How strokes may occur

Fatty deposits in the carotid arteries can severely restrict blood from reaching the brain, or a piece of fatty deposit may break off into the bloodstream and lodge in an artery upstream in the brain. Either way, transient ischemic attack (TIA) or stroke may occur.

The brain receives blood that carries nutrients and oxygen from four main arteries: the right carotid, left carotid, right vertebral and left vertebral. The carotid arteries travel between the heart and the brain in the front of the neck. They carry blood to the cerebral hemispheres, which are responsible for most of a person's day-to-day functioning.

Atherosclerosis (a waxy plaque buildup, also known as hardening of the arteries) occurs when the arteries become clogged with fatty deposits. These deposits can severely restrict blood from reaching the brain and a stroke may occur.

Transient ischemic attack (TIA) or stroke may also occur if a piece of the buildup breaks off into the bloodstream and lodges in an artery upstream in the brain.

Almost 25 percent of strokes result from narrowing of a carotid artery.