[Cerebral consequences of stenosing and occlusive diseases of the interior carotid artery. Importance of transcranial Doppler examination. 1].

By means of transcranial Doppler (TCD), the author reports intracranial haemodynamic consequences of 57 stenosis or occlusions of the internal carotid artery (ICA), 13 dissections and 44 atheromatous lesions, in 50 patients 32 of whom having had angiography. If a stenosis is significant, the curve of the middle cerebral artery (MCA) becomes dampened and PTI (Pulsatility Transmission Index) diminishes. In this series, the association MCA curve dampened and PTI lower than 0.90 is the evidence of a more than 90% stenosis, except in 2 atheromatous and symptomatic occlusions. No precise explanation for these exceptions is given by literature. An ICA stenosis has also an influence on communicating arteries. In this study, collateralisation by the circle of Willis exists in 14% of 50-75% stenosis, 72.7% of 75-90% stenosis and 100% of more than 90% stenosis. It can depend on anterior communicating artery (ACoA) alone, posterior communicating artery (PCoA) alone or both. Detailed study of the 3 groups leads to the hypothesis of a hierarchy in the function of the communicating arteries, ACoA having the priority.