Epidemiological data indicate that cerebrovascular disease in industrialized society is the third leading cause of death after cancer and coronary heart disease. Cerebrovascular disease is also one of the most common causes of physical disability in adults and due to the increase in life expectancy of the general population more people are at risk of developing this disease than ever before.
The causes of cerebral ischemia are numerous. In addition to atherosclerotic disease (which represents the most frequent cause), other causes are; emboligena cardiac disease; trauma; vascular malformations; infectious arteritis or other nature.
Although atherosclerotic disease presents in afferent vessels both in the intra and extra-cranial parts of the brain, extra-cranial presentation is most common and clinically more relevant. The incidence of embolic cerebral ischemia type of carotid can be found in 31 to 88% of the case studies.
The carotid bifurcation, the ostium of the internal carotid artery and the first 2 cm of the vessel are elective sites of localization of atherosclerosis. Among the diagnostic methods designed to diagnose and assess the pathology of afferent cerebral vessels, the color doppler ultrasound of the supra-aortic trunks is presently the diagnostic test of choice for evaluation of the carotid and vertebro-basilare. It is the preferred test due to its non-invasiveness, the possibility of obtaining morphological and hemodynamic information in real time (often more accurate than angiography), and the absence of contraindications or complications.
A color doppler ultrasound of the supra-aortic trunks is performed when a patient exhibits symptoms such as numbness, amaurosi e sintomatologia riconducibile ad episodi anche fugaci di ischemia cerebrale but more frequently as control of intercurrent systemic diseases such as arteriosclerosis and diabetes.
The exam is generally performed in the supine position with the head extended in order to expose the largest possible portion of the skin that covers the artery to the examiner. A probe is placed on the skin which performs the double function of producing the ultrasound waves and collecting the echoes produced by the underlying tissue. A gel is used to give an un-distorted reading of the ultrasound echo as any air caught between the probe and the skin would distort the reading. The duration of the examination is 15-20 minutes with the exception of some special situations that require longer times. The examination has now acquired a diagnostic autonomy such that a carotid stenosis can not only be diagnosed but also measured accurately.