What is usually the underlying cause of ischemic strokes?

Ischemic strokes primarily occur due to thrombotic or embolic events, which lead to a reduction or complete blockage of blood flow to a part of the brain. This lack of blood supply deprives brain tissue of necessary oxygen and nutrients, resulting in cell death and neurological deficits characteristic of an ischemic stroke.

Thrombotic strokes typically occur when a blood clot (thrombus) forms in an artery supplying blood to the brain, often due to atherosclerosis, where plaque builds up in the arterial wall. This process narrows the artery and can result in clot formation. On the other hand, embolic strokes occur when a clot or debris forms in another part of the body, commonly the heart, and travels through the bloodstream to lodge in an artery leading to the brain.

The other options present alternative conditions but are not the primary underlying cause of ischemic strokes. Aneurysm rupture relates more to hemorrhagic strokes than ischemic ones. Severe migraines and vascular malformations, while they may have neurological implications, do not typically lead to the ischemic stroke mechanism described in the context of thrombotic or embolic events. Understanding these distinctions is crucial for recognizing the appropriate underlying causes of ischemic strokes.