Stroke and Cerebrovascular Disease

Stroke is an episode of acute neurological dysfunction caused by focal injury to the brain, spinal cord, or retina from a vascular cause, classically separated into ischemic stroke (from arterial occlusion) and hemorrhagic stroke (from bleeding). This area orients the reader to the major cerebrovascular syndromes, their shared vascular logic, and the way modern definitions tie clinical events to underlying tissue injury.

Definition

Stroke is an episode of acute focal neurological dysfunction attributable to a vascular cause, encompassing infarction of central nervous system tissue (ischemic stroke), intracerebral hemorrhage, and subarachnoid hemorrhage; the modern tissue-based definition links the clinical event to evidence of vascular injury rather than to symptom duration alone.

Scope

This area entry frames the family of cerebrovascular conditions within clinical neurology: ischemic stroke, transient ischemic attack, intracerebral hemorrhage, and subarachnoid hemorrhage. It introduces the common vocabulary of time-critical brain injury, the ischemic-versus-hemorrhagic distinction, and how stroke is defined and classified. It is a reference and educational overview and does not provide diagnostic or treatment recommendations.

Sub-topics

• Intracerebral Hemorrhage
• Ischemic Stroke
• Subarachnoid Hemorrhage
• Transient Ischemic Attack

Core questions

• What distinguishes ischemic from hemorrhagic stroke, and why does the distinction matter?
• How has the definition of stroke shifted from a purely time-based to a tissue-based concept?
• What are the major cerebrovascular syndromes grouped within this area?
• Why is stroke treated as a time-critical emergency across its subtypes?

Key concepts

• Ischemic versus hemorrhagic stroke
• Focal versus global neurological dysfunction
• Tissue-based definition of stroke and transient ischemic attack
• Cerebrovascular territories and the circle of Willis
• Time-critical brain injury ('time is brain')
• Primary versus secondary prevention
• Stroke as a leading cause of death and disability

Mechanisms

Cerebrovascular disease shares a final common pathway of disrupted blood supply to nervous tissue. In ischemic stroke, occlusion of a cerebral artery deprives downstream tissue of oxygen and glucose, producing an infarct core surrounded by potentially salvageable penumbra. In hemorrhagic stroke, rupture of a vessel allows blood to enter the brain parenchyma (intracerebral hemorrhage) or the subarachnoid space (subarachnoid hemorrhage), causing injury through mass effect, raised intracranial pressure, and secondary processes. A transient ischemic attack reflects temporary ischemia without lasting infarction. The contemporary definition reframes these events around demonstrable tissue injury rather than the older 24-hour symptom rule (Sacco et al., 2013).

Clinical relevance

The cerebrovascular syndromes collected here account for a large share of neurological emergencies and of long-term disability worldwide, making them central to clinical neurology. This area describes how these conditions are defined, classified, and studied; it is an educational orientation and not a basis for diagnosing or treating any individual, which depends on clinical assessment and current guidelines.

Epidemiology

Stroke is among the leading causes of death and acquired disability globally. Population-based studies show wide variation in incidence and early case fatality across regions and stroke subtypes (Feigin et al., 2009). Ischemic stroke is the most common subtype in most populations, with intracerebral and subarachnoid hemorrhage making up smaller but high-severity shares.

Evidence & guidelines

Contemporary definitions of stroke and its subtypes are set out in an American Heart Association/American Stroke Association statement (Sacco et al., 2013). Broad clinical overviews summarize the spectrum of cerebrovascular disease (Hankey, 2017), and secondary-prevention principles after stroke and transient ischemic attack are addressed in AHA/ASA guidance (Kleindorfer et al., 2021). Detailed, subtype-specific evidence is covered in the child topics.

History

Cerebrovascular disease was historically described under the umbrella of 'apoplexy,' and for much of the twentieth century stroke and transient ischemic attack were separated by an arbitrary 24-hour symptom cutoff. Advances in neuroimaging revealed that many brief events nonetheless leave infarcts, motivating a shift toward a tissue-based definition that anchors stroke and transient ischemic attack to evidence of injury rather than duration alone (Sacco et al., 2013).

Key figures

• Ralph L. Sacco
• Valery L. Feigin
• Graeme J. Hankey

Seminal works

• sacco-2013
• feigin-2009
• hankey-2017

Frequently asked questions

What is the difference between ischemic and hemorrhagic stroke?

Ischemic stroke results from blockage of a brain artery that deprives tissue of blood flow, while hemorrhagic stroke results from bleeding, either into the brain tissue (intracerebral hemorrhage) or into the subarachnoid space. They share acute neurological consequences but differ in cause and course.

Why is stroke now defined by tissue injury rather than by symptom duration?

Imaging showed that many short-lived events still cause permanent infarction, so the older 24-hour rule did not reliably separate stroke from transient ischemic attack. The updated definition ties the diagnosis to evidence of central nervous system injury from a vascular cause.