The diagnosis of Thoracic Outlet Syndrome (TOS) presents a significant challenge for healthcare providers because its symptoms often mimic those of other musculoskeletal and neurological conditions. To help isolate the cause of a patient’s arm, shoulder, or neck discomfort, physicians rely on a physical examination that includes special tests, also known as provocative maneuvers. These tests are designed to temporarily narrow the space where nerves and blood vessels pass, attempting to reproduce the symptoms experienced by the patient. The following tests represent three common maneuvers used during the initial clinical assessment of suspected TOS.
What is Thoracic Outlet Syndrome?
Thoracic Outlet Syndrome describes a collection of disorders resulting from the compression of nerves or blood vessels as they pass through the thoracic outlet, the narrow passageway situated between the collarbone and the first rib. This anatomical bottleneck is where the neurovascular bundle—comprising the brachial plexus, subclavian artery, and subclavian vein—travels from the neck into the arm. The compression can occur at one of three sites: the interscalene triangle, the costoclavicular space, or the retropectoralis minor space.
TOS is broadly categorized into three types based on the structure being compressed. The most common form is Neurogenic TOS (nTOS), which accounts for over 90% of cases and involves the compression of the brachial plexus nerves. Venous TOS (vTOS) and Arterial TOS (aTOS) are less frequent, involving the compression of the subclavian vein or artery, respectively. The specific symptoms a patient experiences depend on which structure is most affected by the crowding within the outlet.
Adson’s Maneuver
Adson’s Maneuver is used to evaluate potential compression of the subclavian artery, particularly within the interscalene triangle at the base of the neck. The test is performed with the patient seated while the examiner monitors the radial pulse at the wrist. The patient is instructed to extend their neck and rotate their head toward the side being examined, then take a deep breath and hold it for up to 30 seconds. A positive result is indicated by a noticeable diminution or complete disappearance of the radial pulse, or by the reproduction of the patient’s familiar symptoms. This pulse change suggests the subclavian artery is being compressed by the anterior scalene muscle, which tightens during this specific head and neck position.
Wright’s Hyperabduction
Wright’s Hyperabduction test focuses on identifying compression in the sub-pectoral space, beneath the pectoralis minor muscle. The test begins with the patient’s arm passively placed into 90 degrees of abduction and slight external rotation while the examiner monitors the radial pulse. The arm is then moved further into full hyperabduction, bringing it over the patient’s head and holding the position for about one minute. A positive result is noted if there is a weakening or loss of the radial pulse, or if the test reproduces the patient’s symptoms. This suggests that structures, including the axillary artery and the brachial plexus, are being squeezed between the coracoid process and the pectoralis minor muscle.
Roos Stress Test
The Roos Stress Test, also known as the Elevated Arm Stress Test (EAST), is a functional assessment designed to stress the entire neurovascular bundle over a sustained period. The patient is positioned with both arms elevated to 90 degrees of abduction, elbows bent at 90 degrees, forming a “stick-up” position. From this position, the patient slowly and rhythmically opens and closes their hands for up to three minutes. A positive test is indicated if the patient is unable to maintain the position for the full duration, or if symptoms like pain, heaviness, or numbness are reproduced. This maneuver is particularly sensitive to Neurogenic TOS because the sustained posture and muscle activity increase the strain on the compressed brachial plexus.
Limitations and Confirmatory Diagnosis
While provocative maneuvers are useful screening tools, they have significant limitations in definitively diagnosing Thoracic Outlet Syndrome. Research indicates these tests have a high rate of false-positive results, meaning many healthy individuals can exhibit a positive sign like a diminished pulse. Conversely, a patient with confirmed TOS may occasionally have a negative result, highlighting the tests’ low specificity. Therefore, a positive finding is only suggestive of compression and does not serve as a standalone diagnosis.
Imaging studies are necessary to confirm the structural cause and rule out other conditions. These may include X-rays to check for a cervical rib, MRI to evaluate soft tissue compression, or dynamic CT angiography to visualize blood vessel compression during arm movements. Electrodiagnostic studies, such as Nerve Conduction Velocity (NCV) tests and Electromyography (EMG), are also used to assess nerve function. These tests are particularly helpful in confirming Neurogenic TOS.