Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0036572 (seizures)
 80,221 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The employment of neuroimaging studies in the evaluation of individuals with developmental delay/mental retardation (DD/MR) is still highly debated. The Consensus Conference of the American College of Medical Genetics has suggested that "neuroimaging appears to have an especially important role in patients with microcephaly or macrocephaly, seizures, loss of psychomotor skills and neurologic signs," whereas the value of neuroimaging investigations "in the normocephalic patient without focal neurological signs is unclear" [Curry et al., 1997]. However, recent literature reports show how the latest neuroimaging techniques (in vivo proton magnetic resonance spectroscopy [H-MRS]) may prove to be useful in the diagnostic process of those individuals with DD/MR and no neurological signs/symptoms. The use of these techniques can, in addition, help in monitoring treatment in distinct metabolic disorders. This review will focus on the usefulness of neuroimaging studies in some of the newer metabolic disorders. This paper will also cover those recognizable patterns of human malformation where neuroimaging findings seem to be relevant both toward diagnosis and management, and add to our understanding of the related behavior phenotype. The essential role of magnetic resonance imaging (MRI) on the progress in the diagnostic recognition of malformations of cerebral cortical development is stressed.
 ...
PMID:Neuroimaging studies in the evaluation of developmental delay/mental retardation. 1256 Oct 55

The purine nucleoside adenosine is released during seizure activity and exerts an anticonvulsant influence through inhibition of glutamate release and hyperpolarization of neurons via adenosine A(1) receptors. However, activation of adenosine A(2A) and A(3) receptors may counteract the inhibitory effects of A(1) receptors. We have therefore examined the extent to which endogenous adenosine released during seizure activity activates the different adenosine receptor subtypes and the implications for seizure activity in the rat hippocampus in vitro. Brief trains of high-frequency stimulation in nominally Mg(2+)-free artificial cerebrospinal fluid evoked epileptiform activity and resulted in a transient depression of the simultaneously recorded CA1 field excitatory postsynaptic potential. In the presence of 8-cyclopentyl-1,3-dimethylxanthine (CPT), an adenosine A(1) receptor antagonist, the occurrence of spontaneous seizure activity was greatly increased as was the duration and intensity of evoked seizures, whilst the postictal depression of basal synaptic transmission was greatly attenuated. Application of ZM 241385, an adenosine A(2A) receptor antagonist, shortened the duration of epileptiform activity, whereas administration of MRS 1191, an adenosine A(3) receptor antagonist, both decreased the duration and intensity of seizures. Combined application of the A(2A) and A(3) receptor antagonists also resulted in a reduction in seizure duration and intensity. However, no evidence was found for a role for protein kinase C in the regulation of seizure activity by endogenous adenosine. Our data confirm the dominant anticonvulsant role that endogenous and tonic adenosine play via the A(1) receptor, and suggest that the additional adenosine receptor subtypes may compromise this anticonvulsant property through promotion of seizure activity.
 ...
PMID:Endogenous adenosine modulates epileptiform activity in rat hippocampus in a receptor subtype-dependent manner. 1512 7

The effects of the A(3) adenosine receptor agonist 2-Cl-IB-MECA were tested on epileptiform field potentials recorded in the CA3 area of postnatal days 10-20 immature hippocampal slices, during perfusion with the GABA(A) receptor antagonist bicuculline (10 microM). Evoked potentials: 2-Cl-IB-MECA (1-50 microM, n = 17) had consistently excitatory effects, blocked by the A(3) receptor antagonist MRS 1220 (1 microM, n = 7), but not occluded in the presence of the A(1) antagonist DPCPX (1 microM, n = 12) or the A(2A) antagonist ZM-241385 (0.1 microM, n = 12). 2-Cl-IB-MECA reversed the inhibitory effects (n = 5) of the adenosine uptake blocker nitrobenzylthioinosine (NBTI, 50 microM), but did not increase its excitatory effects (n = 19). Spontaneous discharges: 2-Cl-IB-MECA (1 microM) induced them or increased their frequency in 14/30 slices, an effect reversed by MRS 1220 (n = 3), and observed also following pre-perfusion with DPCPX (n = 11), ZM-241385 (n = 11) or both (n = 10). In the presence of the A(1) antagonist DPCPX, NBTI increased the frequency of spontaneous discharges, an effect partially reversed by MRS 1220 (n = 8), thus suggesting that a rise in endogenous adenosine during disinhibition may activate A(3) receptors. In conclusion, these findings suggest strongly that activation of A(3) receptors, following a rise in endogenous adenosine (i.e. during seizures, hypoxia), facilitates excitation, thus limiting the known inhibitory and/or neuroprotective effects of adenosine in immature brain.
 ...
PMID:The A3 adenosine receptor agonist 2-Cl-IB-MECA facilitates epileptiform discharges in the CA3 area of immature rat hippocampal slices. 1524 13

1H and 31P spectroscopy detects relevant metabolite changes in patients with TLE. Numerous studies confirm reduction in NAA and in the ratio of PCr/Pi. In his 1999 review, Kuzniecky concluded that proton MRS, using single-voxel or chemical shift imaging, lateralizes temporal lobe epilepsy in 65% to 96% of cases, with bilateral changes seen in 35% to 45% of cases, whereas phosphorus MRS shows a lateralizing PCr/Pi ratio in 65% to 75% of the TLE patients. There are indications that these changes are reversible with seizure treatment. Improvements in MRS technology, such as the ability to calculate absolute concentrations, to account for differences be-tween gray and white matter and to achieve better spectral resolution by use of a higher magnetic field strength, will now allow more extensive use of this technique for patients with epilepsy.
 ...
PMID:Clinical applications of MR spectroscopy in epilepsy. 1532 61

Long-echo (TR: 2000 ms, TE: 136 ms) proton MRS of the cerebral tissue in the vicinity to intracranial lesion was done in 15 patients, mainly with parenchymal brain tumors. Significant decrease of N-acetylaspartate (NAA) (P<0.001) and more frequent presence of lactate (P<0.01) comparing with distant normal white matter were found in the perilesional brain tissue. The level of NAA in the perilesional brain tissue had negative associations with presence of lactate in the lesion (P<0.05), excess of lactate in the lesion compared to perilesional brain (P<0.01), grade of the perilesional edema (P<0.01) and patient's age (P<0.05). Multivariate analysis disclosed that identification of lactate in the lesion is associated with lower relative NAA content in the perilesional brain tissue, independently on the presence or absence of any other factor, including brain edema (P<0.001). In patients with lobar lesions who had at least one epileptic seizure during course of their disease the relative NAA content in the perilesional brain was significantly lower, comparing with those who were seizure-free (P<0.05). Therefore, lactate diffused from the tumor, or other metabolites secreted by lactate-producing neoplasm, should be considered as important contributors to the neuronal dysfunction in the surrounding brain. Decrease of NAA in the vicinity to intracranial lesions may reflect neuronal alteration responsible for associated epilepsy.
 ...
PMID:Proton MRS of the peritumoral brain. 1569 94

The objectives of this work were to compare concentrations of N-acetylaspartate (NAA), glutamate (Glu), glutamine (Gln), Glx (=Glu + Gln), myo-inositol (mI), total creatine (Cre) and other metabolites in the temporal lobes of patients with mesial temporal lobe epilepsy (mTLE), cryptogenic TLE (cTLE), who show no abnormalities in high-resolution MRI, and healthy controls using single voxel (1)H MRS at 3 T. Twelve patients with mTLE, nine with cTLE and 22 controls were investigated using a short echo time STEAM protocol. Voxels were positioned bilaterally in the medial and lateral temporal lobes. Spectra were processed with LCModel. Significantly lower mean NAA were detected in mTLE patients (P < 0.001) and a trend towards lower NAA in cTLE patients compared to controls (P = 0.053). Glx was not different between groups. Estimates of Glu showed a different metabolic pattern in mTLE with elevated Glu in lateral compared with medial voxels on the ipsilateral side to seizure onset (P = 0.019). MI concentrations were significantly lower in cTLE (P < 0.001) and in mTLE patients (P = 0.005) compared with healthy controls. MI/Cre was significantly reduced in cTLE patients only (P = 0.004). The results confirm low NAA in mTLE and to a lesser extent in cTLE patients. MI and mI/Cre were identified as potential metabolic indicators of the epileptogenic area in cTLE.
 ...
PMID:1H magnetic resonance spectroscopy at 3 T in cryptogenic and mesial temporal lobe epilepsy. 1652 Oct 92

(1)H magnetic resonance spectroscopic imaging (MRSI) was performed on a patient with an admission diagnosis of recurrent astrocytoma. The patient had undergone surgical resection and radiation therapy for a left occipital astrocytoma WHO grade III 12 years previously, and presented with aphasia, right-sided hemiparesis, and severe headache. Postcontrast T1-weighted images showed cortical enhancement of the left parietotemporal lobe near the post-resection cavity. MRSI revealed a marked increase of trimethylamines (TMA), elevated creatine/creatinephosphate (tCr), and reduced N-acetyl-aspartate (tNAA) in the same brain region. The spectroscopic data were consistent with tumor recurrence. However, the pattern of contrast enhancement on magnetic resonance imaging (MRI), evidence of an epileptic focus on electroencephalography (EEG), and spontaneous regression of the symptoms argued against tumor recurrence. In a 4-week follow-up, the contrast enhancement disappeared on MRI and the EEG abnormalities and neurological symptoms resolved. Follow-up spectroscopic data showed a decrease in TMA compared to normal values. The tCr signal remained elevated but returned to normal values after 5 months. In conclusion, postictal neurological deficits with a temporary increase in TMA and tCr were diagnosed. This is the first report of seizure-induced MRS abnormalities mimicking tumor recurrence.
 ...
PMID:Postictal spectroscopy and imaging findings mimicking brain tumor recurrence. 1673 21

Proton magnetic resonance spectroscopy ((1)H MRS) is beneficial in the lateralization of the epileptogenic zone in temporal lobe epilepsy; however, its role in extratemporal and, especially, MRI-negative epilepsy has not been established. This study seeks to verify how (1)H MRS could help in localizing the epileptogenic zone in patients with MRI-negative extratemporal epilepsy. Seven patients (8-23 years) with MRI-negative refractory focal epilepsy were studied using (1)H MRS on a 1.5T MR system. Chemical shift imaging sequence in the transversal plane was directed towards the suspected epileptogenic zone localized by seizure semiology, scalp video/EEG, ictal SPECT and (18)FDG-PET. Spectra were evaluated using the program CULICH, and the coefficient of asymmetry was used for quantitative lateralization. MRS detected lateralization in all patients and was able to localize pathology in five. The most frequent findings were decreased ratios of N-acetylaspartate to choline compounds characterized by increasing choline concentration. The localization of the (1)H MRS abnormality correlated well with ictal SPECT and subdural mapping. In all cases, histopathological analysis revealed MRI-undetected focal cortical dysplasias. (1)H MRS could be more sensitive for the detection of discrete malformations of cortical development than conventional MRI. It is valuable in the presurgical evaluation of patients without MRI-apparent lesions.
 ...
PMID:(1)H MR spectroscopic imaging in patients with MRI-negative extratemporal epilepsy: correlation with ictal onset zone and histopathology. 1734 Jan 2

Disorders of creatine synthesis or its transporter resulting in neurological impairment with mental retardation and epilepsy have only been recognized in recent years. To date, the epileptic disorder observed in creatine transporter deficiency (CRTR-D) has been described as a mild phenotype with infrequent seizures and favorable response to common antiepileptic drugs. We report on a 5 year-old boy with known speech delay who presented with severe and refractory epilepsy. After extensive investigations, metabolite analysis and brain 1H-MRS suggested CRTR-D, which was confirmed by the detection of a known pathogenic mutation in the SLC6A8 gene (c.1631C>T; p.Pro544Leu).
 ...
PMID:Severe epilepsy in X-linked creatine transporter defect (CRTR-D). 1755 21

Tuberous sclerosis complex (TSC) is an autosomal dominant neurocutaneous disease. Cortical tubers are one of the standard intracranial hallmarks of TSC, they comprise subependymal hamartomas protruding into the ventricles, cortical and white matter hamartomas, and giant cell tumors. The clinical course of TSC varies from asymptomatic to severe, with epileptic seizures and psychomotor retardation. We discuss here the correlation between clinical manifestation and features on 1H-MR spectroscopy ( 1H-MRS) of the white matter involving cortical tubers in patients with TSC. Statistical analysis of the N-acetylaspartate (NAA), choline (Cho) and myoinositol (mI)/creatinine (Cr) ratios between tubers and normal controls showed decreased NAA/Cr and increased mI/Cr ratios (P<0.05) in tubers, but no significance difference in Cho/Cr. The significance of the clinical appearance is associated with a decreased ratio of NAA/Cr in tubers with TSC. An elevated ratio of mI/Cr in tuber does not parallel the severity of the clinical features of TSC. These findings suggest that 1H-MRS may be useful for the evaluation of the clinical severity and prognostic diagnosis of TSC.
 ...
PMID:The correlation between 1H-MR spectroscopy and clinical manifestation with tuberous sclerosis complex. 1798 61


<< Previous 1 2 3 4 5 6 7 8 Next >>