The external carotid arteries show minimal irregularity as well. Atherosclerotic disease would be more common overall, but the location of disease would be atypical. Subtypes of this disease include intimal hyperplasia, medial fibroplasia, fibromuscular hyperplasia, and subadventitial fibroplasia, of which medial fibroplasia is the most common. Embolic strokes may be seen as well. The vertebral arteries may also be involved, but this is less common.
Bilateral involvement is common.