Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UMLS:C0027066 (myoclonus)
4,275 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Three new cases of methyl bromide poisoning (leakage from a fire extinguisher) are reported. Two of these were characterized, after an initial period of coma and myoclonic status, by an action myoclonus. Electrical data are presented. A follow up of 4 and 8 years allowed to study the effect of drugs, two of which (clonazepam and baclofene) being pecularly contributive. The third patient outlived for 5 years in a stuporous state with myoclonus. The anatomical findings consisted mainly of a necrosis of both inferior colliculi with gliosis in the upper brain stem reticular formation and moderate changes in the dentate and pontine nuclei. Their significance is discussed in view of physiological and experimental knowledge.
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PMID:[Methyl bromide poisoning. 3 cases, 1 fatal. Neruopathological study of one case of coma with myoclonus followed for 5 years]. 119 82

We report a case of myoclonus from overnight exposure to methyl bromide. Myoclonus was either spontaneous or induced by somatosensory stimulation or voluntary movements, multifocal and sometimes generalized. Median SEP showed normal size P14-N20, but giant parietal P25, N33 and frontal P22-N30 waves. Back-averaging showed a biphasic EEG spike of maximal amplitude at the central region contralateral to the corresponding myoclonic jerk recorded from abductor pollicis brevis and preceding it by a short interval consistent with conduction in corticospinal pathways. Long latency reflexes from cutaneous and mixed nerve stimulation were enhanced. The above electrophysiological findings suggest that myoclonus following methyl bromide poisoning belongs to the cortical reflex myoclonus category.
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PMID:Methyl bromide myoclonus: an electrophysiological study. 232 37

In two cases of action myoclonus following hypoxic or shock encephalopathy, neuropathological examination disclosed mild or moderate scattered changes involving thalamus, griseum centrale mesencephali, and nucleus centralis superior. Other areas were affected only in one of these cases (striatum, nucleus subthalamicus or hippocampus, nuclei pontis, and cerebellar cortex). In another case (an alcoholic patient), the changes, which involved only corpus mamillare and thalamus, were those of Wernicke-Korsakoff encephalopathy. In one case of oscillatory myoclonus following septic shock, there were marked cerebellar changes involving deep nuclei and mild abnormalities in the thalamus and inferior olive. The last case of action myoclonus following acute methyl bromide intoxication was characterized by marked changes in the inferior colliculi and moderate or mild abnormalities of thalamus, griseum centrale mesencephali, nucleus centralis superior, nucleus reticularis tegmenti pontis, nuclei pontis, and dentatus. The findings are compared with the data of seven previously reported neuropathological examinations in action myoclonus following hypoxic encephalopathy.
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PMID:Postmortem studies on posthypoxic and post-methyl bromide intoxication: case reports. 394 11

Several toxins produce encephalopathies in which myoclonus can be a prominent feature. These include intoxications with bismuth, methyl bromide, cooking oil containing anilines, and tetraethyl lead. The clinical features in many cases resemble the action myoclonus syndrome of posthypoxic encephalopathy.
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PMID:Toxic myoclonus. 394 12

Giant and asymmetric SEPs were recorded in a patient with predominantly unilateral, spontaneous and intention myoclonus due to voluntary intoxication with methyl bromide as soon as day 3 after intoxication. The N10 Erb's point potential, cervical N13 and scalp recorded P15 potentials were found to be normal in latency, morphology and amplitude. The somesthetic informations could be considered as normally processed up to the subcortical levels of the somatosensory pathways. The parietal cortical potentials N20 and P25 and the frontal cortical potentials P22 and N30, contralateral to myoclonus, were abnormally large. This suggests that myoclonus could be related with an abnormal reactivity of somatomotor and somatosensory cortices to the afferent volleys triggered by voluntary movements. The prerolandic components P22 and N30 were found to be relatively more enhanced than the parietal N20 and P15.
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PMID:[Rare cause of myoclonus with giant SEP's: methyl bromide poisoning. Apropos of a case with unilateral predominance]. 404 10

Systemic methyl bromide (CH3Br) poisoning with signs and symptoms of varying severity developed in nine greenhouse workers after acute inhalational exposure on two consecutive days. Measurements of CH3Br, carried out at the site within hours after the accident, suggest that exposure on the second day may have been in excess of 200 ppm (800 mg/m3) CH3Br. All workers were admitted for observation. Seven of them were discharged after an uneventful overnight observation and residual symptoms, if any, subsided within three weeks of the accident. Two patients needed intensive care for several weeks because of severe reactive myoclonus and tonic-clonic generalised convulsions. These conditions were unresponsive to repeated doses of diazepam, clonazepam, and diphenylhydantoin but could be suppressed effectively by induction of a thiopental coma that had to be continued for three weeks. In some of the patients prior subchronic exposure to CH3Br, as shown by their occupational histories and high serum bromide (Br-) concentrations, is likely to have been a factor contributing to the severity of their symptoms. A direct association between serum Br- concentrations and the severity of neurological symptoms, however, seemed to be absent. An on site investigation into the circumstances leading to the accident showed the presence of an empty and out of use drainage system that covered both sections of the greenhouse. This was probably the most important factor contributing to the rapid and inadvertent spread of CH3Br.
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PMID:Systemic effects of inhalational methyl bromide poisoning: a study of nine cases occupationally exposed due to inadvertent spread during fumigation. 843 48

A nonlethal poisoning case by methyl bromide in a young woman due to leakage of old fire extinguishers is described. The patient developed major action and intention myoclonus the day following exposure. Inorganic bromide concentrations in plasma were determined by inductively coupled plasma mass spectrometry. The initial plasma bromide level was 202 mg/L, 40-fold in excess than the commonly accepted tolerance limit, and decreased slowly to normal levels within 2 months. Although plasma inorganic bromide concentration is known not to be directly correlated to the severity of organic bromide poisoning, its determination was, in the present case, particularly useful to confirm the diagnosis. One year post-exposure, the patient showed no sign of central nervous system toxicity. While such a case of poisoning is particularly rare today, it illustrates, however, that the danger still exists in France although the destruction
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PMID:An unusual case of methyl bromide poisoning. 1247 94

Used primarily as a fumigant or as a substrate in chemical processes, methyl bromide is a highly toxic gas. The gas is usually absorbed by inhalation and effects on the lungs, gastrointestinal tract, skin, and brain are seen. Numerous instances of acute and chronic neurologic injury have been reported: acute poisoning results in seizures, myoclonus, ataxia or cerebral oedema beginning as early as 30 min after exposure while subacute or chronic intoxication presents with diverse slowly progressive neurological and neurobehavioral symptoms. Serum bromide levels may be elevated, but often return rapidly to normal. Electroencephalography may show frontally-predominant slow waves or polyspikes with following slow wave, and MRI reveals characteristic involvement in the dentate nucleus of the cerebellum, the brainstem, and the splenium of the corpus callosum. Symmetric and selective lesions in characteristic sites are observed on imaging and on histopathological examination. These are likely produced by methylation of intracellular lipids, protein and glutathione; production of toxic metabolites; defective neurotransmitter function; and abnormal oxidative phosphorylation. This article reviews the toxic effects of this gas, the pathophysiology and symptoms of its effects on the nervous system, and characteristic findings on MRI; and presents an illustrative case of methyl bromide intoxication due to exposure at a factory producing the compound commercially.
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PMID:The neurological effects of methyl bromide intoxication. 2409 59

Enlarged cortical components of somatosensory evoked potentials (giant SEPs) recorded by electroencephalography (EEG) and abnormal somatosensory evoked magnetic fields (SEFs) recorded by magnetoencephalography (MEG) are observed in the majority of patients with cortical myoclonus (CM). Studies on simultaneous recordings of SEPs and SEFs showed that generator mechanism of giant SEPs involves both primary sensory and motor cortices. However the generator sources of giant SEPs have not been fully understood as only one report describes clearly giant SEPs following lower limb stimulation. In our study we performed a combined EEG-MEG recording on responses elicited by electric median and tibial nerve stimulation in a patient who developed consequently to methyl bromide intoxication CM with giant SEPs to median and tibial nerve stimuli. SEPs wave shapes were identified on the basis of polarity-latency components (e.g. P15-N20-P25) as defined by earlier studies and guidelines. At EEG recording, the SEP giant component did not appear in the latency range of the first cortical component for median nerve SEP (N20), but appeared instead in the range of the P37 tibial nerve SEP, which is currently identified as the first cortical component elicited by tibial nerve stimuli. Our MEG and EEG SEPs recordings also showed that components in the latency range of P37 were preceded by other cortical components. These findings suggest that lower limb P37 does not correspond to upper limb N20. MEG results confirmed that giant SEFs are the second component from both tibial (N43m-P43m) and median (N27m-P27m) nerve stimulation. MEG dipolar sources of these giant components were located in the primary sensory and motor area.
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PMID:Giant early components of somatosensory evoked potentials to tibial nerve stimulation in cortical myoclonus. 2748 68

Dravet syndrome combines clonic generalized, focal or unilateral seizures, beginning within the first year of life, often triggered by hyperthermia whatever its cause, including pertussis vaccination. Long-lasting febrile seizures are frequent in infancy and repeat status epilepticus (SE) has negative prognostic value. Massive myoclonus, rare absences, complex partial seizures and generalized spikes may appear several years later. Myoclonic status may occur in childhood, but acute encephalopathy with febrile SE followed by ischemic lesions and psychomotor impairment, the most severe condition, occurs mainly within the first five years of life. Generalized tonic-clonic and tonic seizures in sleep predominate in adulthood. Non epileptic manifestations appear with age, including intellectual disability, ataxia and crouching gait. Incidence of SUDEP is high, whatever the age. SCN1A haploinsufficiency producing Na_V1.1 dysfunction mainly affects GABAergic neurons. In cortical interneurons it explains epilepsy, in cerebellum the ataxia, in basal ganglia and motor neurons the crouching gait, in hypothalamus the thermodysregulation and sleep troubles, and dysfunction in all these structures contributes to psychomotor delay. Valproate, stiripentol, topiramate and bromide are the basis of antiepileptic treatment, whereas inhibitors of sodium channel worsen the condition. Benzodiazepines seem to facilitate acute encephalopathy when given chronically, and they should be restricted to SE. Ketogenic diet is useful in both chronic and acute conditions. Only targeting SCN1A haploinsufficiency and Na_V1.1 dysfunction could improve non epileptic manifestations of this condition that deserves being considered as a disease, not only as an epilepsy syndrome.
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PMID:From genotype to phenotype in Dravet disease. 2781 82


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