Interhemispheric propagation time and temporal lobe epileptogenicity

Long-term subdural electroencephalographic (EEG) recording was performed in a series of patients with medically intractable complex partial seizures to test the hypothesis that ictal interhemispheric propagation time (IHPT) is correlated with temporal lobe epileptogenicity. In 41 patients, the duration from initial subdural EEG seizure onset to the first appearance of subdural EEG epileptic activity in the contralateral hemisphere (IHPT) was measured in seconds and analyzed for a quantitative relationship to temporal lobe seizure interval (frequency^?1), in hours. A statistically significant, nonlinear correlation between IHPT and seizure interval was found (Arctan y = ?0.009x² + 0.598x + 75.187, y = IHPT, in seconds, x = seizure interval, in hours, r = 0.326, d.f. = 39, t = 2.15, p < 0.05). The results suggest that, for seizure intervals less than 33 h, increasing IHPT is associated with increasing seizure interval (i.e. decreasing epileptogenicity). Conversely, for seizure intervals greater than 33 h, decreasing IHPT is associated with increasing seizure interval. Because the relationship between IHPT and seizure interval is a trigonometric (i.e. arctangent) function of a second degree polynomial, small changes in IHPT are associated with substantial changes in seizure interval. These findings suggest that temporal lobe epileptogenicity is a complex, nonlinear function of the electrocorticographic EEG time factor (i.e. IHPT) involved in the transmission of ictal epileptic activity from the seizure focus to the contralateral hemisphere. The results suggest that, on an electrophysiologic basis, patients with temporal lobe epilepsy represent two distinct populations based on seizure interval. The results should improve the understanding of the electrocorticographic pathophysiology of temporal lobe epilepsy. The development of cortical neuromodulation strategies designed to suppress temporal lobe seizures should consider this complex relationship between temporal lobe interhemispheric propagation time and epileptogenicity.     

Vascular steal model of human temporal lobe epileptogenicity: the relationship between electrocorticographic interhemispheric propagation time and cerebral blood flow

Human temporal lobe epileptogenicity (i.e. seizure frequency) depends on epileptic and non-epileptic cerebral blood flow (CBF). Increasing non-epileptic cortical CBF is associated with reduction in epileptic cortical CBF. Seizure frequency increases logarithmically with non-epileptic cortical CBF increase and epileptic cortical CBF reduction. A model of human temporal lobe epileptogenicity is derived from the mathematical equivalence to the logarithmic function of seizure frequency of (a) epileptic and non-epileptic CBF differential and (b) electrocorticographic (ECoG) interhemispheric propagation time (IHPT). The vascular steal model of human temporal lobe epileptogenicity suggests that a small CBF redistribution from non-epileptic to epileptic cortex should produce substantial reduction in temporal lobe seizure frequency in association with prolongation of IHPT. The equivalence of these CBF and ECoG parameters to the logarithmic function of seizure frequency suggests that the interhemispheric temporal lobe perfusion gradient and ECoG propagation time may be involved in the fundamental perturbation responsible for human temporal lobe epileptogenicity.     

Relationship of temporal lobe seizures to sleep and arousal: a combined scalp-intracranial electrode study

STUDY OBJECTIVES: The role of arousal from sleep in promoting epileptic seizures is controversial. To examine the question of whether seizures precede or follow arousals from sleep, we defined the timing of temporal lobe seizures in relation to sleep and arousal using combined scalp-intracranial electrodes. DESIGN: Retrospective review of 67 sleep-related mesial temporal lobe seizures in 14 subjects. SETTING: Inpatient epilepsy monitoring laboratory. PATIENTS: Subjects with medically refractory mesial temporal lobe seizures undergoing epilepsy surgery evaluations. INTERVENTIONS: None MEASUREMENTS AND RESULTS: Electroencephalographic (EEG) and/or polygraphic recordings and videotapes were independently reviewed to determine intracranial electrode seizure onset times and time of initial arousal from sleep. In 60 seizures in 13 subjects, intracranial ictal onsets always preceded clinical arousals from sleep. Electrographic signs of arousal in the scalp EEG, defined by the presence of sustained alpha or theta activity, either coincided with or followed, but never preceded, intracranial ictal onsets. In seven seizures in one subject with known seizures upon awakening, intracranial ictal onsets always followed clinical arousals and electrographic signs of arousal from sleep. Seven of the 14 subjects had electrooculogram and chin electromyogram monitoring; in these subjects, no seizures occurred during REM sleep with the majority occurring during NREM stage 2 sleep. CONCLUSIONS: Most sleep-related temporal lobe seizures occurred during NREM sleep and preceded arousals, supporting the premise that processes involved in the initiation and maintenance of NREM sleep play a greater role in facilitating temporal seizures than those involved in promoting REM sleep and arousal. However, arousal from sleep may provoke seizures in exceptional cases.     

Localization of the Epileptic Focus by Low-Resolution Electromagnetic Tomography in Patients with a Lesion Demonstrated by MRI

Patients with medically intractable partial epilepsy and well-defined symptomatic MRI lesions were studied using phase-encoded frequency spectral analysis (PEFSA) combined with low-resolution electromagnetic tomography (LORETA). Ten patients admitted to the epilepsy monitoring unit with MRI-identified lesions and intractable partial epilepsy were studied using 31-electrode scalp EEG. The scalp electrodes were located in three-dimensional space using a magnetic digitizer and coregistered with the patient's MRI. PEFSA was used to obtain a phase-encoded scalp map for the ictal frequencies. The ictal generators were obtained from the scalp map using LORETA. In addition, the generators of interictal epileptogenic spikes were identified using time-domain LORETA. The LORETA generators were rostral to the MRI lesion in 87% (7/8) of patients with temporal lobe lesions, but all were located in the mesial temporal lobe in concordance with the patients' MRI lesions. In patients with frontal lobe epilepsy, the ictal generators at the time that the spectral power was maximal localized to the MRI lesions. Eight of 10 patients had interictal spikes, of which 4 were bilateral independent temporal lobe spikes. Only generators of the interictal spikes that were ipsilateral to seizure onset correlated with the ictal generators. LORETA combined with PEFSA of the ictal discharge can localize ictal EEG discharges accurately and improve correlation with brain anatomy by allowing coregistration of the ictal generator with the MRI. Analysis of interictal spikes was less useful than analysis of the ictal discharge.     

癫癎发作早期Video-EEG监测的临床价值

目的 :探讨Video -EEG监测癫发作早期脑电变化的临床应用价值。方法 :对 96例临床确诊的癫患者进行发作早期Video -EEG监测并分析其结果。结果 :共监测到 3 2例癫发作(3 3 % ) ,其中全身性癫 4例 ;颞叶癫 16例 ,颞外癫 12例。发作早期脑电异常主要分快活动、慢活动及快慢混合活动三大类。根据发作早期脑电变化 ,2 3例 (72 % )作出定位诊断。结论 :癫发作早期脑电图脑电变化对致灶的定位 (定侧 )诊断有重要价值     

Incidence and clinical profile of extra-medial-temporal epilepsy with hippocampal atrophy

We tried to investigate the incidence and the clinical profile of intractable epilepsy with hippocampal atrophy and ictal onset zones located in areas other than the hippocampus (extra-medial-temporal epilepsy; EMTE). We included patients who had hippocampal atrophy confirmed by MRI but with extra-medial-temporal ictal onset zones as verified by invasive intracranial electrodes or video-EEG monitoring. The case histories, interictal EEG, ictal semiology, other MRI findings in addition to hippocampal atrophy, and results of ictal SPECT and PET scans were evaluated. Results were compared with those of surgically proven medial temporal lobe epilepsy with hippocampal atrophy recruited during the same period. 8.5% of the intractable epilepsy patients with hippocampal atrophy had extra-medial temporal epileptogenic zones. A history of encephalitis and hemiconvulsion-hemiparesis were significantly common in the EMTE group. Most of the interictal EEGs of EMTE patients showed extratemporal irritative zones. MRI, ictal SPECT, and FDG-PET seemed to be helpful at localizing the true epileptogenic zones. The predominant EMTE seizure type was focal motor seizure with secondary generalization. Some portion of intractable epilepsy patients with hippocampal atrophy had extra-medial-temporal epileptogenic foci and careful analysis of semiology and neuroimagings could yield clues to correct diagnosis.     

头皮脑电图继发双侧同步(癎)样放电的特点及其临床意义

目的:探讨局灶性癫(癎)患者头皮脑电图(EEG)上继发双侧同步(癎)样放电(SBSD)的表现特点及临床意义.方法:回顾性地分析自2002年3月至2006年3月,于我研究所接受治疗的所有局灶性癫(癎)患者的EEG资料,排除所有颞叶癫(癎),共32例患者的术前EEG上均存在SBSD表现.对这些患者的发作间期与发作期EEG结果进行分析研究.结果:32例患者中,SBSD起源于额区者20例,枕区者10例,顶区者2例.SBSD可表现为棘或尖波、棘慢复合波与快节律三种类型,以棘慢复合波最为常见,占63%.SBSD发作间期较为常见的特点是双侧存在时间差,SBSD始于EEG局灶性异常改变以及局限性慢波一侧;53%的病人发作期EEG表现为局灶性起源.结论:SBSD在局灶性癫(癎)患者中并不少见,而且以额叶最为常见.通过分析SBSD波形的各个特点,有助于判断SBSD原发灶侧别,并与全面性癫(癎)相鉴别,对癫(癎)外科的术前评估具有非常重要的临床意义.     

39例复杂部分性发作癫灶的PET与EEG定位诊断比较

目的 :探讨临床表现不同的癫复杂部分性发作 (CPS)与正电子发射断层扫描 (PET)检查病灶定位的相关性。方法 :39例CPS病人经PET、磁共振成像 (MRI)、录像 脑电监测 (Video EEG)检查 ,并对各种检查和临床表现进行比较分析。结果 :PET和EEG二者完全符合和部分符合均为 31% ,15例不符病例中 ,12例为PET有定位价值而EEG不能定位。仅表现为复杂部分性发作而无继发性全身性强直阵挛发作 (GS)者的 71%的病例 ,PET定位于单侧颞叶 ,表现为CPS继发GS者的 81%为颞顶、颞枕区病灶。结论 :CPS不继发全身性发作的患者 ,病灶多局限于一侧颞叶 ,如发作期和发作间期脑电图均正常 ,更应考虑病灶位于颞叶内侧面 ,或边缘系统 ;CPS继发GS的患者病灶多位于颞叶外侧面与顶、枕交界区。     

A Novel Spatiotemporal Analysis of Peri-Ictal Spiking to Probe the Relation of Spikes and Seizures in Epilepsy

The relation between epileptic spikes and seizures is an important but still unresolved question in epilepsy research. Preclinical and clinical studies have produced inconclusive results on the causality or even on the existence of such a relation. We set to investigate this relation taking in consideration seizure severity and spatial extent of spike rate. We developed a novel automated spike detection algorithm based on morphological filtering techniques and then tested the hypothesis that there is a pre-ictal increase and post-ictal decrease of the spatial extent of spike rate. Peri-ictal (around seizures) spikes were detected from intracranial EEG recordings in 5 patients with temporal lobe epilepsy. The 94 recorded seizures were classified into two classes, based on the percentage of brain sites having higher or lower rate of spikes in the pre-ictal compared to post-ictal periods, with a classification accuracy of 87.4%. This seizure classification showed that seizures with increased pre-ictal spike rate and spatial extent compared to the post-ictal period were mostly (83%) clinical seizures, whereas no such statistically significant (α = 0.05) increase was observed peri-ictally in 93% of sub-clinical seizures. These consistent across patients results show the existence of a causal relation between spikes and clinical seizures, and imply resetting of the preceding spiking process by clinical seizures.     

发作期及发作间期痫性放电对癫痫的诊断价值

目的探讨发作期及发作间期脑电图对癫痫诊断的意义。方法对５６例癫痫患者常规脑电图（ＲＥＥＧ）与２４ｈ脑电图（ＡＥＥＧ）进行比较研究。结果①ＲＥＥＧ的阳性率为３０％，而ＡＥＥＧ的阳性率为８６％；②不同类型癫痫在发作期和发作间期大脑活动的规律和特点，ＲＥＥＧ无１例记录到癫痫发作，而ＡＥＥＧ有２７例（４８％）记录到癫痫发作全过程的大脑电活动变化。结论发作期的ＥＥＧ对确定癫痫类型有重要意义，全身性癫痫在发作的同时发作波在两侧半球同时出现，而部分性发作患者在临床发作的同时ＥＥＧ常局限在某一脑叶有单个棘波发放，此棘波处是癫痫的病灶的部位，这种局限棘波可扩散至全脑而临床出现全身阵挛发作，此类患者为部分性癫痫并非全身性癫痫。     

颅内电极V-EEG对难治性颞叶癫痫致痫灶的定位价值

目的：探讨颅内埋藏电极同步录像脑电图监测（V-EEG）对难治性颞叶癫痫致痫灶的定位作用。方法：对临床、影像学检查及头皮电极脑电图（EEG）不能明确癫痫致痫灶的3例难治性颞叶癫痫患者,采用颅骨钻孔方法埋置硬膜下电极和深部电极,经长程颅内电极V—EEG监测进一步定位致痫灶。结果：3例难治性颡叶癫痫患者通过颅内电极V-EEG监测,并依据发作初始期的EEG异常放电特征确定了致痫灶,并进行病灶切除。结论：依据发作初始期颅内电极EEG痫样放电的部位和范围,能够为难治性癫痫外科手术治疗提供更可靠的定位指标。     

获得性癫癎失语综合征5例报告

目的：研究获得性癫癎失语综合征（Landau-Kleffner syndrome,LKS）的临床、脑电图（EEG）特征、治疗反应和远期预后。方法：对5例LKS患儿的临床表现、EEG特点和临床疗效进行观察,并结合文献进行探讨。结果：起病年龄为4～12岁。5例患儿均有不同类型的癫癎发作,伴有进行性失语,其中1例智力明显低下。5例均有EEG异常,其中3例有颞区局限性棘慢波发放。癫癎发作均可用抗癫癎药物控制。经皮质激素治疗,失语有改善。随访癫癎发作控制均良好,但语言恢复较正常差,EEG癎样放电好转。结论：LKS是一种以获得性失语和癫癎发作两大症状为主要临床表现的儿童时期癫癎性脑病。失语表现为听觉失认,多伴有其他精神行为异常。EEG常见颞区的局限性癎样放电,睡眠期常泛化至全导联,并可呈持续发放。抗癫癎药物可控制癫癎发作,但对失语疗效不佳。早期应用足量皮质激素治疗可明显改善失语情况。EEG及癫癎发作转归良好,但常遗留语言障碍。     

影像学正常的癫痫患者的SPECT与长程EEG研究

目的：探讨影像学（CT和MRI）正常的癫痫病例的发作间期SPECT与脑电图（EEG）特点。方法：对100例影像学正常病例在发作间期进行SPECT显像、EEG长程监测。结果：共100例中,男57例,女43例。年龄1～54岁。病程平均3．77年。可追溯到病因者63％。全身性发作58％（全身强直阵挛发作52％）,局灶性发作42％。发作间期SPECT异常100％,其中低灌注67％,高灌注30％,高一低灌注3％。异常灌注灶156个：脑区151个（97％）,其中颞叶76例94个（60％）。长程EEG监测正常17％,异常83％,异常者中90％有痫样放电。局灶性异常45％和弥漫性异常54％,EEG正常的全身性发作与局灶性发作差异明显（P〈0．01）;局灶性异常中全身性发作与局灶性发作比较差异有统计学意义（P〈0．05）。结论：影像学正常而发作间期SPECT异常的癫痫病例和EEG异常明显增高,全身性发作者各脑区均存在异常灌注灶,其中颞叶异常灌注灶占60．2％。     

儿童癫癎发作的临床特征与录像脑电图分析

目的：分析儿童癫痫发作的临床表现和录像脑电图(Video—EEG)特征。方法：对123例年龄9天至15岁癫痫患儿进行Video—EEG监测，记录并同步分析发作时EEG与临床表现。结果：123例中记录到568次发作，分三种类型。1、全面性发作53例201次发作：①婴儿痉挛18例中53次发作，发作期EEG表现为广泛低波幅快活动或高波幅慢波暴发与低电压抑制；②肌阵挛发作12例中79次发作，发作期EEG表现各导联多棘波、多棘慢波；③强直发作10例中24次发作，发作期EEG表现导联低波幅快节律、多棘慢波；④阵挛发作10例中39次发作，发作期EEG表现各导联棘慢波、尖慢波；⑤失神发作3例中6次发作，发作期EEG表现全导联3Hz棘慢波。2、部分性发作67例中339次发作．分别起源于额、中央、顶、颞、枕，其中38例191次发作为继发全身发作。3、混合发作3例中28次发作。结论：Video—EEG有助于临床医师对儿童癫痫的正确分型及指导治疗。     

颞叶癫癎的头皮和深部电极脑电发作期特点

目的：探讨手术治愈和基本治愈的颞叶癫癎（TLE）患者发作期头皮脑电图（EEG）和深部电极EEG的特点.方法：对25例立体定向射频热凝毁损颞叶内侧结构或常规手术切除后随访12月以上,Engel Ⅰ级（临床治愈）者21例和EngelⅡ级（临床基本治愈）者4例（共25例）的发作期头皮EEG和深部电极发作期特点进行分析.结果：头皮EEG描记时逢临床发作者19例,其中EEG为局限的5～13 Hz的典型阵发性节律波者10例,14～20 Hz的快波者4例,局限的2～5 Hz的正弦节律波者3例,EEG呈平坦化2例;深部EEG描记已临床发作者6例,均有15～6 Hz的节律波发放.结论：对于TLE头皮EEG对大多数发作能提供发作起始参考,对于EEG平坦化者需参考其它临床资料;深部电极EEG发作期脑电起始形式比较单一.     

脑电图在颞叶癫痫伴精神障碍患者中的临床应用

目的 探讨脑电图检查在颞叶癫痫伴精神障碍患者中的临床应用价值。方法 选取2013年6月~2018年7月我院确诊的颞叶癫痫伴精神障碍患者45例,所有患者进行常规脑电图、视频脑电图和蝶骨电极脑电图检查,对比分析其结果。结果 常规脑电图痫样波检出阳性率（24.44%）低于视频脑电图（48.89%）和蝶骨电极脑电图（64.44%）,差异具有统计学意义（P＜0.05）;癫痫样放电以左侧为主,前颞部位多见,定侧率为86.67%、定位率为91.11%;异常放电形式以棘波、尖波为主,5例患者未见癫痫样放电,以颞区θ、δ活动为主;脑电图背景活动异常表现为α节律衰减,β活动、θ和δ活动增加;清醒期患者癫痫波检出率（28.89%）低于睡眠期患者癫痫波检出率（53.33%）,差异有统计学意义（P＜0.05）。结论 颞叶癫痫伴精神障碍患者具有特征性的脑电图表现,背景活动异常、发作间期及发作期异常放电波形与部位等特点对颞叶癫痫的鉴别诊断及临床治疗有重要的临床价值。     

癫痫脑电信号符号动力学分析

癫痫是大脑神经元异常放电所引起的常见神经系统疾病,其发作具有突然性和反复性特点,因此,提前预测发作以便对患者及时采取措施具有重要意义。本文引入符号动力学方法分析癫痫大鼠失神性发作时脑电(EEG)信号的特性,并对影响符号统计量的关键参数的选取进行讨论,计算癫痫发作不同时期EEG信号的符号熵和时间不可逆转性。研究发现正常发作间隙期,符号熵和时间不可逆转性指标值较大;从发作间隙期向发作期的转化阶段,即发作前期,二者明显减小;发作时维持较低水平。研究结果表明符号动力学方法能够揭示癫痫EEG动力学特征变化,符号熵和时间不可逆转性两个指标是表征癫痫发作不同阶段的敏感特征量,具有重要的潜在临床应用价值。     

颞叶癫痫的临床特点与脑电图分析

目的：分析颞叶癫痫患的临床特点及脑电图定位的意义。方法：回顾分析92例颞叶癫痫患的脑电图。结果：左颞有癫痫样波42例，右颞有癫痫样波29例，双颞有癫痫样波21例，临床表现与癫痫样波发放部位有关，癫痫波的传导主要有容积传导和神经传导方式。结论：结合患临床表现与脑电图癫痫样波起始部位分析有助于致痫灶的定位。     

耐药性颞叶癫痫患者记忆功能损害的多因素分析

目的：观察耐药性颞叶癫痫患者记忆功能的损害并分析其影响因素。方法：采用韦氏记忆量表对32例耐药性颞叶癫痫患者记忆功能进行评估,并与32例普通癫痫患者进行比较,同时对可能的影响因素如发病年龄、发作频度、海马体积、脑电图异常放电范围、病程持续时间等进行相关性分析。结果：与普通癫痫患者比较,耐药性颞叶癫痫患者记忆功能普遍降低,尤其以短时记忆为明显。在其各种可能因素中,起病年龄、发作频度、抗癫痫药的种类和海马痫样放电的范围对记忆商（MQ）具有显著影响。结论：耐药性颞叶癫痫患者有明显记忆损害,起病年龄、发作频度、服用抗癫痫药的种类和海马痢样放电的范围是影响记忆功能的主要因素。     

儿童与成人起病的伴海马硬化的颞叶癫癎对比分析

目的对比分析儿童与成人起病组的伴海马硬化的颞叶癫癎（TLE-HS）患者临床特点的异同,以提高对该病的认识。方法：回顾性收集我院癫癎诊疗中心就诊的TLE-HS患者201例,依据患者起病年龄分成儿童起病组和成人起病组,收集病史、发作类型和频率、药物治疗、头部影像学、24 h视频脑电图（V—EEG）等临床资料,作对比分析。结果：儿童起病组较成人起病组伴热性惊厥（FS）史多、间断发作少,频繁发作多,差异均有统计学意义（P=0．013、0．013、0．013）;儿童起病组较成人起病组在发作间期EEG颞区以外癎样放电较多,差异有统计学意义（P=0．015）。两组患者在HS侧别、发作起源、发作类型、单用或联合用药、头部外伤史、脑炎史、家族史、精神发育迟滞、精神异常等方面比较差异均无明显统计学意义。结论：与成人起病组相比,儿童起病组伴FS史多,发作频率更高,这提示FS是导致癫癎患者更早起病的原因之一;儿童起病组发作间期EEG颞区以外癎样放电较多。