- Clinical science
Thoracic outlet syndrome (TOS) is an umbrella term for conditions involving the compression of neurovascular structures (e.g., the brachial plexus or the subclavian artery or vein) as they pass from the lower neck to the armpit. Causes include trauma, tumors, or the presence of a cervical rib. Neurogenic TOS is the most common type and involves the compression of the brachial plexus, leading to neck pain and numbness and tingling in the fingers. Arterial TOS involves compression of the subclavian artery and presents with pain, pallor, coldness, and pulselessness in the affected arm, especially during overhead activities. Venous TOS results in pain, cyanosis, and swelling of the arm. Imaging techniques such as duplex sonography, X-ray, MRI, or electrodiagnostic testing are used to detect the cause of TOS. Mild symptoms should be treated with pain medication and physical therapy. Surgical resection of the causal structures might become necessary in the case of progressive neurologic dysfunction or acute vascular insufficiency.
Compression of subclavian vessels and the lower trunk
- Physical trauma (e.g. hyperextension neck injuries)
- Repetitive motion of the abducted and externally rotated shoulder; (e.g. tennis; , baseball; , swimming, repetitive throwing, carrying heavy objects overhead)
- Structural abnormalities
- Clinical features of TOS depend on the anatomic structure affected by compression; and are more pronounced during and after overhead activity.
Compression of the subclavian artery
- Mild arm ache and fatigue
- Pulselessness, pain, pallor, paresthesia and coldness in the affected arm ()
- ↓ Blood pressure of > 20 mm Hg in the affected arm compared with the contralateral arm
Compression of the subclavian vein
- Venous distention
- Diffuse hand or arm pain
- Risk of thrombosis of the arm; ()
- Compression of parts of the brachial plexus
Swelling and venous distention in the arm may be a sign of venous thrombosis of the arm!
- Radiographs of the spine, shoulder, collarbone → bony abnormalities
- CT or MRI imaging mainly to exclude other conditions that present similarly .
- Other tests depend on suspected underlying pathology
- Arterial ; TOS → MR angiography
- Venous; TOS → duplex ultrasonography
- Neurogenic; TOS → electromyography/nerve conduction studies
- In mild cases: physical therapy; , weight reduction, NSAIDs, thrombolytics with continued anticoagulation in the case of venous thrombosis
In cases of acute vascular insufficiency or progressive neurologic dysfunction, or if conservative treatment fails: thoracic outlet decompression surgery
- Transaxillary resection of the cervical rib or first rib
- Angioplasty or venous or arterial bypass for severely narrowed vessels