Thoracic Outlet Syndrome

Upper Limb

Overview

Thoracic Outlet Syndrome (TOS) is a complex of symptoms resulting from compression of the neurovascular bundle (brachial plexus and/or subclavian vessels) as it passes through the thoracic outlet. The condition manifests as pain, numbness, weakness, and vascular symptoms in the upper limb and is classified into neurogenic, venous, or arterial subtypes depending on which structures are predominantly compressed. TOS often develops secondary to postural dysfunction, muscle imbalance, or anatomical variations and requires careful differential diagnosis.

Pathophysiology

The thoracic outlet is bounded superiorly by the anterior and middle scalene muscles, anteriorly by the clavicle and first rib, and posteriorly by the trapezius. Compression can occur at three anatomical sites: between the scalene muscles (interscalene space), behind the clavicle and first rib (costoclavicular space), or beneath the pectoralis minor muscle (subcoracoid space). Compression may result from muscle hypertrophy or hypertonicity (particularly scalenes and pectoralis minor), postural dysfunction (forward head posture, rounded shoulders), cervical rib or fibrous bands, clavicular or first rib abnormalities, or trauma (whiplash). Neurogenic TOS (95% of cases) compresses the lower trunk of the brachial plexus (C8–T1), causing ischaemia and inflammation of nerve fibres. Venous TOS results from subclavian vein compression, leading to thrombosis and oedema. Arterial TOS (rare) involves subclavian artery compression, risking aneurysm formation and distal embolisation.

Patient Education

TOS often improves with postural correction, muscle relaxation, and ergonomic modification; maintaining good posture, avoiding overhead activities, and performing regular stretching of the neck and chest muscles are essential for long-term management and prevention of recurrence.

Typical Presentation

Site

Arm and hand (often ulnar distribution C8–T1), neck, shoulder, and anterior chest; symptoms may extend from neck to fingertips

Quality

Aching, heaviness, numbness, tingling, weakness; vascular symptoms include coolness, colour changes (cyanosis or pallor), or swelling in severe cases

Intensity

Variable; may range from mild intermittent paraesthesia to severe disabling pain and weakness; often worse at end of day

Aggravating

Overhead activities, carrying heavy loads, prolonged typing or computer use, poor posture, sleeping with arm overhead, neck rotation/extension, cold exposure (vascular symptoms)

Relieving

Rest, lowering the arm, postural correction, neck and shoulder stretching, heat application, sleeping in neutral position

Associated

Forward head posture, rounded shoulders, muscle tension in neck and shoulder girdle, weakness of intrinsic hand muscles, swelling (particularly in venous TOS), colour changes or coolness of limb, reduced grip strength, fatigue

Orthopaedic Tests

Adson Test

Procedure

Patient seated or standing with arm abducted to 90° and externally rotated; examiner palpates the radial pulse while patient turns head toward the affected side and takes a deep breath.

Positive Finding

Obliteration or significant diminution of the radial pulse, or reproduction of vascular symptoms (numbness, tingling, coolness)

Sensitivity / Specificity

72% / 60%

Plewa & Delinger, 1998, American Family Physician

Interpretation

Suggests compression of the subclavian artery or vein by the anterior scalene muscle; positive result supports TOS diagnosis but modest specificity means it should not be used in isolation

Roos Test (Elevated Arm Stress Test – EAST)

Procedure

Patient abducts both arms to 90° with elbows flexed to 90°; patient opens and closes fists for 3 minutes or until fatigue/symptoms develop.

Positive Finding

Inability to sustain the position for 3 minutes, or reproduction of upper extremity symptoms (heaviness, fatigue, pain, numbness, tingling)

Sensitivity / Specificity

See current literature / See current literature

Interpretation

Highly sensitive for functional/dynamic TOS; reproduces symptoms through muscular effort and positional compression; positive result supports clinical diagnosis, particularly in neurogenic TOS

Hyperabduction Test (Wright Test)

Procedure

Patient supine or seated; examiner passively abducts the arm to 180° (or as far as tolerated) with shoulder external rotation; palpate the radial pulse.

Positive Finding

Obliteration or significant reduction of the radial pulse, or reproduction of vascular symptoms (tingling, numbness, coolness, heaviness)

Sensitivity / Specificity

See current literature / See current literature

Interpretation

Suggests compression of neurovascular structures beneath the pectoralis minor muscle; positive result indicates vascular TOS component but low specificity limits diagnostic utility as single test

Costoclavicular Test (Military Brace Test)

Procedure

Patient seated with arms at rest; examiner observes for pulse changes while patient retracts and depresses both shoulders (military posture) for 60 seconds.

Positive Finding

Obliteration or reduction of the radial pulse, or reproduction of symptoms (numbness, tingling, pain, heaviness)

Sensitivity / Specificity

See current literature / See current literature

Interpretation

Reproduces vascular compression between the clavicle and first rib; positive result suggests TOS affecting subclavian vessels, though test has limited sensitivity and specificity for definitive diagnosis

Upper Limb Tension Test (ULTT) – Median Nerve Bias

Procedure

Patient supine; examiner depresses scapula, abducts shoulder to 90°, externally rotates, extends elbow, and extends wrist/fingers; sensitizing maneuver includes cervical contralateral flexion.

Positive Finding

Reproduction of neurological symptoms (tingling, numbness, pain in the hand/forearm), asymmetrical limitation of motion compared to contralateral side, or altered neural tension

Sensitivity / Specificity

See current literature / See current literature

Interpretation

Assesses neural tissue irritability and mobility; positive result suggests neural component of TOS (neurogenic TOS) and rules out joint-specific restrictions; useful for differentiating neural vs. vascular TOS

Neck Tilt Test (Halstead Test Modification)

Procedure

Patient seated; examiner applies gentle downward traction on the affected arm while patient tilts head away from the affected side (or toward, depending on variant); observe for pulse changes and symptom reproduction.

Positive Finding

Obliteration or diminution of radial pulse, or reproduction of symptoms (pain, numbness, tingling, heaviness in the arm and hand)

Sensitivity / Specificity

See current literature / See current literature

Interpretation

Addresses compression from cervical rib or anterior scalene hypertrophy; positive result supports TOS diagnosis when combined with clinical presentation, though test lacks robust sensitivity/specificity values in current literature

⚠ Red Flags

  • •Acute onset with severe swelling, colour change, or coldness suggesting venous or arterial thrombosis requiring urgent vascular imaging
  • •Severe progressive neurological deficit with rapid onset of weakness or paralysis
  • •Signs of spinal cord compression: bilateral symptoms, lower limb involvement, or sphincter changes
  • •Pulsatile mass or bruit suggesting aneurysm formation
  • •Systemic symptoms including fever, weight loss, or night sweats suggesting malignancy or infection
  • •Acute trauma with neurovascular compromise

⚡ Yellow Flags

  • •High levels of psychological distress, anxiety, or catastrophising about symptoms
  • •Significant occupational or functional limitations disproportionate to objective findings
  • •Litigation or compensation claims pending
  • •Multiple previous failed treatments leading to negative recovery expectations and reduced rehabilitation engagement
  • •Chronic pain behaviour with widespread symptoms beyond typical TOS distribution
  • •Health anxiety or belief that condition is progressive and degenerative

Osteopathic Techniques

Region

Scalene muscles (anterior, middle, posterior)

Technique

Soft Tissue

Rationale

Direct soft tissue release and trigger point therapy to reduce muscle hypertonicity and compression of the interscalene space; effective for reducing neurovascular compression and restoring normal muscle length and function

Region

Pectoralis minor

Technique

Soft Tissue

Rationale

Targeted soft tissue release of pectoralis minor to reduce subcoracoid compression; hypertonicity of this muscle is a common contributor to TOS and its release improves neurovascular transit through the thoracic outlet

Region

Cervical and upper thoracic spine

Technique

MET

Rationale

Muscle energy techniques to scalenes, levator scapulae, and upper trapezius to improve muscle balance and reduce tension; MET is particularly effective for restoring cervical mobility and reducing postural dysfunction

Region

Cervical spine and shoulder girdle

Technique

Articulation

Rationale

Grade I–II articulation of cervical segments and shoulder girdle to improve segmental mobility, reduce protective muscle guarding, and restore normal movement patterns contributing to TOS

Region

Clavicle and first rib

Technique

HVLA

Rationale

High-velocity low-amplitude thrust to costoclavicular articulations (when appropriate and in absence of contraindications) to improve first rib mobility and reduce costoclavicular space compression; effective for specific cases of TOS with segmental dysfunction

Region

Upper limb and hand (lymphatic circulation)

Technique

Lymphatic

Rationale

Gentle lymphatic drainage techniques to reduce swelling and improve venous return in the upper limb; particularly valuable in venous TOS to improve fluid dynamics and reduce oedema

Add-On Approaches

Chinese Medicine

Acupuncture and moxibustion targeting acupoints along the Large Intestine, Triple Burner, and Small Intestine meridians (particularly LI-10, LI-5, TE-5, TE-9, SI-3) combined with Tui Na techniques to release muscle tension in the neck and shoulder; TCM diagnosis may focus on Qi stagnation and Blood stasis in the shoulder and arm channels

Chiropractic

Chiropractic manipulation of cervical and thoracic spine with emphasis on first rib mobilisation; thoracic outlet decompression techniques and postural correction; ergonomic counselling and rehabilitation exercises similar to osteopathic approach

Physiotherapy

Progressive therapeutic exercise program including scalene stretching, pectoralis minor release, scapular stabilisation exercises, postural retraining, and gradual return to functional activities; neuromobilisation techniques and nerve gliding exercises to improve neural tension and mobility

Remedial Massage

Remedial massage of scalene muscles, pectoralis minor, levator scapulae, and upper trapezius using sustained pressure, stripping, and cross-friction techniques; soft tissue therapy to reduce muscle hypertonicity and improve tissue extensibility; may include myofascial release techniques

Rehabilitation Exercises

Scalene Muscle Stretch (Lateral Neck Flexion)

StretchingBeginner

Pectoralis Minor Doorway Stretch

StretchingBeginner

Upper Trapezius Stretch (Neck Side Flexion with Rotation)

StretchingBeginner

Levator Scapulae Stretch

StretchingBeginner

Postural Reset – Shoulder Blade Retraction and Depression

PosturalBeginner

Scapular Retraction Isometric Hold

StrengtheningBeginner

Lower Trapezius Activation (Prone Y Raise)

StrengtheningIntermediate

Serratus Anterior Activation (Push-Up Plus)

StrengtheningIntermediate

Cervical Spine Active Range of Motion (Flexion, Extension, Lateral Flexion, Rotation)

Range of MotionBeginner

Chin Tucks (Cervical Retraction)

PosturalBeginner

Shoulder Girdle Mobilisation (Scapular Circles and Rolls)

Range of MotionBeginner

Proprioceptive Upper Limb Stabilisation Exercises (Standing Arm Patterns)

BalanceIntermediate

Referral Criteria

  • •Acute onset with signs of vascular compromise (severe swelling, colour changes, coldness) — refer urgently to vascular surgery for imaging and assessment
  • •Progressive neurological deficit with significant weakness or atrophy — refer to neurology for electrodiagnostic testing and exclusion of other neuropathies
  • •Suspected arterial TOS with risk of aneurysm formation — refer urgently to vascular specialist
  • •Failure to improve after 6–8 weeks of conservative management — consider referral to specialist TOS centre for diagnostic imaging (MRI, CTA, or venography) and possible surgical intervention
  • •Suspected cervical myelopathy or spinal cord compression — refer to neurosurgery or spine specialist
  • •History of significant trauma with persistent neurovascular symptoms — refer to hand surgeon or trauma specialist for evaluation
  • •Diagnostic uncertainty or complex presentation — refer to musculoskeletal physician or specialist for comprehensive assessment and diagnostic confirmation