[Ultrasound measurement of carotid stenosis: recommendations from the Spanish Society of Neurosonology].

In Spain, approximately 28% of ischaemic strokes have an atherothrombotic cause, and most are due to carotid stenosis. Ultrasound is the most commonly used technique for diagnosing carotid stenosis. Changes in blood flow velocity at the point of maximum stenosis, together with haemodynamic changes in proximal regions (common carotid artery) and distal regions (poststenotic internal carotid, ophthalmic artery, and the circle of Willis), allow us to measure carotid stenosis precisely. This review explains the methodology to be followed when evaluating carotid stenosis ultrasonographically, according to the recommendations from the Spanish Society of Neurosonology (SONES). We review the findings that permit us to measure the degree of extracranial carotid stenosis using both carotid and transcranial ultrasound, with particular emphasis on the importance of assessing indirect signs.