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Thoracic Outlet Syndrome

Thoracic Outlet Syndrome (TOS) is caused by pressure (squeezing) on the nerves and blood vessels supplying the arms as they travel through the small space at the base of the neck called the thoracic outlet. During a TOS Evaluation the technologist will place a risk-free, painless non-invasive ultrasound transducer (probe or wand) at various spots along the arms to evaluate the quality of blood flow. You will then be asked to move your arms in various ways to see whether a significant change in blood flow occurs with these maneuvers. Your arm symptoms will also be recorded during each portion of the exam.


  • Pain, numbness, tingling and/or weakness in upper extremities
  • Reduced arm movement or reduced ability to reach overhead 

Patient Preparation

No patient preparation is needed.