Stroke Attack - An embolic stroke occurs when a blood clot travels from other parts of the body (for example, the heart) to the neck or brain and blocks a blood vessel. The red branch-like structure represents blood vessels and the region of the brain outlined by the small white box is the site of the embolism. The orange region represents the brain areas damaged by the stroke. When a clot forms in a blood vessel in the brain or neck it is called a thrombolic stroke. Embolic and thrombolic strokes are categorized as ischemic stroke. Finally, a blood vessel that is not blocked, but is extremely narrowed, can also cause an ischemic stroke. The blocked or narrowed arteries deprive brain cells of oxygen and nutrients, leading to nerve cell death. 80% of all strokes are ischemic.