Ischemic stroke overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Stroke is the rapidly developing loss of brain functions due to a disturbance in the blood vessels supplying blood to the brain. This can be due to ischemia (lack of blood supply) caused by thrombosis or embolism, or due to a hemorrhage.[1]
Stroke is a medical emergency and can cause permanent neurological damage, complications and death if not promptly diagnosed and treated. It is the third leading cause of death and the leading cause of adult disability in the United States and Europe. It is predicted that stroke will soon become the leading cause of death worldwide.[2]
Definition
In medicine, a stroke, fit, or faint is sometimes referred to as an ictus (cerebri), from the Latin icere ("to strike"), especially prior to a definitive diagnosis. The traditional definition of stroke, devised by the World Health Organization in the 1970s,[3] is a "neurological deficit of cerebrovascular cause that persists beyond 24 hours or is interrupted by death within 24 hours". This definition was supposed to reflect the reversibility of tissue damage and was devised for the purpose, with the time frame of 24 hours being chosen arbitrarily. It divides stroke from TIA, which is a related syndrome of stroke symptoms that resolve completely within 24 hours. With the availability of treatments that, when given early, can reduce stroke severity, many now prefer alternative concepts, such as brain attack and acute ischemic cerebrovascular syndrome (modeled after heart attack and acute coronary syndrome respectively), that reflect the urgency of stroke symptoms and the need to act swiftly.[4]
Classification
Strokes can be classified into two major categories: ischemic and hemorrhagic. Ischemia is due to interruption of the blood supply, while hemorrhage is due to rupture of a blood vessel or an abnormal vascular structure. 80% of strokes are due to ischemia; the remainder are due to hemorrhage.
Causes
The cause of stroke is an interruption in the blood supply, with a resulting depletion of oxygen and glucose in the affected area. This immediately reduces or abolishes neuronal function, and also initiates an ischemic cascade which causes neurons to die or be seriously damaged, further impairing brain function.
Risk Factors
Risk factors for stroke include advanced age, hypertension (high blood pressure), previous stroke or TIA (transient ischaemic attack), diabetes mellitus, high cholesterol, cigarette smoking, atrial fibrillation, migraine[5] with aura, and thrombophilia. In clinical practice, blood pressure is the most important modifiable risk factor of stroke; however many other risk factors, such as cigarette smoking cessation and treatment of atrial fibrillation with anticoagulant drugs, are important.
Diagnosis
Physical Examination
A systematic review found that acute facial paresis, arm drift, or abnormal speech are the best findings.[6]
Electrocardiogram
Electrocardiogram (ECG) may be performed to determine the underlying etiology such as arrhythmias which may result in clots in the heart that may spread to the brain vessels through the bloodstream. Holter monitor may be used to identify intermittent arrhythmias.
Echocardiography
Echocardiography may be performed to determine the underlying etiology such as arrhythmias and the resultant clots in the heart that may spread to the brain vessels through the bloodstream.
Ultrasound
Ultrasound/doppler study of the carotid arteries can be used to detect carotid stenosis or dissection of the precerebral arteries.
Other Imaging Findings
When a stroke has been diagnosed, various other studies may be performed to determine the underlying etiology. With the current treatment and diagnosis options available, it is of particular importance to determine whether there is a peripheral source of emboli. Test selection may vary, since the cause of stroke varies with age, comorbidity and the clinical presentation. An angiogram of the cerebral vasculature (if a bleed is thought to have originated from an aneurysm or arteriovenous malformation)
Treatment
Early Assessment
Early recognition of the signs of stroke is generally regarded as important. Only detailed physical examination and medical imaging provide information on the presence, type, and extent of stroke, and hence hospital attendance — even if the symptoms were brief — is advised.
Studies show that patients treated in hospitals with a dedicated Stroke Team or Stroke Unit and a specialized care program for stroke patients have improved odds of recovery.
Medical Therapy
Treatment of stroke is occasionally with thrombolysis ("clot buster"), but usually with supportive care (physiotherapy and occupational therapy) and secondary prevention with antiplatelet drugs (aspirin and often dipyridamole), blood pressure control, statins and anticoagulation (in selected patients).[7]
References
- ↑ Cotran, Ramzi S.; Kumar, Vinay; Fausto, Nelson; Robbins, Stanley L.; Abbas, Abul K. (2005). Robbins and Cotran pathologic basis of disease. St. Louis, Mo: Elsevier Saunders. ISBN 0-7216-0187-1.
- ↑ Feigin VL (2005). "Stroke epidemiology in the developing world". Lancet. 365 (9478): 2160–1. doi:10.1016/S0140-6736(05)66755-4. PMID 15978910.
- ↑ World Health Organisation. Cerebrovascular Disorders (Offset Publications). Geneva: World Health Organization. ISBN 9241700432.
- ↑ Kidwell, C (2003). "Acute ischemic cerebrovascular syndrome: diagnostic criteria". Stroke. 34 (12): 2995–8. doi:10.1161/01.STR.0000098902.69855.A9. PMID 14605325. Unknown parameter
|coauthors=ignored (help) - ↑ headaches.about.com
- ↑ Goldstein L, Simel D (2005). "Is this patient having a stroke?". JAMA. 293 (19): 2391–402. doi:10.1001/jama.296.16.2012 url=http://jama.ama-assn.org/cgi/content/full/296/16/2012 Check
|doi=value (help). PMID 15900010. - ↑ Hackam DG, Spence JD (2007). "Combining multiple approaches for the secondary prevention of vascular events after stroke: a quantitative modeling study". Stroke. 38 (6): 1881–5. doi:10.1161/STROKEAHA.106.475525. PMID 17431209.