[Transcranial pulsed Doppler in the diagnosis of cerebrovascular pathology: methodology, indications and limitations].

Doppler analysis of flow in intracranial arteries is now possible using a 2 MHz probe, allowing sufficient penetration of bone to obtain signals noninvasively and to measure rate of flow in middle (MCA), anterior (ACA) and posterior (PCA) cerebral arteries and in basilar trunk. Practical applications of this new method are numerous in cerebrovascular disease and, despite certain limitations due to anatomic factors, transcranial Doppler may identify stenosis of the intracranial arteries and study the value of collateral flow across the anterior circle of Willis in patients with extracranial carotid artery stenosis.