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

We describe clinical and neurophysiological findings in six related children with congenital microcephaly, seizures that began within the first 2-4 months of life, and severe mental retardation (MR). These affected children (five girls and one boy), born to two women who are half-sisters, inherited the disease as an autosomal recessive trait. Physical examination of these children did not show any of the anomalies in the known cortical malformation syndromes such as lissencephaly types I and II. Neuroradiological studies in these children documented microcephaly and a simplified gyral pattern with no pachygyria. Chromosomal analysis showed neither karyotypic abnormalities nor a microdeletion at 17p13.3, site of the lissencephaly type I gene locus (LIS1). Genetic studies failed to show linkage of this family to LIS1, LIS2 (a region on chromosome 2p homologous to LIS1), or MCPH1 (a locus for primary autosomal recessive microcephaly). The unique clinical and genetic findings in this family suggest that these children may be affected by an as-of-yet unmapped neuronal proliferation disorder.
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PMID:Microcephaly with simplified gyral pattern in six related children. 1032 39

It is clear from the many studies of the prenatally exposed survivors of the atomic bombing of Hiroshima and Nagasaki that exposure to ionizing radiation during gestation has harmful effects on the developing human brain, particularly if that exposure occurs at critical stages in the development of the neocortex. Data on a variety of measures of cognitive function, including the occurrence of severe mental retardation as well as variation in the intelligence quotient (IQ) and school performance, show significant effects on those survivors exposed 8-15 weeks and 16-25 weeks after ovulation. Studies of seizures, primarily those without known precipitating cause, also exhibit a radiation effect on those individuals exposed in the first 16 weeks after ovulation. The cellular and molecular events that subtend these abnormalities are still largely unknown although some progress toward an understanding has occurred. For example, magnetic resonance imaging of the brain of some of the mentally retarded survivors has revealed a large region of abnormally situated gray matter, suggesting an abnormality in neuronal migration, but cell killing could also contribute importantly to the effects on cognitive function that have been seen. The retardation of growth in stature observed in individuals exposed in the first and second trimesters of pregnancy suggests that the development of an atypically small head size, without conspicuously impaired cognitive function, may reflect a generalized retardation of growth.
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PMID:Cognitive function and prenatal exposure to ionizing radiation. 1033 23

23 unselected juvenile firesetters (M age 12.0 yr.) consisted of seven with schizophrenia, three with organic mental disorder, six with posttraumatic stress disorder, two with severe mental retardation, and two with conduct disorders. Three previously nondestructive boys (M age 11.0 yr.), all of them loners, did not fit such traditional diagnoses. Their fleeting (c. 20 min.) symptoms included flat affect, autonomic arousal, and delusions or hallucinations. It appeared that their motiveless, unplanned acts were each preceded by a chance encounter with an individualized stimulus which revived the three boys' repeatedly ruminated memories of intermittently experienced merely moderate stresses associated with fire, smoke, or matches. Such a sequence of events is characteristic of seizure kindling. One boy's abnormal EEG was congruent with seizures in the temporal lobe area, which includes the amygdala, i.e., that part of the limbic system particularly susceptible to seizure kindling. The three boys' consistent symptomatology was very similar to that reported for 17 men with bizarre homicidal acts implicating a kindled partial seizure called "Limbic Psychotic Trigger Reaction." In primates, too, similar partial nonconvulsive "behavioral seizures" with psychosis-like symptoms can be elicited through experiential kindling.
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PMID:Motiveless firesetting: implicating partial limbic seizure kindling by revived memories of fires in "Limbic Psychotic Trigger Reaction". 1040 7

Angelman syndrome is an inherited disorder that includes severe mental retardation and epilepsy. Patients have no speech, puppet-like gait with jerky movements, hyperactivity, disturbed sleep, bouts of inappropriate laughter, a pronounced jaw, and widely spaced teeth. The syndrome results from deletion or mutation within maternal chromosome 15q11-q13. Considerable evidence suggests that the gene or genes responsible for Angelman syndrome are expressed only from the maternal chromosome 15, a situation known as parental imprinting. This epigenetic marking of certain regions of the parental genomes is characterized by parent-of-origin-specific allelic DNA methylation, allele-specific DNA replication timing, and physical pairing of the two chromosome 15 homologues. Imprinting is important for normal development, and its disregulation causes several human disorders. The epilepsy of Angelman syndrome has been studied and indicates a rather typical electroencephalographic abnormality with slowing and notched wave and spikes. Various types of seizures occur, usually including myoclonus and atypical absence. Variable severity among patients suggests potential molecular diversity in the genetic mechanism, possibly the involvement of more than one gene. Angelman syndrome can arise from the following molecular genetic defects: a deletion in 15q11-q13 that covers the Angelman gene or genes, mutations that alter imprinting, and paternal uni-parental disomy for the region. Another 20% or so of patients with clinical symptoms of Angelman syndrome have none of these three defects but are believed to have mutations in one or more genes in the region, and this may be familial. The UBE3A gene, which codes for the enzyme ubiquitin protein ligase involved in protein degradation and processing, has been found to be mutated in many but not all of patients with Angelman syndrome and can be considered a major Angelman candidate gene. Other potential candidate genes in the region include a cluster of three GABAA receptor subunits, which are involved in inhibitory synaptic transmission in the brain. The GABRB3 gene, which codes for the beta 3 subunit, is deleted in most persons with Angelman syndrome. The absence of this gene in mice causes craniofacial abnormalities and neurologic impairment with seizures. The exact role of UBE3A and GABRB3 in the syndrome and their imprinting status are under investigation.
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PMID:Parental imprinting and Angelman syndrome. 1051 31

The GABAergic system has long been implicated in epilepsy with defects in GABA neurotransmission being linked to epilepsy in both experimental animal models and human syndromes (Olsen and Avoli, 1997). However, to date no human epileptic syndrome has been directly attributed to an altered GABAergic system. The observed defects in GABA neurotransmission in human epileptic syndromes may be the indirect result of a brain besieged by seizures. The use of animal models of epilepsy has sought to address these matters. The advent of gene targeting methodologies in mice now allows for a more direct assessment of GABA's involvement in epileptogenesis. To date several genes associated with the GABAergic system have been disrupted. These include the genes for glutamic acid decarboxylase, both the 65- and 67-kDa isoforms (GAD65 and GAD67), the tissue non-specific alkaline phosphatase gene (TNAP) and genes for the GABA(A) receptor subunits alpha6, beta3, gamma2, and delta (gabra6, gabrb3, gabrg2, and gabrd respectively). Gene disruptions of either GAD67 or gabrg2 result in neonatal lethality, while others, GAD65, TNAP, and gabrb3 exhibit increased mortality and spontaneous seizures. GABA receptor expression has been found to be both regionally and developmentally regulated. Thus in addition to their obvious role in controlling excitability in adult brain, a deficit in GABAergic function during development could be expected to elicit pleiotropic neurodevelopmental abnormalities perhaps including epilepsy. The GABA(A) receptor beta3 subunit gene, gabrb3/GABRB3 (mouse/human), is of particular interest because of its expression early in development and its possible role in the neurodevelopmental disorder Angelman syndrome. Individuals with this syndrome exhibit severe mental retardation and epilepsy. Mice with the gabrb3 gene disrupted likewise exhibit electroencephalograph (EEG) abnormalities, seizures, and behavioral characteristics typically associated with Angelman syndrome. These gabrb3 gene knockout mice provide direct evidence that a reduction of a specific subunit of the GABA(A) receptor system can result in epilepsy and support a GABAergic role in the pathophysiology of Angelman syndrome.
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PMID:GABA and epileptogenesis: comparing gabrb3 gene-deficient mice with Angelman syndrome in man. 1051 60

We studied six children (four girls and two boys) suffering from cryptogenic myoclonic absence seizures with early onset. The age at onset of the seizures ranged between 6 and 27.8 months (mean age +/- SD: 18.5+/-12.4 months). The neurologic evaluation was normal in all patients at the first hospital admission. After the diagnosis, we followed up all children for at least 5 years. At the end of follow-up, two of these patients (a girl and a boy) showed severe mental retardation, a high number (from one to three per day) of seizures, and persistent pathologic electroencephalograms. The other patients showed normal electroencephalograms: all of them were seizure free and without mental retardation. The two patients with mental retardation have been treated with polytherapy. In all other children we used valproate alone successfully. Our data suggest that myoclonic absence seizures with early onset can have a good long-term prognosis. Valproate is a useful anticonvulsant drug in these patients. Mental retardation is present only in patients with poor seizure control.
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PMID:Epilepsy with myoclonic absences with early onset: a follow-up study. 1059 54

Adenylosuccinase deficiency is an autosomal recessive inherited defect of purine synthesis. In enzyme deficient patients, two normally undetectable compounds, succinylaminoimidazole carboxamide riboside and succinyladenosine, accumulate in urine, cerebrospinal fluid and, to a minor extent, in plasma. Analysing 150 highly selected urine specimens from patients with unidentified neurogenerative disorders we discovered the first two German cases of adenylosuccinase deficiency. The deficiency causes moderate to severe mental retardation, often accompanied by epileptic seizures and/or autistic features, and is occasionally associated with growth retardation and muscular hypotonia. Of the two German cases we present here, one patient fits into the clinical picture outlined by previous reports. The other patient, however, shows a pattern of symptoms so far undescribed: severe early infantile epileptic encephalopathy with reduced myelination. On mutation analysis this patient is the first to reveal a 39 base pair deletion in the adenylosuccinase gene in contrast to the point mutations detected in previous cases. Adenylosuccinase deficiency may be an underdiagnosed metabolic disorder with variable expression. This should be taken into consideration in patients with unclassified neurological conditions.
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PMID:Adenylosuccinase deficiency: possibly underdiagnosed encephalopathy with variable clinical features. 1072 85

The clinical features of Angelman syndrome (AS) include microcephaly, severe mental retardation, "puppet-like" ataxic gait with jerky arm movements, hyperactivity, bouts of inappropriate laughter, EEG abnormalities, and seizures. The frequency of occurrence of AS is in the range of 1/10,000 to 1/20,000 births. The AS locus maps to the imprinted chromosome 15q11-q13 region and the disease is caused by the absence of a normal maternal contribution to this region. The genetic complexity of AS is revealed by the existence of at least four molecular classes. A candidate AS gene, ubiquitin protein ligase 3A (UBE3A/E6-AP), has been identified, and mutations of this gene have been detected in several cases of AS. Moreover, UBE3A is expressed predominantly from the maternal allele in brain, strongly supporting its causative role in AS. However, there is evidence to suggest that, in addition to UBE3A, another gene(s) may be involved either directly in AS and/or indirectly by regulating UBE3A expression.
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PMID:Angelman syndrome: how many genes to remain silent? 1073 96

The article reports two cases of childhood autism in tuberous sclerosis (TS). Certain atypical features are highlighted. The probands did not show the common seizure types associated with either TS or autism. No ventricular dilatation, cerebral atrophy or temporal lobe involvement was evident. The high prevalence of childhood autism in TS probands with moderate to severe mental retardation has been emphasized.
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PMID:Childhood autism in tuberous sclerosis. 1077 14

A two-year-old male child presented with bizarre hypopigmented skin lesions, severe mental retardation and generalized tonic-clonic seizures. Examination showed hypopigmented patterned whorls and irregular patches over the trunk and linear streaks over the flexor aspects of upper and lower limbs. He also had generalized hypertonia and brisk tendon reflexes. Other systems were normal.
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PMID:Hypomelanosis of Ito. 1083 84


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