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

Motor incoordination, euphoria and hallucinations are symptoms reported for humans voluntarily intoxicated by industrial solvents. An epileptic-like consciousness impairment has also been noted. The present paper describes a technique used for the experimental study of solvent intoxication in which toluene and benzene can be applied directly into the trachea of freely moving cats with chronically implanted electrodes. This technique permits the control of solvent dose and time of exposure. Results showed a 3 Hz spike-wave activity in the gyrus cinguli recording with both toluene or benzene intoxication. Furthermore, benzene inhalation produced generalized tonic-clonic seizures. These effects were dose-related. However, a sensitization period was essential for the development of such alterations, and effects showed a tendency to shortening through chronic exposures. These alterations were correlated with behavioral disturbances such as nodding, twitching and apparent hallucinations. Results are discussed regarding the sensitization period, the optimal peak of effects, and the period of tolerance development relevant to an earlier found amygdalar activation that could be correlated with other methods inducing experimental seizures, such as repetitive stimulation of the brain (kindling).
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PMID:Petit mal and grand mal seizures produced by toluene or benzene intoxication in the cat. 8 22

Previous studies suggest that organic solvents show anticonvulsant and convulsant effects, respectively at low and high doses. In the present study the first experiment was designed to determine low and high doses of injected acute n-hexane, ethyl acetate and toluene in mice through LD50 estimations. In the second experiment, high doses (around LD50) were employed to evaluate the convulsant effects. Finally, the third experiment evaluated the ability of low doses to prevent electroshock- and PTZ-induced convulsions. Results showed that n-hexane increased the severity of the electroshock-induced seizures only at low doses and had no anticonvulsant effects. Ethyl acetate produced generalized clonic seizures and deaths at high doses and was ineffective to prevent electroshock- and PTZ-induced seizures at low doses. Toluene induced forelimb clonus at high doses and protected against electroshock-induced seizures at low doses. Therefore, the biphasic property on convulsant activity seems to be a feature not shared among organic solvents.
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PMID:Anticonvulsant and convulsant effects of organic solvents. 153 82

Rats were subjected to seizures induced by kainic acid, and the resulting changes in CNS zinc staining were studied with the toluene sulfonamide quinoline fluorescence method. Seizures caused a loss of zinc staining from presynaptic boutons in many limbic and cerebrocortical regions. Simultaneously, the postsynaptic neurons that were degenerating (acidophilic) in those regions as a result of the seizure developed intense fluorescence for zinc. A possible role for zinc in the death of the postsynaptic neurons is suggested.
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PMID:Translocation of zinc may contribute to seizure-induced death of neurons. 271 57

Long-Evans hooded rats were exposed to 1000 ppm toluene or 0 ppm toluene 6 hr/day, 5 days/week for 30 days. Following removal from the exposure conditions (18-26 hr) flash-evoked potentials were recorded to paired light flashes and pentylenetetrazol (PTZ) seizure properties were examined. No alterations were found in the response to the first flash, but alterations in the recoverability of the nervous system were demonstrated by significant latency shifts in the response to the second of the paired flashes, using first flash latencies as covariates. No significant alterations were found in PTZ seizures. The data indicated that at these exposure levels toluene produced a small but significant alteration in brain function, even after toluene had been completely metabolized.
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PMID:Neurophysiological effects of 30 day chronic exposure to toluene in rats. 651 99

Psychological tests and EEG investigations were applied for detecting early signs of neurotoxicity of organic solvents present in glues used in the production of shoes (extraction benzin, toluene and n-hexane). In 5% of the obtained samples the permissible benzin concentration was exceeded, and in 10% of samples this permissible concentration of toluene was exceeded. Psychological testing was done in 100 subjects. The intelligence level was at the lower normal range. Organic cortical changes were demonstrated in 35 cases, and borderline pathological changes in 28 cases. The test of L. Bender suggested damage to the occipital cortex in 31, and the Graham-Kendal test demonstrated abnormalities in 13 cases. EEG was done in 56 subjects in this group and in another 9 subjects with a high concentration of toluene metabolite. In 75.4% of subjects the EEG findings were classified as normal, within normal limits or borderline normal. Abnormal EEG tracings were found in 24.0%. Diffuse, slight or moderately intense abnormalities were present in 7 cases, focal abnormalities in 4 and seizure activity in 7. Most subjects with abnormal EEG findings worked under conditions of excessive exposure, with the summarized exposure index exceeding the acceptable one. No correlation was demonstrated between cortical pathological changes and the degree of occupational exposure and the type of EEG tracings. The authors suggest that organic occipital cortical changes may be regarded as an early phase of organic brain damage syndrome and disturbances of cerebral bioelectric activity as a sign of individual biological response to chronic action of organic solvents on the organism.
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PMID:[Effect of organic solvents on the central nervous system]. 664 29

Male rats and female mice were exposed to vapours of toluene, o-xylene and acetone in basic or double concentrations or to binary combinations of basic concentrations, for 4 and 2 hours, respectively. Basic air concentrations were for rats and mice (in ppm): toluene 270 and 380, o-xylene 230 and 320, acetone 1700 and 1530, respectively. The CNS effect-inhibition of electrically evoked seizure discharge-was measured immediately after exposure and blood levels of solvents were monitored during the desaturation phase. The effect of all binary mixtures was lower than that of double concentrations of each single component, the difference being significant only in mice, and lower than the additive effects predicted on the basis of regressions of the effect on air or on blood concentrations of individual components. On the target site in the neuronal membrane, the effects of mixtures were substantially less than additive. Blood concentrations of solvents immediately after the exposure to a mixture were generally higher in aromatics and lower in acetone than after exposure to individual solvents. The decline of blood toluene and even more so that of xylene after exposure was slowed down by acetone. Presumption of additivity seems to protect safely from acute neurotropic effects of solvents at realistic exposure levels. On the other hand, substantially protracted late phases of desaturation of aromatic solvents in the presence of slowly eliminated polar solvent points to a possible underestimation of exposure by biological exposure tests.
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PMID:Neutrotropic effects and blood levels of solvents at combined exposures: binary mixtures of toluene, o-xylene and acetone in rats and mice. 765 5

Solvent blood concentrations and subnarcotic effects (inhibition of electrically evoked seizures) were measured in rats exposed to constant or fluctuating air concentrations of toluene or acetone. A 4 hour exposure of resting rats to toluene at an air concentration of 1 and 2 mg/l, or to acetone at 4 and 10 mg/l, led to blood levels of 6.7 and 12.8 mg/l of toluene, or 183 and 520 mg/l of acetone: seizure inhibition amounted to 18% and 40+, or 10% and 50%, respectively. Blood level and effect attained 1/2 of the final values after 40 min and 60 min of exposure to 2 mg/l toluene, respectively, and dropped to 1/2 70 min and 90 min after exposure cessation: respective values for acetone 10 mg/l were 80 and 120 min, and more than 4 hours. A steep rise and a rapid drop was characteristic also for the course of blood level and effect during an exposure to fluctuating concentrations of toluene: ten minute fivefold jump in the air concentration induced a shortlasting seizure inhibition by more than 80%; the curves for acetone were flat.
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PMID:Pattern of inhalation exposure: blood levels and acute subnarcotic effects of toluene and acetone in rats. 899 30

We reported two patients with severe motor and intellectual disabilities syndrome, who were born to mothers having inhaled organic solvents during pregnancy. They had microcephaly, cerebral palsy, mental retardation, seizures, growth failure and minor craniofacial anomalies, variable growth deficiency including a small midface, narrow bifrontal diameter, low-set ears, thin upper lips and micrognathia. Patient 1, a male, died at 8 years and 8 months. The autopsy of his brain revealed marked cerebral atrophy and destruction of bilateral temporal lobes with ventricular enlargements. Microscopic examination revealed migration disorders with polymicrogria at the remaining cerebrum and the cerebellum as well as very thin white matter. Much hemosiderin was found around ventricles, suggesting recurrent minimal bleedings which led to more brain atrophy. Patient 2, a 5 months old male infant, had infantile spasms. On CT and MRI, he had bilateral temporal lobe defect, which might be due to the infarction of bilateral middle cerebral arteries at the prenatal period. These clinical findings are similar to those of other embryopathies, caused by alcohol, phenytoin and other agents. Hersh et al. reported five cases of toluene embryopathy in 1985 and 1988, but they did not report such central nervous system abnormalities. The pathogenesis of toluene embryopathy remains to be solved, but our cases suggested the possible teratogenesis of toluene.
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PMID:[Two cases of toluene embryopathy with severe motor and intellectual disabilities syndrome]. 929 10

Recent research has shown that bursts of approximately 20 Hz fast waves are elicited in rhinencephalic cortex in rats by the odors of a number of different organic solvents and of components of the secretions of predators such as the weasel and the fox. We now show that a number of phytochemicals (benzyl alcohol, carvacrol, eucalyptol, and salicylaldehyde) will elicit fast wave bursts of about 20 Hz in the rat pyriform cortex. Additional organic solvents (carbon tetrachloride, chloroform, diethyl ether, 1, 2-dimethoxyethane, n-heptane, mesitylene, methylcyclohexane, and commercial gasoline and kerosene, but not N,N-dimethylformamide or dimethyl sulfoxide) and another component of fox secretions (isopentenylmethyl sulfide) were also effective. Many of these compounds will also elicit fast wave bursts of about 20 Hz in the dentate gyrus. The effectiveness of benzyl alcohol, camphor, carvacrol, eucalyptol, isopentenylmethyl sulfide, 2-propylthietane, salicylaldehyde, toluene, and trimethylthiazoline (all of which elicit rhinencephalic fast waves in rats) in suppressing feeding in various small herbivores suggests that the recording of odor-induced rhinencephalic fast waves may provide an easy means of identifying new antifeedants. We found no evidence that the bursts of 20-Hz activity seen in the rat rhinencephalon were kindling-induced seizure-like reactions of the olfactory brain to the vapors of toxic chemicals.
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PMID:Fast wave activity in the rat rhinencephalon: elicitation by the odors of phytochemicals, organic solvents, and a rodent predator. 968 44

Seizures in human temporal lobe epilepsy are characterized by paroxysmal activity in the limbic system. The primary olfactory or piriform cortex is a central part of the limbic system. Since a relationship between olfactory sensation and limbic seizures has been described, we were interested in the effect of strong olfactory stimulation on the seizure susceptibility of amygdala-kindled rats, a model of human temporal lobe epilepsy. Olfactory stimulation with toluene was able to suppress seizures in most kindled rats after stimulation at 20% above the threshold for eliciting epileptic afterdischarges. Olfactory stimulation with toluene or ammonia increased the threshold by 27 and 25% compared to control conditions. Our data substantiate that olfactory brain regions, such as the piriform cortex, are involved in amygdala-kindled seizures and suggest that strong physiological stimulation of this nucleus interferes with on-going seizure activity in the limbic system. Thus, olfactory stimulation could contribute to anticonvulsant therapy.
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PMID:Strong olfactory stimulation reduces seizure susceptibility in amygdala-kindled rats. 1086 29


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