Fibromuscular dysplasia of the carotid artery: Diagnosis with duplex ultrasonography

Purpose.-The diagnosis of carotid artery fibromuscular dysplasia is usually made with conventional angiography performed to evaluate a suspected carotid stenosis. The ultrasound findings with fibromuscular dysplasia have not been well described. This study was performed to assess the characteristics of carotid artery fibromuscular dysplasia with duplex ultrasonography. Methods.-The hospital records for all patients who had carotid duplex ultrasonography were reviewed from January 2000 to October 2003. Patients with findings suspicious for fibromuscular dysplasia formed the basis of this study. The patient demographics, their presenting symptoms, and ultrasound findings were analyzed. Results.-Carotid duplex studies were performed on 9157 patients during the study period. The presumptive diagnosis of fibromuscular dysplasia was made in 13 female patients (1.2%), with a mean age of 67 ± 10 years (range, 52-79 years). Patients were referred for asymptomatic carotid bruits (n = 10, 77%) or transient ischemic attack (n = 3, 23%). Both mid and distal internal carotid artery involvement were seen in five patients (38%), whereas eight patients (62%) had disease isolated to the distal internal carotid artery. Bilateral carotid artery involvement occurred in eight patients (62%). A consistent finding in all patients was multiple areas of alternating focal thickening with thin, dilated arterial walls. Other sonographic findings included velocity increases (mean, 181 cm/sec; range, 135-318 cm/sec), color flow disturbance, and scarcity of plaque in the suspected arterial segment. Magnetic resonance angiography or carotid angiography was performed on seven (54%) patients, confirming the ultrasound diagnoses. One symptomatic patient was successfully treated with open graduated endoluminal dilatation. One patient with asymptomatic carotid bruit underwent carotid stent placement for rapid progression of the disease. No disease progression was seen on follow-up duplex examination in the remaining group, and no patient became symptomatic. Conclusions.-Fibromuscular dysplasia should be suspected in female patients with high-grade mid to distal carotid artery stenosis without significant atherosclerotic disease. This study demonstrates the usefulness of duplex ultrasound as both a screening test and diagnostic examination for carotid artery fibromuscular dysplasia. Follow-up is warranted in these patients.