Thoracic Outlet Syndrome (TOS) refers to a group of disorders that occur when the blood vessels or nerves between the collarbone and first rib become compressed. This compression can cause pain, numbness, tingling, and even weakness in the arm or hand. TOS is relatively uncommon, but when it does occur, it can significantly affect a person's daily life. Diagnosing this condition can be challenging because its symptoms often mimic those of other disorders. Fortunately, there are several simple tests that help healthcare professionals confirm or rule out TOS. These tests are usually performed by a trained medical professional and serve as an initial step in diagnosis.
Understanding Thoracic Outlet Syndrome
Before delving into the tests, it’s important to understand the anatomy and mechanics behind thoracic outlet syndrome. The thoracic outlet is the space between the clavicle (collarbone) and the first rib, through which several key structures pass, including the brachial plexus (a network of nerves that control the arm and hand) and blood vessels like the subclavian artery and vein. When this area becomes narrowed or when there is abnormal pressure placed on these structures, compression can occur. There are three primary types of TOS, depending on which structure is compressed:
- Neurogenic TOS: This is the most common type thoracic outlet syndrome testing, where the brachial plexus is compressed, leading to nerve symptoms like pain, tingling, and weakness.
- Venous TOS: This occurs when the subclavian vein is compressed, leading to swelling and discoloration of the arm due to poor blood flow.
- Arterial TOS: The compression of the subclavian artery causes blood flow problems, which can result in pain and coldness in the arm.
Given that the symptoms of TOS overlap with other conditions, diagnosing it often requires a combination of clinical examination and specific tests designed to reveal the presence of this condition.
Physical Examination and Clinical History
The first step in diagnosing TOS is a thorough physical examination and a detailed history. The healthcare provider will ask about the onset of symptoms, any trauma or repetitive motions that could have contributed to the condition, and whether the patient has any risk factors, such as a history of neck or shoulder injury. A physical examination typically involves testing for the presence of symptoms like arm pain, numbness, or weakness.
In addition to this initial assessment, specific tests are performed to reproduce symptoms and help confirm whether TOS is the cause. These tests are relatively simple, non-invasive, and can give a good indication of whether further diagnostic procedures are needed.
The Adson’s Test
The Adson’s Test is one of the most commonly used diagnostic tests for thoracic outlet syndrome, particularly when neurogenic TOS is suspected. This test involves the patient sitting or standing with the head rotated toward the side being tested, while the arm is extended backward and the wrist is pulled back. The healthcare provider will then check the radial pulse in the wrist while asking the patient to take a deep breath and hold it.
If the test reproduces the patient's symptoms—such as tingling, numbness, or weakness in the arm—it is suggestive of TOS. A positive Adson’s Test indicates that the subclavian artery is being compressed by the structures in the thoracic outlet, although further tests may still be needed to confirm the diagnosis.
The Roos Test
Another test commonly used to diagnose TOS is the Roos Test, also known as the "EAST" (Elevated Arm Stress Test). This test involves the patient raising both arms to 90 degrees, bending the elbows, and then opening and closing the hands for 3 minutes. The test is considered positive if the patient experiences symptoms like numbness, tingling, or weakness in the arms or hands during the test.
The Roos Test can be particularly useful in diagnosing neurogenic TOS, as it stresses the brachial plexus and helps to determine if it is being compressed. However, it is also important to note that this test is not always definitive and may need to be used in conjunction with other tests to reach a firm diagnosis.
The Wright’s Hyperabduction Test
The Wright’s Hyperabduction Test is designed to assess compression of the neurovascular structures in the thoracic outlet. In this test, the patient is asked to raise the arm above their head and then rotate the shoulder backward. This position is held for a few seconds while the healthcare provider checks for a decrease in the radial pulse or the onset of symptoms in the arm, such as tingling or numbness.
A positive result occurs when the radial pulse weakens or the symptoms associated with TOS are reproduced. This indicates that the thoracic outlet is constricted, which may be causing the patient's symptoms. The Wright’s Test is most effective in identifying neurogenic and vascular types of TOS and can help rule out other possible causes of arm pain.
The Costoclavicular Test
The Costoclavicular Test, also known as the "military posture test," is another valuable tool in diagnosing TOS. This test requires the patient to stand with their shoulders pulled back and down as though they are assuming a military stance, while the clinician palpates the radial pulse in the wrist. The patient is asked to draw their shoulders back and take a deep breath.
A positive test occurs when the radial pulse decreases or when the symptoms of TOS, such as pain, numbness, or tingling, are reproduced. This test helps to identify compression of the subclavian artery or brachial plexus as the cause of the symptoms. If the test is positive, further diagnostic imaging may be required to assess the severity and exact location of the compression.
The Allen Test
The Allen Test is used to evaluate the patency of the blood vessels in the arm, particularly the radial and ulnar arteries. In this test, the patient is asked to close their fist tightly, which forces the blood out of the hand. The clinician then compresses both the radial and ulnar arteries at the wrist and asks the patient to open their hand. A positive test is indicated by the hand remaining pale for an extended period, suggesting poor circulation due to vascular compression in the thoracic outlet.
While the Allen Test is not specific to TOS, it can be useful in assessing the vascular component of the condition, especially when venous or arterial TOS is suspected.
Imaging Tests
Although physical tests are helpful for diagnosing TOS, they are often not definitive. In cases where symptoms persist or the clinical tests are inconclusive, imaging tests such as X-rays, MRI scans, or ultrasound may be used to identify structural abnormalities in the thoracic outlet, such as an extra rib (cervical rib) or abnormal muscle groups that may be contributing to the compression.
For example, a chest X-ray can reveal the presence of a cervical rib, which is a common anatomical anomaly linked to TOS. An MRI or CT scan may provide detailed images of the thoracic outlet structures and help pinpoint areas of nerve or vessel compression.
Conclusion
Thoracic Outlet Syndrome can be a complex and challenging condition to diagnose due to the variety of symptoms it presents and its overlap with other conditions. However, a combination of simple, non-invasive tests like the Adson’s, Roos, and Wright’s tests, along with imaging techniques when necessary, can help healthcare providers accurately diagnose the condition. Early detection and intervention are key to managing TOS effectively and preventing long-term complications. If you suspect you may have TOS, it is important to seek medical attention as soon as possible to ensure proper diagnosis and treatment.