الفهرس 
Anatomy of cerebral circulationOnly 14 pages are availabe for public view
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Abstract
The blood supply to the brainstem, cerebellum, occipital lobe and the inferior aspect of the temporal lobe is derived from branches of the vertebral system. The frontal, parietal, upper 75% of the temporal lobes and the insular cortex receive their blood supply from the middle and anterior arteries, both of which are branches of the internal carotid system.
The average rate of blood flow in the brain is approximately 50-55 ml/100 gm/minute. In pathological states, this global flow rate may decrease. The link between flow rate and electrophysiological and clinical findings underlies the concept of “flow thresholds”. Remarkably, clinical evidence for a neurological deficit may not appear until average flow has fallen to 50% or below of normal levels (i.e. to approximately 25-30 ml/100 gm/minute).
As the world health organization defines stroke clinically as a
”rapidly developing clinical signs of focal (at times global) disturbance of cerebral functions, lasting for more than 24 hours or leading to death, with no apparent cause other than of vascular origin.
Cerebral stroke is brain or retinal cell death due to prolonged ischemia. A focused medical history for patients with cerebral stroke aims to identify risk factors for atherosclerotic and cardiac disease, including hypertension, diabetes mellitus, tobacco use, high cholesterol, and a history of coronary artery disease, coronary artery bypass, or atrial fibrillation. Consider stroke in any patient presenting with acute neurologic deficit or any alteration in level of consciousness.
The goals of the physical examination include detecting extracranial causes of stroke symptoms, distinguishing stroke from stroke mimics, determining and documenting for future comparison the degree of deficit, and localizing the lesion. The physical examination always includes a careful head and neck examination for signs of trauma, infection, and meningeal irritation.
Approximately 45% of cerebral stroke results from thromboses of small or large arteries, 20% results from emboli, whereas the remaining 35% are of unknown etiology. Impairment of blood flow to the brain results in insufficient oxygen and glucose delivery to support cellular functions and homeostasis. Because neuronal cells are deficient of gluconeogenesis and glycogenesis.
Imaging in stroke can involve several types of MRI, several types of CT scanning, angiography, ultrasonography, radiology, echocardio-graphy, and nuclear imaging studies.
Best medical management for cerebral stroke includes advice on diet, exercise, smoking and alcohol use. Medication or drug therapy is the most common method of stroke prevention; carotid endarterectomy can be a useful surgical method of preventing stroke.
Ferritin provides the primary form of iron storage in the body. Since the first demonstration of a relationship between: serum Ferritin concentration and the level of iron stores there have been many subsequent studies of this relationship. The possible role of Ferritin during inflammation has been demonstrated. It has been proposed that extracellular ferritin has an important role in host defense against bacteremia by stimulating oxidative metabolism.
A proposed mechanism by which iron may play a role in ischemic vascular disease, which might be more relevant to stroke risk, is through ischemia/reperfusion injury. During reperfusion after cerebral infarction, there is a marked increase in oxygen-radical production as well as a release of iron ions, leading to progressive tissue damage and cellular death.
Because of its specific areas rich in iron, high amounts of polyunsaturated fatty acid side chains in membrane lipids, and low concentrations of antioxidant enzymes, such as superoxide dismutase, catalase, and glutathione peroxidase, the brain may be especially vulnerable to oxidative stress.