Intracellular records from chronic alumina epileptogenic foci in the monkey

Neuronal records from the primate alumina focus revealed synaptic potentials with bursts of action potentials occurring on depolarizing potentials. These depolarizing potentials were not synchronous with electrocorticographic epileptic patterns. The configuration of the membrane potential changes was consistent with a dendritic generator for epileptic bursts. It is proposed that the genesis of these depolarizing potentials is postsynaptic.     

难治性癫过度运动发作的临床特征与致灶定位

目的总结以过度运动发作为主要表现的药物难治性癫的诊疗经验。方法回顾性分析25例药物难治性癫病人的临床资料,均以过度运动发作为主要表现。根据症状特点、MRI、头皮视频脑电图及颅内脑电图监测,综合定位致灶,并行手术切除。结果切除额叶致灶23例,切除前颞叶致灶2例。神经病理学检查显示:皮质发育不良(FCD)Ⅰ型8例,FCDⅡ型12例,节细胞胶质瘤1例,皮质微发育不良1例,灰质异位1例,胶质瘢痕1例,海马硬化1例。术后随访12~60个月,按Engel分级:Ⅰ级19例,Ⅱ级2例,Ⅲ级2例,Ⅳ级2例。结论以过度运动发作为特点的难治性癫病人,其致灶主要位于额叶,但也可位于额叶外的脑区,准确切除致灶后疗效满意。     

外伤性癫癎致癎灶分布和外科治疗

目的探讨外伤性癫癎的致癎灶分布和手术方式及疗效。方法收集本院神经外科2004年9月~2010年9月收治的76例外伤性癫癎患者的临床资料,并对其进行分析。结果 52例患者致癎灶位于外伤软化灶周围（2~7cm）,9例呈弥散性分布,7例在半球同侧或两侧均有两处分布,8例未检出致癎灶。其中符合手术指征的23例患者在皮层电极下行手术治疗,按照谭启富标准,满意11例,显著改善8例,良好2例,较差2例,有效率91.3%,优良率82.6%。结论外伤性癫癎致癎灶常位于外伤软化灶周围且常引起局灶性发作;额叶颞叶癫癎的发生率高于其他部位;外伤性癫癎的手术疗效较好,故符合手术指征者应及时进行手术治疗。     

Amino acid abnormalities in epileptogenic foci

We compared amino acid contents of 54 epileptogenic foci removed neurosurgically from temporal or frontal cortex of 35 patients with focal epilepsy with those of biopsies from the same cortical regions of 14 nonepileptic patients. Neither taurine nor GABA content was reduced in epileptogenic foci. Glycine content was elevated markedly in some foci, whereas aspartic acid content was normal. Mean glutamic acid content was significantly higher in epileptogenic foci than in control cortex, and six foci contained amounts of glutamate more than 2 SD above the control mean. Our findings do not support hypotheses that deficiencies of taurine or GABA are involved in the pathogenesis of focal epilepsy but do suggest a possible etiologic role for the excitatory neurotransmitter, glutamic acid.     

Local cerebral metabolism during enflurane anesthesia: identification of epileptogenic foci.

Electrocorticographic (ECoG) and depth recordings have previously demonstrated the epileptogenic nature of surgical concentrations of the volatile anesthetic enflurane. We contrasted ECoG activity with local cerebral glucose uptake [( 14C]2-deoxyglucose autoradiography) in 23 brain structures in order to identify the epileptogenic foci. Autoradiograms were obtained from sectioned rat brain following a 30 min period of steady-state anesthesia at 1, 1.5, or 2 MAC (minimum alveolar concentration) enflurane. Pseudo-epileptiform ECoGs were obtained at 1 MAC where bursts of slow waves and sharp waves were evoked by peripheral sensory stimulation. At 1.5 MAC, the ECoG displayed frank, spontaneous epileptiform activity with large amplitude spike-wave complexes; repetitive auditory stimulation occasionally precipitated grand-mal seizures. At 2 MAC, spike complexes were less frequent and could not be repetitively driven. At 1 MAC enflurane, regional cerebral metabolism was generally depressed approximately 14% from the awake controls. However, metabolism in the dentate gyrus of the hippocampus and other subcortical structures in the limbic brain was increased. At 1.5 MAC this dichotomy in local cerebral metabolic rate was maximal; we observed increased metabolism in the hippocampus, habenula, habenulo-interpeduncular tract and interpeduncular nucleus and pineal. Metabolism in all other structures was significantly depressed (P less than 0.05) compared to awake values. At 2 MAC, metabolism was decreased in all structures. We conclude that the low seizure threshold hippocampus and related structures associated with the limbic system and its pathways are the epileptogenic foci for seizures induced with enflurane in the rat. At 1.5 MAC, epileptiform activity spreads throughout the visceral brain when seizure threshold is at a minimum.     

Source localization in magnetoencephalography to identify epileptogenic foci

Rationale

Magnetoencephalography (MEG) is useful to localize epileptic foci in epilepsy as MEG has higher spatio-temporal resolution than conventional diagnostic imaging studies; positron emission computed tomography, single photon emission computed tomography and magnetic resonance imaging (MRI).

Methods

We use 204-channel helmet-shaped MEG with a sampling rate of 600 Hz. A single dipole method calculates equivalent current dipoles to localize epileptic sources. The equivalent current dipoles are superimposed onto MRI as magnetic source imaging (MSI). Ictal MEG data are analyzed using time-frequency analysis. The power spectrum density is calculated using short-time Fourier transform and superimposed onto MRI results.

Results

Clustered equivalent current dipoles represent epileptogenic zones in patients with localization-related epilepsy. The surgical plan is reliably developed from source localizations of dipoles and power spectrum of interictal spike discharges, and ictal frequency.

Conclusion

MEG is indispensable in diagnosis and surgical resection for epilepsy to accurately localize the epileptogenic zone.     

癫痫手术前SPECT的定位价值

目的：了解单光子发射计算机断层扫描（ＳＰＥＣＴ）行局部脑血流检查在致痫灶定位中的应用价值。方法：对２４例癫痫患者行ＳＰＥＣＴ检查，结果采用目测和半定量分析两种方法进行判断。结果：１３／２４（５６％）的患者有目测的异常灌注区，其中１１／１３（８５％）与综合定位的结果相一致，半定量分析的方法可发现１２／１２的患者有异常灌注区，其中１０／１２（８３％）可得到与综合定位结果相一致的结论。统计学显示两种方法在阳性检出率和准确率上有显著差异。结论：ＳＰＥＣＴ在致痫灶的定位中有较高的应用价值，半定量分析的方法可明显提高ＳＰＥＣＴ对致痫灶的检出率，但应将检查结果与临床及其他检查资料相结合进行分析以减少假阳性率