From the Guidelines
Thoracic outlet syndrome (TOS) should be evaluated using a combination of clinical tests and imaging studies, with MRI without IV contrast being a preferred initial imaging modality for neurogenic TOS, as it provides inherent advantages in delineating extravascular anatomy and characterizing soft tissues 1.
Clinical Tests
The most common clinical tests for TOS include:
- Adson's test: patient turns their head toward the affected side while extending their neck and taking a deep breath, with a positive result indicated by diminished radial pulse
- Wright test: hyperabducting the arm while the examiner checks for pulse reduction
- Roos test (elevated arm stress test): patient holds their arms in an elevated, externally rotated position while opening and closing their hands for three minutes; reproduction of symptoms suggests TOS
- Costoclavicular maneuver: shoulders are drawn backward and downward, may also diminish the radial pulse in TOS patients
- Upper limb tension test: stretches the brachial plexus
Imaging Studies
Imaging studies that may be used to evaluate TOS include:
- Chest X-rays: to identify cervical ribs
- MRI or CT: to visualize soft tissue abnormalities
- Vascular studies: like duplex ultrasound or angiography for vascular TOS
- CT with IV contrast: preferred for evaluation of vascular TOS, as it provides assessment of vascular patency 1
- MRI without IV contrast: may be performed in the postintervention setting to evaluate interval changes in the thoracic outlet and assess adequate decompression 1
Diagnostic Approach
Diagnosis of TOS often requires a combination of clinical findings, patient history, and appropriate testing, as no single test is definitive 1. The choice of imaging modality depends on the specific type of TOS (neurogenic, vascular, or arterial) and the clinical scenario.
Key Considerations
- MRI without IV contrast is an acceptable alternative to MRI without and with IV contrast for initial and follow-up imaging after surgery or intervention for patients with neurogenic TOS 1
- CT with IV contrast is preferred for evaluation of vascular TOS, as it provides assessment of vascular patency 1
- Imaging in patients with TOS is controversial, but may be appropriate in certain clinical scenarios 1
From the Research
Methods for Testing Thoracic Outlet Syndrome
The diagnosis of thoracic outlet syndrome (TOS) can be challenging, and various methods are employed to test for this condition. The following are some of the methods used:
- Physical examination, including provocative maneuvers such as neck rotation and head tilting, the upper limb tension test, and abducting the arms to 90 degrees in external rotation 2
- Clinical diagnostic tests, including the Halstead maneuver, Wright's test, Cyriax Release test, and supraclavicular pressure test, which have been shown to have good diagnostic accuracy for provoking symptoms in patients with upper extremity pathology 3
- Ultrasonography, electrophysiology, and helical computed tomography (CT) angiography, which can be used to evaluate vascular compression and confirm the diagnosis 4
- Exercise oximetry, which allows for operator-independent recordings of microvascular blood flow impairments during exercise and can be used during upper arm provocative maneuvers, such as the Roos test 5
Types of Thoracic Outlet Syndrome
There are three main types of TOS:
- Neurogenic TOS (NTOS), which is the most common type, accounting for over 90% of all TOS patients, and is caused by brachial plexus compression usually from scarred scalene muscles secondary to neck trauma 2
- Arterial TOS, which is the least common type, accounting for no more than 1% of all TOS patients, and is caused by emboli arising from subclavian artery stenosis or aneurysms 2
- Venous TOS, which presents with arm swelling, cyanosis, and pain due to subclavian vein obstruction, with or without thrombosis 2
Limitations of Diagnostic Tests
Some diagnostic tests, such as the Adson test, have been shown to be of no clinical value and should not be relied upon to make the diagnosis of TOS 2, 3 The Roos test has been shown to have good reliability, but its feasibility and diagnostic performance can be affected by the presence of symptoms and the cutoff point used 5