Perfusion-MRI in cerebral infarct

PURPOSE: To investigate the hemodynamic changes in patients with acute cerebral stroke by perfusion MRI. MATERIAL AND METHODS: In 12 patients with acute stroke in the territory of the middle cerebral artery, perfusion MRI was performed. Peak time, mean transit time, regional cerebral blood volume and regional cerebral blood flow were calculated in the infarction, the peri-infarction area and the contralateral hemisphere. RESULTS: In the infarction the mean blood flow was 29 ml/100 g/min, compared to about 40 ml/100 g/min in the peri-infarction area and the contralateral hemisphere. In two patients increased cortical blood flow was found in the infarction due to luxury perfusion. The cerebral blood volume was reduced in the infarction, but significantly increased, to 7.3 ml/100 g, in the peri-infarction tissue. CONCLUSION: Perfusion MRI allows one to differentiate various patterns of perfusion disorders in patients with acute cerebral stroke. The resulting data may be helpful in describing the pathophysiologic mechanisms of compensation.     

Stem cells in the embryonic cerebral cortex: their role in histogenesis and patterning

The cytoarchitectural simplicity of the cerebral cortex makes it an attractive system to study central nervous system (CNS) histogenesis--the process whereby diverse cells are generated in the right numbers at the appropriate place and time. Recently, multipotent stem cells have been implicated in this process, as progenitor cells for diverse types of cortical neurons and glia. Continuous analysis of stem cell clone development reveals stereotyped division patterns within their lineage trees, highly reminiscent of neural lineage trees in arthropods and Caenorhabditis elegans. Given that these division patterns play a critical part in generating diverse neural types in invertebrates, we speculate that they play a similar role in the cortex. Because stereotyped lineage trees can be observed from cells growing at clonal density, cell-intrinsic factors are likely to have a key role in stem cell behavior. Cortical stem cells also respond to environmental signals to alter the types of cells they generate, providing the means for feedback regulation on the germinal zone. Evidence is accumulating that cortical stem cells, influenced by intrinsic programs and environmental signals, actually change with development-for example, by reducing the number and types of neurons they produce. Age-related changes in the stem cell population may have a critical role in orchestrating development; whether these cells truly self-renew is a point of discussion. In summary, we propose that cortical stem cells are the focus of regulatory mechanisms central to the development of the cortical cytoarchitecture.     

Posttreatment with low molecular weight heparin reduces brain edema and infarct volume in rats subjected to thrombotic middle cerebral artery occlusion

Low molecular weight heparin (LMWH) has similar efficacy to unfractionated heparin with less hemorrhagic complications. We studied the neuroprotective effect of LMWH on a rat model of focal-ischemia. Our results revealed that treatment with LMWH at 1 and 3 h following thrombotic MCA occlusion reduced brain edema and infarct size and improved clinical outcome. Treatment with LMWH initiated at 6 h after thrombin injection only partially ameliorated brain damage.     

Fibrinolytic therapy of acute cerebral infarct

On the basis of our upon own results of local intra-arterial fibrinolysis (LIF), this article gives a short overview of recently established thrombolytic therapy in acute ischemic stroke. Fifty patients with acute occlusions of vertebrobasilar arteries and 118 patients showing occlusions of branches of the internal carotid artery were treated with LIF. The Occlusion type, occlusion site and successful recanalization were associated with a favorable outcome: 92% of embolic occlusions in the vertebrobasilar territory were recanalized and resulted in 50% in a favorable outcome. In the carotid territory, optimal outcome was achieved in main stem and branch occlusions of the middle cerebral artery, due to recanalization rates of 49%-64%. In contrast, occlusions of the intracranial bifurcation of the carotid artery (carotid-"T") resulted in death in 59%. Despite the lack of randomized trials, LIF is an established form of therapy in the vertebrobasilar territory. In the carotid territory randomized clinical studies could demonstrate the efficacy of intravenous fibrinolytic therapy in some stroke patients. It can be presumed from pilot studies that LIF is superior to the intravenous version in the carotid territory.     

The anti-arrhythmic effect of the electrophoresis of a natural shirsal preparation in the 2nd-stage rehabilitation of myocardial infarct patients

Experimental and clinical trials of antiarrhythmic effect of shirsal (natural salt of lake Shira mineral water) have shown that rehabilitation complex including shirsal electrophoresis is beneficial for MI patients with arrhythmia. Shirsal electrophoresis extends indications for sanatorium treatment of MI patients with stable angina of effort (functional class III-IV), grade I-IV arrhythmia, chronic circulatory insufficiency.     

Hemisphere dominance of the cerebral cortex

An outbreak of erythema infectiosum (fifth disease) occurred in a North Carolina elementary school. Because rubella virus has been implicated as a possible cause of some cases of erythema infectiosum, we conducted an investigation to determine if the children were infected with rubella virus and to learn whether or not rubella virus vaccination prevents the disease. Throat swabs were obtained for viral isolation from 20 children with erythema infectiosum and from 25 healthy classmates; questionnaires were completed for 617 of the school's 817 students. One hundred fifty children (24%) reported having an acute exanthematous illness during the study period, and 45% of the ill children had one or more household contacts with a similar rash. No viruses were recovered from the children, and a history of rubella vaccination did not affect the risk of developing erythema infectiosum.     

Neurotransmitter receptors in the developing cerebral cortex

This review deals with several aspects of neurotransmitter receptor development in the primate cerebral cortex. It describes the presence of multiple neurotransmitter receptors in the transient zones of the fetal cerebral wall. These zones are involved in the production and migration of cortical neurons and the establishment of appropriate innervation of the cortex. It also suggests functions that neurotransmitter receptors may perform in these embryonic zones. In addition, this review shows that a remarkable diversity of neurotransmitter receptors develops concurrently in disparate areas of the primate cerebral cortex and discusses the implications of this finding on our understanding of the general principles underlying development of the cerebral cortical circuitry. Finally, it speculates on factors that may be involved in regulation of neurotransmitter receptor development in the primate cerebral cortex.     

Lacunar infarct and deep cerebral hemorrhage: a comparison of the risk factors

INTRODUCTION: Lacunar infarcts (LI) and deep cerebral hemorrhages (DCH) have the same localization and a vasculopathy which appears to be similar, at the level of the small perforating arteries, classically attributed to arterial hypertension (AHT). OBJECTIVES: To compare the vascular risk factors of patients with lacunar ictus (LIc) and those with DCH, to try to determine how these may affect the appearance of one type of stroke or another. PATIENTS AND METHODS: We analyzed a prospective consecutive series of patients with cerebral vascular accidents (CVA), selecting 1,540 patients in the first 1,155 with a first CVA. We recorded demographic data and the following risk factors: previous transient ischemic accident (TIA), AHT, diabetes mellitus (DM), hypercholesterolemia, ischemic cardiopathy, atrial fibrillation and the presence of silent infarcts on CT. RESULTS: Two hundred and four patients had LIc and 163 had DCH. There was a significant dissociation between LIc and a history of TIA, DM, hypercholesterolemia and the presence of silent lacunar-type infarcts on CT. However, after multivariant analysis, DM did not continue to be an independent variable. Arterial blood pressure was found to be greater in the DCH group. CONCLUSIONS: The presence of different risk factors for LIc and DCH may be the key to understanding the mechanism which leads to one type or other of CVA.     

Hypervascularization of the cerebral cortex in lead-induced encephalopathy

Pregnant rats were fed a diet containing 1.8% lead acetate for 8 days before delivery until the young were 3 month old. The density of the cerebral cortex capillaries of the infant rats and their convolution rate were studied morphometrically and noted to increase significantly according to the duration of lead treatment, as demonstrated by two-way analysis of variance. On the other hand, the thickness of the cortex reduced progressively. The increase of both capillary density and convolution rate is supposed to be related with this involution of cortex. This provides a quantitative insight of the previously described 'capillary activation' phenomenon, caused by lead encephalopathy and reveals it as a significant sequel of saturnine action.     

The role of fludrocortisone in a child with cerebral salt wasting

Cerebral salt wasting (CSW) is a syndrome of hyponatremia due to excessive natriuresis described in patients with central nervous system insult. We present a 29-month-old black male with tuberculous meningitis who developed CSW with depressed mineralocorticoid activity. The patient required hypertonic saline and ionotropic support. Mineralocorticoid supplementation effectively treated CSW.     

Influence of an early adrenergic blockade on thrombotic infarct size and myocardial metabolism

To evaluate the extent to which the protective effect of metoprolol was accompanied by changes in myocardial oxygen consumption and metabolism, thrombotic occlusion of coronary artery followed by infusion of metoprolol or placebo was performed in twenty four German Shepherds. To restore a coronary blood flow rt-PA was administered. Plasma levels of oxygen, glucose, lactic acid, non esterified fatty acids, triacylglyceride and adenosine breakdown products were measured before and at the end of the occlusion and in the early and late reperfusion periods. Regional myocardial blood flow was measured by means of radioactive tracer microspheres. Infarct size was estimated after perfusion and staining of excised hearts with Evans blue. Plasma levels of metoprolol were determinated before the end of occlusion and during reperfusion and therapeutic concentrations were confirmed. The infarct size was smaller in dogs receiving metoprolol (21.6 +/- 20.7 vs 43.0 +/- 17.3% p. < 0.02). Coronary collateral blood flow was greater in metoprolol than in placebo dogs (18.68 +/- 7.58 vs 11.05 +/- 6.10 ml/min/100g, p. < 0.01). As a consequence of myocardial ischemia a shift toward carbohydrate utilization, the myocardial lactate release and the accompanying symptoms of diminished myocardial lipid uptake were observed. A washout of adenosine degradation products during early reperfusion was also noticed. In beta 1 blocked animals the reduction of myocardial oxygen consumption and preserved myocardial uptake of lactate and non esterified fatty acids were documented.     

The role of the coronary collateral circulation in limiting myocardial ischemia and infarct size

The role of coronary collateral circulation in limiting ischemia and infarction has been studied prospectively. Transient occlusion of a coronary artery angioplasty has provided evidence that collateral circulation decreases wall motion abnormalities, ST segment changes, and lactate production. Patients who have collateral flow also have a better outcome after coronary artery dissection and acute closure than patients without collateral flow. Collateral circulation also limits infarct size during acute myocardial infarction with and without thrombolysis. Although collateral flow may decrease coronary artery bypass graft patency in certain subgroups of patients, the perioperative infarct rate and mortality is decreased. Growth factors have been identified that increase the development collateral circulation and may improve ventricular function in the setting of myocardial infarction.     

The cerebral control of the somatosensory and auditory afferent projections to the cerebral cortex in man and animals

The main purpose of the present paper was consisted in studying of topology (spreading) of the somatosensory and auditory projections in cortex of both brain hemispheres in humans under different functional states conditions: during quiet walking state and during realization of the meditative programme. At the same time for the purpose of verification these steering mechanisms a number of experiments were realized in animals with neurosurgical cutting of brainstem ascending projections, which control the transfer of somatosensory and auditory sensibility. Experimental study was realized with two groups of subjects--8 subjects (age from 25 to 35 years old) and 25 (age from 25 to 40 years old) subjects practicing technique of Transcendental Meditation (TM). In addition to the mentioned above group some groups of animals were used in the experiments. Among them there were used the groups of monkeys (8 macaque rhesus and macaque nemestrina) and cats (10 animals) in conditions of acute experiment, under tiopenthal anesthesia. Two experimental methods were used in the study: electrophysiological for subjects and neurosurgical, additionally for animals. For evaluation of the brain reactivity in subjects registration of the somatosensory, to median nerve stimulation, and auditory, to bilateral application of auditory clicks, evoked potentials (EPs) in the symmetrical cortical structures of the brain was used. Registration of the somatosensory and auditory evoked potentials in animals was realized not only from the cortex, but from the brainstem somatosensory and auditory structures. SSEP in subjects-meditators were registered before and during meditation programme. In animals SSEP and AEP registration on the corresponding stimuli realized before and after neurosurgical operation--section of the midbrain tegmentum. Specific alterations of the early (up to 80 ms) and late components SSEP and AEP complexes in forms of topology spreading and diminution of registration areas of these components were obtained during the meditation. Origins of these functional reorganization are discussed from the positions of internal 'feed-back' inhibition.     

Neuropsychology and pathology of the cerebral cortex

In all clinics we are faced with questions about certain aspects of cerebral dominance. We consider first the problem of recognition of faces where the right hemisphere plays a leading role. However, the disorders manifesting that function appear only bilateral lesions. This suggests that the left hemisphere participates in this process. The reception of language raises a problem which is analogous with the preceding: we propose the participation of both hemispheres in this activity: the left hemisphere is dominant in the analysis of phonemes and syntax, the right hemisphere seems implicated above all in the processing of prosodic aspects--in particular intonations and individual features of the voice.     

Appearance of a cavernous hemangioma in the cerebral cortex after a biopsy of a deeper lesion

Cavernous hemangiomas are vascular malformations that can occur throughout the central nervous system. In certain patients, multiple lesions are known to occur. We present a patient with multiple cavernous hemangiomas who had a computed tomography-guided biopsy of a deep parieto-occipital lesion through a burr hole. Several passes of a biopsy needle were used. During a 5-year interval, the patient developed a new lesion directly under the burr hole on the cortical surface. The new lesion appears to have occurred from the implantation and growth of a cavernous hemangioma secondary to the biopsy.     

The intracellular mechanisms of glutaminergic and cholinergic signal transduction in the cerebral cortex

Stimulation of glytamate- and cholinoreceptors by the agonists induced a prolonged calcium and phosphoinositide responses to short-term anoxia or administration of an antioxidant agent in cortical structures. Processes of adaptation essentially modified these responses.     

Acute therapy and prevention of ischemic cerebral infarct

The acute therapy of the cerebral infarct necessitates the fast evaluation of the favorable risk factors and the assessment of its pathogenetical mechanisms to facilitate a specific treatment as early as possible. Acute treatment procedures like the rheologic therapy, anticoagulation, thrombolysis, application of calcium antagonists, and antiedematous therapy are discussed. Recommendations for the secondary prophylaxis with drugs like acetylsalicylic acid or triclopidine after transitory ischemic attacks or manifest brain infarctions are given. The indications for the surgical therapy of stenoses of the extracranial vessels supplying the brain are discussed and rules for the emergency management of the transitory ischemic attack are introduced.