A pitfall of neck vessels Doppler ultrasound: left subclavian artery occlusion without vertebral steal syndrome.

In most cases, ostial occlusion of the subclavian artery induces a reversal of the blood flow in the ipsilateral vertebral artery. This hemodynamic diversion is obviously brought out by Doppler ultrasound of the neck vessels. Nevertheless, when the subclavian ostial lesions are less severe or in case of anatomical variations, the alterations of the vertebral flux are more discrete. An accurate Doppler examination is then required to avoid pitfalls. In the light of a particularly complex case, we reviewed the Doppler signs of vertebral blood flow in normal conditions and in patent or less obvious subclavian steals.