From the Guidelines
Diagnosing neurogenic thoracic outlet syndrome (nTOS) requires a comprehensive approach combining clinical evaluation, physical examination, and diagnostic testing, with MRI being the most useful imaging modality to visualize soft tissue abnormalities and nerve compression 1.
Diagnostic Approach
The diagnosis of nTOS begins with a thorough medical history focusing on symptoms such as pain, numbness, or weakness in the neck, shoulder, arm, or hand, particularly with overhead activities. Physical examination should include provocative maneuvers like the Adson test, elevated arm stress test (EAST), and Roos test, which reproduce symptoms by compressing the neurovascular bundle.
Imaging Studies
Imaging studies are essential in diagnosing nTOS, with the following modalities being useful:
- MRI: particularly useful to visualize soft tissue abnormalities and nerve compression, with noncontrast MRI being sufficient to diagnose nTOS 1.
- CT scans: can identify bony abnormalities like cervical ribs or anomalous first ribs, and can be used to evaluate the costoclavicular and interscalene spaces 1.
- Vascular studies: including duplex ultrasound may be performed to rule out vascular TOS.
Diagnostic Testing
Nerve conduction studies and electromyography can help identify nerve compression, though they may be normal in some cases. A diagnostic lidocaine injection into the anterior scalene muscle that provides temporary relief can be both diagnostic and therapeutic.
Multidisciplinary Approach
Since nTOS can mimic other conditions like cervical radiculopathy or peripheral nerve entrapment, differential diagnosis is crucial. A multidisciplinary approach involving neurologists, vascular surgeons, and physical therapists often yields the most accurate diagnosis 2, 3.
Key Considerations
- Understanding the various anatomic spaces, causes of narrowing, and resulting neurovascular changes is important in choosing and interpreting radiological imaging performed to help diagnose TOS and plan for intervention 2.
- The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel 3.
From the Research
Diagnostic Approach
To diagnose neurogenic thoracic outlet syndrome, a thorough approach is necessary due to the complexity and nonspecific nature of the symptoms. The following steps are recommended:
- A thorough patient history to identify symptoms and potential causes of the condition 4, 5
- Physical examination to assess for signs of nerve compression or irritation 4, 5
- Radiologic images, such as MRI, to confirm the diagnosis and identify the location of nerve compression 4, 6
- Electrodiagnostic studies to assess nerve function and rule out other conditions 6
- Stress maneuvers and diagnostic and therapeutic imaging to further evaluate the condition 5
Diagnostic Challenges
Diagnosing neurogenic thoracic outlet syndrome can be challenging due to:
- Nonspecific symptoms that overlap with other conditions 4, 5
- Lack of definitive diagnostic testing 5
- Need for a multidisciplinary approach to diagnosis and treatment 7
- Variability in clinical presentation and response to treatment 8
Imaging Techniques
Advanced imaging techniques, such as:
- High-resolution MRI and tractography, can help confirm the diagnosis and identify the location of nerve compression 6
- MR neurography (MRN) can aid in diagnosing neurogenic thoracic outlet syndrome and guide surgical decompression 6
- A care pathway that combines different diagnostic tests and imaging techniques can help guide diagnosis and treatment 7