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

Glutamate is the principal excitatory neurotransmitter in brain. Our knowledge of the glutamatergic synapse has advanced enormously in the last 10 years, primarily through application of molecular biological techniques to the study of glutamate receptors and transporters. There are three families of ionotropic receptors with intrinsic cation permeable channels [N-methyl-D-aspartate (NMDA), alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and kainate]. There are three groups of metabotropic, G protein-coupled glutamate receptors (mGluR) that modify neuronal and glial excitability through G protein subunits acting on membrane ion channels and second messengers such as diacylglycerol and cAMP. There are also two glial glutamate transporters and three neuronal transporters in the brain. Glutamate is the most abundant amino acid in the diet. There is no evidence for brain damage in humans resulting from dietary glutamate. A kainate analog, domoate, is sometimes ingested accidentally in blue mussels; this potent toxin causes limbic seizures, which can lead to hippocampal and related pathology and amnesia. Endogenous glutamate, by activating NMDA, AMPA or mGluR1 receptors, may contribute to the brain damage occurring acutely after status epilepticus, cerebral ischemia or traumatic brain injury. It may also contribute to chronic neurodegeneration in such disorders as amyotrophic lateral sclerosis and Huntington's chorea. In animal models of cerebral ischemia and traumatic brain injury, NMDA and AMPA receptor antagonists protect against acute brain damage and delayed behavioral deficits. Such compounds are undergoing testing in humans, but therapeutic efficacy has yet to be established. Other clinical conditions that may respond to drugs acting on glutamatergic transmission include epilepsy, amnesia, anxiety, hyperalgesia and psychosis.
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PMID:Glutamate as a neurotransmitter in the brain: review of physiology and pathology. 1073 72

While the intracarotid amobarbital procedure (IAP) was originally utilized to lateralize speech functions as an aid in the surgical treatment of epilepsy, additional uses for the IAP have emerged including: (1) the use of the IAP to predict post-surgical memory changes, including both global amnesia and smaller, yet significant, material-specific memory deficits; (2) the use of the IAP to provide confirmatory evidence of lateralization of seizure focus; and (3) the use of the IAP to predict post-surgical relief from seizures. While the literature on the IAP is extensive and growing, its utility is marred by the wide variability associated with the procedure itself from epilepsy center to center. This variability renders comparisons among IAP studies problematic and conclusions about IAP efficacy difficult. The variability associated with the amobarbital procedures, as well as the reliability and the validity of the IAP in its nonlanguage uses is reviewed here. A special emphasis is devoted to research conducted in the last decade. Also discussed is the future of the IAP including anticipated research directions.
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PMID:Beyond speech lateralization: a review of the variability, reliability, and validity of the intracarotid amobarbital procedure and its nonlanguage uses in epilepsy surgery candidates. 1083 12

Astrocytomas involving the limbic system are usually unilateral in nature. We report a very unusual case where a low-grade astrocytoma originating in the left temporal lobe spread to the right hippocampus through the hippocampal commissure to cause disabling amnesia and seizures. Some improvement in the memory deficit was facilitated by identification of complex partial status epilepticus. EEG should be performed in all patients with lesions of the limbic system and neuropsychological problems if ongoing seizure activity is not to be missed.
Seizure 2000 Jun
PMID:Bilateral astrocytoma involving the limbic system precipitating disabling amnesia and seizures. 1088 Feb 95

37 candidates for epilepsy surgery underwent the intracarotid amytal procedure (IAP; also known as the Wada test) to determine hemispheric speech dominance and memory capacity. 31 demonstrated left hemisphere speech dominance, 2 showed evidence for bilateral language and 4 demonstrated right hemispheric language dominance. Our study supports a correlational relationship between handedness, lesion laterality and age of onset of seizures, as reported in earlier studies. Left-handed patients with a left hemisphere lesion whose seizures began to an early age had a strong tendency for reversed language dominance. Asymmetry of at least 20% in performing the memory test was taken as the cutoff score for demonstrating laterality of lesions. The asymmetry score correctly predicted laterality of lesions in all 28 patients; 6 did not have asymmetry scores and 3 were examined for language only. None of the patients who successfully passed the Wada memory test had any significant postsurgical memory deficits; 1 had transient reduction in verbal memory and 4 who did not pass the test were not operated on for this reason. Our results demonstrate the importance of the Wada test in determining cerebral speech dominance, in predicting post-surgical amnesia, and support its usefulness in predicting laterality of seizure focus in candidates for temporal lobectomy.
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PMID:[Presurgical neuropsychological assessment in epilepsy: the Wada test]. 1088 55

Negative phenomena can occur with seizures, but some ictal negative manifestations are rare and may lead to misdiagnosis. A patient series is presented with unusual ictal negative phenomena: neglect syndrome, catastrophic depression, apraxia, aphasia, amnesia, homonomous hemianopsia, and hemiparesis. One had repeated episodes with PLEDs but no parenchymal lesions. Clinicians should consider seizures in the setting of unexplained deficits, even if there are no positive ictal phenomena.
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PMID:Negative seizures. 1101 19

The aim of this study is to present the incidence of traumatic brain injury (TBI) and identify those characteristics of brain injuries that are associated with the development of seizures. We identified 5984 episodes of TBI (loss of consciousness, post-traumatic amnesia, or skull fracture) in Olmsted County, Minnesota, from 1935 to 1984. Of these, 4541 were followed for seizure. Injuries were classified as mild (loss of consciousness or amnesia less than 30 minutes), moderate (loss of consciousness 30 minutes to 1 day or a skull fracture), or severe (loss of consciousness of more than 1 day, subdural hematoma, or brain contusion). The incidence of TBI in the period from 1975 to 84 peaked at 800 per 100 000 in males aged 15-24. The relative risk of seizures was 1.5 (95 percent confidence interval 1.0-2.2) after mild injuries, but with no increase after 5 years; 2.9 (95 percent confidence interval 1.9-4.1) after moderate injuries; and 17.2 (95 percent confidence interval 12.3-23.6) after severe injuries. Significant risk factors were brain contusion with subdural hematoma, skull fracture, loss of consciousness or amnesia of 1 day or more, and age over 65 years. We conclude that TBI is a major public health problem and contributes to the occurrence of seizures and epilepsy.
Seizure 2000 Oct
PMID:The risks of epilepsy after traumatic brain injury. 1103 67

Clonazepam (CLO) is an anticonvulsant benzodiazepine approved by the Food and Drug Administration for use in the treatment of seizures. It produces pharmacological effects (depression, amnesia) similar to other compounds from the same therapeutic class, and in combination with alcohol, its CNS-depressant action can be significantly potentiated. As with some other benzodiazepines, CLO is a drug possibly used in "date-rape" situations. A method using solid-phase extraction followed by a highly sensitive negative chemical ionization gas chromatography-mass spectrometry for the simultaneous quantitation of CLO and its major metabolite 7-aminoclonazepam (7-ACLO) in hair was developed and validated. The method has potential application to alleged drug-facilitated rape cases. To determine the feasibility of detecting 7-ACLO and CLO in hair, specimens were collected from 10 psychiatric patients treated with CLO, divided into 2-cm segments, and analyzed. Standard curves for 7-ACLO (1-1000 pg/mg) and CLO (10-400 pg/mg) had correlation coefficients of 0.998. All precision and accuracy values were within acceptable limits. 7-ACLO was present in measurable quantities (1.37-1267 pg/mg) in 9 out of 10 patient samples. CLO concentrations in hair were much lower (10.7-180 pg/mg). In 4 out of 10 cases, CLO was not detected in hair. Two patients who had never been treated with CLO before received a single 2-mg dose of the drug. Approximately three weeks later, hair samples were collected, and measurable quantities of 7-ACLO (4.8 pg/mg) were detected in the first segment (proximal) of one of those samples, and traces of the drug were present in the other sample. We concluded that the 7-ACLO is being deposited in hair in much higher quantities than the parent drug and remains there for extended periods of time. Our study also indicates that it is possible to detect 7-ACLO after a single dose of CLO as in the typical date-rape scenarios.
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PMID:Quantitation of clonazepam and its major metabolite 7-aminoclonazepam in hair. 1104 68

The transitory memory disturbance known as transient global amnesia (TGA) remains an enigma from a pathogenic point of view. In spite of its typical benign prognosis, TGA is a frightening experience for patients and their relatives. Moreover, a TGA episode usually leads to extensive investigation of patients in search of organic alterations that might be responsible for the event. Finally, TGA generates queries about therapeutic choices. In this review, we critically re-evaluate the evidence in support of and against the three main pathogenic hypotheses (i.e. ischemia, seizure discharge, and migraine), and we conclude that none of these appears completely convincing. Given the good prognosis and the lack of association with organic and instrumental abnormalities, we advance the hypothesis that TGA may be related to psychological disturbances causing transient alteration in brain metabolism and, consequently, amnesia. Our conclusion has relevant consequences in the evaluation of patients with TGA.
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PMID:Transient global amnesia: a review emphasizing pathogenic aspects. 1108 3

An unusual case of very-late-onset metachromatic leukodystrophy (MLD) with dementia was studied. The patient was a 41-year-old male who presented with mild dementia and a single generalized tonic clonic seizure. Neuropsychological assessment demonstrated mild amnesia, visuospatial dysfunction and attention deficits with a slow psychomotor speed. MR brain imaging displayed confluent hyperintensities of periventricular and subcortical white matter. Low levels of arylsulfatase A confirmed the diagnosis. Impaired cortical glucose metabolism especially of the medial temporal and frontal cortices was observed using positron emission tomography and fluor-18-labeled fluorodesoxyglucose. The neuropsychological deficits are related to the location of deficits in glucose metabolism.
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PMID:Dementia with impaired temporal glucose metabolism in late-onset metachromatic leukodystrophy. 1117 79

A 38-y-old male with occult inhalant abuse underwent an 18-mo evaluation for presumed seizure disorder. Although past medical history was significant for alcohol abuse, his wife confirmed a 6-y histoy of abstinence. His seizures were characterized as episodes of unconsciousness preceded by a feeling of "things slowing down". No muscular activity was witnessed during these episodes, and upon regaining consciousness the patient had slurred speech, disorientation, dissociative amnesia, and bizarre behavior that resolved spontaneously. Despite 4 emergency department visits, 4 hospital admissions, 5 neurologic and 7 psychiatric outpatient evaluations, extensive work-up was non-diagnostic. These episodes recurred until his wife found him huffing trichloroethylene. Questioning of the patient revealed that huffing always preceded these episodes and that he started huffing after discontinuing alcohol. The patient underwent addiction treatment. Toxic inhalants should be suspected as a substitute drug of abuse in patients attempting abstention. Disorientation clinically similar to dissociative amnesia can occur following loss of consciousness during an episode of trichloroethylene use.
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PMID:An unusual presentation of inhalant abuse with dissociative amnesia. 1182 66


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