Thoracic Outlet Syndrome: Overview and Evidence Summary

Condition Overview

Thoracic Outlet Syndrome (TOS) is an umbrella term describing a group of conditions in which the neurovascular structures that pass from the neck into the arm become compressed or irritated. These structures — the brachial plexus, subclavian artery, and subclavian vein — traverse a confined anatomical corridor bounded by the anterior and middle scalene muscles, the first rib, the clavicle, and surrounding fascia. When space is compromised, symptoms can appear in the neck, shoulder, arm, hand, or chest, and may mimic a wide range of other musculoskeletal or neurological conditions.

Clinically, TOS is subdivided into three main categories: neurogenic, venous, and arterial. Neurogenic TOS is by far the most common and involves compression or irritation of the brachial plexus. Patients typically report pain, numbness, tingling, weakness, or a sense of heaviness in the upper limb, often made worse by overhead activity, carrying loads, or prolonged postures. Venous TOS involves compression of the subclavian vein and may present with swelling, cyanosis, and venous congestion. Arterial TOS, the least common but potentially most serious, involves subclavian artery compromise with symptoms such as coolness, pallor, claudication, or even distal emboli.

What makes TOS particularly challenging is that symptoms are often diffuse and non-specific. Many patients have been told they have “neck problems,” “shoulder impingement,” or “carpal tunnel,” and may have undergone multiple investigations before anyone considers compression higher up in the thoracic outlet. Postural factors, muscular imbalance, previous clavicular or rib trauma, congenital cervical ribs, hypertrophy of the scalene or pectoralis minor, and occupational demands all contribute to risk.

The condition exists along a spectrum: some individuals experience mild, intermittent symptoms with overhead work; others have disabling pain, weakness, or vascular compromise that significantly affects daily function. The good news is that a large proportion of patients respond well to carefully structured conservative management that focuses on decompression via postural correction, targeted strengthening, mobility work, and activity modification. In more advanced vascular or structural cases, surgery may be required to remove the compressive source and restore vascular or neural function.

Summary of Current Evidence for Thoracic Outlet Syndrome

Evidence-Based Management Discussion

Anatomical Corridors and Sites of Compression

To understand TOS, it helps to picture the path of the neurovascular bundle as it leaves the neck and enters the arm. There are three main potential sites of compression:

1. The interscalene triangle, bordered by the anterior and middle scalene muscles and the first rib.

2. The costoclavicular space, between the clavicle and first rib.

3. The subcoracoid/pectoralis minor space, beneath the pectoralis minor tendon and the coracoid process.

In many patients, symptoms arise from a combination of subtle narrowing in more than one zone rather than a single, dramatic pinch point. Postural adaptations — forward head posture, rounded shoulders, increased thoracic kyphosis — exaggerate this narrowing, bringing the clavicle closer to the first rib and tightening the scalene and pectoralis minor. Repetitive overhead activity adds further stress, especially when scapular control is poor and the shoulder girdle is held in a chronically elevated or depressed position.

Structural factors such as a cervical rib, fibrous bands, or prior fractures of the clavicle or first rib can create fixed narrowing that greatly increases the likelihood of neural or vascular compromise. However, even without obvious anatomical anomalies, muscular and postural imbalances alone can produce clinically significant TOS.

Clinical Presentation: Patterns and Red Flags

Neurogenic TOS typically presents with a combination of pain, paresthesia, and weakness. Patients may complain of aching in the neck, shoulder, scapular region, arm, or hand; tingling or numbness often affects the ulnar side of the hand, but patterns vary. Symptoms commonly worsen with overhead positions, carrying loads (bags, backpacks), or prolonged static postures such as driving or computer work. Many describe a heavy, tired arm, particularly at the end of the day.

Venous TOS brings a different pattern: swelling of the arm or hand, a feeling of fullness, cyanosis or darkened colour, and sometimes prominent superficial veins. In acute cases, this may present as effort thrombosis (Paget–Schrötter syndrome), where sudden venous clotting develops following intense upper-limb exertion.

Arterial TOS is rarer but more serious, with symptoms including coolness or pallor of the hand, diminished pulses, exertional pain in the forearm or hand, and occasionally digital ischemia or embolic events. Any signs suggesting vascular compromise require urgent medical evaluation.

From a differential diagnosis perspective, TOS can overlap with cervical radiculopathy, shoulder impingement, rotator cuff pathology, peripheral entrapment neuropathies, and myofascial pain syndromes. A thorough assessment must consider all of these possibilities rather than attributing every arm symptom to TOS.

Diagnostic Approach: Beyond Provocative Tests

Traditional provocative tests (such as Adson’s, Roos, or costoclavicular manoeuvres) are widely taught but can be non-specific and yield false positives, especially in healthy individuals. Their value lies more in reproducing the patient’s familiar symptoms rather than in any single “positive test” being diagnostic.

A robust assessment includes:

• Detailed history: onset, aggravating activities, posture, occupational and sporting demands, previous trauma.

• Symptom mapping: distribution of pain, numbness, heaviness, swelling, or colour change.

• Postural and movement analysis: head and neck posture, scapular resting position and movement, breathing patterns, thoracic mobility.

• Neurological exam: reflexes, strength, sensation, upper limb tension tests.

• Vascular assessment where indicated: pulse changes with arm position, temperature, and colour.

Imaging and electrodiagnostic studies are often reserved for cases with persistent or severe symptoms, or where surgery is considered. Duplex ultrasound, CT angiography, or MR angiography can reveal vascular compromise; nerve conduction studies may help confirm longstanding neurogenic involvement, although many neurogenic TOS cases have normal electrodiagnostics.

Conservative Management: Creating Space and Changing Load

For most neurogenic TOS presentations, conservative management is the first choice and often very successful. The overarching goal is to reduce mechanical stress on the neurovascular bundle by improving posture, enhancing mobility of key structures, and strengthening the systems that support the shoulder girdle.

Postural Correction and Education

Patients benefit greatly from understanding how their everyday posture and movement habits contribute to symptoms. Forward head posture, rounded shoulders, and prolonged slumped sitting all reduce thoracic outlet space. Education focuses on restoring a more neutral spine, gently lengthening the thoracic region, and repositioning the scapulae so they rest in a balanced, stable way.

Rather than chasing a rigid “perfect posture,” the emphasis is on movement variability and reducing the amount of time spent in compressive positions. Simple strategies — changing desk setup, altering screen height, using armrests more effectively, taking regular movement breaks — can dramatically reduce symptom load.

Exercise Therapy: Strength, Endurance, and Mobility

A typical exercise approach for TOS includes:

• Scapular stabilisation: targeting lower trapezius, serratus anterior, and middle trapezius to create a stable base for the shoulder. Improving scapular posterior tilt and upward rotation reduces the need for excessive upper trapezius and levator activity, decreasing compressive forces at the outlet.

• Deep neck flexor training: gently retraining these muscles helps counteract forward head posture and reduces strain on the posterior cervical structures and scalenes.

• Pectoralis minor and scalene lengthening: carefully dosed stretching and mobility work around these muscles can open space in the costoclavicular and subcoracoid regions.

• Thoracic mobility: extensions and rotations of the thoracic spine improve the alignment of the shoulder girdle and decrease reliance on neck musculature for support.

• Graded upper-limb loading: gradually reintroducing overhead activity, carrying, and functional tasks in a controlled way allows the system to adapt safely.

The process is rarely quick. Patients should expect a steady, incremental recovery rather than a rapid resolution, particularly in long-standing cases. Consistency with home exercise and postural habits is crucial.

Manual Therapy: Supportive, Not Standalone

Manual therapy can be highly effective in reducing pain, improving movement quality, and facilitating the exercise programme. Techniques may include:

• Soft-tissue work to scalenes, upper trapezius, levator scapulae, pectoralis major and minor, and periscapular muscles.

• Gentle mobilisation of the cervical and upper thoracic spine to restore segmental mobility.

• Costotransverse and costovertebral joint mobilisation to improve rib mechanics.

• Clavicular and first-rib mobilisation, where appropriate, to optimise the dimensions of the thoracic outlet.

These techniques provide short- to medium-term symptom relief and help patients feel more comfortable engaging with their exercise and activity modifications. They are not a replacement for strengthening and postural retraining but can be powerful facilitators.

Medical and Surgical Pathways

In neurogenic TOS, medication may include analgesics or neuropathic pain agents when symptoms are severe. For venous TOS with thrombosis, anticoagulation is typically instituted, sometimes alongside thrombolytic therapy, followed by decompression surgery.

Surgery — such as first rib resection, scalenectomy, or pectoralis minor tenotomy — is reserved for cases where:

• Significant vascular compromise exists.

• Structural anomalies are clearly compressive.

• Comprehensive conservative care fails to provide meaningful improvement.

Post-surgical rehabilitation remains essential to prevent recurrence of functional compression patterns and to restore full upper-limb capacity.

Long-Term Outcomes and Prevention

Many patients with neurogenic TOS achieve substantial improvement or full resolution with well-delivered conservative care. Those with vascular or significant structural TOS often do well following surgery, particularly when combined with rehabilitation that reinforces better movement and postural strategies.

Prevention hinges on maintaining good thoracic and scapular mobility, balanced strength in the neck and shoulder girdle, and avoiding prolonged static postures without breaks. For overhead athletes, careful workload management, technique refinement, and conditioning programmes focused on the entire kinetic chain are important in reducing risk.

References

Sanders, R., et al. “Neurogenic Thoracic Outlet Syndrome: A Review of Diagnosis and Management.” Journal of Vascular Surgery.

Illig, K., et al. “Thoracic Outlet Syndrome: Consensus and Management Guidelines.” Journal of Vascular Surgery.

Brantigan, C., et al. “Thoracic Outlet Syndrome: Biomechanics, Diagnosis, and Treatment.” Clinical Orthopaedics and Related Research.

Roos, D. “The Place for Conservative Management in Thoracic Outlet Syndrome.” Annals of Vascular Surgery.

Hooper, T., et al. “Physiotherapy Management of Neurogenic Thoracic Outlet Syndrome.” Manual Therapy and Rehabilitation Review.

Disclaimer

Disclaimer:
The information in this article is intended for educational purposes within the context of continuing education for massage therapists, continuing education for athletic trainers, continuing education for physical therapists, continuing education for chiropractors, and continuing education for rehabilitation professionals. It is not a substitute for medical advice, diagnosis, or treatment. Although every effort has been made to ensure accuracy and reflect current understanding at the time of publication, practitioners must always work within the legal scope of their professional practice and follow all regional regulatory guidelines.

Hands-on techniques and clinical applications described in this material should only be performed by appropriately trained and licensed professionals. Individuals experiencing pain or symptoms should be referred to a qualified healthcare provider for assessment. Niel Asher Education is not responsible for any injury, loss, or damage resulting from the use or misuse of the information provided in this content.