Research

A Closer Look at False-Negative Thoracic Outlet Syndrome Diagnoses

Washington University School of Medicine faculty study the impact of false-negative diagnoses in Venous Thoracic Outlet Syndrome.

Upper extremity duplex ultrasound is the standard initial evaluation for patients suspected to have venous thoracic outlet syndrome (VTOS): a rare condition affecting the veins in the area around the collarbone. A recent study led by Washington University School of Medicine in St. Louis faculty found flaws in using duplex ultrasound as the initial form of diagnosis due to its rate of false-negative results.

VTOS is most common among athletes—especially those who perform repetitive, overhead arm motions. These types of motions can lead to compression of the subclavian vein (SCV). The SCV, which is one of the main veins serving the arm, runs through the area between the clavicle and first rib, called the thoracic outlet. Compression of the SCV restricts blood flow through the thoracic outlet, leading to blood clots. Because of its association with athletes, SCV thrombosis is sometimes referred to as “effort” thrombosis.

Symptoms of VTOS do not always present right away. A patient could have the condition without realizing there is anything wrong until blood clots begin to form. Once SCV thrombosis occurs, the patient might experience swelling, heaviness, pain and even bluish discoloration of the entire arm. This is when a patient is most likely to seek help.

“We see a lot of patients who have suffered from symptoms for many, many years before they found us,” study author Robert W. Thompson, MD, says. Thompson, who is Director of the Washington University Center for Thoracic Outlet Syndrome at Barnes-Jewish Hospital, emphasizes the importance of “prompt and effective treatment” for patients with SCV thrombosis in this study published in the Journal of Vascular Surgery.

The study reviewed data from surgical treatment of VTOS over nearly 10 years. In these cases, duplex ultrasound—a noninvasive form of imaging used to see how blood flows through the veins and arteries—was the first test used to evaluate patients.

Ultrasound is said to have high levels of sensitivity and specificity for upper extremity imaging, but the study’s findings suggest that it has limitations in the area of the thoracic outlet. Because the SCV is located between the clavicle and first rib, it is difficult to visualize with ultrasound technology. The presence of other veins in the area creates another limitation—ultrasounds may misinterpret these veins to be the SCV, thus missing the thrombosis entirely. These limitations contribute to the false-negative results found in 21% of patients with proven VTOS.

Robert Thompson, a leading specialist in diagnosing and treating VTOS, has performed more operations to treat the condition than any other surgeon.

 

The sooner a patient is diagnosed with VTOS, the better chance they have of an optimal outcome. Non-surgical treatment involves thrombolysis, which breaks down existing clots, while surgical treatment decompresses the SCV and restores normal blood flow. These treatment options become more challenging for patients with long-segment occlusion, which is often the result of a delayed diagnosis.

In order to ensure the most optimal patient outcomes, the study cautions against relying too heavily on duplex ultrasound results. Though it is more invasive, definitive diagnostic imaging, such as catheter-based upper extremity venography, provides more certain results for patients suspected of having VTOS and SCV thrombosis. For these reasons, the study cautions that ultrasound should be used in diagnoses with the “understanding that a negative study should not delay definitive imaging, thrombolysis, and surgical intervention.”

Fortunately for patients like Chris Young, pitcher for the 2015 World Series-winning Kansas City Royals, the Center for Thoracic Outlet Syndrome is a nationally recognized center with a highly knowledgeable staff and a multidisciplinary approach. The Center sees one of the largest volumes of TOS patients in the United States. Patients of all ages, from all walks of life, are referred to Thompson at the center. In fact, Thompson recently performed the 1,000th operation at Barnes-Jewish Hospital to treat VTOS, the most procedures of this kind performed by any surgeon in the world.

While it is true that many VTOS and SCV “effort” thrombosis patients are younger and involved in athletics, Thompson notes that there are other causes of the condition. “Other patients may develop thoracic outlet syndrome as the consequence of an injury,” he says, “such as a motor vehicle collision or a fall on the arm.” Regardless of the cause, patients at the Center for Thoracic Outlet Syndrome have access to a full spectrum of treatment options, including physical therapy, pain management and radiology, in addition to surgical expertise.