Thoracic outlet syndrome

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

Last reviewed: 11 Aug 2025

Last updated: 15 Nov 2024

Thoracic outlet syndrome (TOS) refers to an uncommon but potentially disabling group of conditions characterised by symptoms that result from compression of neurovascular structures crossing through the anatomical space of the thoracic outlet.

The main types of TOS include neurogenic, venous, and arterial. Patients may present with signs and symptoms of nerve, vein, or artery compression, or a combination of these.

Neurogenic TOS is the most common type, followed by venous TOS and then arterial TOS. Neurogenic TOS primarily develops in people in their late teens up to the age of 60 years and is more common in women. It usually occurs in the setting of a previous injury. Initial management is usually conservative and includes physiotherapy.

Venous TOS is less common, but clinical presentation may be quite dramatic and requires prompt intervention. It is a potential cause of upper extremity deep vein thrombosis.

Arterial TOS is relatively rare and arguably the most important to recognise, owing to the risk of limb-threatening ischaemic complications.

Definition

Thoracic outlet syndrome (TOS) is a general term that refers to symptoms and findings which follow from compression of the principal neurovascular structures that course across and through the spaces of the thoracic outlet (brachial plexus nerves, subclavian vein, or subclavian artery).The thoracic outlet is the area of the upper chest and base of the neck that is bound by the scalene muscles and the first rib deep to the clavicle and extending to the front of the shoulder and the pectoralis minor muscle.[1][2][3][4]

There are three spaces within the thoracic outlet where neurovascular structures may be extrinsically compressed: the interscalene triangle, the costoclavicular space, and the subcoracoid space (also called the pectoralis minor space).[1][4]

There are three distinct types of TOS, characterised by the specific neurovascular structures that are affected and the resulting clinical findings.[1][2]

Neurogenic TOS

Neurogenic TOS refers to pain, paraesthesia, and upper extremity weakness arising from compression of the brachial plexus nerves as these nerves cross the thoracic outlet.[1] Any part of the brachial plexus may be affected, but compression of the lower trunk (combining the C8 and T1 nerve roots) is most frequent. Nerve compression can be localised to the scalene triangle and/or the subcoracoid space. Symptoms typically do not follow the distribution of a single nerve root or peripheral nerve and can be quite variable, and may range in severity from mild and intermittent to constant and disabling.[5][6][7][8][9][10][11][12]

Venous TOS

Venous TOS refers to symptoms caused by compression of the axillary-subclavian vein at the thoracic outlet, principally in the costoclavicular space.[1] The most common symptoms include the spontaneous onset of substantial arm swelling, cyanotic discoloration, aching discomfort, and enlargement of the superficial subcutaneous veins in the shoulder, upper chest, and arm. Paget-Schroetter syndrome, or 'effort thrombosis' of the axillary-subclavian vein, is the acute presentation of venous TOS with a blood clot in the axillary-subclavian vein and it is the most common clinical presentation of venous TOS.[13][14] Contrary to some specialty guidelines, this condition is better classified as a secondary provoked cause of upper extremity deep vein thrombosis (UE-DVT), rather than a primary unprovoked idiopathic form of UE-DVT. Subclavian vein thrombosis is classified as 'acute' if within 2 weeks of the onset of symptoms, 'subacute' with symptoms for 2 weeks to 3 months, and 'chronic' if symptoms have been present beyond 3 months.[1] Non-thrombotic venous TOS occurs with symptoms of upper extremity venous congestion due to intermittent or positional vein compression, prior to or in the absence of thrombosis, and is known as McCleery’s syndrome.[15][16] Another variant of venous TOS is positional obstruction of the axillary vein in the infraclavicular space.[17]

Arterial TOS

Arterial TOS refers to symptoms arising from long-standing compression and damage to the subclavian artery, usually in the setting of a bony abnormality (e.g., cervical rib).[1][18] The injury results from chronic external compression of the artery at the scalene triangle and may take the form of chronic arterial narrowing (stenosis), thrombotic occlusion, or the development of aneurysmal enlargement. Arterial pathology may be accompanied by formation of chronic or acute thrombosis within the artery, which can in turn cause thromboembolism and occlude more distal arteries in the arm, hand, or fingers. In instances where major arteries are occluded in the upper extremity, symptoms are typically acute and severe with concern for possible tissue loss in the extremity, prompting emergency treatment.[19][20][21][22] In some instances, retrograde embolism from the subclavian artery to the vertebral artery can cause vertebrobasilar stroke.[23][24][25] A subset of arterial TOS occurs with repetitive extrinsic compression of the axillary artery at a level opposite the head of the humerus. This can also lead to similar forms of arterial pathology (stenosis, aneurysmal dilatation, thrombosis) and distal thromboembolism.[26][27][28][29]

History and exam

Key diagnostic factors

history of repetitive jobs or overhead hobbies/activities
pain in upper extremity and adjacent areas
paraesthesias in arms, hands, and/or fingers
circulatory changes in upper extremity
upper extremity fatigue

Full details

Other diagnostic factors

history of clavicular fracture
palpation of cervical rib
subcutaneous venous collateral distention around shoulders (Urschel's sign)
motor weakness
hyperhidrosis
thenar eminence muscle atrophy
exertional pain/claudication
supraclavicular systolic bruit
blood pressure difference between extremities
positive Adson's (scalene) test
positive costoclavicular test
positive hyperabduction test
positive elevated arm stress test (Roos test)
positive stretch test
positive upper limb tension tests
positive Wright's manoeuvre
oedema/swelling of upper extremity

Full details

Risk factors

cervical ribs (partial or complete)
abnormal (hypoplastic) first rib or bony abnormalities
anomalies of muscular development (interdigitation, scalene minimis muscle)
fibro-fascial or ligamentous bands
fractures of clavicle or first rib
over-development of muscles (bodybuilding, heavy labour with upper extremities)
traumatic injuries (whiplash, upper extremity distraction injuries)

Full details

Diagnostic investigations

1st investigations to order

CXR
cervical spine x-ray
electrodiagnostic testing (nerve conduction velocity and electromyography)
duplex ultrasonography
contrast venography, catheter-directed therapy
CT angiography

Full details

Investigations to consider

MRI neck/clavicle/shoulder
muscle block
conventional arteriography
magnetic resonance angiography (MRA)
magnetic resonance venography (MRV)
FBC, coagulation, and thrombophilia studies

Full details

Treatment algorithm

ACUTE

neurogenic TOS (NTOS)

venous TOS (vTOS)

arterial TOS (ATOS)

neurovascular (combined)

Contributors

Authors

Robert W. Thompson, MD

Center for Thoracic Outlet Syndrome

Department of Surgery (Section of Vascular Surgery)

Washington University School of Medicine and Barnes-Jewish Hospital

St. Louis

Disclosures

RWT is an author of several references cited in this topic, has co-authored articles with other authors on this topic, has contributed to educational events on this topic, has provided expert witness testimony on this topic, and has directed use of philanthropic funds received by Washington University School of Medicine to support staff for research on this topic.

Hugh A. Gelabert, MD

Division of Vascular Surgery

Gonda (Goldschmied) Vascular Center

David Geffen School of Medicine at UCLA

Los Angeles

Disclosures

HAG is an author of several references cited in this topic, has co-authored articles with other authors on this topic, has contributed to educational events on this topic, has provided expert witness testimony on this topic, and has directed use of philanthropic funds received by University of California Los Angeles School of Medicine to support research on this topic.

Joep A. W. Teijink, MD

Department of Vascular Surgery

Catharina Hospital

Eindhoven

The Netherlands

Department of Epidemiology

CAPHRI School for Public Health and Primary Care

Faculty of Health, Medicine and Life Sciences

Maastricht University

Maastricht

The Netherlands

Disclosures

JAWT is co-author of several references cited in this topic, has contributed to educational events on this topic, and has provided expert witness testimony on this topic. No financial disclosures.

Acknowledgements

Dr Robert W. Thompson, Dr Joep A.W. Teijink, and Dr Hugh A. Gelaber would like to gratefully acknowledge Dr Chaney Stewman, Dr Marc I. Harwood, Dr Pedro K. Beredjiklian, Dr Peter C. Vitanzo, Dr Harold C. Urschel Jr, Rachel Montano, and Brenda Knee, previous contributors to this topic. CS is the author of a reference cited in this topic. MIH is the author of a reference cited in this topic. PKB has stock ownership in Wright Medical Inc. PCV is the author of a reference cited in this topic. HCU is an author of several references cited in this topic. RM and BK declare that they have no competing interests.

Peer reviewers

Ian Loftus, BSc, MB, ChB, FRCS, MD

Professor of Vascular Surgery

St. George's NHS Healthcare Trust

London

Disclosures

IL declares that he has no competing interests.

Scott R. Laker, MD

Assistant Professor

University of Colorado School of Medicine

Aurora

Disclosures

SRL is the author of a reference cited in this topic.

John A. Kern, MD

Chief

Cardiothoracic Surgery

University of Virginia School of Medicine

Charlottesville

Disclosures

JAK declares that he has no competing interests.

Peer reviewer acknowledgements

BMJ Best Practice topics are updated on a rolling basis in line with developments in evidence and guidance. The peer reviewers listed here have reviewed the content at least once during the history of the topic.

Disclosures

Peer reviewer affiliations and disclosures pertain to the time of the review.

References

Our in-house evidence and editorial teams collaborate with international expert contributors and peer reviewers to ensure that we provide access to the most clinically relevant information possible.

Key articles

Illig KA, Donahue D, Duncan A, et al. Reporting standards of the Society for Vascular Surgery for thoracic outlet syndrome. J Vasc Surg. 2016 Sep;64(3):e23-35.Full text Abstract

Vemuri C, McLaughlin LN, Abuirqeba AA, et al. Clinical presentation and management of arterial thoracic outlet syndrome. J Vasc Surg. 2017 May;65(5):1429-39.Full text Abstract

Vemuri C, Salehi P, Benarroch-Gampel J, et al. Diagnosis and treatment of effort-induced thrombosis of the axillary subclavian vein due to venous thoracic outlet syndrome. J Vasc Surg Venous Lymphat Disord. 2016 Oct;4(4):485-500.Full text Abstract

George EL, Arya S, Rothenberg KA, et al. Contemporary practices and complications of surgery for thoracic outlet syndrome in the United States. Ann Vasc Surg. 2021 Apr;72:147-58. Abstract

Peek J, Vos CG, Ünlü Ç, et al. Outcome of surgical treatment for thoracic outlet syndrome: systematic review and meta-analysis. Ann Vasc Surg. 2017 Apr;40:303-26. Abstract

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

Differentials
- Vasospasm, embolism, or insufficiency
- Coronary artery disease
- Myocardial infarction
More Differentials
Guidelines
- Thoracic outlet syndrome part I: systematic review of the literature and consensus on anatomy, diagnosis, and classification of thoracic outlet syndrome by the European Association of Neurosurgical Societies’ section of peripheral nerve surgery
- Thoracic outlet syndrome part II: consensus on the management of neurogenic thoracic outlet syndrome by the European Association of Neurosurgical Societies' section of peripheral nerve surgery
More Guidelines
Patient information
Raynaud's phenomenon
More Patient information
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Thoracic outlet syndrome

Summary

Definition

History and exam

Key diagnostic factors

Other diagnostic factors

Risk factors

Diagnostic investigations

1st investigations to order

Investigations to consider

Treatment algorithm

neurogenic TOS (NTOS)

venous TOS (vTOS)

arterial TOS (ATOS)

neurovascular (combined)

Contributors

Authors

Robert W. Thompson, MD

Disclosures

Hugh A. Gelabert, MD

Disclosures

Joep A. W. Teijink, MD

Disclosures

Acknowledgements

Peer reviewers

Ian Loftus, BSc, MB, ChB, FRCS, MD

Disclosures

Scott R. Laker, MD

Disclosures

John A. Kern, MD

Disclosures

Peer reviewer acknowledgements

Disclosures

References

Key articles

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

Differentials

Guidelines

Patient information

Log in or subscribe to access all of BMJ Best Practice

Log in or subscribe to access all of BMJ Best Practice

Log in to access all of BMJ Best Practice