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Query: UMLS:C0278134 (anesthesia)
 110,339 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of some general anaesthetics, for example thiopentone, Althesin (alphaxalone + alphadolone) and ketamine, on cerebral vascular smooth muscle are those which would be expected from their metabolic actions. With other anaesthetics, mainly those administered by inhalation, and especially the volatile agents, cerebral blood flow increases in excess of the metabolic activity, which is usually depressed to varying degrees. During general anaesthesia with any of these agents, responses to changes in arterial Pco2 or blood pressure are maintained. Furthermore, when seizure activity occurs during enflurane administration, there is a flow response to the associated metabolic stimulation. The time course of the flow response to the metabolically depressant drug Althesin has been measured in baboons and shown to be very rapid. Wtih this drug cerebrovascular resistance begins to increase within 2 s of its arrival in the brain. This rapid flow change occurs also after sympathetic denervation. Extracellular fluid pH of the cortex does not alter until after the initiation of the vascular smooth muscle response.
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PMID:Control of cerebral vascular smooth muscle during general anaesthesia. 2 39

A new model of transient, bilateral hemispheric ischemia in the unanesthetized rat is described. During ether anesthesia the rat's vertebral arteries were electrocauterized through the alar foramina of the first cervical vertebra and reversible clasps placed loosely around the common carotid arteries. Twenty-four hr later, the awake rats were restrained and the carotid clasps tightened to produce 4-vessel occlusion. The carotid clasps were removed after 10, 20 or 30 min of 4-vessel occlusion and the animals killed by perfusion fixation 72 hr later. Rats which convulsed during the ischemic or post-ischemic period were excluded from further study. All rats subjected to 20 or 30 min of 4-vessel occlusion demonstrated ischemic neuronal damage. The H1 and paramedian hippocampus, striatum and layers 3, 5 and 6 of the posterior neocortex were the regions most frequently damaged. The advantages of this model are the ease of preparation of large numbers of animals, a high rate of predictable ischemic neuronal damage, a low incidence of seizures and the absence of anesthesia.
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PMID:A new model of bilateral hemispheric ischemia in the unanesthetized rat. 3 14

Effects of intraventricular injection of sheep anti-somatostatin gamma-globulin (anti-SSG) on strychnine-induced seizures, strychnine LD50, and pentobarbital LD50 were examined in male rats under light ether anesthesia. Ten microliters of anti-SSG given 2 h earlier significantly decreased the duration of strychnine-induced seizures as compared with that in the control rats pretreated with normal sheep gamma-globulin (NSG). This effect of anti-SSG seemed to be specific, as there was no difference in seizure duration between sheep anti-LHRH gamma-globulin (anti-LHRHG)- and NSG-pretreated rats. Survival rates in anti-SSG-pretreated rats after injection of strychnine and pentobarbital were significantly larger (P less than 0.01 and P less than 0.05, respectively) than those in the control rats receiving NSG. The administration of anti-SSG resulted in 26.7% and 22.9% increases in the LD50 of strychnine and pentobarbital, respectively. These results indicate that endogenous somatostatin in the cerebrospinal fluids and/or the periventricular tissue nodulates the response of the central nervous system to strychnine and pentobarbital in rats.
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PMID:Effect of intraventricular administration of anti-somatostatin gamma-globulin on the lethal dose-50 of strychnine and pentobarbital in rats. 8 54

Electrocorticographic (ECoG) and depth recordings have previously demonstrated the epileptogenic nature of surgical concentrations of the volatile anesthetic enflurane. We contrasted ECoG activity with local cerebral glucose uptake [( 14C]2-deoxyglucose autoradiography) in 23 brain structures in order to identify the epileptogenic foci. Autoradiograms were obtained from sectioned rat brain following a 30 min period of steady-state anesthesia at 1, 1.5, or 2 MAC (minimum alveolar concentration) enflurane. Pseudo-epileptiform ECoGs were obtained at 1 MAC where bursts of slow waves and sharp waves were evoked by peripheral sensory stimulation. At 1.5 MAC, the ECoG displayed frank, spontaneous epileptiform activity with large amplitude spike-wave complexes; repetitive auditory stimulation occasionally precipitated grand-mal seizures. At 2 MAC, spike complexes were less frequent and could not be repetitively driven. At 1 MAC enflurane, regional cerebral metabolism was generally depressed approximately 14% from the awake controls. However, metabolism in the dentate gyrus of the hippocampus and other subcortical structures in the limbic brain was increased. At 1.5 MAC this dichotomy in local cerebral metabolic rate was maximal; we observed increased metabolism in the hippocampus, habenula, habenulo-interpeduncular tract and interpeduncular nucleus and pineal. Metabolism in all other structures was significantly depressed (P less than 0.05) compared to awake values. At 2 MAC, metabolism was decreased in all structures. We conclude that the low seizure threshold hippocampus and related structures associated with the limbic system and its pathways are the epileptogenic foci for seizures induced with enflurane in the rat. At 1.5 MAC, epileptiform activity spreads throughout the visceral brain when seizure threshold is at a minimum.
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PMID:Local cerebral metabolism during enflurane anesthesia: identification of epileptogenic foci. 9 9

A method of surgical management for intractable epilepsy is described. The essential features are: 1) all surgical manipulation is carried out under general, rather than local, anesthesia; 2) the sensorimotor region is readily identified in the anesthetized patient by recording cortical sensory evoked responses; and 3) the epileptogenic focus is localized by extraoperative electrocorticography via indwelling epidural electrode arrays, localization deriving from recordings made during spontaneously occuring clinical seizures. Cases are presented to demonstrate that: 1) in some instances, recording of sensory evoked responses is the only means of sensorimotor localization in both the awake and anesthetized patient, and 2) spontaneous and electrically induced electroencephalographic seizure activity may provide false localization of the focus, the correct localization requiring recordings made during spontaneous clinical seizures. The outcome of surgery and the various epileptogenic lesions encountered are described. A good result has been achieved in 61% of patients followed 1 to 10 years. When the results obtained in children are analyzed alone, 70% have benefited from surgery.
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PMID:A method for surgical management of focal epilepsy, especially as it relates to children. 9 16

The mechanisms of petit mal epilepsy remain a mystery despite successful therapy. Previous workers have proposed that paroxysmal activity of cortical inhibitory systems plays a role in absence seizures. In this study, we have compared the effects of bicuculline, a potent convulsive agent and GABA antagonist, with ethosuximide, a drug used to treat petit mal epilepsy, on the thalamocortical motor system of the cat. Under chloralose anesthesia, sequential pairs of pulses were delivered to ventrolateral thalamus (VL) varying either pulse amplitude or interval. The evoked responses were recorded from sensorimotor cortex, analyzed on-line by computer, and plotted as an excitability curve (mean response amplitude as a function of pulse interval), or a family of threshold curves (mean response amplitude as a function of stimulus amplitude at various fixed intervals). Administration of each drug resulted in increased thalamocortical excitability and decreased threshold to stimulation for short pulse-pair intervals, with diminished duration of the excitability curve. Increased alertness was produced by both drugs. Studies with grand mal anticonvulsants demonstrated entirely different effects. Because GABA is thought to be the primary inhibitory transmitter in VL and cerebral cortex, bicuculline would be expected to result in disinhibition. The similarity of the data for ethosuximide suggests that ethosuximide also suppresses inhibition in the thalamocortical motor system and adds further to the accumulating evidence of the role of inhibitory system in petit mal epilepsy.
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PMID:Ethosuximide and bicuculline inhibition in petit mal epilepsy. 9 76

Drug treatment of status epilepticus is reviewed. Tonic-clonic, focal motor, complex partial and absence status epilepticus are discussed. In managing tonic-clonic status epilepticus one should: (1) maintain vital functions at all times, (2) identify and treat precipitating factors and (3) administer an intravenous loading dose of phenytoin sodium or phenobarbital sodium. Careful use of i.v. diazepam sometimes helps to achieve these objectives. Intravenous phenytoin sodium and phenobarbital sodium provide definitive, long-term control of tonic-clonic seizures but must be administered slowly and require time to reach peak brain concentrations. Intravenous diazepam appears to enter and exit from the brain rapidly and may control seizures while therapeutic brain concentrations of long-acting drugs are being achieved. Phenytoin, phenobarbital and diazepam should not be administered intramuscularly in treating status epilepticus. Treatment of focal motor and complex partial status epilepticus is similar to that of tonic-clonic status epilepticus, but i.v. diazepam is required less frequently and loading doses of phenytoin and phenobarbital sometimes can be given more slowly. Status epilepticus of the absence type is managed with i.v. acetazolamide sodium or diazepam. Paraldehyde, muscle relaxants, general anesthesia and lidocaine may be tried when conventional therapies fail.
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PMID:Drug therapy reviews: drug therapy of status epilepticus. 15 Feb 28

Three organo-selenium compounds have been synthetized : methyl seleno-2 benzoic acid, acetylseleno-2 benzoic acid and diselenosalicylic acid. These compounds induce convulsive seizures in the rat, the most active of them being methyl seleno 2 benzoic acid. Convulsions are stopped after anaesthesia with pentobarbitone.
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PMID:[Convulsive properties of various organoselenium compounds]. 15 Sep 32

A total of 600 handicapped patients had dental rehabilitation under general anesthesia during an eight-year period. Handicaps included mental retardation, cerebral palsy, Down syndrome, seizure disorders, autism, cystic fibrosis, osteogenesis imperfecta, and muscular dystrophy. No significant complications developed in the majority of patients. This is attributed to thorough preoperative evaluation, appropriate anesthetic management, and vigilant postoperative observation.
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PMID:Complications related to the administration of general anesthesia in 600 developmentally disabled dental patients. 15 47

In 14 patients operated upon for focal cerebral seizures under local anesthesia, cortical electrical activity was compared with the levels of nicotinamide adenine dinucleotide (NADH) observed fluorometrically. NADH levels fell 3 to 15% in response to 5-second intervals of cortical stimulation in 42 of 70 observations. Although a rough correlation was seen between the quantity of current delivered (milliamperes X seconds) and the NADH decrease, this varied from case to case. The presence of cortical afterdischarge often, but not invariably, corresponded to a greater percentage of change in the NADH levels. Averaging the NADH response to sporadic interictal epileptiform discharges failed to demonstrate concomitant NADH reductions. A similar lack of change was seen in four patients in whom low frequency spike foci were induced by topically applied penicillin in cortex destined for excision. Preliminary studies of the topography of spread of NADH change after cortical stimulation indicate that this is usually asymmetrical in human epileptogenic cortex. Under experimental conditions in cats, it seemed possible to differentiate primary from projected epileptiform activity, in that the projected activity had little or no concomitant fall in the NADH level after the electrographic spike. Pathological examination of the excised sites of NADH recording showed, with one exception, fibrous astrocytic transformation of the central cortex layers.
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PMID:Fluorometric monitoring of NADH levels in cerebral cortex: preliminary observations in human epilepsy. 21 33


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