What is the definition of a stroke
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Understanding the Definition of Stroke
Introduction to Stroke Definition
Stroke is a significant medical condition that has been defined and redefined over the years to incorporate advances in medical science and technology. Despite these advancements, the term "stroke" is not consistently defined across clinical practice, research, and public health assessments .
Classic and Updated Definitions
Classic Definition
Traditionally, stroke has been defined as the abrupt onset of symptoms of focal neurological dysfunction that last more than 24 hours or lead to earlier death, caused by acute vascular injury to part of the brain . This definition includes both ischemic strokes, caused by inadequate blood supply, and hemorrhagic strokes, caused by spontaneous bleeding into the brain .
Updated Definition
The American Heart Association/American Stroke Association has updated the definition to better reflect modern understanding and diagnostic capabilities. According to this updated definition, stroke encompasses central nervous system infarction, which includes brain, spinal cord, or retinal cell death attributable to ischemia, based on neuropathological, neuroimaging, and/or clinical evidence of permanent injury. This definition also includes intracerebral hemorrhage and subarachnoid hemorrhage, broadening the scope of what constitutes a stroke.
Types of Stroke
Ischemic Stroke
Ischemic stroke refers to central nervous system infarction accompanied by overt symptoms. It is the most common type of stroke, accounting for approximately 85% of all cases. It is primarily caused by small vessel arteriolosclerosis, cardioembolism, and large artery athero-thromboembolism.
Hemorrhagic Stroke
Hemorrhagic stroke results from bleeding into the brain and accounts for about 15% of all strokes. It can be further classified into deep hemorrhages, often caused by hypertensive arteriopathy, and lobar hemorrhages, mainly due to cerebral amyloid angiopathy or arteriolosclerosis.
Silent Infarction
Silent infarction is a type of ischemic stroke that causes no known symptoms but can be detected through neuroimaging or neuropathological evidence.
Minor Stroke
The term "minor stroke" lacks a consensus definition but generally refers to strokes with less severe symptoms and better short-term and medium-term outcomes. Various definitions include criteria such as low scores on the National Institutes of Health Stroke Scale (NIHSS) and the absence of severe deficits like aphasia or decreased consciousness.
Conclusion
The definition of stroke has evolved significantly, incorporating both clinical and tissue criteria to provide a more comprehensive understanding. This updated definition helps in better diagnosis, treatment, and prevention strategies, ultimately aiming to improve patient outcomes and public health assessments. Understanding the different types of stroke and their specific characteristics is crucial for effective management and intervention.
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