Doppler monitoring of middle cerebral artery emboli from carotid stenoses.

The aim of this study was to prove the existence of clinically silent embolization arising from carotid stenoses. Simultaneous bilateral transcranial Doppler sonography of the middle cerebral artery was carried out during 10 minutes in 30 patients having ultrasonically demonstrated unilateral (n = 12) or bilateral internal carotid stenoses (n = 18). Twenty-four of the stenoses were clinically considered to be symptomatic and 24 were asymptomatic. Emboli signals were detected in 5 of the 30 patients. All occurred unilaterally on the side of a high-grade carotid stenosis. Four of the 5 lesions were symptomatic, and 1 was asymptomatic.