neck and pectoralis minor near the front of the shoulder.
The key structures that can be affected include the brachial plexus (a network of nerves that controls sensation and movement in the arm and hand), the subclavian vein, and the subclavian artery. When compression occurs, symptoms can range from tingling and arm heaviness to swelling or coldness of the hand, depending on what is being compressed.
For most people, TOS is not dangerous, but it can be frustrating and function-limiting. Everyday tasks such as desk work, carrying a backpack, driving, lifting, or sustained overhead work (hanging washing, painting, hairdressing, childcare, sport training) can trigger symptoms. Some people describe symptoms that “don’t follow a neat nerve map”, which is a common feature of neurogenic TOS.
Physiotherapists play a central role in recognising suspected TOS, ruling out other common causes of arm and neck symptoms (such as cervical radiculopathy, carpal tunnel syndrome, or shoulder pathology), and delivering physiotherapy for thoracic outlet syndrome focused on reducing compression and improving function. TOS symptoms often respond best to a targeted plan that addresses posture, breathing mechanics, neck and shoulder control, and gradual exposure to provoking activities rather than simply resting.
It is also important to know that TOS is a spectrum. Some people have primarily “nerve symptoms” (neurogenic TOS), while others have vein or artery compression that needs more urgent medical assessment. A physiotherapist can help identify red flags early and refer appropriately.
Key Facts
- TOS is an umbrella term for symptoms caused when nerves or blood vessels get compressed as they travel from the neck into the arm. 🔗
- TOS can affect nerves or blood vessels, which is why symptoms can range from pain and tingling to colour changes or swelling in the arm. 🔗
- Neurogenic TOS is by far the most common type, making up well over 90% of cases. 🔗
- Arterial TOS is very rare (around 1% of cases), but is important because it can involve reduced blood flow to the arm. 🔗
- Because common tests like the Adson’s test can produce false positives, TOS diagnosis is usually based on a combination of clinical assessment and modern imaging (such as MRI, CT angiography, or dynamic ultrasound) to improve accuracy and guide management. 🔗
Risk Factors
- Repetitive overhead sport or work (throwing athletes, swimmers, trades, hairdressers, manual workers, childcare).
- Prolonged desk-based work with poor ergonomics and limited movement breaks.
- Postural tendencies such as rounded shoulders and forward head posture, especially when combined with weak scapular control.
- Previous trauma (for example whiplash, clavicle fractures, or shoulder girdle injuries) that changes tissue tone or mechanics.
- Anatomical variations such as cervical ribs or fibrous bands (a cervical rib is present in roughly 0.5 to 1.5% of the population).
- High training loads without adequate recovery, especially when strength and control around the shoulder blade are underdeveloped.
Symptoms
- Pins and needles, numbness, or tingling in the arm, hand, or fingers, often worse with overhead positions (neurogenic-type symptoms).
- Aching pain in the neck, shoulder, chest, or arm, sometimes described as a deep “heaviness” rather than a sharp pain.
- Weakness, clumsiness, or reduced grip endurance (dropping objects, hand fatigue with typing or tools).
- Symptoms that do not match a single nerve root pattern (for example, widespread hand tingling rather than a neat dermatome).
- Headache, upper shoulder tension, or a “tight band” sensation around the neck and shoulder girdle.
- Arm swelling, bluish colour, or prominent superficial veins near the shoulder/chest (more suggestive of venous TOS and requires medical review).
- Cold, pale hand, cramping with use, or reduced pulse changes (more suggestive of arterial involvement and requires urgent medical assessment).
Aggravating Factors
- Prolonged overhead activities (hanging washing, painting, hair work, gym presses, swimming or throwing) that hold the arm in abduction and can increase compression.
- Sustained desk posture with rounded shoulders and forward head position, especially without regular movement breaks.
- Carrying heavy loads, particularly backpacks, shoulder bags, or tools that drag the shoulder down and narrow the space under the collarbone.
- Repetitive shoulder work (manual handling, hospitality, trades, childcare), especially when combined with poor recovery and high weekly volume.
- Stress and shallow breathing patterns that keep the neck/scalene muscles overactive, which can increase symptom sensitivity in some people.
Causes
TOS usually develops when the space in the thoracic outlet becomes crowded or when tissues around the outlet become sensitive and overactive. There are three broad types, based on what structure is compressed:
Neurogenic TOS involves irritation or compression of the brachial plexus and is the most common presentation. It often causes tingling, numbness, pain, and weakness that is worse with overhead positions or sustained postures. Symptoms can be widespread and inconsistent, which is one reason diagnosis can be challenging.
Venous TOS involves compression of the subclavian vein. This can cause swelling, heaviness, colour change, and sometimes prominent veins around the shoulder or chest. If symptoms appear suddenly or there is concern for clotting, this needs urgent medical assessment.
Arterial TOS involves the subclavian artery and can present with a cold or pale hand, reduced endurance with arm use, cramping, or in severe cases skin changes in the fingers. This is less common but potentially more serious, and it needs prompt medical review.
Why does compression happen? In many cases, it is a mix of anatomical and functional factors. Some people have bony or fibrous variations such as a cervical rib or bands that reduce available space. Others develop TOS after trauma (for example whiplash or a clavicle fracture), or through a gradual build-up of muscle tightness and altered shoulder mechanics. Rounded shoulders, a forward head posture, a stiff upper back, and overactive neck muscles can all reduce the “room” for nerves and vessels. Repetitive overhead work and heavy load carriage can further narrow the outlet.
From a physiotherapy perspective, this is good news: many of the functional drivers are modifiable. Thoracic outlet syndrome physiotherapy typically focuses on reducing the compressive positions, improving thoracic and shoulder mobility, restoring strength and endurance of key stabilisers (particularly the scapular muscles), and calming neural sensitivity with graded exposure rather than repeated provocation.
How Is It Diagnosed?
TOS is primarily a clinical diagnosis supported by a detailed history, physical examination, and appropriate investigations to rule out other causes. This is important because there is no single test that definitively confirms neurogenic TOS, and provocative tests can be positive in people without TOS.
A physiotherapist assessment typically includes:
1) A symptom map and behaviour pattern. Your physio will clarify where symptoms are felt, what triggers them (overhead work, desk posture, carrying loads), and whether symptoms are more consistent with nerve irritation (tingling, burning, heaviness, weakness) or vascular issues (swelling, colour change, coldness).
2) Posture, breathing, and shoulder mechanics. Many people with neurogenic TOS have an over-reliance on neck muscles (including scalenes) to stabilise the shoulder. A physio will assess rib cage position, upper back mobility, scapular control, and how the neck behaves during arm movement.
3) Neurological and vascular screening. This can include strength testing, sensation checks, reflexes, and screening of pulses and colour changes. If your symptoms suggest venous or arterial TOS, your physio should recommend prompt medical review.
4) Provocative tests and neurodynamic testing. Tests such as the Roos (EAST) test, Adson’s manoeuvre, costoclavicular tests, and upper limb neurodynamic tests may be used, but they must be interpreted cautiously. The reason is that these tests can reproduce symptoms in other conditions and can have false positives. A Roos test summary citing Gillard et al. (2001) reports sensitivity around 84% and specificity around 30%, which illustrates why tests are not used in isolation.
A physiotherapist can also help identify when symptoms are more consistent with cervical radiculopathy, peripheral nerve entrapment, shoulder pathology, or systemic contributors. If the picture is unclear, referral to a GP or specialist for investigations is often appropriate.
Investigations & Imaging
- Chest X-ray
- Used to identify bony contributors such as a cervical rib or abnormal first rib shape, and to support the broader clinical picture.
- Nerve conduction studies / EMG
- Can help rule out other nerve conditions (for example carpal tunnel syndrome or cervical radiculopathy). These tests may be normal in many neurogenic TOS presentations and are often more useful for differential diagnosis rather than confirming TOS on their own.
- MRI of the cervical spine
- Used to assess for disc or degenerative changes that could explain arm symptoms. This is especially relevant when symptoms behave like nerve root irritation.
- MRI shoulder
- Used when shoulder pathology is suspected as a primary or contributing source (for example rotator cuff-related pain).
- Duplex ultrasound with provocative manoeuvres
- More relevant for suspected vascular TOS, to assess venous/arterial compression and to identify thrombosis in venous TOS.
- CTA or MRA with arms at sides and in hyperabduction
- Used in suspected vascular TOS to map anatomy and compression patterns and assist surgical planning when required.
Grading / Classification
- Neurogenic TOS (nTOS)
- Compression or irritation of the brachial plexus. Typically causes pain, tingling, heaviness, and weakness that often worsens with overhead activity and does not neatly match a single dermatome. This is the most common form and most likely to respond to targeted thoracic outlet syndrome physiotherapy.
- Venous TOS (vTOS)
- Compression of the subclavian vein. Presents with swelling, heaviness, venous congestion, and sometimes cyanosis. Sudden swelling or suspected clotting requires urgent medical assessment.
- Arterial TOS (aTOS)
- Compression of the subclavian artery. Presents with hand coolness, pallor, exertional cramping, or signs of ischaemia. This is less common and can be more serious, requiring prompt medical evaluation.
Physiotherapy Management
Physiotherapy for thoracic outlet syndrome is the first-line approach for most people with neurogenic TOS. The aim is to reduce compression of the neurovascular bundle by improving how the rib cage, collarbone, shoulder blade, and neck share load during posture and arm movement. Physiotherapy also targets nerve sensitivity, which can be a major driver of symptoms even when structural compression is mild.
High-quality TOS rehab is rarely “one exercise”. It usually combines postural retraining, breathing mechanics, thoracic mobility, scapular control, and a progressive return to the activities that trigger symptoms (overhead work, desk work, carrying loads). A useful way to think about it is: create more space, reduce irritation, then build tolerance.
Physiotherapy is also essential for triage. If symptoms suggest venous or arterial involvement (arm swelling, colour change, cold/pale hand, reduced pulses), a physiotherapist should recommend immediate medical assessment rather than trying to treat the presentation as a routine shoulder or neck problem.
Exercise
Physiotherapy exercises are selected based on what is driving compression in your case. For many people with neurogenic TOS, the focus is on three pillars: thoracic mobility, scapular control, and neck control.
Thoracic mobility and rib cage mechanics: A stiff upper back can keep the shoulder blade stuck in a forward-tilted, rounded position. This can narrow the thoracic outlet during reaching and overhead work. Your physio may prescribe gentle thoracic extension drills, upper back rotation, and rib cage expansion work. Breathing matters here. If you primarily breathe into the upper chest and neck, the scalenes and accessory muscles can become overactive, which may increase symptoms. Retraining a calmer, lower-rib breathing pattern can reduce neck loading and improve tolerance of posture work.
Scapular control and endurance: Many people with TOS have poor endurance in the lower trapezius and serratus anterior, leading to a shoulder blade that sits forward and upwardly shrugged. Rehab often starts with low-load scapular setting, wall-based serratus drills, and controlled rowing patterns, then progresses to functional strength for work and sport. The emphasis is usually on quality and endurance rather than maximal strength early on, because sustained positions are often the trigger.
Neck control: Deep neck flexor training (for example, chin tuck variations) can reduce overactivity of the superficial neck muscles. This does not mean forcing a rigid posture. It means improving your ability to control head and neck position during arm movement, lifting, and desk work without gripping through the scalenes.
As symptoms improve, your physiotherapist should progress you back to overhead tasks with graded exposure. This might look like short, controlled overhead sets with plenty of recovery at first, gradually building time under tension and weekly volume. That progression is often what makes the difference between temporary improvement and long-term change.
Activity Modification
Activity modification is a practical part of TOS rehab, especially early on. The goal is not to avoid using your arm forever. The goal is to reduce symptom-provoking positions long enough to build capacity safely.
For overhead triggers, your physio may recommend temporarily limiting long holds above shoulder height and switching to shorter sets with breaks. For desk triggers, changes might include raising the screen, supporting the forearms, reducing reaching for the mouse, and scheduling brief movement breaks to reset shoulder position. If carrying loads triggers symptoms, using a two-strap backpack (worn higher), reducing weight, and avoiding single-strap bags can reduce traction on the shoulder girdle. Manual workers may benefit from task rotation and staged return to high-risk duties.
A key feature of successful physiotherapy for thoracic outlet syndrome is learning pacing. Many people feel okay during an activity and flare later. Your physiotherapist can help you find your current threshold, then build it gradually so your weekly activity becomes more consistent and less flare-driven.
Manual Therapy
Manual therapy can support thoracic outlet syndrome physiotherapy when it is used to enable better movement patterns rather than as a stand-alone fix. A physiotherapist may use soft tissue techniques to reduce guarding in the scalenes, pectoralis minor, upper trapezius, and levator scapulae if these tissues are contributing to symptom provocation. Gentle joint mobilisation of the thoracic spine can improve extension and rotation, which can make postural work and overhead control exercises easier.
First rib mobility is often discussed in TOS, but it should be approached carefully and only where clinically appropriate. The goal is not aggressive manipulation. The goal is to reduce stiffness and improve how the upper chest and shoulder move together. Manual techniques are commonly paired with breathing and scapular drills so that any mobility gain is “locked in” by improved control.
Manual therapy should always be symptom-guided. If a technique reliably reproduces nerve symptoms in a way that lingers, it is usually a sign to modify approach and prioritise graded exercise and neural sensitivity strategies.
Postural Retraining
Postural retraining is a core feature of physiotherapy for thoracic outlet syndrome, but it should be realistic. The aim is not “perfect posture” all day. The aim is to reduce sustained compressive positions and improve your ability to change positions frequently without symptoms.
Common patterns in neurogenic TOS include forward head posture, rounded shoulders, and a rib cage that sits high, encouraging neck muscle overuse. Your physiotherapist may work on rib cage positioning, breathing mechanics, and scapular setting so you can sit and stand with less neck tension. This often includes workstation advice and “micro-break” routines that take under one minute to perform but are done multiple times across the day.
For people with sport or gym triggers, postural retraining is integrated into technique. This might mean changing how you set the shoulder blade for pressing and pulling, improving thoracic extension for overhead lifts, and reducing the tendency to shrug during effort.
Bracing & Taping
Bracing is not commonly the main strategy for TOS, but taping can be useful in selected cases as a short-term aid to postural awareness and shoulder blade positioning. For example, scapular or postural taping can provide a gentle reminder to avoid sustained rounding and shrugging, which can reduce symptom frequency while you build strength and endurance.
In physiotherapy for thoracic outlet syndrome, taping is typically used as a bridge, not a dependency. The long-term goal is improved control and tolerance without external support. If taping makes symptoms worse (for example, by adding pressure over a sensitive area), it should be modified or avoided.
Ergonomic supports, such as forearm supports at a desk, can sometimes act like a “brace for posture” by reducing sustained load through the shoulder girdle. A physio can help you choose options that reduce compression without creating stiffness through over-support.
Heat & Ice
Heat and ice can be used for symptom relief in some people with TOS, but they are not curative. Heat may help reduce muscle guarding around the neck and upper shoulder, which can make it easier to perform mobility and control exercises. Ice may be useful if symptoms flare after activity and there is a strong pain component.
Your physiotherapist can guide how to use these tools so they support rehab rather than replace it. If symptoms are primarily neurological (tingling, numbness), the priority is usually activity modification and graded loading rather than relying on passive modalities alone.
Tens
TENS can be considered as part of pain management when symptoms are limiting sleep or participation in exercise. It does not change compression mechanics, but it may reduce pain sensitivity in some people and allow better engagement with TOS rehab.
If a physiotherapist uses TENS in thoracic outlet syndrome physiotherapy, it should be paired with the active plan: posture and breathing work, scapular endurance training, and graded return to overhead activity. TENS is most helpful when it supports movement and function, not when it becomes the only strategy.
Education
Education is one of the most valuable parts of physiotherapy for thoracic outlet syndrome. TOS can be confusing and worrying, especially when symptoms include numbness, weakness, or vascular-type changes. A physiotherapist can explain what is likely happening in your case, what red flags require medical review, and what a realistic rehab timeline looks like.
Education typically includes: recognising aggravating positions, understanding why prolonged overhead holds often trigger symptoms, learning pacing strategies to avoid “boom-bust” cycles, and understanding that provocative tests can be misleading if used alone. This is why physiotherapists combine tests with symptom history, movement assessment, and screening for other diagnoses.
Education also includes self-management skills, such as short movement breaks, breathing drills to reduce neck overactivity, gradual exposure plans for the tasks you need to return to, and how to track progress using function-based markers (time at the desk, time overhead, load carried, sport tolerance) rather than pain alone.
Other
Other strategies used in thoracic outlet syndrome physiotherapy may include neurodynamic techniques and specific stretching, but they must be used carefully. If the brachial plexus is sensitive, aggressive nerve stretching can flare symptoms. A physiotherapist may choose gentle nerve “sliders” rather than long holds, and only within a symptom-safe range.
Targeted stretching is often directed at pectoralis minor/major, scalenes, levator scapulae, and upper trapezius if these muscles contribute to rounded shoulders and neck tension. Stretching is generally most effective when paired with strengthening and posture training so you do not return to the same compressive resting position.
Work and sport conditioning is also a major piece. Many people improve on basic exercises but relapse when they return to overhead tasks or heavy carrying. A physiotherapist can build task-specific capacity using graded exposure, technique adjustments, and endurance-based strengthening so your improvements hold in real life.
Other Treatments
Other treatments depend on the type and severity of TOS.
Medication may include anti-inflammatories for pain relief, muscle relaxants in selected cases, or neuropathic pain medications when nerve pain is severe and persistent. Medication decisions should be guided by a GP or specialist, and they generally work best when combined with physiotherapy-based rehabilitation rather than used as a stand-alone solution.
Injections can be considered in resistant cases, sometimes including botulinum toxin injections into tight or overactive scalene muscles under specialist care. In some pathways, response to a scalene block may help predict benefit from surgical decompression, particularly when the diagnosis remains challenging and symptoms are severe.
Vascular management for venous or arterial TOS can include anticoagulation, thrombolysis, or surgical management depending on presentation. These are medical emergencies or urgent specialist issues rather than physiotherapy-led care. A physiotherapist’s role is to recognise the presentation and refer appropriately, then support rehabilitation as part of the broader care plan.
Surgery
Surgery is not the first step for most people with neurogenic TOS, because many improve with targeted physiotherapy and lifestyle changes. Surgery is usually considered when symptoms remain disabling despite a well-structured conservative program, or when there is significant vascular compromise.
Surgical options vary depending on the type of TOS and the surgical approach. Procedures may include first rib resection, scalenectomy (removing part of the scalene muscles), and decompression of the neurovascular structures. Vascular TOS may also involve vascular reconstruction or management of thrombosis.
Physiotherapy remains important both pre-operatively and post-operatively. Pre-operative physio focuses on optimising thoracic mobility, scapular control, posture, and conditioning so recovery is smoother. Post-operative physio helps restore shoulder and neck movement, reduce protective guarding, address scar and soft tissue mobility as appropriate, rebuild strength and endurance, and progressively return to work and sport tasks. Post-operative rehab should be guided by the surgical team’s protocols and the individual’s symptom response.
Prognosis & Return to Activity
The prognosis for TOS depends on the type and how early it is identified. Most people with neurogenic TOS can improve with a targeted physiotherapy program and activity modification, particularly when treatment addresses both mechanics (posture, scapular control, thoracic mobility) and neural sensitivity (graded exposure rather than repeated provocation). The RACGP notes initial management is non-operative with targeted physiotherapy, with escalation options such as botulinum toxin and surgery when conservative care is unsuccessful.
For vascular TOS (venous or arterial), prognosis is strongly linked to timely medical diagnosis and management, especially when thrombosis or ischaemia is a risk. Early recognition improves outcomes and reduces the likelihood of long-term complications.
Return to activity is usually best managed as a staged process. Many people flare when they jump straight back into long overhead holds, heavy carrying, or high-volume training. A physiotherapist can create a graded return plan using measurable exposure targets (time overhead, load carried, desk tolerance) so progress is steady and setbacks are less frequent.
Complications
- Persistent nerve irritation leading to chronic pain, ongoing tingling, and reduced hand endurance if neurogenic symptoms are not addressed early and progressively.
- Functional limitations at work or sport due to reduced overhead tolerance, reduced grip endurance, and avoidance of provoking activities.
- Deconditioning and increased neck/shoulder muscle guarding from prolonged avoidance, which can amplify symptoms and widen the pain area over time.
- In venous TOS, risk of thrombosis and complications if swelling and venous congestion are not assessed promptly (medical emergency pathways apply).
- In arterial TOS, risk of ischaemic complications in severe cases if arterial compression is not managed promptly.
Preventing Recurrence
- Build overhead tolerance gradually. Increase time and load above shoulder height in small steps rather than doing long holds or big volume jumps, as overhead abduction commonly increases compression and triggers symptoms.
- Maintain scapular endurance and upper back mobility long-term. Continuing your thoracic outlet syndrome physiotherapy exercises (especially lower trapezius/serratus endurance and thoracic mobility) helps keep the outlet as open as possible during daily life.
- Avoid heavy single-strap bags and reduce traction loads. Use a two-strap backpack worn higher, reduce carrying weight, and break loads into smaller trips to reduce downward pull on the shoulder girdle.
- Use desk micro-breaks to prevent sustained compression. Brief movement resets (30 to 60 seconds) repeated through the day can reduce the build-up of symptoms more effectively than one long stretch session.
- Keep breathing mechanics calm under load. If you tend to “breathe into the neck” during stress or exercise, practise lower-rib breathing strategies taught by your physiotherapist to reduce scalene overactivity.
When to See a Physio
- You have arm tingling, heaviness, or pain that consistently worsens with overhead activity or prolonged posture, and you want assessment and a thoracic outlet syndrome rehab plan.
- You have symptoms that are not behaving like a single pinched nerve, or you have recurrent symptoms despite resting, and you need help differentiating TOS from other conditions.
- You are getting headaches, neck tension, or shoulder heaviness linked with arm symptoms, and you suspect posture and shoulder control may be contributing.
- You are returning to gym, overhead sport, or manual work and need a graded exposure plan to prevent flare-ups.
- You have arm swelling, colour change, coldness, or vascular-type symptoms. A physiotherapist can screen and refer urgently to a GP or emergency care when appropriate.