Carotid artery fibromuscular dysplasia.
Extracranial carotid artery fibromuscular dysplasia (FMD) is a rare finding that is frequently incidental and asymptomatic. It usually occurs in middle-age women and is secondary to medial fibrodysplasia or, less commonly, intimal fibrodysplasia. The carotid artery may be elongated or kinked and associated aneurysms have been reported. Symptoms including transient ischemic attack or stroke are uncommon and are due to low flow or embolization of platelet aggregates. Digital subtraction angiography demonstrates high-grade stenosis with the characteristic "string of beads" pattern. Antiplatelet medication with sequential imaging is the accepted therapy for asymptomatic lesions. Graduated endoluminal dilation under direct vision should be reserved for patients with documented lateralizing symptoms.