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Tests and diagnosis
By Mayo Clinic staffDiagnosing thoracic outlet syndrome can be difficult because the symptoms and their severity can vary greatly among people with the disorder. To diagnose thoracic outlet syndrome, your doctor may do a physical exam and ask about your medical history.
- Physical exam. Your doctor will perform a physical examination to look for external signs of thoracic outlet syndrome, such as a depression in your shoulder, a pale discoloration in your arm or limited range of motion.
- Medical history. Your doctor will also likely ask about your medical history and symptoms, as well as your occupation and physical activities.
Provocation tests
Provocation tests are designed to reproduce your symptoms. The tests may help your doctor determine the cause of your condition, and also will help rule out other causes that may have similar symptoms.
Some of the more common provocation tests that can suggest the presence of thoracic outlet syndrome include:
- Adson's maneuver. For this test, you'll be asked to turn your head toward the symptomatic shoulder while you extend your arm, neck and shoulder slightly away from your body. While you inhale, your doctor will check for a pulse on the wrist of your extended arm. If your pulse is diminished or if your symptoms are reproduced during the maneuver, your doctor considers this a positive test result, which may indicate thoracic outlet syndrome. Because false-positives often occur, your doctor may repeat the test on the unaffected side.
- Wright test. From a sitting position and with the help of your doctor, you'll hold your arm up and back (hyperabduction), rotating it outward, while your doctor checks your pulse to see if it's diminished. As in the Adson's maneuver, your doctor will want to know if your symptoms are reproduced during the test.
- Roos stress test. From a sitting position, your doctor will ask you to hold both elbows at shoulder height while pushing your shoulders back. You will then repeatedly open and close your hands for several minutes. If your symptoms are present after the test, or if you feel heaviness and fatigue in your shoulders, this can indicate the presence of thoracic outlet syndrome.
Imaging and nerve study
To confirm the diagnosis of thoracic outlet syndrome, your doctor may also order one or more of the following tests:
- X-ray. Your doctor may order an X-ray of the affected area, which may reveal an extra rib (cervical rib) and can also rule out other conditions that may be causing your symptoms.
- Magnetic resonance imaging (MRI) scan. MRI is a painless procedure that uses a magnetic field and radio waves to create computerized images of the soft tissues of your body. These images can help your doctor determine the location and cause of compressions of the brachial plexus nerves or the subclavian artery. The scans may also reveal any congenital anomalies — such as a fibrous band connecting your spine to your rib or a cervical rib — that may be the cause of your symptoms.
- Electromyography (EMG). This test enables your doctor to see and hear how your muscles and nerves are working. To conduct the test, a small electrode needle is inserted through your skin and into the muscles near where you're having symptoms. The electrical activity detected by this electrode is displayed on a monitor and may be heard through a speaker.
- Nerve conduction study. Also called nerve conduction velocity, this test measures the speed of conduction of impulses through a nerve. Doctors use the test to evaluate possible nerve damage. Small electrodes are placed on your skin over the area being tested, and a tiny electrical current is sent to the nerves in your thoracic outlet. The electrical signals produced by nerves and muscles are picked up by a computer, and the information is interpreted by a doctor trained in electrodiagnostic medicine.
- Sheon RP. Overview of the nerve entrapment syndromes. http://www.uptodate.com/home/index.html. Accessed Sept. 7, 2010.
- NINDS thoracic outlet syndrome information page. National Institute of Neurological Disorders and Stroke. http://www.ninds.nih.gov/disorders/thoracic/thoracic.htm. Accessed Sept. 4, 2010.
- Thoracic outlet syndrome. American Academy of Orthopaedic Surgeons. http://orthoinfo.aaos.org/topic.cfm?topic=a00336. Accessed Sept. 4, 2010.
- Thoracic outlet syndrome. National Pain Foundation. http://www.nationalpainfoundation.org/articles/577/what-is-it? Accessed Sept. 4, 2010.
- Thoracic outlet compression syndromes. The Merck Manuals: The Merck Manual for Healthcare Professionals. http://www.merck.com/mmpe/sec16/ch223/ch223k.html?qt=thoracic%20outlet%20syndrome&alt=sh. Accessed Sept. 4, 2010.
- Thoracic outlet syndrome. Society for Vascular Surgery. http://www.vascularweb.org/vascularhealth/Pages/ThoracicOutletSyndrome.aspx. Accessed Sept. 4, 2010.
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