Thoracic Outlet Syndrome
- 353.0 (Brachial plexus lesions; cerical rib syndrome, costoclavicular syndrome, scalenus anticus sydrome, thoracic outlet syndrome)
TOS Etiology / Epidemiology / Natural History
- Etiology: compression of the neurovascular structures (subclavian vessels, brachial plexus, cervical ganglia, and vertebral artery) in the cervicoaxillary region. May be congenital or acquired.
- Bony causes: long transverse process of the 7th cercial vertebra, cervical rib, anomalous 1st rib, clavicle fracture, 1st rib fracture.
- Soft tissue causes: congenital bands, poor posture, mass lesions, cervical strain, hypertrophy and/or injury of the anterior and middle scalene muscles or the pectoralis minor muscle.
- must rule out all other possible diagnoses
- aggravating factors=trapezius weakness, obesity, excessively large breasts.
TOS Clinical Evaluation
- Numbness, tingling, early fatigue, weakness, pain in neck or shoulder. Numbness and tingling may involve entire upper limb or forearm and hand.
- ulnar side of limb and two ulnar digits are predominantly involved
- nocturnal pain and paresthesias common
- difficulty with overhead activity. Occasional c/o numbness carrying things, typing or driving.
- +/- pain in arm, shoulder, neck, chest, limb swelling,
- Trapezious atrophy, eval neck ROM,
- Complete Neurovascular exam indicated.
- Adson’s: arm at side, neck hyperextended, head turned toward affected side reproduces symptoms
- modified Adson’s
- Wright’s:arm abducted and ER, pt takes deep breath and holds it.
- provocative position and compression test(manual compression to the brachial plexus in various positions)=most reliable (Novak CB, J Hand Surg 18A;292:1993)
TOS Xray / Diagnositc Tests
- NCV, EMG, xray, CT, sensory test all will be normal
- angiography/ultrasound are frequently abnormal in a normal poplulation
- NCV/EMG indicated to r/u more distal lesion
- Anterior scalene and/or pectoralis minor muscle blocks using local anesthetics have been used in diagnosis(Jordan SE, Ann Vasc Surg 1998;12(3):260).
TOS Classification / Treatment
- Initial=correction of posture, supraclavicular muscular stretching and strengthening exercises of the lower scapular stabilizers and activity modification (Novak CB, J Hand Surg 20A;542:1995); often takes 2+months to show improvement.
- Avoid enciting activities, lose weight, better supporting bra/reduction mammoplasty.
- Operative = thoracic outlet decompression via transaxillary or supraclavicular approach, typically removal of the first rib, resection of the anterior/middle scalene muscles, +/- brachial plexus neurolysis; in cases associated with localized tenderness over the subpectoral space, consider pectoralis minor tenotomy. (Thompson RW, Ann Vasc Surg 1997;11:315).
- Supraclavicular decompression allows more complete anterior/ middle scalenectomy and ability to perform brachial plexus neurolysis with direct visual protection of the brachial plexus nerve roots.
TOS Associated Injuries / Differential Diagnosis
- Brachial plexus injury
- Vascular injury
TOS Follow-up Care
- Up to 40% recurrence after transaxillary first rib resection (Altobelli GG, J Vasc Surg 2005;42:122).
- Up to 10% recurrence after supraclavicular decompression
TOS Review References
- Leffert, RD, JAAOS 1994;2:317
- Sanders RJ. Thoracic outlet syndrome: a common sequelae of neck injuries. Philadelphia: J.B. Lippincott Company; 1991.