Thoracic Outlet Syndrome

Thoracic Outlet Syndrome (TOS) is a compressive neuropathy of the upper extremity caused by compression of the neurovascular bundle as it passes into the thoracic outlet. Potential causes include cervical rib, muscle compression, repetitive movements, and extreme arm positions. Upper extremity pain, swelling, cold intolerance, Raynaud’s phenomenon and paresthesias are the most common symptoms. Provocative physical exam maneuvers have variable reliability and electromyography (EMG) and nerve conduction velocity (NCV) are recommended to localize and quantify the lesion in the brachial plexus and rule out other segmented neuropathies. TOS non-operative treatment includes physical therapy, activity modifications, and posture reeducation. Scalene block may be indicated if TOS is caused by scalene syndrome. Neurological and vascular decompression are rarely used, and only recommended when there is objective quantifiable neurological deficits, vascular insufficiency and after conservative methods have failed.