<unk>  is a narrowing or constriction of any part of the<unk>  arteries, usually caused by atherosclerosis.
Carotid artery stenosis
Carotid artery dissection
Orthostatic hypertension
Cerebral atherosclerosis
Arterial tortuosity syndrome
Cerebral vasospasm
Arteriolosclerosis
Carotid-cavernous fistula