Surgical decompression of the thoracic outlet is necessary for patients with a diagnosis of TOS who have failed conservative management. Many surgeons prefer the transaxillary approach because of its relative ease, excellent cosmesis, and durable results. Specific indications for surgery depend on the TOS subtype.

Neurogenic TOS is the most common form of TOS accounting for approximately 95% of cases. The most common causes of neurogenic TOS include neck trauma involving a hyperextension neck injury (i.e., whiplash) or repetitive strain injuries at work. Anatomic structures previously mentioned are predisposing factors to the development of TOS. Hyperextension or repetitive strain to the anterior scalene muscle likely leads to chronic inflammation, fibrosis, and stricture of the muscle that can ultimately cause
compression and irritation to the brachial plexus. Affected patients, who are typically young women, complain of unilateral paresthesia, pain, and weakness throughout the hand and arm which do not follow a specific nerve distribution. These symptoms often extend toward the shoulder, upper back, and neck producing occipital headaches. On physical examination, symptoms are often reproducible upon palpation of various “trigger points” along the scalene triangle. The elevated arm stress test (EAST) is perhaps the most helpful maneuver in diagnosing neurogenic TOS. During this test, the patient raises both arms directly above the head and repeatedly opens and closes the fists. A patient with neurogenic TOS typically will develop arm pain and paresthesia within 60 seconds of starting this exercise. The initial treatment of neurogenic TOS is physical therapy directed at correcting posture and disordered movement patterns along with nonsteroidal anti-inflammatory drugs, tricyclic antidepressants, serotonin reuptake inhibitors, and muscle relaxants. Conservative treatment is successful in up to 60% of patients. Surgery is reserved for those patients who fail an 8-week trial of these conservative measures.

Venous TOS accounts for about 5% of all cases and is usually due to repetitive, vigorous overhead arm activities and developmental anomalies of the costoclavicular space resulting in occlusion of the subclavian–axillary vein. The first rib and clavicle as well as the subclavius and anterior scalene muscles contribute to extrinsic mechanical compression of and repetitive injury to the subclavian vein. Patients with this “effort thrombosis,” referred to as Paget-Schroetter syndrome, are traditionally young, healthy men who present with acute edema, cyanosis, and dull pain of the affected (often dominant) upper extremity. However, in our practice, nearly half of all patients are women reflecting an increase in participation in sports and weight training. Some patients can have a more insidious process as they present with intermittent swelling which is due to chronic subclavian vein thrombosis or stenosis. Historically, patients were treated with anticoagulation alone but this resulted in very high residual functional impairment rates. The advent of catheter-directed thrombolytic therapy in the 1970s dramatically improved restoration of venous luminal patency; however, a substantial portion of patients developed recurrent thrombosis within 30 days due to uncorrected extrinsic compression. As such, early or immediate surgical decompression of the thoracic outlet following thrombolytic therapy is routinely performed in patients with venous TOS in order to minimize both symptoms and reocclusion rates. Of note,
simple anticoagulation can be effectively used instead of thrombolytic therapy prior to first rib resection. In a retrospective review from our institution, there was no difference in vein patency rates at 1 year between preoperative anticoagulation and thrombolysis.

Arterial TOS is the least common form of TOS accounting for less than 1% of patients but is a very serious entity requiring surgical intervention. Pathophysiology most commonly relates to the presence of a short, broad cervical rib that compresses the subclavian artery against the anterior scalene muscle resulting in chronic stenosis. Over time, the subclavian artery develops poststenotic dilatation which can progress to aneurysmal degeneration with secondary thrombosis or distal embolization. Although many are asymptomatic, patients with arterial TOS can present with critical hand and digit ischemia from microembolization to mild exertional arm claudication. On examination, a pulsatile supraclavicular mass or bruit can be detected with shoulder abduction. The Adson test, although not perfect due to its high false-positive rate, can be helpful. A positive test occurs when there is a reduction in the radial pulse after the patient takes a long breath in, elevates his chin, and turns it to the affected side. Surgical intervention aimed at arterial decompression, removal of the embolic source, and distal reperfusion is warranted for all symptomatic patients with ischemia and for asymptomatic patients with documented aneurysmal changes or intimal damage. Both a cervical rib and first rib can be successfully removed through a transaxillary approach so long as the subclavian artery has no evidence of aneurysm or thrombus as these findings would require a supraclavicular approach for arterial repair or bypass grafting.

No absolute contraindication to thoracic outlet decompression via a transaxillary approach exists; however, the transaxillary approach should be avoided in patients with arterial TOS who need vascular reconstruction, given the limited exposure of the subclavian artery with this approach. Also, patients with recurrent symptoms and evidence of residual first rib despite previous transaxillary first rib resection should undergo reoperative resection through a supraclavicular approach. As per routine, all comorbidities need to be identified, corrected, and/or compensated preoperatively, thereby minimizing the risks of general anesthesia. Perhaps more importantly, TOS can be difficult to diagnose because symptoms and signs are often vague and overlapping. Accordingly, ensuring that the patient has been correctly diagnosed with TOS is paramount for a successful operative outcome.