Thoracic Outlet Syndrome

Normal Anatomy

The neurovascular container described as the ‘thoracic outlet’ runs proximally from the cervicoaxillary canal, distally to the axilla
Within this container are three important neurovascular structures: the subclavian artery, subclavian vein and the trunks of the brachial plexus
The thoracic outlet is the term used to describe a series of spaces extending from the cervical spine and mediastinum to the lower border of the pectoralis minor muscle
These structures run through three compartments within the thoracic outlet:
The interscalene triangle
Boundaries are made up of the anterior scalene (anteriorly), the middle scalene (posteriorly) and the first rib (inferiorly)
Very small at rest but can be made even smaller with certain provocative positions of the upper limbs and neck
The costoclavicular space
Made up of the clavicle (anteriorly), first rib (posteromedially) and the upper border of the scapular (posterolaterally)
The subcoracoid space
Below the coracoid process and deep to the pectoralis minor tendon
Also known as retropectoralis minor space or thoraco-coracopectoral space

Pathology

Compression or compromise of the brachial plexus, subclavian artery or the subclavian vein at any of the three spaces along their pathway (interscalene triangle, costoclavicular space or subcoracoid space)
Resulting in pain, paraesthesia, weakness or discomfort in the upper limb
Symptoms do not follow a nerve root pattern

Mechanism of injury

Traumatic

Very rare
Traumatic thoracic outlet syndrome can occur secondary to clavicle fracture, posterior subluxation of acromioclavicular joint or road traffic accidents

Insidious

Congenital abnormalities such as first rib deformities, cervical rib development, deformity of the C7 transverse process or an enlarged scalene tubercle
Poor posture
Occupational stressors i.e repetitive overuse
Associated soft tissue adaptations e.g hypertonic pec minor or scalenes

Co-Existing or Associated Pathologies

Whiplash Associated Disorder
Chronic Obstructive Pulmonary Disease (shortening of scalenes -muscle of inhalation)
Presence of cervical rib
Deformity of first rib
Deformity of C7 transverse process
Fracture or trauma to clavicle, sternum or acromioclavicular joint

Classification

Thoracic outlet syndrome can be classified according to which structures are being compromised.

Thoracic Outlet Syndrome

Vascular Thoracic Outlet Syndrome

Neurogenic Thoracic Outlet Syndrome

Arterial TOS / Venous TOS / True Neurogenic TOS / Symptomatic TOS

Compression of the subclavian artery which is very rare but presents as unilateral pain, with ischemia and necrosis following as a result of occlusion to the vessel.

Compression of the subclavian vein, very rare, patient often experiences sudden unilateral pain after having arm elevated, this causes spontaneous thrombosis of the vein resulting in cyanosis and swelling of the entire limb.

/ Very rare, but is almost always caused by a bony anomaly compressing the brachial plexus, patient will experience unilateral pain, weakness, paraesthesia but not in a nerve root pattern. / Most common of the 4 varieties and is often caused by acute trauma (WAD) or repetitive trauma, NOT an anatomical anomaly. Presents with unilateral arm pain, weakness, paraesthesia but not in a nerve root pattern. (Also known as disputed or non-specific thoracic outlet syndrome.)

Examination

Each classification of thoracic outlet syndrome will present differently, therefore careful subjective assessment must be taken including history and mechanism of injury as well as an extensive objective assessment, ruling out peripheral nerve compression or cervical radiculopathies.

Subjective

More common in females than men (ratio between 2:1 and 4:1)
Normally aged between 20-50 years
Unilateral symptoms
Pain can be reported in the shoulder, neck, trapezius, chest, occipitals, forearm, hand and fingers
Paraesthesia - often in the forearm and hand
Weakness or fatigue of muscles in the affected limb
Change in skin colour, temperature, hair growth and oedema
Reduction of arterial pulses in the affected extremity
Aggravating factors are typically sustained shoulder elevation, suspensory holding activities (i.e painting ceiling), lying on the arm, carrying a handbag or prolonged postures
Many report pain waking them at night

Objective

Abnormal cervical, thoracic and shoulder posture
Restricted and painful cervical, thoracic and or upper limb ROM (shoulder through to fingers)
Pain on sustained arm elevation
Poor scapular positioning at rest and moving
Change in skin temperature
Change in sensation (will present in non-dermatomal pattern)
Change in power (will present in non-myotomal pattern)
Hypermobility or hypermobility of cervical, thoracic or upper limb joints.
Tightness and pain on palpation of surrounding soft tissues

Special Tests

There are a number of classic provocation tests for thoracic outlet syndrome. However, these have been reported to be unreliable and frequent false positives, with poor specificity, sensitivity and predictability.

Adson’s Test
Wright’s Test
Roos Test
The military brace
Postural and scapular corrective exercises
Tinnels at the supraclavicular fossa
Morley Test

Further investigation

Chest X-Ray with or without angiography (vascular)
MRI
Ultrasound with Doppler
Nerve conduction studies
Anterior scalene block

Management

Conservative

Advice for posture, activity modification, avoiding aggravating factors and pain
Reduce pain, swelling and inflammation
Medications (opioids, NSAIDs)
Ice and or heat
Light soft tissue massage
Increase Range of Movement
Decrease tone
Soft tissue massage: paraspinals, scalenes, trapezius, pectoralis minor, pathway of peripheral nerves
Diaphragmatic breathing (offloads scalenes)
Stretching
Light ROM exercises
Dry needling
Improve Joint Movement
Joint mobs: cervical spine, thoracic spine, glenohumeral joint, first rib
Soft tissue massage
Manipulations
Restore Normal motor control and strength
Deep neck flexors, scapular control and mobility, core stability, shoulder dynamic stability (rotator cuff)
Restore dynamic stability and proprioception
Strengthen under load, improve scapular mobility throughout range, sport and activity specific

Surgery

Pec minor release
Excision of first rib
Removal of cervical rib if present
Surgery for thromboectomy if indicated following venous vascular TOS
Botulinim Toxin injections at hypertonic muscles has been investigated
Scalenectomy and scalenotomy
Removal of callus from previous clavicle fracture
Subclavian artery decompression and or repair

References

(Abdul-Jabar, Rashid et al. 2009, Watson, Pizzari et al. 2009, Hooper, Denton et al. 2010, Hooper, Denton et al. 2010, Watson, Pizzari et al. 2010, Twaij, Rolls et al. 2013, Povlsen, Hansson et al. 2014)

Abdul-Jabar, H., A. Rashid and F. Lam (2009). "Thoracic outlet syndrome." Orthopaedics and Trauma23(1): 69-73.

Hooper, T. L., J. Denton, M. K. McGalliard, J. M. Brismee and P. S. Sizer, Jr. (2010). "Thoracic outlet syndrome: a controversial clinical condition. Part 1: anatomy, and clinical examination/diagnosis." J Man Manip Ther18(2): 74-83.

Hooper, T. L., J. Denton, M. K. McGalliard, J. M. Brismee and P. S. Sizer, Jr. (2010). "Thoracic outlet syndrome: a controversial clinical condition. Part 2: non-surgical and surgical management." J Man Manip Ther18(3): 132-138.

Povlsen, B., T. Hansson and S. D. Povlsen (2014). "Treatment for thoracic outlet syndrome." Cochrane Database Syst Rev11: Cd007218.

Twaij, H., A. Rolls, M. Sinisi and R. Weiler (2013). "Thoracic outlet syndromes in sport: a practical review in the face of limited evidence--unusual pain presentation in an athlete." Br J Sports Med47(17): 1080-1084.

Watson, L. A., T. Pizzari and S. Balster (2009). "Thoracic outlet syndrome part 1: clinical manifestations, differentiation and treatment pathways." Man Ther14(6): 586-595.

Watson, L. A., T. Pizzari and S. Balster (2010). "Thoracic outlet syndrome part 2: conservative management of thoracic outlet." Man Ther15(4): 305-314.