What is the diagnostic approach for thoracic outlet syndrome?

From the Guidelines

The diagnostic approach for thoracic outlet syndrome (TOS) should begin with a thorough clinical history and physical examination, followed by imaging studies such as chest X-rays, MRI or CT scans, and vascular studies like duplex ultrasound, CT angiography, or MR angiography, as recommended by the American College of Radiology 1.

Diagnostic Approach

The diagnostic approach for TOS involves several steps:

• A thorough clinical history and physical examination to identify symptoms like pain, numbness, or weakness in the neck, shoulder, arm, or hand.
• Provocative maneuvers such as the Adson test, the elevated arm stress test (EAST), and the costoclavicular maneuver to assess for compression of the brachial plexus, subclavian artery, and/or subclavian vein.
• Imaging studies to confirm the diagnosis and identify anatomical abnormalities, including:
  • Chest X-rays to detect cervical ribs or bony abnormalities.
  • MRI or CT scans to visualize soft tissue compression.
  • Vascular studies such as duplex ultrasound, CT angiography, or MR angiography for vascular TOS.

Imaging Studies

Imaging studies play a crucial role in the diagnosis of TOS. The choice of imaging study depends on the type of TOS suspected:

• For neurogenic TOS, MRI without IV contrast or CT with IV contrast of the chest may be used to evaluate the brachial plexus and cervical spine 1.
• For venous TOS, US duplex Doppler of the subclavian artery and vein, CT with IV contrast of the chest, or catheter venography of the upper extremity may be used 1.
• For arterial TOS, CTA with IV contrast, MRA without and with IV contrast, US duplex Doppler, or arteriography of the upper extremity may be used 1.

Electrodiagnostic Studies

Electrodiagnostic studies like nerve conduction studies and electromyography can help evaluate neurogenic TOS by assessing nerve function.

Laboratory Tests

Laboratory tests may be ordered to rule out other conditions with similar presentations. The comprehensive approach is necessary because TOS can be challenging to diagnose due to its variable presentation and overlap with other conditions affecting the neck, shoulder, and upper extremity, as noted in the American College of Radiology's appropriateness criteria 1.

From the Research

Diagnostic Approach for Thoracic Outlet Syndrome

The diagnostic approach for thoracic outlet syndrome (TOS) involves a combination of clinical evaluation, physical examination, and imaging studies. The following are the key components of the diagnostic approach:

• A thorough patient history to identify symptoms such as pain, paresthesia, pallor, and weakness in the shoulder and upper extremity area 2, 3
• A physical exam to assess for signs of compression of the brachial plexus and subclavian vessels, including tenderness, weakness, and decreased sensation 4, 5
• Stress maneuvers, such as the Adson's test and Wright's test, to assess for compression of the subclavian artery and brachial plexus 5
• Imaging studies, such as duplex imaging, electrophysiological nerve studies, and magnetic resonance imaging (MRI), to rule out other conditions and identify anatomical abnormalities potentially responsible for compression 5, 6
• Assessment of disability using standardized patient-centered instruments to evaluate the impact of TOS on patient health-related quality of life 4

Imaging Studies

Imaging studies play a crucial role in the diagnosis of TOS. The following are some of the commonly used imaging studies:

• Duplex imaging: a non-invasive test that uses ultrasound to evaluate blood flow in the subclavian artery and vein 5
• Electrophysiological nerve studies: tests that assess the function of the nerves in the brachial plexus, such as electromyography (EMG) and nerve conduction studies (NCS) 5
• MRI: a non-invasive test that uses magnetic fields and radio waves to produce detailed images of the thoracic outlet and surrounding structures 6
• MRI with dynamic maneuvers: a test that uses MRI to evaluate the thoracic outlet during different positions and movements, such as abduction and external rotation of the arm 6

Diagnostic Accuracy of MRI

MRI has been shown to be effective in diagnosing the source of compression in TOS, particularly in identifying anatomical abnormalities such as hypertrophy of the anterior scalene muscle and cervical ribs 6. However, the sensitivity of MRI is too low for it to be used as a screening test, and it should be used in combination with clinical assessment and other investigations to assist in the diagnosis of TOS 6.