To Temporal Lobe Epilepsy Research Articles

Coronary microvascular function and myocardial metabolism in patients with dilated cardiomyopathy

Status epilepticus (SE) is one of the recognized primary precipitating events that can lead to temporal lobe epilepsy (TLE) associated with hippocampal sclerosis. This type of epilepsy is characterized by poor response to drug treatment, often requiring surgical intervention to remove the mesial temporal regions involved in the seizure onset. However, even neurosurgery may not be completely successful. Thus, the prevention of hippocampal damage and epileptogenesis is currently evaluated as a possible alternative therapeutic approach to prevent the development of pharmacoresistant TLE. Lines of evidence suggest that ischemic–hypoxic lesions might occur in different brain regions, including the hippocampus, during SE. Especially in the hippocampal CA3 region, an ischemic-like lesion develops in the stratum lacunosum-moleculare and is mainly characterized by a loss of astrocytes and neuronal processes and increased immunostaining of pimonidazole which probes areas exposed to hypoxia. Interestingly, these mechanisms can contribute to neuronal cell loss and may be counteracted by drugs that can afford vascular protection, as in the case of ligands of the ghrelin receptor. Notably, some of the ghrelin receptor ligands possess a double edge effect, since they are anticonvulsant and vascular-protective, thus, potentially representing new tools to counteract the consequences of SE.This article is part of a Special Issue entitled “Status Epilepticus”.

M129V polymorphism in the prion protein gene is not associated with mesial temporal lobe epilepsy in a Han Chinese population

Prion protein (PrP) predominantly localized at synapses can modulate neuronal excitability. The prion protein gene (PRNP) has been considered one of the candidate genes that play a role in seizure susceptibility. A recent study demonstrated that the 129V allele in the PRNP gene was associated with susceptibility to temporal lobe epilepsy (TLE) in female patients in an Italian population. We screened variations in the open-reading frame (ORF) of the PRNP gene and also replicated the association of the M129V polymorphism with TLE in a Han Chinese population. The M129V polymorphism was genotyped in 320 MTLE patients and 558 non-epilepsy controls. All subjects were Han Chinese. No novel polymorphism in the ORF of the PRNP gene was detected. Differences in the genotype distributions and allele frequencies of this polymorphism between cases and controls were insignificant (P = 0.24). Further analysis with stratification of the results by gender or age and analysis of clinical features in relation to M129V genotypes also yielded negative findings. The present study provides evidence that the M129V polymorphism in the PRNP gene is not associated with MTLE in a Han Chinese population.

Serotonin transporter gene (5-Htt): Association analysis with temporal lobe epilepsy

Two functional polymorphisms, a 44bp insertion/deletion polymorphism in the 5' regulatory region and a variable number of tandem repeat polymorphisms in the second intron of the serotonin transporter gene (5-HTT), were previously identified and suggested to modulate transcription. The current study was designed to determine the contribution of these polymorphisms in the 5-HTT gene to susceptibility to temporal lobe epilepsy (TLE). Two hundred and seventy six patients with TLE, and 309 age- and sex-matched healthy controls from Calabria (Southern Italy) were studied. Patients and controls were genotyped using the WAVE TM DNA Fragment Analysis System for the insertion/deletion polymorphism in the promoter region (5-HTTLPR), and the GENESCAN TM System for the variable number tandem repeat (VNTR) in the second intron of the 5-HTT gene (5-HTTVNTR). The program UNPHASED was used to compare genotype, allele and haplotype frequencies between cases and controls, including age and gender as covariates in the model. No significant differences between cases and controls were observed for 5-HTTLPR, but a significant association was obtained for the 5-HTTVNTR polymorphism, both modeling genotypes (P-value=0.0145) or alleles (P-value=0.0086). Patients with TLE showed lower frequencies of the 10 repeat at 5-HTTVNTR than the controls (26.2% in patients versus 40.8% in controls). The frequency of homozygous individuals for the 10 allele was observed to be lower among patients than the controls (5.2% of patients were 10/10 versus 18.8% of controls). Haplotype analysis did not increase the evidence for association. These results suggest that the serotonin transporter gene may play a role in the etiology of TLE.

Relevance of seizure-induced neurogenesis in animal models of epilepsy to the etiology of temporal lobe epilepsy.

Seizure induction in laboratory animals is followed by many changes in structure and function, and one of these is an increase in neurogenesis-the birth of new neurons. This phenomenon may be relevant to temporal lobe epilepsy (TLE), because one of the regions of the brain where seizure-induced neurogenesis is most robust is the dentate gyrus-an area of the brain that has been implicated in the pathophysiology of TLE. Although initial studies predicted that neurogenesis in the dentate gyrus would be important to normal functions, such as learning and memory, the new neurons that are born after seizures may not necessarily promote normal function. There appears to be a complex functional and structural relationship between the new dentate gyrus neurons and preexisting cells, both in the animal models of TLE and in tissue resected from patients with intractable TLE. These studies provide new insights into the mechanisms of TLE, and suggest novel strategies for intervention that could be used to prevent or treat TLE.

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Is Variation in the GABA(B) Receptor 1 Gene Associated with Temporal Lobe Epilepsy?

gamma-Aminobutyric acid (GABA)-receptor genes are prime candidates for a role in seizure susceptibility. An association between the c.1465G-->A variant in the GABA(B) receptor 1 gene (GABBR1) and susceptibility to temporal lobe epilepsy (TLE) has been reported in an Italian cohort. We sought to replicate this association in an independent Australian cohort. The 234 patients with TLE and 164 healthy controls were genotyped for the c.1465G-->A variant, by using inclusion criteria identical to those of the first study. The c.1465G-->A variant was found in one TLE patient and one control subject. Genotype and allele frequencies did not differ between groups. We did not replicate the reported associations between the c.1465G-->A variant and susceptibility to TLE. We suggest that the initial positive association may be due to undetected population stratification; the importance of genomic control is emphasized. Population-specific effects also may play a role, and we highlight the need to demonstrate an in vitro functional effect to give biologic meaning to any proposed association.

The Relationship Between Measures of Declarative Memory and the Test of Memory Malingering in Patients With and Without Temporal Lobe Dysfunction

ABSTRACT The relationship between performance on measures of declarative memory and a commonly used forced-choice recognition measure of malingering was explored. The Test of Memory Malingering (TOMM) was developed to be sensitive to lack of effort and/or simulated malingering while being relatively insensitive to neurological impairment. The present study was designed to examine the sensitivity of TOMM performance to memory related deficits in a group of individuals with memory impairment secondary to temporal lobe epilepsy (TLE). A group of individuals who displayed psychogenic non-epileptic seizures (PNES) in the absence of neurologic dysfunction were included as controls. For both groups, a combination of memory and emotion variables shared a significant proportion of variance with TOMM Trial 2 performance. A similar relationship held true for the PNES group when accounting for TOMM Retention Trial performance. In contrast, for epilepsy patients, memory but not emotional measures were significantly re...