Ultrasound of the carotid arteries - Stenosis grading and risk assessment

Neurosonographic examinations for the grading and risk assessment of extracranial stenoses of the internal carotid artery (ICA) are widely used in clinical and practical aspects and are often the only technique for accurate stenosis grading in 10% steps. The combination of extracranial and transcranial color duplex sonography, as required by the German Society for Ultrasound in Medicine (DEGUM) criteria, not only increases the understanding of ICA stenoses not as a single vessel but as a systemic cerebrovascular disease but also indirectly enables risk assessment above the degree of stenosis itself. While the combination of accurate stenosis grading in connection with an ischemic ipsilateral stroke or ipsilateral transient ischemic attack is currently still sufficient as an indication for treatment, the situation with asymptomatic ICA stenoses is significantly more complex. Mixed, predominantly echolucent plaques, stenosis progression over the course of the disease, a juxtaluminal echo-free zone, poor or absent collateralization (with limited autoregulation) and microemboli are criteria for a vulnerable plaque but also for an increased therapeutic risk including a hyperperfusion syndrome and must be taken into account when choosing the best form of invasive treatment (carotid endarterectomy or stenting); however, even in high grade ICA stenoses there is often already good collateralization and a stable echogenic arteriosclerosis, which may be indicative for best medical treatment and not invasive revascularization. Overall, a dedicated neurosonography should not be missing in the neurovascular board in order to make the best individual treatment decision for symptomatic and asymptomatic ICA stenoses.