MedifocusHealth

The same procedures regarding the medical history and physical examination are followed for the evaluation of vascular TOS. However, there are additional components which need to be evaluated to determine the presence of arterial or venous TOS.

Arterial TOS

In addition to symptoms resulting from provocative maneuvers described above, the physical exam for arterial compression may include palpation to reveal a pulsatile mass in the supraclavicular area. Listening to the subclavian artery with a stethoscope may also reveal a bruit (abnormal sound). If arterial compression is involved, the affected arm will become pale when raised and will become hyperemic (increased amounts of blood) when lowered. The effects of arterial compression may also be apparent in locations distal to the thoracic outlet, including:

• Atrophy in the arm
• Skin changes (e.g., color)
• Ulcerations at the tips of the fingers
• Decreased blood pressure (typically found in advanced cases)

Other testing procedures to determine the presence of arterial compression may include:

• Noninvasive testing

  • pulse volume recordings - a noninvasive test that measures blood flow within the blood vessels; may be more helpful for advanced cases
  • radiographs to evaluate bony abnormalities
  • color flow duplex ultrasound scanning to identify interruption of blood flow to the affected extremity

• Invasive testing

  Transfemoral arteriography - the study of the blood flow in the artery subclavian. It is considered to be a reliable test since it assists in defining compression points at early stages. It is also helpful in revealing blockage of the artery from thrombus and emboli as well as associated complications. However, it is usually not included in the assessment of TOS since the physical exam can identify arterial involvement.

  Arteriography may be performed under certain circumstances, such as:

  • suspected arterial embolism
  • suspected aneurysm (weakening in the wall of a blood vessel causing a bulging or outpouching of the vessel wall)
  • blood pressure difference between both arms is greater than 20mm Hg
  • bruit (sound) is heard in the subclavian artery when the arm is at rest

Venous Thoracic Outlet Syndrome

If there is venous compression, patients may develop swelling of the arm and cyanosis. Some patients with thoracic outlet syndrome find provocative maneuver tests too painful and distressing and cannot even complete the test. Venous compression of the subclavian vein is confirmed by:

• Dynamic venography - this is the most reliable test in which the site of obstruction or occlusion of the vein and collateral development can be seen, as well as the presence of thrombus. Venography is associated with adverse side effects including:

  • potential allergic reaction to the iodine-based contrast dye
  • nephrotoxicity (toxic to the kidneys)
  • technical difficulty injecting the dye into a swollen arm (edematous)

Despite these difficulties, venography is considered a "standard" in confirming the diagnosis of venous TOS especially when the ultrasound may be negative and suspicion for a clot remains. Also, venography is required before invasive procedures (e.g., thrombolysis) can proceed.