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Thoracic Outlet Syndrome

Thoracic outlet syndrome (TOS) is a group of rare conditions involving compression of the nerves or blood vessels that serve the arm and hand, as they pass through the base of the neck and behind the collarbone on the way to the arm. Patients with nerve compression caused by TOS can experience pain in the neck and shoulder, as well as pain, numbness, tingling and weakness in the hand and fingers. These symptoms are often worse during arm activity or with the arm elevated overhead. Others may experience arm swelling and discoloration due to a clot in the vein to the arm, and some have cold painful fingers and arm fatigue due to an aneurysm of the artery.

Symptoms can be disabling and diagnosis is a substantial challenge, but fortunately, many patients with TOS respond well to targeted physical therapy or surgery when necessary. Thoracic outlet syndrome is difficult to diagnose and not well understood by physicians who haven’t seen many cases, and treatment has for many years been considered controversial. At the Barnes-Jewish & Washington University Heart & Vascular Center, our multidisciplinary team offers nationally-recognized expertise on all aspects of thoracic outlet syndrome, including comprehensive diagnosis, conservative treatment, and surgical care for patients with all three forms of the condition. Our Center for Thoracic Outlet Syndrome provides hope to patients with TOS from the St. Louis region and across the country.

Understanding Thoracic Outlet Syndrome

There are three types of thoracic outlet syndrome: 

  • Neurogenic TOS: Caused by compression of the brachial plexus nerves due to subtle variations in anatomy, coupled with previous injury to the neck or upper extremity. Tearing within the scalene muscles leads to fibrosis and persistent muscle spasm, with compression and irritation of the nerves between the scalene muscles and first rib. Some patients may have nerve compression caused by injury and spasm within the pectoralis minor muscle, located just beyond the first rib. Symptoms of neurogenic TOS are exacerbated by postural disturbances and repetitive use of the arm and hand, particularly in overhead positions.

  • Venous TOS: Characterized by compression of the subclavian vein between the collarbone and first rib, resulting in vein injury, scarring and narrowing, and eventual clot formation and vein occlusion. Subclavian vein occlusion, also known as “effort thrombosis” or Paget-Schroetter syndrome, is characterized by sudden swelling and bluish discoloration of the arm. This condition is often associated with heavy use of the arm in overhead positions or lifting, and can lead to pain and heaviness with arm activity. Although venous TOS often occurs in athletes, it can develop in any young active healthy individual.

  • Arterial TOS: Caused by occlusion or aneurysm of the subclavian artery in the neck, usually in association with an extra “cervical” rib or first rib anomaly. Small clots forming within the subclavian aneurysm may break off and travel to the hand, which turns cold, painful, and numb. Overhead athletes may develop a similar problem in the axillary artery in the upper arm, due to repetitive compression and arterial injury.

In general, each type of TOS occurs in young people that are otherwise healthy and active. In neurogenic TOS, more than 50 percent of patients are women, but there is no gender predisposition for venous or arterial TOS. Of patients diagnosed with TOS, the following occurrence pattern is revealed:

  • 80 percent are diagnosed with neurogenic TOS

  • 15 percent are diagnosed with venous TOS

  • 5 percent are diagnosed with arterial TOS

Treating Thoracic Outlet Syndrome

Caught early, mild symptoms of neurogenic TOS usually respond to appropriate physical therapy. Surgery is indicated for patients with disabling neurogenic TOS that have not improved sufficiently with conservative management, with most patients achieving a substantial improvement and some patients achieving dramatic results.

To provide the best chances for restoration of function and a return to full activity, surgical treatment is almost always indicated for venous and arterial TOS. Because most practicing physicians, surgeons and physical therapists rarely care for patients with TOS, the best approach to diagnosis and treatment for such patients is through referral to a specialist with dedicated expertise and vast experience.

In all three forms of thoracic outlet syndrome, surgery begins with a transverse incision above the collarbone. The anterior scalene muscle is removed, revealing the underlying brachial plexus nerve roots. Fibrous scar tissue is meticulously cleared away from each nerve to ensure complete mobility. Behind the nerves is the middle scalene muscle, which is also removed. With the nerves then protected under direct vision, the first rib is exposed, divided, and removed. In some cases, a second incision is made near the shoulder in order to divide the pectoralis minor muscle tendon. This completes the surgery for neurogenic thoracic outlet syndrome.

If the patient has arterial thoracic outlet syndrome, the procedure usually includes removal of an extra “cervical” rib. Surgery then continues with repair of the subclavian artery, in which the aneurysm is removed and a graft is used to replace the damaged artery. After the arterial repair, it may be necessary to use small balloon catheters and thrombolytic drugs, in an effort to clear any additional small clots from blood vessels in the lower arm and hand.

In venous thoracic outlet syndrome, the same steps as surgery for neurogenic TOS are used, followed by a second incision just below the collarbone. This allows the surgeon to remove the entire first rib as well as any scar tissue from around the subclavian vein. If the subclavian vein remains narrowed despite removal of scar tissue, the vein is opened and repaired with a vein patch; in some cases, particularly where the subclavian vein remains occluded, it is replaced with a bypass graft.

Learn more about the Thoracic Outlet Syndrome Center at Washington University School of Medicine.

To make an appointment with a Washington University heart or vascular specialist at Barnes-Jewish Hospital, call 855.925.0631.