Hemodynamics in subclavian-steal syndrome: difficulties in their evaluation.

In a patient with subclavian-steal syndrome transcranial Doppler sonography detected transient retrograde basilar blood flow whereas routine angiography failed to document this condition. Thus, orthograde basilar blood flow at routine angiography does not rule out basilar steal. Presumably the forced injection of contrast media conceals less pronounced steal phenomena. Our exemplary case indicates that a subgroup of patients with vertebro-basilar symptoms concomitant with basilar flow abnormalities may benefit from invasive or semi-invasive treatment.