thoracic outlet syndrome

THORACIC OUTLET SYNDROME

Thoracic outlet syndrome (TOS)- a collection of symptoms brought about by abnormal compression of the neurovascular bundle by bony, ligamentous or muscular obstacles in the narrow space between clavicle and 1st rib – the thoracic outlet.

ANATOMY

interscalene triangle Med : 1st rib Ant : clavicle,

scaleneus anterior Post : scaleneus

medius

Costoclavicular space Med : 1st rib Ant : clavicle Post : scaleneus

medius Lat : costoclavicular

ligament, subclavius muscle

contents

Brachial plexus Subclavian artery Subclavian vein

Causes Cervical rib Long C7 transverse process Anomalous insertion of scalene muscles Scalene muscle hypertrophy scaleneus minimus Abnormal bands, ligaments Fracture clavicle/ 1st rib Exostosis Tumours Brachial plexus trauma / diseases

Cervical rib

Clinical features

Most commonly seen in middle aged women Usually due to neural compromise.

Interscalene triangle Artery , Nerves

Costoclavicular space Vein

Subcoracoid area Artery, Vein , Nerves

Interscalene triangle

Costoclavicular space

Subcoracoid area

Arterial compromise

Fatigue Weakness Coldness Upper limb claudication Thrombosis Paraesthesia Raynaud's phenomenon due to thrombosis with

distal embolisation

Venous compromise

Edema Venous distension Collateral formation Cyanosis Paget-Schroetter syndrome – effort thrombosis

"Effort" axillary-subclavian vein thrombosis (Paget-Schroetter syndrome) is an uncommon deep venous thrombosis due to repetitive activity of the upper limbs.

Neural compromise

Paraesthesia Pain in shoulder, arm, forearm and fingers Occipital headache – referred from tight

scalene muscles Weakness of forearm, hand.

Clinical tests

Roos Test

Hold both arms in surrendering position (90°overhead with shoulders in external rotation) – reproduction of symptoms within 1 minute . Arm collapses if continued.

modified Roos test / Extended Arm Stress Test(EAST)– same as above. Symptoms precipitated by opening and closing fists continuously.

Elevated arms stress test

Adson's (Scalene) Test

Radial pulse diminishes and disappears on turning chin to same side.

Decreases space between scaleneus anterior and medius .

Adsons test

Halsted's costoclavicular compression test

45° abduction and extension of arm with downward pressure on shoulders –neck turned to opposite side- reproduce symptoms

Exaggerated military position

Patient shrugs shoulders with deep inhalation while drawing the shoulders backward in an exaggerated military position – radial pulse diminishes.

Military position

Wright's hyperabduction test

Arm hyperabducted to 180°-diminishing radial pulse.

Neurovascular structures compressed in subcoracoid region by pectoralis minor tendon, head of humerus or coracoid process.

Wright's hyperabdution test

Tinel sign – in supra and infraclavicular region Phalens sign – in carpel tunnel syndrome (CTS)

Differential diagnoses

Carpel tunnel syndrome Spinal canal tumors Shoulder myositis Angina pectoris Raynaud's disease Ulnar nerve compression - epicondylitis

investigations

Chest x ray, cervical spine x ray MRI, cervical myelography

r/o narrowing of intrevertebral foramen, disc compression.

Doppler , vascular imaging(angiogram/venogram) r/o aneurism, thrombosis

Nerve conduction study, electromyography confirm neurogenic TOS, localise the area of

compression- r/o CTS

Double crush syndrome – TOS with other peripheral sites of nerve compression(CTS)

Treatment

Non operative treatment

Posture improving exercises. Breathing exercises. Avoid aggravating activities. Avoid repetitive upper extremity mechanical

work and muscular trauma. Analgesics,muscle relaxants, antidepressants. Physiotherapy .

Surgical treatment

Indications: Symptoms persists with non operative

treatment. Associated vascular compression. Progression of neurological symptoms. Nerve conduction velocity < 60m/s

Trans cervical or trans axillary(Roos) resection of 1st rib often with release of scalene muscles.

Cervical rib excision.

Roos approach

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