condition of unknown aetiology that involves the extracranial internal carotid arteries and vertebral arteries. The internal carotid is involved in about 75% of cases and the vertebral in less than 25%. It is characterized by narrowing of the affected vessel with a string of beads appearance , due to focal annular repetitive intimal and medial proliferative changes. Not infrequently an incidental finding, fibromuscular hyperplasia may be a cause of dissection and is associated with an increased incidence of intracranial aneurysms.
Reviewed by Sumer Sethi on Saturday, October 30, 2004 Rating: