Cerebral blood supply

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A number of methods have been described for the production of persistent hypertension in animals. Neurogenic hypertension follows the impairment of cerebral blood supply. This can be achieved either through... 

Diseases of the arteries can cause serious problems, namely coronary artery disease, cerebral vascular disease, and peripheral vascular disease Drug therapy for vascular diseases may include dragp that dilate blood vessels and thereby increase blood supply to an area... 

Ischemic stroke is the abrupt development of a focal neurologic deficit that occurs due to inadequate blood supply to an area of the brain. Most often, this is due to a thrombotic or embolic arterial occlusion leading to cerebral infarction. 

Ischemic stroke is the abrupt development of a focal neurologic deficit that occurs due to inadequate blood supply to an area of the brain. Most often, this is due to a thrombotic or embolic arterial occlusion leading to cerebral infarction. A thrombotic occlusion occurs when a thrombus forms inside an artery in the brain. An embolism refers to a clot originating outside of the brain in which a piece of the clot breaks loose and is carried to the brain. 

During phase I, each seizure causes a sharp increase in autonomic activity with increases in epinephrine, norepinephrine, and steroid plasma concentrations, resulting in hypertension, tachycardia, hyperglycemia, hyperthermia, sweating, and salivation. Cerebral blood flow is also increased to preserve the oxygen supply to the brain during this period of high metabolic demand. Increases in sympathetic and parasympathetic stimulation with muscle hypoxia can lead to ventricular arrhythmias, severe acidosis, and rhabdomyolysis. These, in turn, could lead to hypotension, shock, hyperkalemia, and acute tubular necrosis. 

Although the brain constitutes only 2% of body weight, it receives approximately 15% of the blood supply and consumes nearly 20% of the total oxygen and glucose available to the body. In order to supply these essential nutrients for brain function, there must be a consistent and rapid blood supply to the brain in order that the brain cells may function. This is supplied by the cerebral arteries derived from the internal carotid arteries which branch over the surface of the brain and send smaller branches into the deeper subcortical structures. The capillaries are highly branched and it has been calculated that every nerve cell is no more than 40-50 fim from a capillary. 

Cerebral blood flow (CBF) was monitored in the cerebral cortex of the ischemic hemisphere corresponding to the supply territory of the middle cerebral artery by laser-doppler flowmetry (DRT4, Moor Instruments, Devon, UK). To this aim, a rectangular bent laser-doppler probe was glued onto the parietal bone (2 mm posterior and 5 mm lateral from bregma) and local CBF was continuously measured from 20 min before the onset of ischemia until 10 min after reperfusion, keeping the animal under isoflurane anaesthesia. Flow values were collected every 5 min before MCAo and after reperfusion whereas data were collected at 10 min intervals during occlusion. 

Many individuals with LA also harbor lacunar and/or cortical infarcts. Presence of LA serves as an intermediate surrogate both for ischemic stroke and intracerebral hemorrhage as they all share similar risk factors and similar pathophysiological mechanisms (Inzitari 2003). LA is widely found in dementing illnesses, such as Alzheimer s disease, vascular dementia, and cerebral autosomal dominant arteri-opathy with subcortical infarcts and leukoencepha-lopathy (CADASIL). Failure of blood supply in the... 

The brain uses a substantial proportion of body oxygen and there is a generous blood supply to the brain from the carotid and vertebral arteries. Interruption of brain blood flow for more than a very short time causes neuronal damage and ultimately cell death. Cerebral blood flow is normally controlled by autoregulation. 

Transient ischemic attack. An acute loss of focal brain or monocular function with symptoms lasting less than 24-hours and which is thought to be caused by inadequate cerebral or ocular blood supply as a result of arterial thrombosis, low flow or embolism associated with arterial, cardiac or hematological disease (Hatano 1976). 

Knowledge of the anatomy of the blood supply of the brain is often helpful in understanding the etiology and mechanisms of TIA and stroke, which enable accurate targeting of acute treatment and secondary prevention. An awareness of the mechanisms underpinning the regulation of cerebral blood flow allows the clinician to identify patients at risk of stroke and assess the possible effects of treatments. 

The posterior cerebral artery encircles the midbrain close to the oculomotor nerve at the level of the tentorium and supplies the inferior part of the temporal lobe, and the occipital lobe (Marinkovic et al. 1987). Many small perforating arteries arise from the proximal portion of the posterior cerebral artery to supply the midbrain, thalamus, hypothalamus and geniculate bodies. Sometimes a single perforating artery supplies the medial part of each thalamus, or both sides of the midbrain. In approximately 15% of individuals, the posterior cerebral artery is a direct continuation of the posterior commrmicating artery, its main blood supply then coming from the internal carotid artery rather than the basilar artery. 

The presence of cranial neuropathy may result in a misdiagnosis of brainstem stroke. Cranial nerve palsies may result from local pressure from the false internal carotid artery lumen, thromboembolism or hemodynamic compromise to the blood supply of the nerve. Cranial nerve III receives its blood supply from the ophthalmic artery, branches of the internal carotid or the posterior cerebral artery and, consequently, may rarely become ischemic after carotid dissection. 

Arteriovenous malformations present most commonly with signs consistent with a space-occupying lesion or seizures and consist of an abnormal fistulous connection(s) between one or more hypertrophied feeding arteries and dilated draining veins (Clatterbuck et al. 2005) (Fig. 7.5). The blood supply is derived from one cerebral artery or, more often, several, sometimes with a contribution from branches of the external carotid artery. Arteriovenous malformations vary from a few millimeters to several centimeters in diameter. Approximately 15% are associated with aneurysms on their feeding arteries. Some grow during life but a few shrink or even disappear, and some are multiple. These fistulae occur in or on the brain, or in the dura of the intracranial sinuses. 

Cerebral ischemia, (i.e., absolute or relative shortage of blood supply to a part of the brain such as following an ischemic stroke) is a serious condition that can lead to physical impairment or death. Stroke is a leading cause of death and adult disability in the industrialized part of the world (Thom et al., 2006). The outcome of a cerebral ischemic episode is greatly influenced by the duration, that is, the time from onset of ischemia until reperfusion treatment is directed at the cause of the impaired blood supply, that is, thrombolysis or surgical intervention (e.g., see the review by Juttler et al., 2006). 

The cerebral hemispheres and diencephalon receive blood from the anterior and posterior circulations (Figure 3.5). The cerebral cortex receives its blood supply from the three cerebral arteries the anterior and middle cerebral arteries, which are part of the anterior circulation, and the posterior cerebral artery, which is part of the posterior circulation. The diencephalon, basal gan-... 

The posterior cerebral artery supplies the occipital lobe and portions of the medial and inferior temporal lobe. The arterial supply of the spinal cord is derived from the vertebral arteries and the radicular arteries. The brain is supplied by the internal carotid arteries (the anterior circulation) and the vertebral arteries, which join at the pon tomedullary junction to form the basilar artery (collectively termed the posterior circulation). The brainstem is supplied by the posterior system. The medulla receives blood from branches of the vertebral arteries as well as from the spinal arteries and the posterior inferior cerebellar artery (PICA). The pons is supplied by paramedian and short circumferential branches of the basilar artery. Two major long circumferential branches are the anterior inferior cerebellar artery (AICA) and the superior cerebellar artery. The midbrain receives its arterial supply primarily from the posterior cerebral artery as well as from the basilar artery. The venous drainage of the spinal cord drains directly to the systemic circulation. By contrast, veins draining the cerebral hemispheres and brain stem drain into the dural sinuses. Cerebrospinal fluid also drains into the dural sinuses through unidirectional valves termed arachnoid villi. 

Usually it is the skeletal or striated muscles that will require therapy for painful spasm or will need to be relaxed to allow the surgeon to gain access to the abdomen easily. Muscle spasm may be associated with a trauma or may be brought on by multiple sclerosis, cerebral palsy, stroke, or an injury to the spinal cord. Severe cold, an interruption of blood supply to a muscle, or over exertion of the muscle also can lead to spasms. A muscle spasm actually is an increase in muscle tone brought on by an abnormality in motor control by the spinal nerves. 

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