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The Value of MRI in Diagnosing Thoracic Outlet Syndrome

In this study, the value of magnetic resonance imaging (MRI) was measured in testing for thoracic outlet syndrome (TOS). TOS is a condition caused by pressure on the nerves and blood vessels as they leave the neck and travel down the arm.

With TOS, symptoms of neck and arm pain, numbness and tingling, and swelling in the hands are common. Weakness of the arms is also reported. All symptoms present are made worse by working with the arms overhead. Fatigue and stress can also make the symptoms worse.

Doctors rely on clinical tests to diagnose TOS. These are called provocative tests because they put the patient's arm in a position that will put pressure on the nerves and blood vessels, bringing on the symptoms.

Scientists are studying the various tests used to diagnose TOS. They hope to find one or two tests that can be relied upon to test for TOS. MRI may be one of those tests. In fact, the results of this study showed that MRI findings are valuable in the diagnosis of TOS.

Two groups of subjects were included in the study. The first group had a known diagnosis of TOS. Group 2 (the control group) were normal, healthy adults with no known TOS and no current symptoms of TOS. MRIs were taken for both groups in two positions. One was lying down with the arms at the sides. The second was taken with the arms overhead. This is one of the provocative test positions.

As expected, there was a big difference between the TOS group and the control group. And there was a significant difference in the TOS group between arms down at the sides and arms overhead. The control group showed signs of vascular compression but no nerve compression.

The authors conclude that MRI can give good information about vascular or neural structures in the area of the thoracic outlet. It can show the presence of fibrous bands across the blood vessels and nerves that might be causing the problem. It is not necessary to do the MRIs with the arms down at the sides. Only MRI images with the patient in the provocative position are necessary.

References: Derya Demirbag, MD. The Relationship Between Magnetic Resonance Imaging Findings and Postural Maneuver and Physical Examination Tests in Patients with Thoracic Outlet Syndrome: Results of a Double-Blind, Controlled Study. In Archives of Physical Medicine and Rehabiliation. July 2007. Vol. 88. No. 7. Pp. 844-851.

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