[Transcranial Doppler pulse. Methodology, diagnostic value and limitations]

Vessels of base of skull were inaccessible to conventional ultrasonic image until 1982, when the use of pulsed Doppler emitting a beam of 2 MHz coupled with a frequency analyzer allowed direct exploration of terminal branches of the internal carotid artery (ICA) and the basilar trunk. It is now possible to measure rate of flow in middle cerebral artery (MCA), anterior (ACA) and posterior (PCA) cerebral arteries, communicating arteries and those of basilar trunk. Practical applications of this new method are numerous in cerebrovascular disease: diagnosis of brain stem lesions, evaluation of effects of extracranial lesions, detection and follow up of arteriovenous malformations, functional value of the circle of Willis prior to carotid surgery. Despite certain limitations due to anatomic factors, angiographic confrontations attest the value and reliability of this new examination.