Thoracic Outlet Syndromes in Microsoft Office

Drawer QR-Code in Microsoft Office Thoracic Outlet Syndromes

A number of anatomic anomalies occur in the lateral cervical region; these may, under certain circumstances, compress the brachial plexus, the subclavian artery, and the subclavian vein, causing muscle weakness and wasting, pain, and vascular abnormalities in the hand and arm The condition is undoubtedly diagnosed more often than is justi ed and the term is applied ambiguously to a number of conditions, some of which are almost certainly nonexistent The most frequent of the abnormalities that cause neural compression and are encompassed by the term thoracic outlet syndrome are an anomalous incomplete cervical rib, with a sharp fascial band passing from its tip to the rst rib; a taut brous band passing from an elongated and down-curving transverse process of C7 to the rst rib; less often, a complete cervical rib, which articulates with the rst rib; and anomalies of the position and insertion of the anterior and medial scalene muscles Thus, the sites of potential neurovascular compression extend all the way from the intervertebral foramina and superior mediastinum to the axilla Depending on the postulated abnormality and mechanism of symptom production, the terms cervical rib, anterior scalene, costoclavicular, and neurovascular compression have been applied to this syndrome The international anatomic term is superior thoracic aperture syndrome In addition, a droopy shoulder syndrome has been identi ed that ostensibly stretches the brachial plexus and gives rise to similar symptoms; a majority of the patients are women in early or midadult life (female-to-male ratio 5:1) in whom sagging of the shoulders, large breasts, and poor muscular tone may be of importance

Figure 11-8 Course of the brachial plexus and subclavian artery between the anterior scalene and middle scalene muscles Dilatation of the subclavian artery just distal to the anterior scalene muscle is illustrated Immediately distal to the anterior and middle scalene muscles is another potential area of constriction, between the clavicle and the rst rib With extension of the neck and turning of the chin to the affected side (Adson maneuver), the tension on the anterior scalene muscle is increased and the subclavian artery compressed, resulting in a supraclavicular bruit and obliteration of the radial pulse

exor muscles of the forearm may be present in advanced cases Tendon re exes are usually preserved In addition, most patients with this form of the syndrome complain of an intermittent aching of the arm, particularly of the ulnar side, and about half of them complain also of numbness and tingling along the ulnar border of the forearm and hand A loss of super cial sensation in these areas is a variable nding It may be possible to reproduce the sensory symptoms by rm pressure just above the clavicle or by simple traction on the arm Vascular features are often absent or minimal in patients with the neurologic form of the syndrome Diagnostic measures should include the Adson test or the

Wright maneuver, described earlier, preferably with digital plethysmography to quantitate the degree of positional vascular compromise; also, lms of the cervical spine should be obtained looking for a cervical rib or an elongated C7 transverse process (the brous bands are not visualized) In the droopy shoulder syndrome, the upper two to four thoracic vertebrae are seen as a result of the low-lying shoulders Typically, nerve conduction studies disclose a reduced amplitude of the ulnar sensory potentials There may be a decreased amplitude of the median motor evoked potentials, a mild but uniform slowing of the median motor conduction velocity, and a prolongation of the F-wave latency Concentric needle examination of affected hand muscles reveals large-amplitude motor units, sug-

gesting collateral reinnervation The application of somatosensory evoked potentials may be a useful adjunct to the conventional nerve conduction and EMG studies (Yiannikas and Walsh) Brachial artery angiography is usually reserved for patients with a suspected arterial occlusion, an aneurysm, or an obvious cervical rib The place of venography in the diagnostic workup is uncertain, for a number of otherwise normal individuals can occlude the subclavian vein by fully abducting the arm In the authors experience, unambiguous instances of thoracic outlet syndrome are not common This has also been the experience of Wilbourn, whose review of this subject is recommended Neck and arm pain in slender, neurotic women presents particularly dif cult problems in diagnosis; often the physician assumes the presence of a thoracic outlet syndrome, only to discover that operation affords little or no lasting relief One should be skeptical of the diagnosis unless the clinical and EMG criteria enumerated above have been met Common mistakes are to confuse the thoracic outlet syndrome with carpal tunnel syndrome, ulnar neuropathy or entrapment at the elbow, or cervical radiculopathy due to arthritis or disc disease Brachial neuritis may have a similar presentation Imaging studies and careful nerve conduction and EMG studies may be necessary to exclude all of these disorders Treatment of the Thoracic Outlet Syndrome A conservative approach is advisable If the main symptoms are pain and paresthesias, Leffert suggests the use of local heat, analgesics, muscle relaxants, and an assiduous program of special exercises to strengthen the shoulder muscles Twice a day, holding a 1- or 2-lb weight in each hand, the patient intermittently shrugs and relaxes the shoulders forward and upward, then backward and upward, and then upward, each performed 10 times In a second exercise, with the weights held at the side, the extended arms are lifted over the head until the backs of the hands meet; again this is done 10 times In a third exercise, the patient faces a corner of a room and places one hand on each wall; with elbows bent, he or she leans into the wall and at the same time inhales, then exhales as he or she pushes away A full range of neck motions is then practiced On such a regimen, some patients experience a relief of symptoms after 2 to 3 weeks Instruction by a quali ed physical therapist is invaluable Only if pain is severe and persistent and is clearly associated with the vascular and/or neurogenic features of the syndrome is surgery indicated The usual approach is through the supraclavicular space, with cutting of brous bands and excision of the rudimentary rib In cases of venous or minor arterial forms of the syndrome, some thoracic surgeons favor the excision of a segment of the rst rib through the axilla Pain is often dramatically relieved, but the sensorimotor defects improve only slightly Sectioning of the scalenus muscle is endorsed only in exceptional cases, since as already noted, the role of muscle in causing thoracic outlet syndrome has been questioned Vasomotor, sudomotor, and trophic changes in the skin, with atrophy of the soft tissues and decalci cation of bone, may follow the prolonged immobilization and disuse of an arm (ie, frozen shoulder syndrome) or leg for whatever reason The patient may be reluctant to move the limb because of pain or a lack of motivation to get well or for reasons of monetary gain Surgery in this group of patients is ill-advised, and the physician s efforts should be directed to mobilization of the affected part through an intensive physical therapy program and settlement of litigation if this is a factor