Association of single nucleotide polymorphisms of brain-derived neurotrophic factor gene and multidrug resistance 1 gene to refractory epilepsy in Chinese Han children

BACKGROUND： There are two hypotheses for the underlying cause of refractory epilepsy： ＂target＂ and ＂transport＂. Studies have shown that brain-derived neurotrophic factor （BDNF） is over-expressed in refractory epilepsy. Multidrug resistance 1 （MDR1） gene encodes for P-glycoprotein, the primary ATP-binding cassette transporter in the human body. Some single nucleotide polymorphisms of the MDR1 gene have been associated with refractory epilepsy. OBJECTIVE： To investigate the association between BDNF gene C270T polymorphism and MDR1 T-129C polymorphism with refractory epilepsy in Chinese Han children through the use of polymerase chain reaction （PCR）-restriction fragment length polymorphism analysis. DESIGN, TIME AND SETTING： A case-control, genetic association study was performed at the Central Laboratory, Third Xiangya Hospital of Central South University from June 2005 to November 2007. PARTICIPANTS： A total of 84 cases of unrelated children with epilepsy, including 41 cases of refractory epilepsy and 43 cases of drug-responsive epilepsy, were enrolled. An additional 30 healthy, Chinese Han children, whose ages and gender matched the refractory epilepsy patients, were selected as normal controls. METHODS： Venous blood was collected and genomic DNA was extracted from the blood specimens. C270T polymorphism in BDNF gene and T-129C polymorphism in MDR1 gene were genotyped using PCR-restriction fragment length polymorphism analysis. Association analysis using the Ftest and Chi-square test was statistically performed between C270T polymorphism in BDNF gene and T-129C polymorphism in MDR1 gene and refractory epilepsy. MAIN OUTCOME MEASURES： The distribution of genotypes and allele frequencies of C270T polymorphism in BDNF gene and T-129C polymorphism in MDR1 gene. RESULTS： The distribution of CC, CT, and TT genotypes, as well as C and T allele frequencies, in the BDNF gene was not significantly different between the refractory epilepsy group, drug-responsive epilepsy group, or the normal control group （P 〉 0.05）. The distribution of TT genotype and T allele frequencies of the MDR1 gene was significantly different in the refractory epilepsy group compared with the drug-responsive epilepsy and normal control groups （P 〈 0.05）. Comparison of haplotype combinations demonstrated that there were no significant differences in combinations of TT＋CC, -FI-＋CT, TC＋CC, and TC＋CT among the three groups （P 〉 0.05）. CONCLUSION： C270T polymorphism of the BDNF gene was not associated with refractory epilepsy in Chinese Han children, but T-129C polymorphism in the MDR1 gene was associated with refractory epilepsy in Chinese Han children. The TT genotype and T allele frequencies could serve as susceptibility loci for refractory epilepsy. Interactions between C270T in BDNF gene and T-129C in MDR1 gene were not observed in refractory epilepsy in Chinese Han children.

Brain-derived neurotrophic factor expression is higher in brain tissue from patients with refractory epilepsy than in normal controls

The role of the brain-derived neurotrophic factor in epilepsy remains controversial. The present study utilized light and electron microscopy to investigate pathological and ultrastructural changes in brain tissue obtained from the seizure foci of 24 patients with temporal epilepsy. We found that epileptic tissue showed neuronal degeneration, glial cell proliferation, nuclear vacuolization, and neural cell tropism. Immunoelectron microscopy and immunohistochemistry showed that brain-derived neurotrophic factor was expressed at significantly higher levels in patients with refractory temporal epilepsy compared with normal controls, demonstrating that the pathological changes within seizure foci in patients with refractory epilepsy are associated with brain-derived neurotrophic factor expression alterations.

Brain stimulation for treatment of refractory epilepsy

Objective We review the targets of the deep brain and the responsive neurostimulation system （RNS） to identify the best optimal stimulation parameters and the best mode of stimulation, whether cyclical, continuous, or smarter. Data sources This review is based on data obtained from published articles from 1950 to 2013. To perform the PubMed literature search, the following keywords were input： deep brain stimulation （DBS）, RNS, and refractory epilepsy. Study selection Articles containing information related to brain stimulation or RNS for the treatment of refractory epilepsy were selected. Results The currently available treatment options for those patients who resist multiple antiepileptic medications and surgical procedures include electric stimulation, both direct and indirect, of brain nuclei thought to be involved in epileptogenesis. The number of potential targets has increased over the years to include the anterior nucleus of the thalamus, the centromedian nucleus of the thalamus, the hippocampus, the subthalamic nucleus, the caudate nucleus, and the cerebellum, among others. The results of a randomized controlled trial and the RNS trial were published to reveal the effectiveness. Conclusions Although statistically significant reductions in seizures have been observed using several different stimulation techniques, including vagus nerve stimulation, DBS, and RNS, these effects are currently only palliative and do not approach the efficacy comparable with that seen in resection in appropriately selected patients. More research is needed to determine optimal stimulation targets and techniques as well as to determine which epilepsy patients will benefit most from this technology.

Long-term outcomes and prognosis factors of vagus nerve stimulation in patients with refractory epilepsy

Background:Vagus nerve stimulation(VNS)is an effective treatment for patients with refractory epilepsy,yet with varied predictive factors and heterogeneous long-term outcomes.Adjustment of VNS parameters is critical for obtaining favorable efficacy.In this study,we aimed to investigate the long-term outcomes and the possible predictive factors of VNS in patients with refractory epilepsy.Methods:Eighty-six patients(59 males and 27 females)who underwent VNS implantation for treatment of refractory epilepsy between May 2016 and May 2017 at five Epilepsy Centers were enrolled.The clinical data,including sex,age at epilepsy onset,VNS implantation,epilepsy duration,seizure type,MRI findings,history of neurosurgical operations,and responder rate(responders were those with≥50%seizure reduction),were analyzed.Results:Four-year follow-up data were available for 76 patients(53 males and 23 females).The mean current intensity at the last follow-up was 1.8±0.3 mA(range:0.75–2.5 mA).The mean seizure reduction was 36.2%at 6 months,38.5%at 1 year,69.4%at 3 years,and 56.7%at 4 years.A favorable outcome of≥50%reduction in seizure frequency occurred in 40.0%of the patients at 6 months,55.9%at 1 year with 4 patients being seizure-free,63.2%at 3 years with 5 patients being seizure-free,and 68.4%at 4 years with 5 patients being seizure-free.Earlier onset age(P<0.001)and shorter duration(P=0.042)were associated with favorable prognosis.Compared with generalized tonicclonic seizures,tonic seizures had a favorable outcome(P=0.026).Twenty-three patients underwent neurosurgical operations before VNS implantation,and the responder rate was 60.9%at the last follow-up.Conclusions:VNS is an adjunctive and effective treatment for patients with refractory epilepsy who are not good candidates for surgical resection or have failed to respond to surgical treatment.The stimulation efficacy increases over time after implantation,and earlier exposure to VNS improves the prognosis.

MicroRNAs as biomarkers in molecular diagnosis of refractory epilepsy

MicroRNA (miRNA) is a type of endogenous non-coding RNA that can regulate cell proliferation,differentiation,invasion,apoptosis and several other biological activities by specially inducing gene silencing,and thereby is related to development and disease in life course.In recent years,researchers have found that miRNAs are closely related with refractory epilepsy.MiRNAs can intervene in the modification of mRNAs,the synthesis of proteins and some the connectivity of signal pathways in pathogenesis of epilepsy.Furthermore,some miRNAs in neurons are of great importance in neuronal differentiation.Therefore,miRNA may play a very important role in the occurrence,development and episodes of refractory epilepsy.These discoveries can provide a new direction for the research of pathogenesis,diagnostic methods and therapeutic approach of refractory epilepsy.Although research about miRNA and intractable epilepsy has progressed,more remains to be done before miRNA can be used in clinical diagnosis and treatment strategies.This paper focuses on the research progress of molecular diagnosis about miRNA in intractable epilepsy.

Vagus nerve stimulation for refractory epilepsy:long term efficacy and side-effects

Background In general vagus nerve stimulation (VNS) can serve as an adjunctive treatment for patients with refractory partial -onset seizures. And we evaluated the long-term efficacy and safety of VNS in a group of Chinese patients with refratory epilepsy. Methods Of 127 patients with refractory epilepsy,13 patients who were not eligible for surgical intervention were implanted with the Cyberonics VNS system. Seizure frequency,physical examination and side effects profile were recorded at follow-up visits for a minimum of 18 months. Results Mean duration of treatment was 47.4 months,and the longest follow-up period was 71 months. Mean baseline seizure frequency was 26.6 seizures per month. The mean percentage reductions in convulsions were 33.2%,47.1% and 40.0% at 6,12 and 18 months,respectively. One patient became seizure free,and six (46%) had 50% or more reduction in seizure frequency. Response was poor (<20% reduction) in five patients (39%). Side effects were uncommon. Conclusions The effectiveness of VNS was sustained and was well tolerated but benefited only a sub-group of patients with intractable convulsions.

Pharmacokinetic, pharmacodynamic, and neurochemical investigations of lamotrigine-pentylenetetrazole kindled mice to ascertain it as a reliable model for clinical drug-resistant epilepsy

Background:Pentylenetetrazole kindling has long been used for the screening of investigational antiseizure drugs.The presence of lamotrigine,at a very low dose,does not hamper kindling in mice;rather it modifies this epileptogenesis process into drug-resistant epilepsy.The lamotrigine-pentylenetetrazole kindled mice show resistance to lamotrigine,phenytoin,and carbamazepine.It may also be possible that other licensed antiseizure drugs,like the mentioned drugs,remain ineffective in this model;therefore,this was the subject of this study.Methods:Swiss albino mice were kindled with pentylenetetrazole for 35 days in the presence of either methylcellulose vehicle or lamotrigine(subtherapeutic dose,ie,5 mg/kg).Vehicle vs lamotrigine-kindled mice were compared in terms of(a)resistance/response toward nine antiseizure drugs applied as monotherapies and two drug combinations;(b)lamotrigine bioavailability in blood and brain;(c)blood-brain barrier integrity;and(d)amino acids and monoamines in the cerebral cortex and hippocampus.Results:Lamotrigine vs vehicle-kindled mice are similar(or not significantly different P>.05 from each other)in terms of(a)response toward drug combinations;(b)lamotrigine bioavailability;and(c)blood-brain barrier integrity except for,significantly(P<.05)reduced taurine and increased glutamate in the cerebral cortex and hippocampus.Aside from these,lamotrigine-kindled mice show significant(P<.05)resistant to lamotrigine(15 mg/kg),levetiracetam(40 mg/kg);carbamazepine(40 mg/kg),zonisamide(100 mg/kg),gabapentin(224 mg/kg),pregabalin(30 mg/kg),phenytoin(35 mg/kg),and topiramate(300 mg/kg).Conclusion:Lamotrigine-pentylenetetrazole kindling takes longer to develop(~5 weeks)in comparison to lamotrigine-amygdale(~4 weeks)and lamotriginecorneal(~2 weeks)kindling models.However,drug screening through this model may yield superior drugs with novel antiseizure mechanisms.

Long-Term Impact in the Quality of Life of Patients with Drug-Resistant Epilepsy That Use Cannabidiol

Introduction: Epilepsy is considered a chronic neurological condition that manifests itself with seizures, where 30% - 40% of patients do not achieve control of their seizures despite proper management. Seizures represent a significant limitation in the patient’s daily activities and are often accompanied by emotional and relational difficulties that have a great impact on the quality of life of the patient and their families. Cannabidiol (CBD) has been found to be effective in controlling seizures and may also improve cognitive and behavioral abilities. Material and Methods: The Quality of Life of the Patient with Epilepsy (CAVE) scale was applied to patients with refractory epilepsies who use Cannabidiol (CBD) added to their base therapy, before the use of CBD and after 12 months of follow-up. The presentation of collateral effects was also evaluated. Results: Out of 34 patients, 26 (76.5%) increased their CAVE value at the end of the study and only 1 (2.9%) decreased. 19 (55.9%) improved in learning and behavior, 55.8% in the frequency of seizures and 79.4% reported a decrease in the intensity of seizures. There were other positive side effects such as improvement in alertness, language, sleep and behavior. The main side effects were mild and transitory, including drowsiness, and constipation. There was a correlation between the global perception of improvement and seizure control. Conclusions: This study shows that in the long term CBD improves the quality of life of patients with refractory epilepsies, through the control of seizures and the improvement of cognitive and behavioral functions.

High-frequency and brief-pulse stimulation pulses terminate cortical electrical stimulation-induced afterdischarges

Brief-pulse stimulation at 50 Hz has been shown to terminate afterdischarges observed in epilepsy patients. However, the optimal pulse stimulation parameters for terminating cortical electrical stimulation-induced afterdischarges remain unclear. In the present study, we examined the effects of different brief-pulse stimulation frequencies（5, 50 and 100 Hz） on cortical electrical stimulation-induced afterdischarges in 10 patients with refractory epilepsy. Results demonstrated that brief-pulse stimulation could terminate cortical electrical stimulation-induced afterdischarges in refractory epilepsy patients. In conclusion,（1） a brief-pulse stimulation was more effective when the afterdischarge did not extend to the surrounding brain area.（2） A higher brief-pulse stimulation frequency（especially 100 Hz） was more likely to terminate an afterdischarge.（3） A low current intensity of brief-pulse stimulation was more likely to terminate an afterdischarge.

A case report of microcephaly and refractory West syndrome associated with WDR62 mutation

The autosomal recessive form of primary microcephaly(MCPH)is a rare disorder characterized by microcephaly with variable degree of intellectual disability.WDR62 has been reported as the second causative gene of MCPH2.West syndrome is a severe epilepsy syndrome composed of the triad of spasms,hypsarrhythmia,and mental retardation.There are limited clinical reports regarding WDR62 mutation and West syndrome.Here we report a boy who was identified with WDR62 mutation and was followed up from age 3 months to 5 months and 14 days.He had the first seizure as the classic epileptic spasm at the age of 3 months.Psychomotor retardation was noted before the seizure occurred.The head circumference was 38.5 cm(SD 2.6)when he was 4 months old,no dysmorphic facial features were observed.He couldn’t support his head steadily or turn over.He was able to laugh when tricked by the parents,but couldn’t track the sound and light.At the early stage,the electroencephalogram showed multifocal discharges,which evolved into hypsarrhythmia one month later,and brain MRI showed developmental malformation of cerebral gyrus.Two heterozygous mutations were identified in WDR62 by whole exome sequencing c.1535G>A,p.R512Q and c.2618dupT,p.K874Qfs40.The patient was administrated with oral sodium valproate,nitrazepam,intramuscular adrenocorticotropic hormone for 2 weeks,and followed by prednisone,levetiracetam,topiramate and vigabatrin.However,there was no significant improvement on the seizure control after these treatments.According to the genetic report and clinical manifestation,we speculated that the WDR62 compound heterozygous mutation is responsible for the serious clinical phenotype.