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

Hemorrhage related to systemic heparinization is the major complication of extracorporeal membrane oxygenation (ECMO). Intracranial hemorrhage (ICH) is the most devastating complication. ICH developed in 13 of our 25 ECMO patients (52%). Six died, six survived with normal neurologic function, and one is severely impaired. In nine of 13 patients (69%) ECMO was discontinued when serial cranial ultrasounds showed progressive ICH. Seizures developed in six infants while receiving ECMO, and ICH developed in all. There is a correlation between hypertension and ICH. A hypertension index (hours systolic BP greater than 90/hours receiving ECMO) was 0.1 +/- 0.12 for infants without ICH and 0.37 +/- 0.28 for infants with ICH (P less than .05). ICH developed in 79% of the patients with an index greater than 0.1. Twenty neck explorations were required in the first 20 patients for incisional bleeding (mean blood loss, 21.9 +/- 18.0 mL/kg/d). We now use fibrin glue following cannulation and have done only one neck exploration in the last five patients (mean blood loss, 2.8 +/- 2.2 mL/kg/d, P less than .05). Endobronchial bleeding has responded to phenylephrine lavage and increased positive end-expiratory pressure. We have controlled pleural space bleeding with topical thrombin. None of the hemorrhagic complications encountered correlate with the activated clotting time or the amount of heparin used. There is an increased risk of hemorrhage associated with platelet counts less than 100,000/microL for 75% of a day (P less than .05) so that aggressive platelet transfusion remains important in preventing hemorrhagic complications during ECMO.
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PMID:Hemorrhagic complications during extracorporeal membrane oxygenation: prevention and treatment. 349 94

Two patients with well documented systemic lupus erythematosus developed a syndrome resembling thrombotic thrombocytopenic purpura. Both had severe thrombocytopenia, microangiopathic hemolytic anemia, seizures, and renal dysfunction. Prothrombin time, partial thromboplastin time, thrombin time, and fibrinogen levels were normal; fibrin degradation products were minimally elevated. Histologic evaluation of renal biopsies in both patients confirmed the impression of intravascular thrombosis. Therapy with corticosteroids, other immunosuppressive drugs and splenectomy (in one case) proved unsuccessful. The infusion of fresh frozen plasma, with or without plasmapheresis, reversed the syndrome. This report indicates that patients with systemic lupus may develop a thrombotic thrombocytopenic purpura like syndrome which responds to fresh plasma infusion.
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PMID:Thrombotic thrombocytopenic purpura syndrome in systemic lupus erythematosus: treatment with plasma infusion. 404 Nov 34

The effects of hypoglycemia on cerebrovascular permeability to a protein, horseradish peroxidase (HRP), were studied in mice given 3 or 8 units of crytalline zinc insulin intraperitoneally. HRP (10 mg in 0.1 ml saline) was injected intravenously 15 to 20 minutes prior to sacrifice. Both mildly and severely hypoglycemic groups of mice showed a drastic reduction in the normal transit of HRP across cerebral arterioles. The number of normally-stained vessel segments and of HRP-filled endothelial vesicles decreased in insulin-treated mice. In the brains of severely hypoglycemic mice, however, increased parenchymal HRP accumulation occurred. A ruptured blood vessel was found in the center of one-fourth of the focal exudates examined. Electron microscopic examination revealed thrombin, sometimes extending through the vessel wall, and hemorrhage, yet inter-endothelial tight junctions remained intact. Seizures were associated with severe hypoglycemia in 6 out of 10 mice with serum glucose levels below 40 mg/100 ml following 8 units of insulin, but the number of focal exudates per brain was similar in all 10 mice. We conclude that insulin-induced hypoglycemia is associated with decreased HRP transit across cerebral arterioles, and that severe insulin shock is also accompanied by actual rupture of vessel walls and extravasation of blood and HRP into the parenchyma of the brain.
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PMID:Effects of insulin-induced hypoglycemia on cerebrovascular permeability to horseradish peroxidase. 698 50

Two cases of a 13-year-old girl and a 14-year-old boy with postinfectious focal encephalitis due to influenza are reported. The clinical and magnetic resonance imaging (MRI) findings included: (1) partial motor seizures as the initial central nervous system manifestation, appearing more than 20 days after the influenzal infection, (2) no change in the level of consciousness although a boy demonstrated apraxia, and (3) high signal intensity lesions noticed with T2-weighted MRI located mainly in the cortex. The girl's lesion appeared to resolve within 10 days on MRI, while that of the boy (demonstrated in the thalamus on a third MRI) resolved within 1 week. However, a new lesion appeared in the cortex approximately 1 month later, that was visualized on a fourth MRI. Small gadolinium-enhanced lesions also were noticed during earlier stages in both patients. The pathogenesis of these MRI lesions is unknown, but the coexistence of small enhancing lesions, rapidly resolving lesions, and the elevated thrombin anti-thrombin III complexes, may indicate the presence of an angiopathy. Serial MRI examinations in patients with postinfectious encephalitis may lead to a better understanding of the pathogenesis of this disorder.
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PMID:Serial magnetic resonance imaging in post-infectious focal encephalitis due to influenza virus. 756 51

The coagulation cascade plays an important role in brain edema formation caused by intracerebral blood. In particular, thrombin produces brain injury via direct brain cell toxicity. Seizures and increased cerebral electrical activity are commonly associated with intracerebral blood and are possible effects of thrombin leading to cell injury in the brain. In this study, artificial clots containing concentrations of thrombin found in hematomas were infused intracerebrally in rats. The animals were observed clinically for seizure activity, behavior, and neurological deficits. Several animals underwent video electroencephalographic (EEG) monitoring during intracerebral infusion and for 30 minutes postinfusion. All animals were killed 24 hours after injection, and brain water and ion contents were measured to determine the amount of brain edema. Clinically, thrombin produced focal motor seizures in all animals. None of the control animals or those receiving N[alpha]-(2-Naphthalenesulfonyl-glycyl)-4-amidino-DL-phenylalanine -piperidide (alpha-NAPAP), a thrombin inhibitor added to the thrombin, showed clinical evidence of seizures. Of the rats undergoing EEG monitoring, all animals receiving thrombin showed electrical evidence of seizure activity, whereas none of the control animals exhibited seizure activity. There was no evidence of seizure activity on EEG monitoring when alpha-NAPAP was injected along with the thrombin. In addition, the artificial clots containing thrombin produced agitation and a circling tendency in the rats, along with brain edema. These results indicate that the coagulation cascade is involved in seizure production and increased brain electrical activity, which contribute to the neurological deficits and brain edema formation that are seen with intracerebral hemorrhage.
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PMID:Seizures induced by intracerebral injection of thrombin: a model of intracerebral hemorrhage. 920 68

The blood coagulation cascade proteolytic enzyme, thrombin, affects many cell types, including neurons and astrocytes, in which it prevents process outgrowth and induces significant morphological degeneration and even cell death. Since thrombin may contribute significantly to pathological conditions in the central nervous system (CNS), where it is synthesized locally, we measured the levels of thrombin and its precursor, prothrombin, in the cerebrospinal fluid (CSF) of 67 individuals from 6 groups: non-neurologic controls (NNC); spinal degenerative disease (SDD); peripheral nerve disease (PND); cerebrovascular, neuroimmune and seizure disorders and tumor (CNSD); traumatic brain injury (TBI) and neurodegenerative disorders (NDD). We employed a sensitive chromogenic assay utilizing the thrombin specific tripeptide substrate, S-2238, to evaluate CSF levels of thrombin and prothrombin. The latter estimated after its conversion to active enzyme by the snake venom prothrombinase, ecarin. No measurable active thrombin was detected in these CSF samples. However, activatable prothrombin was measured in all groups. The mean activatable prothrombin concentrations (in nM) were 7.26 +/- 3.39 (NNC); 8.85 +/- 3.09 (SDD); 6.78 +/- 2.58 (PND); 6.33 +/- 3.87 (CNSD); 5.10 +/- 1.86 (TBI), and 7.80 +/- 3.27 (NDD). Duncan's multiple comparison test showed significant reduction (p <0.05) in prothrombin levels of the TBI group. Our data suggests that the prothrombin zymogen gains access to the CSF, likely across either an intact or compromised blood-brain barrier (BBB), in increased amounts with age. Reduced levels in TBI patients may have diagnostic and/or prognostic value.
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PMID:Thrombin and its precursor in human cerebrospinal fluid. 942 97

An increased incidence of cerebral thromboembolic events has been reported in young patients with inflammatory bowel disease (IBD). It has been suggested that a hypercoagulable state is associated with clinical activity of the disease, with elevation of factors V, VIII, fibrinogen and platelets and a lowering of anti-thrombin III. We present the case of a 35 y/o male with refractory Crohn's disease who complained of headaches, blurred vision and tonic-clonic seizures. The studies demonstrated an ischemic stroke of the left cerebral hemisphere, without vascular abnormalities. Elevation of factor VIII, platelets, and antithrombin III were found. The symptoms were relieved with medical treatment and the patient has continued in good health after resection of the diseased terminal ileum.
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PMID:Cerebral thrombosis associated with active Crohn's disease. 988 77

Although serine proteases and their receptors are best known for their role in blood coagulation and fibrinolysis, the CNS expresses many components of an extracellular protease signaling system including the protease-activated receptor-1 (PAR1), for which thrombin is the most effective activator. In this report we show that activation of PAR1 potentiates hippocampal NMDA receptor responses in CA1 pyramidal cells by 2.07 +/- 0.27-fold (mean +/- SEM). Potentiation of neuronal NMDA receptor responses by thrombin can be blocked by thrombin and a protein kinase inhibitor, and the effects of thrombin can be mimicked by a peptide agonist (SFLLRN) that activates PAR1. Potentiation of the NMDA receptor by thrombin in hippocampal neurons is significantly attenuated in mice lacking PAR1. Although high concentrations of thrombin can directly cleave both native and recombinant NR1 subunits, the thrombin-induced potentiation we observe is independent of NMDA receptor cleavage. Activation of recombinant PAR1 also potentiates recombinant NR1/NR2A (1.7 +/- 0.06-fold) and NR1/NR2B (1.41 +/- 0.11-fold) receptor function but not NR1/NR2C or NR1/NR2D receptor responses. PAR1-mediated potentiation of recombinant NR1/NR2A receptors occurred after activation with as little as 300 pm thrombin. These data raise the intriguing possibility that potentiation of neuronal NMDA receptor function after entry of thrombin or other serine proteases into brain parenchyma during intracerebral hemorrhage or extravasation of plasma proteins during blood-brain barrier breakdown may exacerbate glutamate-mediated cell death and possibly participate in post-traumatic seizure. Furthermore, the ability of neuronal protease signaling to control NMDA receptor function may also have roles in normal brain development.
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PMID:Potentiation of NMDA receptor function by the serine protease thrombin. 1084 28

The protective blood-brain barrier normally allows diffusion of small molecules such as oxygen and carbon dioxide, and transport of essential nutrients, but excludes large proteins and other blood constituents from the interstitial space of the CNS. However, head trauma, stroke, status epilepticus and other pathological conditions can all compromise the integrity of this barrier, and allow blood proteins as large as albumin to gain access to the extracellular spaces that surround neurons and glia. Given their possible entry into brain tissue during cerebrovascular insult, the effects of blood-derived proteases such as thrombin, tissue plasminogen activator and plasmin in the CNS have come under increasing scrutiny. Evidence now supports a role for serine proteases in the sequence of events that can lead to glial scarring, edema, seizure and neuronal death.
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PMID:Serine proteases and brain damage - is there a link? 1126 39

In the last two decades it has become apparent that thrombin has many extravascular effects that are mediated by a family of protease-activated receptors (PARs). PAR-1, -3 and -4 are activated via cleavage by thrombin. The importance of extravascular thrombin in modulating ischemic, hemorrhagic and traumatic injury in brain has recently become clear. Thus, in vitro, thrombin at low concentration protects neurons and astrocytes from cell death caused by a number of different insults. In vivo, pretreating the brain with a low dose of thrombin (thrombin preconditioning), attenuates the brain injury induced by a large dose of thrombin, an intracerebral hemorrhage or by focal cerebral ischemia. Thrombin may also be an important mediator of ischemic preconditioning. In contrast, high doses of thrombin kill neurons and astrocytes in vitro and cause disruption of the blood-brain barrier, brain edema and seizures in vivo. This review examines the role of thrombin in brain injury and the molecular mechanisms and signaling cascades involved.
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PMID:The role of thrombin and thrombin receptors in ischemic, hemorrhagic and traumatic brain injury: deleterious or protective? 1248 96


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