Thoracic Outlet Syndrome
Thoracic outlet syndrome (TOS) occurs when the nerves or blood vessels in the neck and shoulder regions are compressed by surrounding structures, such as the first rib or an abnormal rib, and the scalene muscles. Most patients have pain, weakness, numbness, or tingling in the neck, shoulder, or arm. There are three types of TOS: neurogenic, venous, and arterial. Treatment may involve surgical decompression of the thoracic outlet – removal of the first rib or an anomalous rib, partial removal of the anterior and middle scalene muscles, and decompression of the brachial plexus. Dr. Natalie Lui in Stanford’s Division of Thoracic Surgery has a special interest in the surgical management of TOS.
Types of Thoracic Outlet Syndrome
There are three types of thoracic outlet syndrome: neurogenic, venous, and arterial.
Neurogenic TOS is the most common type and occurs when the nerves in the brachial plexus are compressed, usually between the first rib and the scalene muscles. Most patients have pain, weakness, numbness, or tingling in the neck, shoulder, and arm. These symptoms usually worsen when the thoracic outlet is narrowed in certain body positions, such as when the arm is raised overhead. Many patients with neurogenic TOS have abnormal anatomy in the thoracic outlet (for example, an extra rib called a cervical rib) and a history of neck trauma (for example, a car accident or repetitive movements while playing sports or working). Other patients have no clear cause, but their symptoms are concerning for TOS.
Venous TOS is rare and occurs when the subclavian vein is compressed, usually between the first rib and clavicle (or collarbone), causing a blood clot. It is also called "effort thrombosis" and Paget-Schroetter disease. Many patients suddenly develop a swollen and discolored arm, and immediate treatment is critical. Patients usually require catheter-directed thrombolysis, anticoagulation, and then surgery to decompress the thoracic outlet.
Arterial TOS is extremely rare and occurs when the subclavian artery is compressed, usually near a cervical rib or anomalous first rib. This compression may lead to an aneurysm (widening) of the artery and formation of blood clots that can prevent blood flow to the arm and hand. Patients may have sudden pain, weakness, numbness, and/or tingling in their hands, and they almost always require surgery.
Diagnosis of neurogenic TOS requires an extensive history and physical examination, as well as radiologic imaging such as a computed tomography (CT) scan or magnetic resonance imaging (MRI).
Scalene muscle botulinum toxin injection may be performed for diagnostic and therapeutic purposes. Botulinum toxin causes temporary paralysis of the scalene muscles, which then relax around the nerves in the thoracic outlet. If patients have significant improvement in their symptoms, they are more likely to improve after treatment for TOS.
Other studies such as electromyography and nerve conduction studies may be performed to evaluate for other diseases that may cause similar symptoms. Cervical spine disorders, musculoskeletal disorders, carpal tunnel syndrome, fibromyalgia, and other conditions can all be mistaken for neurogenic TOS if a careful work-up is not performed.
The first step in the treatment of TOS is physical and occupational therapy, which includes exercises that widen the thoracic outlet, correct posture, and improve ergonomics.
Scalene muscle botulinum toxin injection, as described above, can be used for both diagnosis and as a temporizing therapy.
Surgery is performed in patients who have a clear diagnosis of TOS and have debilitating symptoms despite physical and occupational therapy. Patients whose symptoms improved after scalene muscle botulinum toxin injection are more likely to have a good outcome after surgery.
Surgery for thoracic outlet syndrome involves decompression of the thoracic outlet – removal of the first rib or an anomalous rib, partial removal of the anterior and middle scalene muscles, and decompression of the brachial plexus. This operation, in Dr. Natalie Lui's hands, is performed through a three-inch incision above the clavicle (or collarbone). Patients stay in the hospital for about two to three days after the operation and resume physical and occupational therapy afterwards.
Some patients have symptoms primarily at the pectoralis minor area below the clavicle (or collarbone). These individuals may benefit from division of the pectoralis minor muscle, either in addition to, or instead of, thoracic outlet decompression. This operation is performed through a two-inch incision in the axilla. Patients are usually discharged home the same day as the procedure.
In carefully selected patients, surgery can lead to an improved quality of life and reduced need for pain medications or interventions.
The Division of Thoracic Surgery in the Department of Cardiothoracic Surgery at the Stanford School of Medicine is located in the San Francisco Bay Area in northern California. For more information about our services, please contact Donna Yoshida at (650) 721-2086 or Angela Lee, RN, MS, at (650) 721-5402. For new patient Thoracic Surgery Clinic Scheduling, please call (650) 498-6000.