Thoracic Outlet Syndromes

True TOS is a clear syndrome with weakness and sensory loss in the arm and hand usually caused by a fibrous band over which the lower trunk of the brachial plexus is stretched and angulated. It may coexist with a small rudimentary cervical rib.

Arterial TOS involves ischemia or even emboli in fingers and hands from a cervical rib causing stenosis and poststenotic dilatation of the subclavian artery. This type is more common in athletes.

Venous TOS is an acute or chronic syndrome with swelling of the arm due to stenosis or thrombotic occlusion of the subclavian vein.

Disputed (or nonspecific nonneurologic) TOS are chronic aching and pains or paresthesias in arms and shoulders with no findings. This is a large group, but neurologic signs are "either nonexistent or meager."

Posttraumatic TOS asociated with clavicular fracture and associated brachial plexopathy see separate article.

Clinical presentations
True TOS young to middle aged women develop paresthesias , pain and weakness on the ulnar border of the hand, rarely much pain, and no vascular symptoms. Per Thomas Swift they may have hand,arm, shoulder and neck pain. They have low set shoulders, long graceful "swan" necks and horizontal or downsloping clavicles. Muscle wasting resembles CTS with wasted APB but usually some ulnar innervated muscles waste as well. Sensory loss does not split the fourth digit. There is often weakness of the forearm flexors. The differential is median and ulnar neuropathy, lower trunk plexus lesion, radiculopathy. CT and MRI usually miss the fibrous band but may show other causes of plexus lesion. Plain films show characteristic bony abnormality most of the time. Treatment is supraclavicular exploration with division of the band.

Notes-- Adson;s test is valueless, because 11-80 % healthy controls obliterate radial pulse by holding hand above head. Other similarly useless tests are photoplethysmographic studies of blood flow in the fingers following Adson's test, the elevated arms stress test (east) with the arm abducted to 90 degrees, the elbow flexed and braced, the fist opened and closed for several minutes. Bruits are of no significance in the subclavian fossa. Arteriography and dopplers are useless. In contrast, there may be a Tinel's in the fourth and fifth fingers tapping the brachial plexus, and symptoms may be exacerbated pulling arm down to ground and relieved by pushing up (again from Swift). Patients are better when lying down (contrast to CTS) and by using armrests.

Plain films may show upper 3-4 thoracic vertebrae due to shoulders. OBLIQUE CERVICAL SPINE FILMS WILL SHOW CERVICAL RIBS IF THEY ARE PRESENT! Symptoms are usually unilateral but cervical rib may be bilateral, usually C 7 also occassionally C 6. The cervical rib has a one percent prevalence, again not all symptomatic. The fibrous band extending off the rib technically compresses the C8 and T1 roots.

The best treatment of nonspecific neurologic TOS may involve posture correction, stretching and strengthening exercises (of rhomboids, levator and trapezius, the shoulder elevators), and an orthosis designed to elevate the shoulder. Operate if a band is present it will help.

The association of TOS in musicians is debated by Stewart