Stroke definition
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Stroke Definition: Clinical and Modern Criteria
Stroke is commonly defined as a sudden onset of neurological dysfunction due to a vascular cause, affecting the brain, spinal cord, or retina. The classic definition, as outlined by the World Health Organization, describes stroke as rapidly developing signs of focal or global disturbance of cerebral function, lasting more than 24 hours or leading to death, with no apparent cause other than vascular origin 259. This definition emphasizes the abruptness of symptoms and their persistence, distinguishing stroke from transient ischemic attacks, which resolve within 24 hours.
Types of Stroke: Ischemic and Hemorrhagic
Stroke encompasses both ischemic and hemorrhagic events. Ischemic stroke results from an obstruction in a blood vessel supplying the brain, leading to tissue infarction, while hemorrhagic stroke is caused by bleeding into or around the brain due to vessel rupture 1467. Both types can cause similar neurological deficits, but their underlying mechanisms and treatments differ.
Updated Definitions: Incorporating Imaging and Tissue Criteria
Recent advances in neuroimaging have led to updated definitions of stroke. Modern criteria include not only clinical symptoms but also evidence of brain, spinal cord, or retinal cell death attributable to ischemia, as seen on imaging or pathology. The American Heart Association/American Stroke Association now defines central nervous system infarction as cell death due to ischemia, confirmed by clinical, imaging, or pathological evidence. This updated definition also recognizes "silent" infarcts, which are detected on imaging but do not cause noticeable symptoms . Additionally, stroke now broadly includes both intracerebral and subarachnoid hemorrhages .
Key Clinical Features and Risk Factors
Stroke typically presents with sudden loss of neurological function, such as weakness, speech difficulties, sensory loss, or visual disturbances. The specific symptoms depend on the area of the brain affected. Risk factors for stroke include hypertension, atrial fibrillation, diabetes, hyperlipidemia, smoking, and physical inactivity 46. Stroke is a leading cause of death and disability worldwide, making its recognition and prevention a major public health priority 146.
Historical Evolution of the Stroke Definition
The concept of stroke has evolved over centuries, from early descriptions of "apoplexy" to the current understanding based on vascular pathology and neuroimaging. While the core idea of sudden neurological loss due to vascular causes remains, the definition has been refined to reflect advances in medical knowledge and technology 3810.
Conclusion
In summary, stroke is defined as a sudden loss of neurological function due to a vascular cause, with symptoms lasting more than 24 hours or resulting in death. Modern definitions incorporate clinical, imaging, and pathological evidence, and include both ischemic and hemorrhagic events. Understanding the definition and types of stroke is essential for accurate diagnosis, treatment, and prevention.
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