What distinguishes ischemic stroke from hemorrhagic stroke?

Ischemic stroke and hemorrhagic stroke are distinguished primarily by the underlying cause of the disruption in cerebral blood flow. In the case of ischemic stroke, the underlying pathology involves the presence of a thrombus (a clot that forms in a blood vessel) or an embolus (a clot that travels from another part of the body to occlude a cerebral artery). This blockage reduces or completely stops blood flow to a portion of the brain, leading to tissue ischemia and possible infarction.

On the other hand, a hemorrhagic stroke occurs due to the rupture of a blood vessel, leading to bleeding within or around the brain. As such, the cause of hemorrhagic stroke is related to vascular integrity rather than blockage by thrombus or emboli, which is the hallmark of ischemic stroke.

The other options listed do not pertain to the primary mechanisms distinguishing these two types of stroke. Hormone regulation, metabolic bone diseases, and neurofibrillary tangles are not directly relevant to the acute cerebrovascular events that define ischemic versus hemorrhagic strokes. Understanding the distinction is crucial for diagnosis and treatment, as the management strategies differ significantly between the two conditions.