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Thoracic Outlet Syndrome: Transaxillary Approach

  • Margaret Clarke Tracci
    Correspondence
    Address reprint requests to Margaret Clarke Tracci, MD, JD, Assistant Professor, Division of Vascular and Endovascular Surgery, University of Virginia, PO Box 800679, Charlottesville, VA 22908-0679
    Affiliations
    Division of Vascular and Endovascular Surgery, University of Virginia, Charlottesville, Virginia
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      Compression of neural or vascular structures within the constrained space of the thoracic outlet may give rise to 3 separate symptom complexes with distinct diagnostic and therapeutic considerations (Fig. 1). The transaxillary approach is one of the most frequently used in addressing thoracic outlet syndrome (TOS) of the neurogenic or venous type. In the management of arterial-type compression syndromes, many clinicians find that a supraclavicular exposure is preferable when vascular reconstruction is anticipated.
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      Figure 1Normal bony anatomy and neurovascular relationships of the thoracic outlet. a. = artery; m. = muscle; v. = vein.

      Diagnosis and Preoperative Management

      Neurogenic Thoracic Outlet Syndrome

      Neurogenic thoracic outlet syndrome (nTOS) remains the most frequently encountered type of thoracic outlet compression syndrome. The diagnosis and management of nTOS have evolved in tandem with our understanding of the wide range of anatomic variations leading to brachial plexus compression (Fig. 2). Despite the efforts of clinicians to develop definitive neurodiagnostic testing and objective criteria for the diagnosis of nTOS, history and physical examination remain the mainstays of diagnosis. Presenting symptoms may include pain, paresthesia, or weakness of the hand or arm, headaches, or local neck or shoulder pain. These are frequently associated with repetitive use or stress positions, but may also be noted on waking or without clear activity association. Direct palpation over the anterior scalene may produce pain or reproduction or arm symptoms. Roos and others distinguish “upper plexus” (C5, 6, 7) and “lower plexus” (C8, T1) distributions with differing anatomic etiologies.
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      Figure 2Common bony anomalies in thoracic outlet syndrome.
      Neurogenic symptoms must be distinguished from other nerve compression syndromes, such as carpal tunnel, cubital compression, or pectoralis minor syndromes. Diagnostic testing, such as nerve conduction velocity, electromyography, and somatosensory-evoked potentials, are used only selectively in the evaluation of nTOS by most clinicians given their cost, inconvenience, and limited specificity, although they may have utility in distinguishing nTOS from other nerve compression syndromes. A variety of provocative tests have also been used, the most useful of which is likely the elevated arm stress test, in which the patient, after assuming the “surrender position” with upper arm extended laterally from the thorax and flexed 90 degrees at the elbow, is instructed to open and close his or her fist for 3 minutes in an effort to reproduce symptoms. A chest radiograph should be obtained to evaluate for bony anomalies, such as the presence of a cervical rib or abnormalities of the transverse processes, first rib, or clavicle. Computed tomography (CT) and magnetic resonance imaging are not routinely used in the diagnosis or treatment of nTOS. Scalene muscle block may also be of use in establishing the diagnosis of nTOS. In mild to moderate cases, symptomatic relief may be obtained through physical therapy. Given the complexity of diagnosis and attendant medicolegal concerns, many clinicians recommend a trial of physical therapy as the initial course of treatment over a 1- to 3-month period. In addition, any neurological symptoms or deficits must be fully assessed and documented.

      Venous Thoracic Outlet Syndrome

      The presenting symptoms of venous thoracic outlet syndrome (vTOS) result from the narrowing or even thrombosis of the axillary-subclavian vein because of extrinsic compression in the costoclavicular space. The first rib, costoclavicular ligament, subclavius tendon and muscle, and the anterior scalene muscle are the structures constraining the space occupied by the vein and most frequently contribute to its compression. The clinical presentation generally involves swelling, discomfort, and dusky discoloration of the affected upper extremity. Chronic progression is associated with the development of prominent collaterals of the shoulder, chest wall, and neck, while acute presentation is associated with “effort thrombosis” or “Paget-Schroetter syndrome” in the setting of strenuous, repetitive motion.
      The gold standard of diagnosis remains venography. Findings may range from severe narrowing of the axillary-subclavian vein at the level of the first rib to complete occlusion. The study should include images obtained with at least 90 degrees of abduction of the arm, a position that will frequently provide more pronounced extrinsic compression. Noninvasive imaging may also provide useful information in the diagnosis of vTOS. Duplex ultrasonography is relatively inexpensive and may suggest central venous stenosis or occlusion. The role of CT and magnetic resonance venous imaging continues to evolve. When acute thrombosis is diagnosed, immediate catheter-directed thrombolysis is appropriate, accompanied by heparinization and arm elevation to relieve venous congestion. Thrombolysis of subacute or chronic thrombus yields less satisfying clinical results. Postthrombolysis venography may demonstrate the characteristic underlying extrinsic compression and stenosis associated with vTOS. Either transition to warfarin or full anticoagulation using low-molecular-weight heparin is appropriate to bridge until definitive operative repair. Clinical practice varies with regard to the interval to repair, with some clinicians, including the author, advocating immediate or short-interval (1-2 weeks) repair and others preferring 3-6 months of anticoagulation before surgical decompression.

      Arterial Thoracic Outlet Syndrome

      Arterial thoracic outlet syndrome (aTOS) is the least common of the thoracic outlet compressive syndromes and is generally associated with bony abnormalities, such as cervical rib, anomalous first rib, enlarged C7 transverse process, or clavicular fracture with malunion or prominent bony callus. Less frequently, fibrous bands may contribute. The extrinsic compression characteristic of aTOS is often accompanied by poststenotic dilatation or frank aneurysms of the affected subclavian artery. Where aneurysmal degeneration has occurred, patients may present with embolization to the hand or with claudication because of subclavian thrombosis. Physical examination may demonstrate a palpable, high-riding subclavian pulse, a bruit, or even a palpable aneurysm, as well as hand findings characteristic of embolization.
      Positional maneuvers in conjunction with physical examination, duplex ultrasonography, or pulse volume recordings with segmental pressure readings have frequently been used to evaluate patients for aTOS. These tests are, however, not particularly specific as a large proportion of the normal population will demonstrate positional dampening of pulses or waveforms. A chest radiograph should be obtained to evaluate for bony abnormalities. At the present time, CT and traditional angiography are considered equivalent for diagnosing aTOS, although catheter-based angiography continues to provide better images of the distal vasculature of the arm and hand in patients with embolic symptoms.

      Operative Technique

      The patient is placed in a modified supine position with a rolled blanket or bean bag used to raise the operative side 20-30 degrees and the head turned slightly away. The operative field is prepped sterilely, including the arm, which is covered in an impervious stockinette to permit positioning by an assistant throughout the operation. The arm is extended anteriorly with the elbow flexed. Care must be taken to avoid hyperabduction with attendant strain on the brachial plexus. In addition, it is prudent to instruct the assistant to return the arm to the neutral position every 20 minutes or so during the course of the operation to further minimize positioning-related brachial plexopathy. The incision is located just above the lower border of the axillary hair line and extends from the border of the latissimus to the border of the pectoralis (Fig. 3). The dissection is carried through the subcutaneous tissues to the chest wall. Care should be taken to preserve the thoracodorsal and long thoracic nerves, which will course cephalad to caudad along the chest wall in the lateral portion of the exposure, and the second intercostobrachial cutaneous nerve, which exits between the first and second ribs and courses medially to laterally across the axilla to the medial upper arm.
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      Figure 3Patient positioning and incision site for the transaxillary approach.
      Once the chest wall has been reached, blunt dissection cephalad will expose the first rib and permit palpation of the subclavian artery. At this stage, a Wylie vein retractor permits focused deep retraction. The surgeon may use the subclavian pulse to guide initial retractor placement just anterior to avoid inadvertent compression or tension on the brachial plexus. At this stage, a blunt Wietlaner or Henly self-retaining retractor to the skin and subcutaneous tissues is used to maintain general exposure of the surgical field (Fig. 4).
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      Figure 4Operative exposure provided by the transaxillary approach.
      Attention may then be turned to division of the anterior scalene muscle. The phrenic nerve courses laterally to medially across the anterior surface of the muscle at or even somewhat above the cephalad extent of the field of exposure. In general, the phrenic nerve courses posterior to the subclavian vein, but the surgeon must be aware that in rare cases it will pass anterior to the vein. The anterior scalene may be separated carefully and bluntly from the underlying structures and a right-angle clamp is passed. The Metzenbaum scissors are then used to divide the muscle carefully as cephalad as it may be adequately visualized, permitting an effective resection or scalenectomy at the time of first rib removal, rather than a simple division or scalenotomy. This additional effort is of importance in averting the portion of persistent or recurrent TOS that is attributed to inadequate resection of this muscle (Fig. 5). A periosteal elevator or the Metzenbaum scissors may then be used to separate the middle scalene from its insertion on the first rib, a technique that preserves the long thoracic nerve that courses rather variably through the belly of this muscle, thus avoiding denervation of the serratus anterior muscle and the attendant complication of “winged scapula” (Fig. 6). If a scalenus minimus is present between the subclavian artery and the brachial plexus, it should be resected at this stage, as should any other ligamentous bands encountered constraining the plexus. These may insert on the first rib or even extend to insert into Sibson's fascia over the pleural cupola.
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      Figure 5Resection of the anterior scalene muscle, preserving the phrenic nerve.
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      Figure 6Division of the middle scalene, preserving the long thoracic nerve.
      Either a periosteal elevator or the Metzenbaum scissors then may be used to dissect the inferior border of the first rib free from the intercostal musculature, exposing the underlying parietal pleura (Fig. 7). The parietal pleura should be gently bluntly dissected free of the posterior surface of the rib, with care taken to avoid entering the pleural space. The rib should be dissected free from the level of the costochondral junction medially to the lateral-most extent of the middle scalene posteriorly. The Roos bone shear should then be inserted carefully, with the surgeon's finger placed between the shear and the brachial plexus. Additional repositioning should be avoided and the rib should be divided just beyond the divided insertion of the middle scalene muscle. Anteriorly, the Roos bone shear should be used to resect the first rib segment as close as possible to the costochondral junction (Fig. 8). Following removal of the rib segment, a Kerrison rongeur may be used to smooth the rib end posteriorly and, where necessary, to extend the resection to the level of the costochondral junction anteriorly to permit full decompression in cases of vTOS (Figure 9, Figure 10). In the setting of vTOS, care should be taken at this stage to complete resection of the costoclavicular ligament and the subclavius tendon and muscle to permit full venolysis and decompression of the vein at this key point of entrapment.
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      Figure 7Dissection of the inferior border of the first rib.
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      Figure 8Resection of the first rib using the Roos first rib shear.
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      Figure 9Completion of medial rib removal using the Kerrison rongeur may be, in the treatment of vTOS, accompanied by resection of the costoclavicular ligament, the subclavius tendon and muscle, and full venolysis.
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      Figure 10Completion of lateral rib removal using the Kerrison rongeur.
      The wound is then inspected for hemostasis. Cautery must be used very judiciously, given the risk of nerve injury because of transmitted energy. Sterile saline is then instilled and the anesthesiologist asked to provide 30 mm Hg of positive pressure to check for evidence of pleural injury, which will manifest as bubbles rising from the pleura or drainage of instilled fluid into the pleural space. If either of these are detected, a small (19-French) drainage catheter is placed in the pleural space. A drainage catheter is left in the operative field and brought out through a separate stab incision and the wound is closed in 2 layers. The pleural catheter should be placed to 20-mm Hg suction initially to evacuate the space and, in the absence of an air leak, may be placed subsequent to water seal. The wound drain may be placed to close bulb suction.

      Postoperative Management

      An upright chest radiograph should be obtained in the recovery room and, for patients with a pleural drainage catheter or small residual amounts of pleural air or fluid, daily. A full neurological examination should be performed as soon as the patient is sufficiently recovered from anesthesia. Adequate pain control is essential and may require a combination of intravenous and oral narcotics, nonsteroidal anti-inflammatory drugs, and muscle relaxants. Physical therapy should be initiated on postoperative day 2 with the initial goal of maintaining range of motion. Heavy lifting and strenuous activity using the arm are discouraged for 4-6 weeks and should be resumed based on the individual's progress in physical therapy. Any new or residual neurological symptoms should be assessed and fully documented at regular intervals.

      Suggested Reading

      Juvonen T, Satta J, Laitala P, et al: Anomalies at the thoracic outlet are frequent in the general population. Am J Surg 170:33-37, 1995
      Roos DB: Transaxillary approach for first rib resection to relieve thoracic outlet syndrome. Ann Surg 163:354-358, 1966
      Roos DB: Congenital anomalies associated with thoracic outlet syndrome. Anatomy, symptoms, diagnosis, and treatment. Am J Surg 132:771-778, 1976
      Sanders RJ: Thoracic Outlet Syndrome: General Considerations, in Rutherford’s Vascular Surgery. Philadelphia, PA, W.B. Saunders, 2010, pp 1865-1877
      Thompson RW, Petrinec D: Surgical treatment of thoracic outlet compression syndromes: Diagnostic considerations and transaxillary first rib resection. Ann Vasc Surg 11:317-323, 1997
      Thompson RW, Driskill M: Thoracic Outlet Syndrome: Neurogenic, in Rutherford’s Vascular Surgery. Philadelphia, PA, W.B. Saunders, 2010, pp 1878-1898