Neuropathological profile of the pentylenetetrazol (PTZ) kindling model

ABSTRACT

Introduction: There are three phases of seizure developing in pentylenetetrazol (PTZ)-induced kindling animal model: (i) pre-kindling phase; (ii) kindling phase or after animals are fully kindled; (iii) post-kindling phase with non-provoked spontaneous recurrent seizures. The aims of this review were to summarize the progress over time of the electroencephalographic features and neuropathological alterations in kindled PTZ treated animals.

Materials and methods: Keywords relevant to PTZ kindling were used to a guide a literature search on Pubmed, Medline and Cochrane Library.

Results: Clonic seizures induced PTZ at kindling phase led to a strong c-Fos expression in the hippocampus. Although, decline hippocampal neuron and metabolism disturbances were detected at pre-kindlig phase. Repeated PTZ induced seizures alter the GABA-mediated inhibition and glutamate-mediated excitation, which may contribute to increased seizure susceptibility. Similar to chemical animal models such as the pilocarpine and the kainic acid models, mossy fiber sprouting, hippocampal damage, and glucose hypometabolism had been seen after PTZ induced seizures.

Conclusion: PTZ kindling model may improve understanding of the seizures development provided that the differences existing between the phases of kindling model are taken into account.     

Unraveling the biological mechanisms in Alzheimer's disease--lessons from genomics

Alzheimer's disease (AD) is the most common form of dementia and the most common neurodegenerative disease, with a complex genetic background. Genome-wide association studies (GWAS) have yielded important new insights into genetic mechanisms of AD pathology. Current results unequivocally confirm apolipoprotein E (APOE) as a major genetic risk factor for development of late onset AD. Additional associations of more than twenty genes have also been identified and replicated in subsequent genetic studies. Despite the exciting new GWAS data which have emerged in the last few years, it has become clear that common variants within the genome cannot fully explain the underlying genetic risk for AD. Novel approaches such as genome-wide analysis of copy number variations (CNV) or low-frequency rare functional gene variants may provide additional insight into genetic basis of AD. In this review we summarize the findings of eighteen GWAS studies in AD performed to date, with an emphasis on potential future developments in the quest for genetic risk factors of AD.     

Clinical and neurophysiologic features of progressive myoclonus epilepsy without renal failure caused by SCARB2 mutations

Purpose: Mutations of the SCARB2 gene cause action myoclonus renal failure syndrome (AMRF), a rare condition that combines progressive myoclonus epilepsy (PME) with severe renal dysfunction. We describe the clinical and neurophysiologic features of PME associated with SCARB2 mutations without renal impairment. Methods: Clinical and neurophysiologic investigations, including wakefulness and sleep electroencephalography (EEG), polygraphic recording (with jerk‐locked back‐averaging and analysis of the EEG–EMG (electromyography) relationship by coherence spectra and phase calculation), multimodal evoked potentials, and electromyography were performed on five Italian patients with SCARB2 mutations. Key Findings: The main clinical features were adolescent–young adulthood onset, progressive action myoclonus, ataxia, absence of cognitive deterioration and, in most cases, epilepsy. The severity of the epilepsy could vary from uncontrolled seizures and status epilepticus in patients with adolescent onset to absent or rare seizures in patients with adult onset. Relevant neurophysiologic findings were a pronounced photosensitivity and massive action myoclonus associated with rhythmic myoclonic jerks at a frequency of 12–20 Hz, clinically resembling a postural tremor. The cortical origin of rhythmic myoclonus was demonstrated mainly by coherence and phase analysis of EEG–EMG signals indicating a significant EEG–EMG coupling and a direct corticospinal transfer. Significance: Our patients with SCARB2 mutations showed the clinical and neurophysiologic phenotype of PME, in which epilepsy could be extremely severe, extending the spectrum reported in the typical AMRF syndrome. Patients with PME of unknown origin of adolescent or young adult onset, with these neurophysiologic features, should be tested for SCARB2 mutations, even in the absence of renal impairment.     

Serial changes of prefrontal lobe growth in the patients with benign childhood epilepsy with centrotemporal spikes presenting with cognitive impairments/behavioral problems

Several studies have reported a higher incidence of learning and behavioral difficulties in association with frontal lobe dysfunctions in children with benign childhood epilepsy with centrotemporal spikes (BCECTS). We studied serial changes in frontal and prefrontal lobe volumes using three-dimensional magnetic resonance imaging in BCECTS with or without cognitive impairments and behavioral problems and evaluated correlations between prefrontal lobe growth and active seizure period. Serial changes in regional cerebral volumes were measured in two patients with cognitive impairments and behavioral problems (BCECTS(+)) and five patients without neuropsychiatric deficits (BCECTS(−)). Eleven normal subjects (4-13 years old) served as controls. Volumes of the frontal and prefrontal lobes were determined using a workstation, and the prefrontal-to-frontal lobe volume ratio was calculated. Frontal and prefrontal lobe volumes revealed growth disturbance in BCECTS(+) compared with BCECTS(−) and control subjects. In addition, prefrontal-to-frontal lobe volume ratio increased serially in BCECTS(−) similarly to controls, but was stagnant or decreased in BCECTS(+). Prefrontal growth also revealed more rapid recovery in a BCECTS(+) patient with shorter active seizure period. These findings suggest that longer active seizure period as frequent spike-waves coupled with the occurrence of frequent seizures may be associated with prefrontal lobe growth disturbance, which relates to neuropsychological problems.     

全面性癫癎伴热性惊厥附加症的临床和遗传学特点(附9家系报告)

目的探讨全面性癫癎伴热性惊厥附加症(GEFS+)的临床和遗传学特点。方法回顾性分析9个GEFS+家系的临床资料。结果本组9例先证者中男7例,女2例;起病年龄1~3岁;发作类型均为全面性强直-阵挛发作(GTCS)。其中,1例为GTCS,4例为热性惊厥(FS),4例为热性惊厥附加症(FS+)。脑电图检查示6例有典型疒间样波,1例有θ波,2例无异常。9个GEFS+家系184人中共有患者45例,男32例,女13例;男性发病比率(34.4%)明显高于女性发病比率(14.3%)(P<0.05)。其中,2例为GTCS,39例为FS,4例为FS+。家系系谱图分析显示,17例患者(37.8%)父母一方或双方患病,符合常染色体显性遗传;28例患者(62.2%)父母不发病或发病情况不详,但其近亲中至少有2例或以上患者。结论 GEFS+的脑电图不一定有异常波。GEFS+具有遗传异质性,本组中男性显著多于女性,不完全符合常染色体显性遗传。     

癫癎撤药的研究进展

癫癎并非完全是一种终身疾病,60%~70%患者经过一定时间抗癫癎药(AEDs)治疗后症状能得到缓解(至少5年不发作),缓解后及时合理地AEDs撤药将对患者的预后包括避免或减少药物不良反应以及改善生活质量等产生重要影响。对AEDs撤药的研究已有60年历史,然而目前仅依据临床经验撤药,缺乏循证医学依据。对达到撤药的要求、时机及具体方法亦无统一被认可的标准。本文就AEDs撤药对癫癎复发的影响,撤药时机、速度,撤药后复发的危险因素等方面的研究进行综述。     

Ictal involvement of the nigrostriatal system in subtle seizures of ring chromosome 20 epilepsy

Studies in animal models and patients with epilepsy have suggested that basal ganglia circuits may control epileptic seizures and that striatal dopaminergic transmission may play a role in seizure modulation and interruption. Chromosome 20 [r(20)] syndrome is a well-defined chromosomal disorder characterized by epilepsy, mild-to-moderate mental retardation, and lack of recognizable dysmorphic features. Epilepsy is often the most important clinical manifestation of the syndrome, with prolonged episodes of nonconvulsive status epilepticus suggesting dysfunction in the seizure control system. We present the ictal blood oxygen level-dependent (BOLD) changes in brief seizures recorded by means of electroencephalography-functional magnetic resonance imaging (EEG-fMRI) coregistration in a patient with [r(20)] syndrome. We observed ictal BOLD increments in a cortical-subcortical network involving substantia nigrastriatum and frontal cortex. At present, this is the first functional neuroimaging evidence of the involvement of the nigrostriatal system during ictal EEG discharges in [r(20)] syndrome supporting a role of the basal ganglia circuits in human epileptic seizures.     

Choice with delayed or uncertain reinforcers in rats: influence of timeout duration and session length

Interest is rising for animal modeling of impaired behavioral inhibition. Impulsivity and risk proneness, key symptoms of impulse-control disorders, are classically measured by Intolerance to Delay (ID) and Probabilistic Delivery (PD) tasks, requiring choice between a "Small & Soon" or "Sure" (SS) versus a "Large & Late" or "Luck-Linked" (LL or LLL, respectively) reinforcer. Several temporal parameters shall be set, which are not always explicit. Here, we focused on duration of timeout (TO; three groups: 15, 30, or 45 s; Exp. 1) and on session length (SL; three groups: 60, 90, or 120 min; Exp. 2) to determine whether these parameters may affect rats' performance in ID and PD tasks, respectively. In Exp. 1, rats' reaction to increasing experimental delays (absolute values 0-90 s, delay-equivalent odds 0 to 1.94 ± 0.11) was critically affected by TO duration: a steeper impulsivity curve was found in subjects tested with the longest TO, while random performance was elicited with too short TO. In Exp. 2, a specific "gambling" part was presented (LLL probability lower than 20%). Subjects tested with the shortest session length (60 min), who had a low number of gambling opportunities (performed trials = 84.33 ± 1.91), exhibited a profile of risk proneness, with sustained LLL preference despite high uncertainty and low payoff. Present data demonstrate that TO and SL crucially influence rats' performance in these operant tasks. Their methodological refinement is highly relevant to validate preclinical models for inhibitory-control impairments.     

结节性硬化合并婴儿痉挛症的外科治疗

目的 探讨结节性硬化所致婴儿痉挛症的手术适应证、方法和预后.方法 回顾性分析采用外科手术治疗17例结节性硬化症伴婴儿痉挛症的经验.结果 术后疗效按Engel分级,Ⅰ级11例,Ⅱ级4例,Ⅲ级2例.术前评估为单致痫灶的2例患者均为Ⅰ级.局限在一侧大脑半球的8例多灶性癫痫患者中,6例Ⅰ级,2例Ⅱ级.双侧大脑半球均有致痫灶但以一侧为主的7例患者中,3例Ⅰ级,2例Ⅱ级,2例Ⅲ级.平均智商(IQ)从术前的52.6分提高到61.8分.结论 结节性硬化所致婴儿痉挛症具有良好的外科预后,对部分药物难治性患者在评估确定责任结节后可以考虑进行外科干预.

Abstract：

Objective To investigate the surgical indications, methods and outcomes of infantile spasms with tuberous sclerosis(TS). Method Surgical treatment of 17 infantile spasms patients with TS was reviewed. Single epileptogenic tuber or lobe was resected when a focal epileptic discharge was indicated according to preoperative evaluation and EcoG, and multiple lobes or tubers resection were chosen to deal with hemisphere limited multiple epileptic foci. Anterior corpus callosotomy was added when contralateral hemisphere showed epileptic discharges. Results Acording to follow - up of 3 years in average after surgery, 11 patients had an Engel Class Ⅰ outcome, 4 patients had rare seizure ( Engel Class Ⅱ ), and 2 patients had a reduction in seizure frequency (Engel Class Ⅲ ). The mean IQ of patients was improved from 52.6 to 61. 8. Conclusions Epilepsy surgery in tuberous sclerosis with infantile spasms showes a favourable outcome,and surgical intervention should be considered in some intractable infantile spasms after corresponding tuber is derermined.     

Successful removal and reimplant of vagal nerve stimulator device after 10 years

The number of implanted vagal nerve stimulators is growing and the need for removal or revision of the devices will become even more frequent. A significant concern about Vagus Nerve Stimulation (VNS) therapy is the presence of the spiral stimulating electrodes, wrapped around the nerve, once treatment is considered ineffective or is no longer desired. Our purpose is to demonstrate the feasibility of complete removal and replacement of the vagal nerve stimulator electrodes using microsurgical technique even after a long period, without damaging the nerve. We attempted removal and replacement of spiral stimulating electrodes from a patient who received a 10-year long VNS therapy for drug-resistant epilepsy. Our results indicate that the spiral electrodes may be safely removed from the vagus nerve, even after several years. The reversibility of lead implantation may enhance the attractiveness of VNS therapy. Furthermore, with a correct microsurgical technique, it is possible to respect the normal anatomy and functionality of vagal nerve and to reimplant a new VNS system with all its components, maintaining the same therapeutic efficacy after many years.