From the Guidelines
Thoracic outlet syndrome (TOS) diagnosis should be approached through a combination of clinical evaluation, provocative maneuvers, and imaging studies, prioritizing a thorough history and physical examination to identify symptoms like arm pain, numbness, weakness, or discoloration, as recommended by the American College of Radiology in 2020 1.
Clinical Evaluation
The diagnosis of TOS begins with a comprehensive clinical evaluation. This includes a detailed history focusing on the nature and duration of symptoms, as well as any exacerbating or relieving factors. The physical examination should assess for signs of neurovascular compression, including tenderness over the thoracic outlet, diminished pulses, or changes in skin temperature and color.
Provocative Maneuvers
Specific provocative tests are useful in reproducing symptoms or demonstrating diminished blood flow. These include:
- Adson's test: Checking the radial pulse while the patient extends their neck and turns toward the affected side.
- The elevated arm stress test (EAST): Having the patient hold their arm in an elevated position to see if symptoms are reproduced.
- The costoclavicular maneuver: Applying pressure in the costoclavicular space to assess for symptom reproduction.
Imaging Studies
Imaging plays a crucial role in confirming the diagnosis and planning treatment. Essential imaging studies include:
- Chest X-rays to identify bony abnormalities such as cervical ribs.
- MRI or CT scans to visualize soft tissue compression and the relationship between the neurovascular structures and the surrounding anatomy.
- Vascular studies like duplex ultrasound or angiography to assess blood flow through the subclavian artery and vein.
- Nerve conduction studies and electromyography to evaluate neurogenic TOS by identifying nerve compression.
Diagnostic Blocks and Multidisciplinary Approach
Diagnostic lidocaine blocks into the anterior scalene muscle can provide temporary relief of symptoms, supporting the diagnosis of TOS. Given the complexity and variability of TOS presentations, a multidisciplinary approach involving neurology, vascular surgery, orthopedics, and radiology is beneficial for accurate diagnosis and treatment planning, as emphasized in the 2020 guidelines from the American College of Radiology 1. This approach helps in ruling out other conditions with similar presentations, such as cervical disc disease, peripheral nerve entrapment, or shoulder pathology.
From the Research
Diagnosis of Thoracic Outlet Syndrome
The diagnosis of thoracic outlet syndrome (TOS) is often challenging and controversial, with various approaches and investigations employed to establish the diagnosis 2. A thorough clinical examination, including history taking and physical examination maneuvers, is crucial in diagnosing TOS 3, 4.
Clinical Features
The clinical features of TOS can vary depending on the subtype, including:
- Neurogenic TOS: presents with arm pain, swelling, arm fatigue, paresthesias, weakness, and discoloration of the hand 3
- Arterial TOS: caused by emboli arising from subclavian artery stenosis or aneurysms, presenting with symptoms of arterial ischemia 4
- Venous TOS: presents with arm swelling, cyanosis, and pain due to subclavian vein obstruction, with or without thrombosis 4
Diagnostic Investigations
Diagnostic investigations, such as:
- Nerve conduction study (NCS) and needle electromyography (EMG) of the upper extremity 5
- Brachial plexus MRI and computed tomography angiography (CTA) 5
- Imaging studies to detect structural abnormalities, such as focal stenosis of the subclavian artery 5 can aid in establishing the diagnosis of TOS.
Diagnostic Criteria
The diagnosis of TOS should be based on evidence of a physical anomaly that can be corrected, rather than being a diagnosis of exclusion 3. A combination of clinical features, physical examination findings, and diagnostic investigations can help establish the diagnosis of TOS 3, 2, 4.
Provocative Maneuvers
Provocative maneuvers, such as: