From the Guidelines
To diagnose Thoracic Outlet Syndrome (TOS), a combination of physical examination maneuvers and imaging tests should be used, including the Adson's test, elevated arm stress test (EAST), Wright test, and Roos test, as well as nerve conduction studies, electromyography, and imaging such as MRI, CT, or ultrasound. The choice of imaging test depends on the type of TOS suspected, with MRI being the most appropriate for neurogenic TOS, and CT or ultrasound being more suitable for venous or arterial TOS 1.
Some key points to consider when diagnosing TOS include:
- The Adson's test involves having the patient extend their neck while turning their head toward the affected side and taking a deep breath, with a positive result indicated by a diminished radial pulse.
- The EAST involves raising both arms to 90 degrees with elbows bent and opening and closing hands for 3 minutes, with reproduction of symptoms suggesting TOS.
- The Wright test requires the patient to rotate their head away from the affected side while the arm is elevated, with a decreased pulse indicating possible TOS.
- The Roos test involves holding both arms in a surrendering position with elbows at 90 degrees and repeatedly opening and closing hands for 3 minutes, with symptom reproduction being positive.
- Imaging tests such as MRI, CT, or ultrasound can help visualize anatomical abnormalities and differentiate between neurogenic, venous, and arterial TOS.
- Early diagnosis is important as treatment options vary based on TOS type and severity.
It's also important to note that the American College of Radiology Appropriateness Criteria recommend the use of specific imaging protocols for each type of TOS, including MRI for neurogenic TOS, and CT or ultrasound for venous or arterial TOS 1.
In terms of specific imaging tests, MRI is typically performed with high-resolution T1-weighted and T2-weighted sequences in sagittal and axial planes to delineate anatomy and evaluate cervical radiculopathy, the brachial plexus, muscular attachments, and sites of compression 1. CT evaluation of TOS is typically performed in “neutral” and “stressed” positions, with images obtained from the elbow to aortic arch with the arms adducted (neutral), followed by abduction (stressed) and repeat imaging 1.
Overall, a comprehensive diagnostic approach that includes physical examination maneuvers and imaging tests is necessary to accurately diagnose TOS and develop an effective treatment plan.
From the Research
Diagnostic Tests for Thoracic Outlet Syndrome (TOS)
The diagnostic tests for TOS include:
- A careful and detailed medical history and physical examination 2
- Electromyography (EMG) and nerve conduction studies (NCS) to assess nerve function 2, 3, 4, 5
- Imaging studies such as:
- X-rays to evaluate the cervical spine and chest 2, 6, 5
- Computed Tomography (CT) scans to visualize the thoracic outlet and detect compressive anatomic abnormalities 4, 6, 5
- Magnetic Resonance Imaging (MRI) to evaluate the brachial plexus and detect structural abnormalities 3, 6
- Ultrasonography to visualize vascular parietal abnormalities and detect vascular compression 4, 6
- Computed Tomography Angiography (CTA) to evaluate the subclavian artery and detect focal stenosis 3
- Provocative tests, such as the Adson test, hyperabduction test, and Wright test, to reproduce symptoms and assess vascular compression 4, 5
Electrodiagnostic Features
Electrodiagnostic studies, including NCS and EMG, can provide helpful information regarding diagnosis, particularly in true neurogenic TOS 3. Medial antebrachial cutaneous (MABC) sensory nerve action potential amplitude is often decreased in patients with TN-TOS 3. The abductor pollicis brevis (APB) muscle is commonly involved in EMG studies 3.
Imaging Features
Radiologic studies, including CT and MRI, can detect structural abnormalities, such as focal stenosis of the subclavian artery, and confirm the diagnosis of TOS 3, 4, 6. Helical CT angiography can provide accurate information on the location and mechanism of vascular compression, but its usefulness in establishing the diagnosis of TOS is unclear 4.