Prevalence of carotid siphon stenosis in patients referred for cerebrovascular evaluation

Introduction. - The carotid siphon is second only to the carotid bifurcation in the prevalence of hemodynamically significant atherosclerotic plaque formation, yet few non-invasive vascular laboratories report interrogation of this region during routine noninvasive vascular evaluations. The purpose of this investigation was to determine the prevalence of carotid siphon stenosis in patients referred for noninvasive cerebrovascular evaluation. Materials and Methods. - During a 2-month period, 178 patients (94 male, 84 female, mean age, 71.8 years) were referred to the vascular laboratory for cerebrovascular evaluation, which included interrogation of the extracranial carotid, vertebral, and subclavian arteries as well as the intracranial ophthalmic artery and carotid siphon. All intracranial examinations were performed using a phased array imaging transducer (2-4 MHz). Results. - Ten patients (6%, 10/178) were found to have hemodynamically significant carotid siphon stenosis. There was a statistically significant association between the presence of carotid siphon stenosis and cervical bruit (p ≤ 0.05), follow-up of known extracranial carotid artery atherosclerosis (p ≤ 0.001), and a combination of hypertension, hyperlipidemia, and coronary artery disease (p ≤ 0.01). Conclusion. - Investigation of the carotid siphon is worthwhile when performed in conjunction with extracranial carotid duplex examinations. Siphon lesions detected during the cerebrovascular examination, especially in those with cervical bruits, known extracranial atherosclerotic disease, and combinations of risk factors, may affect medical or interventional therapy and can lead to a reduction in neurovascular events.