Thoracic Outlet Syndrome: Positional Duplex Testing

Indications for Examination

According to the AIUM Practice Parameter for the Performance of Peripheral Arterial Ultrasound (2025 Revision), the evaluation of patients with suspected thoracic outlet syndrome (TOS) is included in the list of indications for peripheral arterial ultrasound with color and spectral Doppler. Clinically, these are patients with positional numbness, pain, tingling, or a cold hand.

Role of Positional Tests

The main technical principle for diagnosing dynamic compression is positional testing. In a neutral position, arterial compression may be completely absent, so it is the provocative maneuvers (e.g., changing the position of the arm/head) that reveal the dynamic nature of the compression—something that static CT in one position does not provide. Duplex is valuable here for its ability to document dynamics in real-time.

Method Limitations

Duplex does not directly show bony anatomy, so confirmation and treatment planning require CT/CTA with 3D artery reconstruction. Optimal is dynamic imaging that replicates what the duplex has revealed.

Important Interpretation Warning

According to the literature, the analysis of the Doppler waveform during provocative maneuvers in the assessment of arterial TOS is accompanied by a high rate of false-positive results (Bishop L, Bartlett M, 2021). This requires cautious interpretation of positive tests and correlation with the clinical picture.

Report

Specific numerical velocity thresholds and criteria for a positive test specifically for arterial TOS are not provided in the source fragments [clarify]. It is advisable to document the position of the limb/head where changes occur, the nature of the spectrum, and the return to baseline blood flow in the description.