What is a stroke defined as?

A stroke is primarily defined as the interruption of blood supply to the brain, which leads to a deprivation of oxygen and nutrients in brain tissue. This lack of blood flow can be caused by a blockage (ischemic stroke) or by bleeding (hemorrhagic stroke). The brain is highly dependent on a constant supply of oxygen, and any disruption can result in the death of brain cells, leading to symptoms that vary based on the area of the brain affected.

The correct choice emphasizes the critical aspect of oxygen deprivation, highlighting how essential it is for brain function. Loss of balance and coordination, excess blood flow, and rapid eye movement dysfunction are symptoms or conditions that can be associated with strokes but do not encapsulate the primary definition of what a stroke fundamentally is. Understanding this definition is crucial for recognizing the seriousness of a stroke and its implications for patient care.