What is the medical definition of a stroke?

A stroke is defined medically as a sudden focal neurologic deficit resulting from brain infarction. This definition encompasses both types of strokes: ischemic and hemorrhagic.

In ischemic strokes, a blockage in a blood vessel leads to a lack of blood flow and oxygen to a specific area of the brain, resulting in the death of brain cells, which can cause deficits in neurological function such as weakness, speech difficulties, or changes in sensation. In hemorrhagic strokes, a blood vessel ruptures, causing bleeding within or around the brain, which also leads to sudden neurological deficits.

This definition emphasizes the acute onset of symptoms and the direct impact on brain tissue and function, which is a defining characteristic of a stroke. The inclusion of "focal" indicates that the symptoms generally affect specific regions of the body and correlate with the particular areas of the brain that are injured.

The other options do not fully capture the medical definition of a stroke. A transient ischemic attack refers to temporary symptoms that resolve quickly and do not cause lasting brain injury. A sudden brain hemorrhage could describe one type of stroke but fails to encompass ischemic strokes, which are more common. A gradual loss of cognitive function does not align with the acute nature of a stroke,