Usefulness of focal rhythmic discharges on scalp EEG of patients with focal cortical dysplasia and intractable epilepsy

We examined the significance and frequency of occurrence of rhythmic epileptiform discharges (REDs) on the scalp EEGs of 74 patients with intractable partial epilepsy. We also analyzed the relationship of this abnormality to the continuous epileptiform discharges (CEDs) recorded on ECoG. Both REDs and CEDs had been found to be highly specific and sensitive indicators of focal cortical dysplastic lesions. Thirty-four patients (group I) had focal cortical dysplastic lesions (FCDLs) and 40 (group II) had non-dysplastic structural lesions. REDs were observed in 15 (44%) of the 34 patients of group I and in none of group II. REDs did not occur in isolation, were associated with more intermittent interictal spikes involving other regions, but had a greater (P < 0.05) significance for the localization of the epileptogenic area. A strong relationship was observed between the presence of REDs on scalp EEG and the occurrence of CEDs on ECoG recordings. Twelve (80%) of 15 patients with REDs had CEDs. Focal cortical dysplastic lesions are likely to be present when rhythmic epileptiform discharges are found.     

Neurophysiologic findings of neuronal migration disorders: intrinsic epileptogenicity of focal cortical dysplasia on electroencephalography, electrocorticography, and magnetoencephalography

We define specific neurophysiologic characteristics for focal cortical dysplasia, a neuronal migration disorder. We reviewed data from published reports and our patients with focal cortical dysplasia. Our patients underwent preoperative scalp video-electroencephalography (EEG), magnetic resonance imaging (MRI), magnetoencephalography, and intraoperative or extraoperative electrocorticography monitoring. Scalp EEG showed trains of rhythmic epileptiform spike or sharp waves. Positive spikes correlated with early seizure onset, MRI lesion around the rolandic fissure, hemiparesis, and a less favorable outcome. Interictal electrocorticography showed continuous epileptogenic discharges: repetitive electrographic seizures and bursting discharges or continuous or quasicontinuous rhythmic spiking. Ictal electrocorticography showed paroxysmal fast and/or repetitive spiking. Magnetoencephalography showed clustered spike sources within and extending from the lesion. Cortical stimulation gave more frequent, lower-threshold afterdischarges and higher-threshold primary motor function. Focal cortical dysplasias are highly and intrinsically epileptogenic. For surgical seizure control, EEG, electrocorticography, and magnetoencephalography must delineate the intrinsic epileptogenic zone within and extending from the focal cortical dysplasia identified by MRI.     

Cortical resection with electrocorticography for intractable porencephaly-related partial epilepsy

PURPOSE: We evaluated the results of cortical resection of epileptogenic tissue for treatment of intractable porencephaly-related epilepsy. METHODS: We examined clinical features, electrophysiological data, surgical findings, and seizure outcomes after cortical resection in eight patients with intractable epilepsy related to porencephalic cysts. RESULTS: All eight patients had hemiparesis. Five retained motor function in the hemiparetic extremities; six retained visual fields. All had partial seizures, six with secondary generalization. Seven patients had simple and three had complex partial seizures (CPSs); two also had drop attacks. Four patients had multiple seizure types. Long-term scalp video-EEG (LVEEG) localized interictal epileptic abnormalities that anatomically corresponded to the cyst location in three patients. LVEEG recorded ictal-onset zones in five; these anatomically corresponded to the cyst location in three of the five. EEG recorded generalized seizures in two patients, hemispheric in one, and multifocal in two. Intraoperative electrocorticography (ECoG) revealed interictal epileptic areas extending beyond the margins of the cyst in seven patients. We resected ECoG-localized interictal epileptic areas completely in five patients and partially in two. Cortical resection was based on seizure semiology and LVEEG in one patient whose ECoG showed no epileptiform discharges. After a minimum follow-up of 1 year, six patients had excellent seizure outcome (Engel class I), and two had a >90% seizure reduction (Engel class III) without complications. CONCLUSIONS: Cortical resection guided by ECoG allows preservation of motor function and visual field and provides an effective surgical procedure for treatment of intractable epilepsy secondary to porencephaly.     

Continuous electrocorticogram epileptiform discharges due to brain gliosis.

Cortical dysplasia is known to produce continuous epileptiform discharges (CEDs) on electrocorticogram (EcoG) and EEG recordings. The authors studied the incidence of CEDs on ECoGs and correlated this data with pathologic findings. Thirty ECoGs were reviewed that were performed on patients with parietal or occipital lobe epilepsy operated on since 1960. CED was classified as: (1) continuous or semicontinuous rhythmic spikes or sharp waves at frequencies ranging from 2 to 8 Hz, and (2) repetitive bursts of rhythmic polyspike activity lasting 2 to 10 s. All nontumoral pathologic specimens were reviewed. Epileptiform activity was classified using the following criteria: focal (one gyrus), regional (two gyri), lobar (three gyri), bilobar, or multilobar. Pathologic examination showed gliosis in eight specimens, focal cortical dysplasia in five specimens, tumoral lesions in eight specimens, and other pathology in nine specimens. CED was found in 11 ECoGs. In seven pathology specimens, significant gliosis was shown, and in the remaining four specimens, a dysplastic lesion was diagnosed. Epileptiform activity was widespread (lobar, bilobar, or multilobar) when gliosis or focal cortical dysplasia was present. Absence of epileptiform activity or a focal/regional distribution was found in tumors and other lesions. These data suggest that extensive gliotic lesions are highly epileptogenic and produce CEDs, which are morphologically undistinguishable from those produced by focal cortical dysplasia.     

Safety of single and repetitive focal transcranial magnetic stimuli as assessed by intracranial EEG recordings in patients with partial epilepsy

The safety of single and repetitive (paired and quadruple) focal transcranial magnetic stimuli as possible inducers of epileptic discharges or clinically manifest seizures was investigated in 21 patients with intractable epilepsy during invasive presurgical monitoring. Subdural and/or intracerebral depth electrodes had been implanted in close proximity to the suspected epileptogenic zone, and the anticonvulsant medication had been reduced. Focal transcranial magnetic stimuli were applied by a Magstim QuadroPulse magnetic stimulator over the hand area of the motor cortex ipsilateral to the epileptogenic focus at intensities of 120% and 150% of motor threshold and additionally as close as possible to the suspected epileptogenic zone at 40–100% of maximal stimulator output. Stimulation did not induce any complex partial or secondary generalized tonic-clonic seizures. One patient with hippocampal sclerosis experienced an aura associated with rhythmic electroencephalographic discharges restricted to the ipsilateral intrahippocampal depth electrode after stimulation over his left temporal lobe. This patient, however, also had frequent spontaneously occurring auras with focal ictal discharges originating from this hippocampus. Interictal discharges were not influenced significantly by single or repetitive magnetic stimuli. In conclusion, from this study there is no evidence that single or serial focal transcranial magnetic stimuli activate epileptogenic foci. At least four high-frequency repetitive stimuli of high intensity may thus be applied with a low risk of seizure induction even in patients with low seizure threshold. Received: 17 December 1998 Received in revised form: 17 March 1999 Accepted: 6 April 1999     

外伤性癫痫的临床特征分析及手术治疗

目的 总结外伤性癫痫的临床特征及手术效果。方法 对病人进行神经学检查及EEG、CT、MRI及ECT检查，确定致痫灶后手术治疗，手术中行皮层及深部脑电监测。结果 外伤性癫痫病人32例，年龄10至45岁。临床主要表现有全身强直痉挛性发作、部分性发作、精神运动发作、失神发作。头皮脑电图显示32例病人中30例患者有与损伤部位或对冲部位相符的恒定局限性高波幅尖波、棘波和棘慢波。所有病人均在皮层及深部脑电监测下切除病灶。术后15例已完全停止发作，16例已明显好转，1例无明显改变。结论 外伤性癫痫的临床特点包括局灶性发作多见，癫痫发作形式多样和致痫灶在影像学改变附近。手术切除病灶能获良好效果。     

Localization of the Epileptic Focus During Methohexital-Induced Anesthesia

A short anesthesia was provided by methohexital for painless percutaneous removal of subdural electrodes in 27 patients with medically intractable, complex partial seizures who had undergone invasive preoperative evaluation. Electrocorticographic(ECoG) recordings performed before and during the narcosis were submitted to visual (n = 27) and computerized (n = 3) analysis to obtain additional information about the location of the epileptic focus (or foci). The following observations were made: focal epileptiform potentials were induced in 24 of 27 patients (89%); (b) in 20 of these 24, the induced spikes appeared amid or were followed by isoelectric or subdelta activity. These spikes were characterized by high amplitude as well as rhythmic and synchronized appearance over a circumscribed focal area (or areas) known to be spontaneously epileptogenic. This phenomenon, termed spike-burst-suppression (SBS) pattern, allowed identification of the primary epileptic focus in many patients with temporal lobe epilepsy. Furthermore, it indicated a good outcome of epilepsy surgery. Computerized analysis of the induced synchronized spikes (n = 3) allowed further delineation of the primary site of epileptogenicity and quantitative comparison of multiple epileptic generators. ECoG recording during deep methohexital-induced narcosis is a valuable tool for lateralization and delineation of the primary epileptogenic focus.     

Epilepsy with temporal encephalocele: Characteristics of electrocorticography and surgical outcome

Temporal lobe encephaloceles (TEs) are increasingly identified in patients with epilepsy due to advances in neuroimaging. Select patients become seizure‐free with lesionectomy. In practice, however, many of these patients will undergo standard anterior temporal lobectomy. Herein we report on the first series of patients with refractory temporal lobe epilepsy (TLE) with encephalocele to undergo chronic or intraoperative electrocorticography (ECoG) in order to characterize the putative epileptogenic nature of these lesions and help guide surgical planning. This retrospective study includes nine adult patients with magnetic resonance imaging/computed tomography (MRI/CT)–defined temporal encephalocele treated between 2007 and 2014 at University of California San Francisco (UCSF). Clinical features, ECoG, imaging, and surgical outcomes are reviewed. Six patients underwent resective epilepsy surgery. Each case demonstrated abnormal epileptiform discharges around the cortical area of the encephalocele. Two underwent tailored lesionectomy and four underwent lesionectomy plus anterior medial temporal resection. Postoperatively, five patients, including both with lesionectomy only, had Engel class Ia surgical outcome, and one had a class IIb surgical outcome. The role of TE in the pathogenesis of epilepsy is uncertain. ECoG can confirm the presence of interictal epileptiform discharges and seizures arising from these lesions. Patients overall had a very good surgical prognosis, even with selective surgical approaches.     

Brain stimulation for epilepsy: can scheduled or responsive neurostimulation stop seizures?

PURPOSE OF REVIEW: Scheduled and responsive direct brain stimulation may be an effective and safe therapy for medically intractable epilepsy. RECENT FINDINGS: Scheduled stimulation (open loop) has been provided via electrodes implanted in thalamic nuclei, the cerebellum and the hippocampus using devices commercially available for treatment of tremor and Parkinson's disease. Small pilot trials suggest that seizure frequency is reduced in some patients with intractable epilepsy. Responsive stimulation requires systems that detect abnormal electrographic activity and provide stimulation (closed loop). Studies in inpatients and outpatients suggest that abnormal electrographic discharges can be detected before there is evolution into a clinical seizure, and that focal stimulation of the epileptogenic region terminates electrographic seizures and reduces the frequency of clinically evident seizures. SUMMARY: Direct brain stimulation appears to be safe and may be efficacious in treating medically intractable epilepsy. The optimal location (deep brain or cortical) and characteristics of the stimulation (frequency, current, duration), and whether stimulation should be focal or responsive are still to be determined. If ongoing studies of a deep brain stimulator and of a cranially implanted responsive neurostimulator demonstrate effectiveness, then neurostimulation may become available as adjunctive therapy for medically intractable epilepsy.     

脑穿通畸形相关性癫(癎)的手术治疗(附12例分析)

目的 评价外科切除致(癎)皮质治疗脑穿通畸形相关性顽固性癫(癎)的疗效.方法 回顾性分析12例脑穿通畸形病人的临床特征、电生理数据、术中所见及致(癎)皮质切除后的癫(癎)发作情况.本组均为部分性发作,继发全面性发作9例,复杂部分性发作3例.长程视频脑电图(VEEG)显示:发作间期VEEG异常与囊肿位置吻合7例,分布弥散5例;发作期VEEG异常6例,其中5例与囊肿位置吻合.对术前VEEG和术中皮质脑电图(ECoG)显示的间期异常区、可能的症状区、硬化皮质和磁共振流体抑制翻转复原序列(MRI-flair像)上的高信号区等予以切除.结果 随访6个月～7年,本组均获Engel Ⅰ级控制,其中2例仍有先兆发作.无并发症发生.结论 在脑穿通畸形病人中,致(癎)灶不仅涉及电生理异常区(包括术前VEEG及术中ECoG异常区),也可能涉及解剖异常区(包括术前MRI-flair像上的高信号区及术中所见硬化皮质).这些异常区的充分切除和功能区的确切保护为脑穿通畸形性顽固性癫(癎)的外科治疗提供了一个有效的办法.     

Intrinsic epileptogenicity of focal cortical dysplasia as revealed by magnetoencephalography and electrocorticography

Focal cortical dysplasia (FCD) is often associated with severe partial epilepsy. In this study, we performed magnetoencephalography (MEG) and electrocorticogrsphy (ECoG) on four patients with FCD-associated epilepsy to confirm the 'intrinsic' epileptogenicity of FCD. In all patients, we determined the three-dimensional locations of the magnetic sources of the interictal paroxysmal activities by a single dipole model, and then the estimated dipole localization was superimposed on the magnetic resonance image. The dipole clusters were located in the T2-prolonged lesions, namely in the FCD lesions themselves. All patients underwent surgery for their medically intractable epilepsy, and the acute and/or chronic ECoG were thereafter recorded. Either frequent or continuous paroxysmal activities were recorded from the ECoG electrodes which were placed over the surface of the FCD lesion, while few paroxysmal activities were observed on the normal appearing adjacent cortex. Intraoperative depth recordings were performed in a patient with the needle electrode inserted into the FCD lesion and they revealed these paroxysmal foci to be located not on the cortical surface but at a depth of 15 mm from the cortical surface where both abnormal giant neurons and bizarre large eosinophilic cells (so-called balloon cells) were also prominently observed on the postoperative histological sections. Following a lesionectomy combined with the removal of the underlying white matter, three patients demonstrated a favorable seizure outcome. Our findings thus suggest the FCD lesions to be highly and intrinsically epileptogenic lesions.     

Subdural Recording of Ictal DC Shifts in Neocortical Seizures in Humans

Summary: Purpose: Invasive ictal EEG recording is often necessary to delineate epileptogenic areas in patients with intractable partial epilepsy, but even intracranial ictal recordings often reveal ill-defined onset zones in neocortical epilepsy. We studied the physiologic significance of ictal direct current (DC) potentials recorded intracranially in human epilepsy.
Methods: We made intracranial ictal EEG recordings in three patients with intractable partial seizures arising from frontal, lateral temporal, and parietal neocortical areas by using closely spaced subdural electrodes (platinum in two patients and stainless steel in one patient) with both standard (1.5 Hz) and open (0.016 Hz) low-frequency filter (LFF) settings.
Results: The initial ictal pattern was localized to two to nine subdural electrodes and characterized by very low voltage and high-frequency rhythmic activity ("electrode-cremental pattern"). A slow-rising negative potential (DC potential) was seen in a slightly more restricted area (two to six electrodes) and occurred 1–10 s before the initial ictal EEG discharges in two patients.
Conclusions: These results agree with those of previous studies of ictal DC shifts in animals and suggest that ictal DC shifts may be helpful in delineating the epileptogenic area more precisely in human epilepsy.     

Continuous potential display of ictal electrocorticography.

The objective of this study was to determine whether the animation of electrical activity recorded on ictal electrocorticograms (ECoGs) can demonstrate the propagation of seizure discharges from the epileptogenic zone (EZ) to the surrounding cortical area. A computer program, continuous potential display (CPD), was designed to animate the color-coded potential changes in 5-msec intervals at each recorded site. This program was used to analyze 35 ictal ECoGs recorded by subdural grid electrodes from 11 subjects who underwent epilepsy surgery for intractable partial seizures. Continuous potential display demonstrated recurrent cycles of seizure propagation from the EZ to the surrounding cortical area even when seizure discharges appeared widespread on ECoG. Hence, the EZ could be mapped at any time during the seizure course. The EZ mapped by analyzing a small fraction of ECoG during widespread seizure discharges using CPD only overlapped 69 +/- 24% (mean +/- standard deviation) of the surgical area. The EZ mapped by CPD had 34 +/- 22% false positives and 35 +/- 27% false negatives. Animation of potential changes recorded by ictal ECoG can assist in studying the temporal and spatial patterns of seizure propagation and in mapping the EZ for surgical resection.     

Surgical management of intractable epilepsy associated with cerebral neurocytoma

Neuronal neoplasms of the CNS constitute a rarely encountered group of tumors. This report concerns the surgical management of seizures encountered in four cases (ranging from 2 to 10 years-of-age at onset; consisting of two males and two females) of a recently recognized morphologically unique tumor, called 'cerebral neurocytoma'. All patients were associated solely with intractable complex partial seizures. The tumor involved the temporal lobe in two cases, and the frontal in two. Magnetoencephalography (MEG) clearly demonstrated an accumulation of equivalent current dipoles originating from the interictal spikes on the cortex around the tumor. On intra-operative electrocorticography (ECoG), the epileptogenic zone was topographically distinct from the region of the tumor. No definite ECoG activities were observed at the tumor site, although this tumor did consist of small mature neuronal cells. Either a complete or a subtotal resection of the tumor and the epileptogenic cortex was performed and, post-operatively, universal freedom from seizures was demonstrated in all patients. A histological examination of the epileptogenic cortex revealed the presence of minute cortical dysplasia or tumor involvement in the hippocampus. A resection of the epileptogenic cortex along with the tumor was thus found to improve the seizure outcome in patients with neurocytoma-associated epilepsy without inducing any identifiable neurological deficits attributable to the incremental resection.     

Epileptogenicity of focal malformations due to abnormal cortical development: direct electrocorticographic-histopathologic correlations

PURPOSE: Malformations due to abnormal cortical development (MCDs) are common pathologic substrates of medically intractable epilepsy. The in situ epileptogenicity of these lesions as well as its relation to histopathologic changes remains unknown. The purpose of this study was to correlate the cellular patterns of MCDs with the expression of focal cortical epileptogenicity as assessed by direct extraoperative electrocorticographic (ECoG) recordings by using subdural grids. METHODS: Fifteen patients with drug-resistant focal epilepsy due to pathologically confirmed MCD who underwent subdural electrode placement for extraoperative seizure localization and cortical mapping between 1997 and 2000 were included in the study. Areas of interictal spiking and ictal-onset patterns were identified and separated during surgery for further pathologic characterization (cellular and architectural). Three pathologic groups were identified: type I; architectural disorganization with/without giant neurons, type IIA; architectural disorganization with dysmorphic neurons, and type IIB; architectural disorganization, dysmorphic neurons, and balloon cells (BCs). The focal histopathologic subtypes of MCDs in cortical tissue resected were then retrospectively correlated with in situ extraoperative ECoG patterns. RESULTS: Cortical areas with histopathologic subtype IIA showed significantly higher numbers of slow repetitive spike pattern in comparison with histopathologic type I (p = 0.007) and normal pathology (p = 0.002). The ictal onset came mainly from cortical areas with histopathologic type IIA (nine of 15 patients). None of the seizures originated from neocortical areas that showed BC-containing MCD (type IIB). CONCLUSIONS: This study shows that areas containing BCs are less epileptogenic than are closely located dysplastic regions. These results suggest a possible protective effect of BCs or a severe disruption in the neuronal networks in BCs containing dysplastic lesions. Further studies are needed to elucidate the nature and the potential role(s) of balloon cells in MCD-induced epileptogenicity.     

皮层脑电图辅助立体定向下手术治疗颅内钙化灶引起的难治性癫痫

目的研究立体定向下开放式手术联合术中皮层脑电图(ECoG)监测治疗颅内钙化灶性癫痫的手术方法、注意事项及效果。方法 21例颅内单发钙化灶引起的癫痫患者(其中主要功能区钙化灶9例),在立体定向仪导向下,开放直视手术,ECoG监测钙化灶周围皮层脑电活动情况,切除钙化灶后再次ECoG监测,确定致痫灶的范围及处理方式。结果所有钙化灶均被顺利切除。钙化灶区域ECoG监测无明显异常5例,表现为阵发性与动脉搏动相一致的单发性棘慢复合波发放9例,表现为明显癫痫样放电7例。单纯钙化灶切除术14例,钙化灶+周边增生组织+致痫皮层切除术4例,钙化灶切除+功能区致痫皮层低功率电凝热灼术3例。术后ECoG监测发现异常放电消失11例,仍残存轻中度痫样放电5例。无严重并发症。随访6个月～8年,EngelⅠ级16例,EngelⅡ级5例,总有效率100%。结论 ECoG监测是立体定向下手术治疗颅内钙化灶性癫痫的重要辅助手段,能够指导术中采取相应的手术方式切除钙化灶,妥善处理致痫灶,避免过多损伤脑皮层。     

Can intraoperative electrocorticography patterns predict surgical outcome in patients with temporal lobe epilepsy secondary to unilateral mesial temporal sclerosis?

INTRODUCTION: Intraoperative electrocorticography (ECoG) can be performed in cases of temporal lobe epilepsy due to hippocampal sclerosis (TLE-HS). However, its significance and correlation with surgical outcome are still controversial. OBJECTIVES: To analyze the electrophysiological characteristics of temporal lobe structures during ECoG of patients with TLE-HS, with emphasis on the comparison between pre- and post-resection recordings and surgical outcome. PATIENTS AND METHODS: Seventeen patients with refractory TLE-HS submitted to corticoamigdalohipocampectomy were included in the study. Clinical variables included age at the onset, duration of epilepsy and seizure outcome. The post-operative follow-up ranged from 24 to 36 months. According to outcome subjects were divided in two subgroups: (A) individuals free of seizures (Engel 1A), and (B) individuals not-free of seizures (Engel 1B-IV). Four patterns of ECoG findings were identified: isolated discharges; high frequency spikes (HFS); continuous discharges; combination of isolated discharges and HFS. According to predominant topography ECoG was classified as mediobasal, lateral (or neocortical), mediobasal and lateral. RESULTS: The progressive removal of the temporal pole and the hippocampus was associated with significant decrease of neocortical spikes. No correlation between clinical variables and seizure outcome was observed. Patients who only had isolated spikes on intraoperative ECoG presented a statistical trend for excellent surgical control. Patients who presented temporal pole blurring on MRI also had better post-surgical seizure outcome. CONCLUSIONS: This study showed that out of diverse clinical and laboratory variables, only isolated discharges on intraoperative ECoG and temporal pole blurring on MRI predicted excellent post-surgical seizure outcome. However, other studies with larger number of patients are still necessary to confirm these findings.     

Ictal electrocorticographic findings related with surgical outcomes in nonlesional neocortical epilepsy

PURPOSE: To characterize ictal electrocorticographic features related to surgical outcomes in nonlesional neocortical epilepsy (NE). METHODS: We analyzed 187 ictal electrocorticograms (ECoG) obtained from 18 patients who had undergone presurgical evaluation and subsequent neocortical resections (frontal: seven, parietal: one, occipital: four, multilobar: six). None of them had any MRI-detectable lesions. Various ECoG data sets recorded from eight patients who achieved a favorable surgical outcome (either seizure free or more than 90% reduction of seizure frequencies) were compared with that from ten patients with unfavorable outcome (less than 90% reduction of seizure frequencies) (follow up duration: 47+/-11 months). RESULTS: Reproducible ictal onset zone (IOZ) in recurrent seizures (P=0.013) and persistent ictal discharges in IOZ from the onset to the end of seizure (P=0.004) were found more frequently in the patients with good outcome. Ictal onset patterns consisting of low voltage fast or high amplitude beta spikes predicted a good surgical outcome while rhythmic sinusoidal activity or rhythmic spike/sharp waves of slow frequency were predictive of poor outcome (P=0.01). The ictal onset rhythm consisting of gamma or beta frequencies was more prevalent in the favorable group (P=0.015). CONCLUSIONS: The presence of stable ictal circuit suggested by the consistent earliest activation of specific electrodes in the repetitive seizures (reproducible IOZ) and the active participation of IOZ throughout the attack were valuable prognostic factors in addition to the morphology and frequency of ictal onset rhythm.     

The clinical and prognostic relevance of the postictal slow focus in the electrocorticogram

Electrocorticograms of 192 complex partial seizures which were recorded via chronically implanted subdural electrodes during presurgical evaluation of 64 patients with medically intractable epilepsy were visually analysed. The objective was to assess the diagnostic and prognostic relevance of postictal slow foci (PISF) in the electrocorticogram which were defined as focal isoelectric activity or as a focal burst-suppression pattern. The following results were obtained: (1) PISF were seen in a total of 114 of 192 seizures (59.4%), (2) 48 of 64 patients (75%) demonstrated at least 1 PISF in 3 seizures, (3) PISF were more frequent in seizures of temporal lobe origin (66%) than in those of extratemporal origin (33.3%), (4) no PISF developed if the electrographic seizure duration was < 32 sec, (5) PISF were (predominantly) localized in the lobe of seizure origin in 85%v of the seizures, (6) there was a strong correlation between frequent occurrence of temporal PISF and favourable seizure outcome following temporal lobe surgery. In conclusion, PISF contribute valuable data as to the localization of the epileptogenic zone during presurgical evaluation of epilepsy and indicate favourable seizure outcome following temporal lobe surgery.     

难治性癫痫的致痫灶定位及手术治疗研究

目的评价难治性癫痫的致痫灶定位方法和皮层电极监测下致痫灶切除,加行多处软脑膜下横纤维切断术(MST)治疗癫痫的疗效。方法对47例难治性癫痫病人的致痫灶,采用CT MRI EEG 单光子发射计算机体层摄影(SPECT) 皮层脑电脑(ECoG)联合检测定位。对检出的阳性病灶在皮层电极监测显微镜下行致痫灶切除,切除后监测仍有癫痫波者加行MST;致痫灶位于重要功能区者单行MST。结果致痫灶阳性检出率86%。皮层电极检测显微镜下致痫灶切除加MST,术后91%的病人癫痫发作停止,半年后约15%的病人复发,但症状较术前减轻,持续时间较术前短。结论CT MRI EEG SPECT ECoG联合检测,对手术定位具有较高价值。皮层电极监测下致痫灶切除术及MST创伤轻微、效果比较可靠、治愈率高、并发症少、复发率低。病灶及致痫灶的不完全切除和形成皮层软化及疤痕,可能是导致癫痫复发的重要原因。