Thoracic Outlet Syndrome (TOS): Symptoms, Causes and Physiotherapy Treatment

Have you experienced persistent arm pain, tingling or numbness without a clear explanation?

Perhaps your symptoms become worse when you reach overhead, hold your arms in one position or perform certain activities at work or in the gym.

For some people, these symptoms can be frustrating and difficult to understand, particularly when previous assessments or scans have not identified a clear cause.

One condition that may be considered is thoracic outlet syndrome (TOS).

Thoracic outlet syndrome describes a group of conditions involving the nerves or blood vessels travelling between the neck, chest and upper limb.

However, not every painful or numb arm is caused by TOS. Several other conditions can produce similar symptoms, and distinguishing between them is an important part of clinical assessment.

At RHP Physiotherapy in Kelvin Grove, Brisbane, our physiotherapists assess neck, shoulder and upper-limb symptoms to help understand their possible causes and determine whether physiotherapy, further investigation or medical referral is appropriate.

This guide explains the different types of thoracic outlet syndrome, common symptoms, how the condition is assessed and the role physiotherapy may play in management.

Understanding the Anatomy: Where Is the Thoracic Outlet?

The nerves and blood vessels supplying the upper limb travel from the neck and chest into the shoulder and arm.

Along the way, they pass through several relatively confined anatomical spaces.

Important structures include:

• Brachial plexus: A network of nerves originating from the lower cervical and upper thoracic spinal nerve roots. These nerves contribute to sensation and movement throughout the upper limb.
• Subclavian artery: Carries oxygenated blood towards the arm.
• Subclavian vein: Returns blood from the upper limb towards the heart.
• Scalene muscles: Muscles in the neck that help define one of the anatomical spaces through which the nerves and artery pass.
• Clavicle and first rib: Form boundaries of another important passage between the neck and upper limb.
• Pectoralis minor: A muscle beneath the front of the shoulder, close to another region where neurovascular structures can potentially be compressed.

The main anatomical regions considered in thoracic outlet assessment include the interscalene triangle, costoclavicular space and the region beneath the pectoralis minor.

These spaces change their shape and relationships as we move the neck, shoulder and arm.

For most people, these normal changes do not cause symptoms.

However, in some individuals, the interaction between anatomy, movement and tissue sensitivity may contribute to clinically significant nerve or vascular problems.

What Are the Three Types of Thoracic Outlet Syndrome?

The symptoms of TOS depend substantially on whether nerves, veins or arteries are primarily involved.

Understanding this distinction helps explain why some people experience tingling and weakness, while others develop swelling or changes in circulation.

Neurogenic TOS accounts for the majority of diagnosed cases, while arterial and venous presentations are less common.

However, exact proportions vary between studies and clinical populations.

1. Neurogenic Thoracic Outlet Syndrome

Neurogenic thoracic outlet syndrome, or NTOS, involves the brachial plexus.

The brachial plexus is responsible for transmitting motor and sensory information between the spinal cord and the upper limb.

People with neurogenic TOS may experience:

• Pain around the neck, shoulder or upper chest.
• Discomfort extending down the arm.
• Tingling or pins and needles.
• Numbness in the arm or hand.
• A feeling of heaviness or fatigue in the arm.
• Difficulty tolerating particular arm positions.
• Weakness or reduced hand function in some cases.

Symptoms may be particularly noticeable with overhead activity, but other sustained positions can also be troublesome.

For some people, even allowing the arm to hang beside the body for long periods can aggravate symptoms.

More significant neurological impairment may involve objective muscle weakness or wasting.

These findings require particular attention and may change the urgency of specialist referral.

2. Venous Thoracic Outlet Syndrome

Venous TOS involves the subclavian vein, which helps return blood from the upper limb to the heart.

Compression or damage involving the vein may interfere with blood flow.

Possible symptoms include:

• Swelling of the arm or hand.
• Heaviness or tightness in the affected limb.
• A blue or purple change in skin colour.
• More visible veins around the arm or shoulder.
• Pain or discomfort following physical activity.

One important complication is thrombosis, or a blood clot, within the axillary or subclavian vein.

This is sometimes called effort thrombosis or Paget-Schroetter syndrome, particularly when it occurs in otherwise active individuals.

This presentation requires prompt medical assessment and should not be managed as a routine shoulder or neck complaint.

3. Arterial Thoracic Outlet Syndrome

Arterial TOS is uncommon but can have serious consequences.

It involves the subclavian artery and may affect blood supply to the upper limb.

Symptoms can include:

• Unusual coldness of the hand.
• Pale or discoloured fingers.
• Pain associated with impaired circulation.
• Reduced pulses in some presentations.
• Symptoms related to arterial damage or embolisation.

Acute impairment of arterial circulation is a medical emergency.

For this reason, distinguishing vascular from neurological symptoms is an essential part of assessment.

How Common Is Thoracic Outlet Syndrome?

Thoracic outlet syndrome is generally considered an uncommon and sometimes difficult-to-recognise condition.

However, determining its true frequency is challenging.

Published prevalence and incidence estimates vary substantially because studies have used different diagnostic definitions and included different clinical populations.

A 2021 review by Illig and Rodriguez-Zoppi highlighted that the incidence of neurogenic TOS is not accurately established and may have been considerably overestimated in earlier literature.

As a result, statements claiming that a fixed percentage of the general population has TOS should be treated cautiously.

Some clinical series report greater numbers of affected women, but these findings do not mean that the condition is restricted to one sex or particular age group.

The more useful consideration is whether an individual’s history and examination findings support the diagnosis.

What Causes Thoracic Outlet Syndrome?

Thoracic outlet syndrome does not always develop from one identifiable cause.

Several anatomical and historical factors may contribute, sometimes in combination.

1. Anatomical Variations

Some people have structural differences that can influence the available space around the nerves or blood vessels.

These include:

• A cervical rib, which is an additional rib arising from the lower cervical spine.
• Differences in first-rib or clavicle anatomy.
• Fibrous bands or other anatomical variations.
• Differences in scalene muscle anatomy.

However, having a cervical rib or another anatomical variation does not automatically mean someone has TOS.

Many people with these findings never develop relevant symptoms.

2. Previous Injury or Trauma

Some people develop symptoms following trauma involving the neck, clavicle or shoulder region.

This may include previous fractures, substantial soft-tissue injuries or other events that influence local structures.

Not every person with TOS reports an injury, and the presence of previous trauma does not establish the diagnosis.

3. Repetitive or Sustained Upper-Limb Activities

People completing repeated overhead activity may experience symptoms associated with neurovascular structures around the thoracic outlet.

Relevant activities can include:

• Swimming.
• Throwing sports.
• Overhead gym training.
• Some physically demanding occupations.
• Tasks involving prolonged arm elevation.

These activities do not necessarily cause TOS, and most people participating in them do not develop the condition.

However, they can be relevant when symptoms consistently appear during particular physical demands.

4. Neck, Shoulder and Scapular Factors

In clinical practice, we may also consider the person’s neck movement, shoulder strength, scapular control and tolerance to sustained upper-limb positions.

For some individuals, these factors may influence symptoms or become useful targets for rehabilitation.

However, it would be too simplistic to claim that poor posture or tight scalene muscles are the primary cause of all neurogenic TOS.

People with and without TOS can have similar resting postures or muscular characteristics.

Assessment should focus on the individual presentation and whether a particular factor appears clinically relevant.

How Is Thoracic Outlet Syndrome Diagnosed?

Diagnosing TOS can be challenging because several other conditions produce similar symptoms.

Arm pain, tingling and numbness may arise from the cervical spine, peripheral nerves, shoulder or other medical conditions.

Consequently, a comprehensive assessment is important before concluding that symptoms originate from the thoracic outlet.

For neurogenic TOS in particular, there is no single clinical test or investigation that reliably confirms the diagnosis in every person.

Current consensus guidance emphasises the importance of the history and physical examination.

What Does a Physiotherapy Assessment Involve?

Depending on the symptoms, assessment may involve:

• A detailed history of symptom onset and progression.
• Identifying which activities and positions reproduce symptoms.
• Neck and shoulder examination.
• Assessment of arm and hand sensation.
• Testing relevant upper-limb muscle strength.
• Reflex testing where indicated.
• Screening for peripheral nerve entrapment.
• Assessing relevant movement and physical capacity.
• Checking for signs that suggest vascular involvement.

The aim is to identify the most plausible explanation for the symptoms and determine whether further medical investigation is needed.

Our Neck Physiotherapy and Shoulder Physiotherapy services involve assessment of neck, shoulder and upper-limb presentations, including cases where nerve-related symptoms may be relevant.

What About the Roos Test and Other Thoracic Outlet Tests?

Several clinical tests have historically been used when investigating neurogenic TOS.

These include the elevated arm stress test, commonly called the Roos test, and examination for tenderness or tingling around the scalene region.

Other tests may assess how symptoms respond to positions that place the brachial plexus under different mechanical demands.

However, these tests have limitations.

A person may experience symptoms during a provocative test without having TOS.

Likewise, a negative result does not necessarily exclude the condition.

The tests are therefore best interpreted alongside the clinical history, neurological examination and other findings.

What Do the Current Diagnostic Guidelines Recommend?

The Society for Vascular Surgery proposed diagnostic criteria for neurogenic TOS in 2016.

These included findings consistent with thoracic outlet pathology, symptoms of nerve involvement, consideration of competing diagnoses and response to an appropriately performed scalene injection.

However, recommendations have continued to evolve.

In 2024, the International Neurogenic Thoracic Outlet Syndrome (INTOS) Workgroup published updated expert consensus recommendations.

The modified criteria place emphasis on three principal areas:

• Local findings: Symptoms and examination findings suggesting irritation around the scalene triangle or related anatomical region.
• Peripheral findings: Relevant arm or hand symptoms, often aggravated by particular upper-limb positions or activities.
• Consideration of other diagnoses: Ensuring another condition does not better explain the majority of symptoms, while recognising that conditions can coexist.

The INTOS recommendations do not require a positive scalene injection as a mandatory diagnostic criterion.

Importantly, these are expert consensus recommendations rather than a perfectly validated diagnostic test.

There remains disagreement and uncertainty about aspects of neurogenic TOS diagnosis.

Can Thoracic Outlet Syndrome Be Diagnosed With MRI or Nerve Tests?

Investigations may help, but the most appropriate test depends on the type of TOS suspected.

X-Ray

An X-ray of the chest or cervical spine may identify a cervical rib or another bony variation.

However, an abnormality on X-ray does not necessarily establish that it is causing the symptoms.

MRI

MRI may help investigate relevant structures or identify other explanations for symptoms, including certain cervical spine conditions.

A normal MRI does not necessarily exclude neurogenic TOS.

Nerve Conduction Studies and Electromyography

These investigations can help assess nerve function or identify other neurological disorders.

They may be particularly useful when there is concern about cervical radiculopathy or peripheral nerve compression.

However, electrodiagnostic findings may be normal in some people with clinically suspected neurogenic TOS.

Normal results should therefore be interpreted within the wider clinical assessment.

Vascular Ultrasound and Other Imaging

When venous or arterial TOS is suspected, duplex ultrasound and other vascular investigations can be important.

CT angiography, MR angiography or other specialist imaging may be used in selected cases.

These investigations are different from the assessment pathway for uncomplicated neck or shoulder pain.

Where vascular compromise is suspected, medical investigation takes priority over routine rehabilitation.

What Other Conditions Can Feel Like Thoracic Outlet Syndrome?

Several conditions can produce arm pain, tingling, numbness or weakness.

Depending on the symptom pattern, these may include:

• Cervical radiculopathy: Irritation or dysfunction of a nerve root in the neck.
• Carpal tunnel syndrome: Median nerve compression at the wrist.
• Cubital tunnel syndrome: Ulnar nerve irritation around the elbow.
• Other peripheral nerve conditions: Affecting different parts of the upper limb.
• Shoulder-related pain: Including presentations involving the rotator cuff or other shoulder structures.
• Brachial neuritis: A neurological condition that may involve acute shoulder and arm pain followed by weakness.
• Other vascular conditions: Particularly when symptoms involve swelling, temperature or colour changes.

Some of these conditions can coexist with TOS.

Consequently, the aim of assessment is not simply to find one positive test, but to understand which diagnosis or combination of diagnoses best explains the presentation.

Physiotherapy for Neurogenic Thoracic Outlet Syndrome

For many people with neurogenic TOS, physiotherapy and other conservative approaches are recommended before considering surgery.

The 2024 INTOS consensus generally supports a trial of conservative management for approximately three to six months before surgical consideration, provided there are no findings that warrant earlier specialist management.

This is not a requirement for every patient to complete six months of physiotherapy.

People with significant objective weakness, muscle wasting or progressive neurological deficits may require earlier specialist evaluation.

And vascular forms of TOS follow different management pathways.

1. Understanding and Modifying Aggravating Activities

An initial aim is to understand which activities consistently reproduce symptoms.

For example, a person may notice that symptoms increase during prolonged overhead work, particular gym exercises or sustained arm positions.

Temporarily modifying these activities may help make symptoms more manageable.

However, the long-term aim is not necessarily to avoid using the arm overhead forever.

When appropriate, rehabilitation can gradually develop tolerance to the activities that matter to the individual.

2. Shoulder Blade Strength and Control

Exercises involving the shoulder blade are commonly used in neurogenic TOS rehabilitation.

These may include strengthening exercises for muscles that contribute to scapular movement and upper-limb function.

Possible exercises include:

• Progressive rowing variations.
• Serratus anterior strengthening.
• Lower and middle trapezius strengthening.
• Wall-supported shoulder movements.
• Gradual exposure to higher arm positions.

However, no single scapular position has been established as the correct posture for every person with TOS.

The exercises should be selected according to physical capacity, symptom behaviour and activity goals.

3. Neck and Upper-Body Exercise

Some people may benefit from exercises targeting neck strength, movement or endurance.

Thoracic mobility and upper-body strengthening may also be considered where relevant.

These exercises should not automatically be prescribed because someone has been told their neck muscles are tight or their posture is poor.

The useful question is whether a particular movement or physical limitation appears relevant to the person’s presentation.

4. Nerve Mobilisation Exercises

Nerve mobilisation exercises, sometimes called nerve glides or neural mobilisation, are used in some neurogenic TOS rehabilitation programs.

They aim to expose neural structures to appropriately graded movement.

However, evidence for their specific effectiveness in TOS remains limited, and aggressive stretching of an irritable nerve can aggravate symptoms.

These exercises should therefore be introduced and progressed according to the person’s response rather than assumed to be suitable for everyone.

5. Manual Therapy and Symptom Relief

Manual therapy may be useful as an adjunct to rehabilitation for some people.

Depending on the presentation, this might involve treatment directed towards the neck, shoulder or surrounding soft tissues.

However, the evidence does not support claiming that massage or manual therapy reliably removes the underlying anatomical compression in TOS.

Hands-on treatment may help someone tolerate movement or exercise, but it should be considered within a broader management plan.

Any intervention that worsens neurological or vascular symptoms should be reconsidered.

6. Gradually Rebuilding Functional Capacity

Ultimately, rehabilitation needs to relate to the activities the person wants to perform.

For some, that means using a computer comfortably throughout the workday.

For others, it may mean returning to swimming, gym training or a physically demanding occupation.

The physical progression should consider:

• Symptoms during the activity.
• Symptoms following activity.
• Upper-limb strength and endurance.
• Tolerance to relevant positions.
• The individual’s confidence.
• Any persistent or progressive neurological findings.

Our Physiotherapy service supports individualised assessment and exercise-based management, while our Sports Physiotherapy service may be relevant for athletes returning to demanding upper-limb activities.

Does Posture Cause Thoracic Outlet Syndrome?

Posture is frequently discussed in relation to TOS.

In clinical practice, some people notice that their symptoms change when they alter their shoulder or neck position.

This makes position and movement reasonable factors to explore.

However, that is different from claiming that rounded shoulders or poor posture are the underlying cause of every case.

There is no universally correct resting posture that prevents TOS.

Different positions place different demands on the body, and a person may find some positions more comfortable than others.

Where relevant, physiotherapy may involve exploring alternative positions, improving strength or gradually developing tolerance to sustained tasks.

The goal is useful function rather than forcing everyone into one ideal alignment.

Can Thoracic Outlet Syndrome Be Treated Without Surgery?

Many people with neurogenic TOS are initially managed without surgery.

Depending on the presentation, care may involve education, exercise, activity modification and other appropriate treatments.

However, the evidence for specific rehabilitation approaches remains limited and no particular exercise program has been established as consistently superior.

Some people respond well to conservative management.

Others continue to experience significant symptoms and may require further specialist assessment.

It is therefore important not to promise a complete recovery simply because someone has been diagnosed with TOS.

What About Injections and Botox?

In selected neurogenic TOS presentations, specialists may consider injections involving the scalene or pectoralis minor muscles.

Local anaesthetic injections are sometimes used as part of specialist diagnostic assessment or surgical decision-making.

Botulinum toxin injections have also been investigated, but the evidence for their effectiveness remains uncertain.

These interventions should not be presented as routine requirements for everyone with TOS.

Their potential role depends on specialist assessment and the individual clinical circumstances.

When Is Surgery Considered for Thoracic Outlet Syndrome?

Surgery may be considered when carefully selected patients have persistent neurogenic TOS symptoms despite appropriate conservative treatment.

Earlier specialist consideration may be appropriate when there is significant objective weakness, muscle wasting or other concerning neurological findings.

Surgical procedures vary and may involve decompression of structures around the thoracic outlet.

Depending on the presentation, this can involve:

• Scalene muscle procedures.
• Removal of the first rib in selected cases.
• Removal of cervical rib or fibrous structures when appropriate.
• Other procedures guided by specialist assessment.

Not every patient requires first-rib removal.

There remains debate about the optimal surgical approach for some neurogenic TOS presentations.

Venous and arterial TOS may require different vascular treatments, including urgent management of thrombosis or impaired circulation.

These decisions require specialist medical and surgical care.

How Long Does Thoracic Outlet Syndrome Take to Improve?

Recovery varies considerably.

The course depends on which type of TOS is present, the severity and duration of symptoms, neurological or vascular involvement and the management required.

For neurogenic TOS, conservative management is often trialled over several months.

However, this should not be interpreted as a guaranteed recovery timeline.

Some people experience improvement relatively early, while others require longer-term management or specialist intervention.

Useful indicators of progress may include:

• Reduced frequency or severity of arm symptoms.
• Improved tolerance to everyday activities.
• Greater ability to use the arm overhead.
• Improved strength or endurance where previously limited.
• Less disruption to work, exercise and sleep.
• Improved confidence in upper-limb activity.

Persistent or progressively worsening weakness, new swelling or other vascular symptoms should not be treated as normal rehabilitation discomfort.

Frequently Asked Questions About Thoracic Outlet Syndrome

Thoracic Outlet Syndrome Assessment and Physiotherapy in Kelvin Grove, Brisbane

At RHP Physiotherapy, we recognise that pain, tingling and numbness in the upper limb can have several possible explanations.

Our physiotherapists assess the person’s symptoms, physical examination findings and everyday activity limitations before deciding which management pathway may be appropriate.

When neurogenic TOS is suspected, our role may include:

• Assessing neck, shoulder and upper-limb symptoms.
• Completing appropriate neurological screening.
• Considering alternative or coexisting diagnoses.
• Identifying symptoms that require medical referral.
• Providing individualised activity advice.
• Developing an appropriate exercise and rehabilitation program.
• Supporting a gradual return to work, exercise or sport when appropriate.

Our clinic is located at AMA Place, 88 L’Estrange Terrace, Kelvin Grove, Brisbane.

Depending on your symptoms, these services may be relevant:

• Neck Physiotherapy for neck and potentially related upper-limb symptoms.
• Shoulder Physiotherapy for assessment of shoulder and upper-limb presentations.
• Physiotherapy for individualised musculoskeletal assessment and rehabilitation.
• Sports Physiotherapy for athletes managing upper-limb symptoms or returning to demanding sporting activities.

The important message is that thoracic outlet syndrome should not be diagnosed solely because an arm is painful or numb.

Nor should every person with TOS be assumed to need the same treatment.

Understanding which structures may be involved, considering other explanations and recognising when specialist investigation is needed are the foundations of good care.

Original article by Mal Fayers, Physiotherapist. This updated article provides general health information and does not replace individual medical assessment. Suspected vascular thoracic outlet syndrome or progressive neurological impairment requires appropriate medical assessment.