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Query: UMLS:C0036572 (seizures)
 80,221 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Evidence from studies of experimental animals indicates that electrical stimulation of the vagus nerve alters EEGs under certain stimulus parameters. We report EEG effects of electrical stimulation of the vagus nerve in 9 patients with medically intractable seizures as part of a clinical trial of chronic vagal stimulation for control of epilepsy. The mechanism of action of the vagal antiepileptic effect is unknown, and we believed that analysis of electrophysiologic effects of vagal nerve stimulation would help elucidate the brain areas affected. The left vagus nerve in the neck was stimulated with a programmable implanted stimulator. Stimulation at various stimulus frequencies and amplitudes had no noticeable effect on EEG activity whether the patient was under general anesthesia, awake, or asleep, but vagus nerve stimulation may interrupt ongoing ictal EEG activity.
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PMID:Electrophysiological studies of cervical vagus nerve stimulation in humans: I. EEG effects. 146 57

Hyperglycemia is known to worsen the outcome of transient global or forebrain ischemia. The aggravating effect is believed to be mediated by the additional formation of lactate- and of H+. Recent evidence suggests that reactive oxygen species contribute to the damage after brain ischemia. Since acidosis accelerates free radical damage in vitro, we decided to explore if ischemic damage in hyperglycemic subjects is ameliorated by dimethylthiourea (DMTU), an established free radical scavenger. In one series of hyperglycemic rats, we studied whether preischemic administration of DMTU alters the clinical outcome, notably the incidence and frequency of seizures. In two different series, the effect of DMTU on tissue damage was assessed by light microscopy after 15 h of recovery. Longer periods could not be studied since seizures developed. In the first of these series the animals were anesthetized with isoflurane, and in the second with halothane. The latter anesthesia largely suppressed the "early" postischemic seizures, i.e. those occurring after 1-4 h. Dimethylthiourea treatment altered the clinical outcome after ischemia. Thus, the "late" postischemic seizures appeared milder and occurred significantly later than in untreated animals. The fatal outcome was also delayed since treated animals died after 35.5 +/- 8.2 h (mean +/- SD) of recirculation, as compared to 19.8 +/- 3.6 h of recirculation in control animals. However, all DMTU-treated (and control) animals died. In the first morphological series (isoflurane anesthesia) the histopathological analysis was complicated by the occurrence of prefixation seizures; such seizures were recognized in 4/16 animals. When these 4 animals were excluded from the analysis (2 treated and 2 control animals), DMTU pretreatment did not ameliorate the damage, except in the substantia nigra pars reticulata (P < 0.05). In the second series, comprising animals anesthetized with halothane, only one animal out of 16 had "early" seizures, and none showed "late" seizures before death. Among these animals DMTU treatment significantly ameliorated damage to caudoputamen and cingulate cortex (P < 0.01). We conclude that treatment with the free radical scavenger DMTU partly ameliorates ischemic brain damage associated with excessive acidosis, and marginally delays the development of post-ischemic seizures. However, the effects were moderate and could, at least in part, have been caused by nonspecific effects of DMTU. Furthermore, all DMTU-treated animals died. The results thus give little support to the notion that the aggravating effects of acidosis is due to enhancement of free radical production.
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PMID:Effects of dimethylthiourea on ischemic brain damage in hyperglycemic rats. 148 54

Total intravenous anaesthesia with propofol and alfentanil is an established alternative to inhalation anaesthesia for intracranial neurosurgical procedures. Its usefulness has been somewhat overshadowed by reports of seizure-like movements, both during anaesthesia and in the recovery period. These can be related to the use of either anaesthetic agent, but true epileptogenic properties still remain to be demonstrated in man. Opioid-induced rigidity is a well known phenomenon and must not be mistaken for an epileptic seizure. Myoclonic motor activity can be observed even under physiological conditions, e.g. sleep. Almost all anaesthetic agents have been found to produce "epileptic" EEG changes (spikes, polyspikes, spike-wave complexes), but in man these have never been correlated to motor reactions. Propofol's pro- or anticonvulsive action is unclear. While some groups found shortened convulsing times in patients undergoing electroconvulsive therapy with propofol instead of methohexitone, others have reported activation of epileptogenic foci in the EEGs of known epileptic patients. A synergistic effect of propofol and alfentanil in the generation of seizure-like movements cannot be excluded. Whether seizure-like movements indicate a true "epileptogenic potency" of the anaesthetic drugs or are related to other phenomena remains to be studied. Electro-encephalographic monitoring during anaesthesia as well as careful observation and documentation of motor reactions may contribute to elucidation of the problem. We report a case of seizure-like movements during propofol-alfentanil anaesthesia for an elective craniotomy. A 52-year-old patient presented with a history of headaches of increasing frequency. A CT brain scan demonstrated a tumor in the left occipital region.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[A myoclonic seizure during propofol-alfentanil anesthesia?]. 149 34

The "transurethral resection of prostate" syndrome (TURPS) is the clinical manifestation of the resorption into the patient's body of a large amount of glycocolle-containing irrigating fluid used for this procedure. The full clinical picture, which is seldom seen, consists of dyspnoea, nausea, arterial hypertension, an increased central venous pressure, cerebral oedema, cardiogenic shock and renal failure. Improved surgical techniques, as well as incomplete and atypical forms of the syndrome could explain this low incidence. Absorption into the blood stream may be rapid, by way of the prostatic venous plexi, or slower, from the spaces around the prostate and under the peritoneum. The present-day pathophysiological theory explains this syndrome by an acute hyponatraemia, sometimes dissociated from the hypoosmolality, the toxicity of glycocolle, and the neurological effects of hyperammonemia. Acute hyponatraemia, with blood sodium concentrations below 115 to 120 mmol.l-1, should be considered as potentially serious. The different mechanisms involved may act alone or together, thus explaining that the minor forms of the syndrome mostly consist of a neurological picture. The emergency treatment depends on the natraemia. It includes diuretics and progressive reloading of the patient with sodium in case of severe hyponatraemia with seizures. The best prevention is a correct surgical indication and technique. The resection should not last for more than 90 to 120 min. The major problem remains the early diagnosis of TURPS. Carrying out this surgery under regional anaesthesia is helpful for this purpose, but, in the near future, the best means might be the monitoring of expired ethanol concentrations.
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PMID:[Prostate transurethral resection syndrome]. 150 91

A semi-quantitative estimation has been made of the effect of anaesthetics, anticonvulsants and glutamate antagonists on the extent of neuronal loss in the hippocampus caused by the local injection of the excitotoxin kainic acid, and on the vulnerability of neurons in various extrahippocampal regions due to the resulting seizure activity. Following the intrahippocampal injection of 0.47 nmol kainic acid (a submaximal dose), the amount of neuronal loss in the dorsal hippocampus was greater when given under the short-acting anaesthetics halothane and ketamine (a non-competitive glutamate antagonist), than when given under pentobarbital anaesthesia (with or without co-administration of ketamine (30 mg/kg)). When kainic acid was injected under halothane or ketamine anaesthesia a greater number of extrahippocampal limbic regions (distal toxicity) were also affected, usually on the ipsilateral side, and the extent of damage in each of these regions was generally more extensive. The anticonvulsants MK 801 and diazepam, or multiple injections of ketamine over a period of 5 h, decreased both the local and distal toxicity of kainic acid injected under short duration anaesthesia, to levels similar to those found under pentobarbital anaesthesia. However, these compounds, even at high doses, could not reliably prevent all seizure-related damage in extrahippocampal areas.
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PMID:Effects of anaesthetics, anticonvulsants and glutamate antagonists on kainic acid-induced local and distal neuronal loss. 151 56

Frontal opercular gliosis in the dominant hemisphere caused medically refractory partial epilepsy in two patients. Both patients were aphasic during their seizures, but otherwise had normal speech. Magnetic resonance images showed well-demarcated lesions resembling tumors in each patient; on heavily T2-weighted images, the lesions were hyperintense compared with normal brain. Cortical mapping with subdural grids localized speech to the area of the lesions; therefore, the resections were performed under local anesthesia and speech was tested throughout the procedure. Postoperatively, both patients were seizure-free and had no new neurological deficits. Well-demarcated lesions, even in the dominant operculum, can be safely removed in patients with medically refractory partial epilepsy.
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PMID:Resection of dominant opercular gliosis in refractory partial epilepsy. Report of two cases. 152 25

The question as to what extent the hematocrit (Hct) is a strong indicator for or against the need for transfusion of whole blood or blood products is still controversial. In order to enable the clinician to make a definite decision, a number of aspects have to be taken into consideration. The human organism has only limited oxygen reserves, and these are even more limited under pathological conditions. Oxygen flux - the amount of oxygen transported by the blood in 1 min - is a critical factor in the oxygenation of the human body. Another critical factor is oxygen consumption, which is highly variable depending on the presence of conditions such as rest, shivering, seizures, hypothermia, etc. Furthermore, different organ systems have different oxygen consumption rates. The ratio of oxygen consumption to oxygen flux is referred to as the oxygen extraction rate or oxygen utilization. Under normal conditions oxygen uptake is independent of oxygen flux, and thus independent of blood flow. Under conditions of organ dysfunction, however, oxygen deficiency may be present without being recognized on standard clinical diagnostic parameters. The normal human organism has a number of possibilities to compensate for acute or chronic anemia, i.e., increases in cardiac output, organ perfusion, 2,3-DPG content, a shift in the oxygen dissociation curve, etc. These compensatory mechanisms may, however, be restricted or cease to function under conditions of acute or chronic disease. Arterial and mixed-venous PO2 and oxygen content are some of the parameters used to assess the oxygen reserves available to the organism even under critical conditions. Although oxygen content is the most significant of these parameters, accurate measurement of this parameter remains a problem of laboratory medicine. PVO2 is of only limited importance under conditions of anemia. Minimum oxygen content or minimum oxygen flux values should under no conditions be approximated during anesthesia or intensive care. The critical Hct as an indicator for or against transfusion of blood or blood products is considerably modified by restricted organ function, anesthesia, intensive care treatment, resuscitation, etc.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:[Which factors determine the critical hematocrit as an indication for transfusion?]. 153 35

Clonic and tonic seizure-like movements of the extremities were observed during induction of anaesthesia with sevoflurane in a 9-yr-old girl. The tonic movements were associated with respiratory alkalosis and were not abolished by an i.v. injection of thiamylal 75 mg. Arterial pressure, heart rate and body temperature remained normal during the episode. Ventilation was assisted easily and then controlled via a face mask. No neurological abnormalities were obvious after the anaesthesia. The movements may have been the result of seizure activity in the central nervous system, or myoclonus of the extremities.
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PMID:Seizure-like movements during induction of anaesthesia with sevoflurane. 154 Apr 67

This report describes an unusual presentation of focal motor activity resembling Jacksonian march, which developed during fentanyl induction of general anesthesia. Simultaneous spectral-edge activity recording of electroencephalography (EEG) failed to show evidence of an epileptic focus. A negative history of previous seizures, as well as failure to show postoperative postictal symptoms or seizure activity by 16-lead EEG, suggested a myoclonic rather than epileptic nature of the observed muscle activity. Pertinent literature and current theories regarding opioid-induced seizures are discussed.
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PMID:Apparent focal motor seizure with a jacksonian march induced by fentanyl: a case report and review of the literature. 156 37

The author presents a four-year-old boy with Pelizaeus-Merzbacher disease who required anaesthesia during placement of PE (pressure equalization) tubes and a permanent silastic intravascular device (Broviac catheter). Pelizaeus-Merzbacher is one of a group of progressive, degenerative disorders of the cerebral white matter known as the leukodystrophies. They include metachromatic leukodystrophy, adrenoleukodystrophy, Krabbe's disease, Canavan's disease, Alexander's disease and Pelizaeus-Merzbacher disease. Due to the progressive nature of the disorders and their devastating effects on the central nervous system, these children frequently require anaesthesia during imaging procedures such as MRI or during various surgical procedures. Of concern to the anaesthetist is the high prevalence of seizure disorders, gastroesophageal reflux with the risk of aspiration, and airway complications related to poor pharyngeal muscle control and copious oral secretions. In addition, adrenal involvement and hypofunction may be seen in patients with adrenoleukodystrophy. Identification of these associated conditions during the preoperative examination will allow safe anaesthesia for these children.
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PMID:Anaesthetic considerations for the child with leukodystrophy. 156 64


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