Thoracic Outlet Syndrome

A thoracic outlet syndrome is a group of disorders where blood vessels and nerves are entrapped between following potential spaces.

It contains:

• Subclavian artery
• Subclavian vein
• Brachial plexus

3 potential space for compression

Interscalene Space

The costa-clavicular space

Space between:

• 1^st Rib
• Clavicle
• Subclavis muscle

Sub-pectoralis minor space

The enclosure is formed by the coracoid, the pectoralis minor tendon, and the costo-coracoid membrane

Contributing factors for TOS

Dynamic factors

Fully hyperabduction above the head (Axillary artery bend 180 degrees)

Static factors

Vigorous occupation: Increase muscle bulk: Compression

Inactivity: Lacks muscle mass: Sagging of shoulder: Angulate and compress the neurovascular bundle

Anatomical Predisposition/ Congenital factors:

Congenital bands and ligaments with neurogenic thoracic outlet syndrome (nTOS)

Cervical rib

Traumatic factors

nTOS: Neck trauma + anatomical predisposition

• Malunited clavicle
• Nonunion with excess callus
• Single/ repeated subacromial dislocation

Arteriosclerotic factors

Unusual vigorous activities (arteriosclerosis extremity)

Thrombosis and further narrowing of vessels

Miscellaneous factors

• Tumors
• Cervico-thoracic scoliosis
• Scalene muscles insertion

Clinical Features of TOS

Depends upon which structure is involved

Neck pain/ shoulder pain + paraesthesia involving upper limb and forearm

The medial side of the upper limb/ two ulnar digits (Nocturnal pain + paresthesia ) if inferior portion o brachial plexus (C8-T1) involved (It hangs over 1st rib)

Medial brachial, medial antebrachial + Ulnar nerve (Numbness + tingling + pain)

Pain of neuritis

• Intermittent
• Burning in character
• Brought out by certain movements

Vascular Pain

• Constant of diffuse
• Varies from the coldness of fingers, intolerance to cold and pallor, and cyanosis of fingers
• In 1/4th patient: Raynold’s phenomena
• Venous compression:- intermittent/ less constant, swelling of limb + cyanosis
• Effort thrombosis: Acute thrombosis of subclavian vein

Intermittent Claudication Test

Exercising forearm muscle in the presence of impaired arterial blood flow

Special tests for thoracic outlet syndrome

Palpation of supra clavicular fossa (detect bony prominence due to cervical rib)

A soft, pulsatile mass is due to an aneurysmal dilation of the artery beyond the point of constriction in the Interscalene triangle.

Systolic bruits: Below the clavicle at the junction of the middle and outer third

Thrombosis of the axillary-subclavian vein (Paget-Schroette syndrome)= Progressive swelling of the arm. Venogram shows constriction.

When an artery is compressed in the extremities: Soft systolic bruits may be detected

Subclavian artery compressed: Wrist pulsation decreases, pulse pressure decrease by 15mmHg

Symptoms develop acutely and dramatically.

Radial/ Ulna artery occlusion detected by Allen’s test

Treatment Options of TOS

Conservative treatment

• Lifestyle modification (Occupation, Sleeping attitude)
• Therapeutic exercises

Surgery

Indication:

• Symptoms progressively severe
• Increase ischemia
• Signs of neurological deficit
• Expanding post-stenotic arterial dilation
• Emboli phenomena of the distal vessel of extremity
• Complete thrombotic obstruction of large artery
• Compressive structure: malunion of clavicle

Options:

• Anterior scalenectomy
• Removal of 1^st rib
• Removal of cervical rib
• Removal of a portion of clavicle when arterial reconstruction is needed