Surgery for extratemporal nonlesional epilepsy in children: a meta-analysis

Purpose

Previous small studies have demonstrated that seizure outcomes following surgery for extratemporal lobe epilepsy (ETLE) in children are worse than those for temporal lobe epilepsy. We have conducted a meta-analysis of the available literature to better understand ETLE surgical outcomes in children.

Methods

We searched PubMed (1990–2009) for appropriate studies using the following terms: ETLE, ETLE surgery, ETLE surgery outcome, frontal lobe epilepsy, occipital lobe epilepsy, and parietal lobe epilepsy. Our collected data included patient age at seizure onset and surgery, the cerebral lobe involved with epileptogenesis, MRI findings, predominant seizure semiology, intracranial monitoring use (electrode implantation), epileptic region histopathology, and postoperative seizure outcome. Statistical analysis was performed to determine associations among these variables and postoperative outcome.

Results

Ninety-five patients from 17 studies satisfied the inclusion criteria. Pathological findings (p?=?0.039) and seizure type (p?=?0.025) were significantly associated with outcome: A larger proportion of patients with cortical dysplasia and complex partial seizures experienced better outcomes. Age at surgery (p?=?0.073) and the cerebral resection site (p?=?0.059) were marginally associated with seizure outcome.

Conclusions

This study confirms previous reports: Surgical outcomes for ETLE epilepsy are significantly worse than those for temporal lobe epilepsy. The reasons for this difference may include the diffuse nature of the pathology involved in ETLE, difficulty in localizing the seizure focus in young children, and involvement of “eloquent” nonresectable cortex in epileptogenesis. Because of the reporting variability among different epilepsy centers, more uniform protocols are necessary for fair evaluation and comparison of outcomes among the different centers.     

Mesial Frontal Epilepsy

Summary: The mesiofrontal cortex comprises a number of distinct anatomic and functional areas. Structural lesions and cortical dysgenesis are recognized causes of mesial frontal epilepsy, but a specific gene defect may also be important, as seen in some forms of familial frontal lobe epilepsy. The predominant seizure manifestations, which are not necessarily strictly correlated with a specific ictal onset zone, are absence, hyper-motor, and postural tonic seizures. Other seizure types also occur. The task of localization of the epileptogenic zone can be challenging, whether EEG or imaging methods are used. Successful localization can lead to a rewarding outcome after epilepsy surgery, particularly in those with an imaged lesion.     

Musicogenic seizures can arise from multiple temporal lobe foci: intracranial EEG analyses of three patients

PURPOSE: To determine the ictal-onset zone of musicogenic seizures by using intracranial EEG monitoring. METHODS: Musicogenic seizures in three patients with medically intractable musicogenic epilepsy were first localized by using noninvasive methods including, in one patient, ictal magnetoencephalography (MEG) and magnetic resonance spectroscopy (MRS). The ictal-onset zones in these patients were then further localized using by intracranial EEG monitoring, and the outcomes of the two patients who underwent epilepsy surgery were determined. RESULTS: Patient 1's musicogenic seizures localized to the right lateral temporal lobe, patient 2's originated in the right mesial temporal lobe, and patient 3's arose independently from both mesial temporal lobes. Patients 1 and 2 underwent resective epilepsy surgery and are seizure free (Engel class I). CONCLUSIONS: Musicogenic epilepsy is a heterogeneous syndrome with seizures that can arise from multiple temporal lobe foci. Patients with medically intractable musicogenic epilepsy and with unilateral ictal onset zones may be considered candidates for resective epilepsy surgery.     

Seizure-related injuries are underreported in pharmacoresistant localization-related epilepsy

Purpose:   To investigate and compare injury rates, associated risk factors, circumstances, and medical record documentation in patients with pharmacoresistant temporal lobe epilepsy (TLE) and extratemporal lobe epilepsy (ETLE).
Methods:   The study cohort consisted of fifty-two consecutive adults with treatment-resistant epilepsy and seizure classification confirmed by video-electrocardiography (EEG) (28 with TLE and 24 with ETLE) who consented to participate. All subjects had their seizures classified with prior video-EEG monitoring, were followed in a tertiary-care center in northwest New York City, and received a semistructured phone interview regarding injuries experienced since being diagnosed with epilepsy.
Results:   Injuries were reported in 16 (57%) of the patients with TLE and 4 (17%) of the patients with ETLE (p = 0.004 after controlling for duration of epilepsy and seizure burden); 83% of all injuries were designated by patients as seizure-related. Most injuries (22 of 41; 54%) were classified as moderate or greater in severity. In addition, one motor vehicle accident (MVA) was reported in the TLE group and one episode of sudden unexpected death (SUDEP) was identified in the ETLE group. More than half (55%) of the injuries were not documented as seizure-related in medical records.
Conclusion:   A substantial number of potentially serious injuries are not documented as seizure related, even in a tertiary-care setting. Patients with pharmacoresistant TLE may be at higher risk for experiencing an injury than patients with pharmacoresistant ETLE.     

Continuous Source Imaging of Scalp Ictal Rhythms in Temporal Lobe Epilepsy

Summary: Purpose: We wished to determine whether continuous EEG source imaging can predict the location of seizure onset with sublobar accuracy in temporal lobe epilepsy (TLE).
Methods : We retrospectively analyzed the earliest scalp ictal rhythms, recorded with 23- to 27-channel EEG, in 40 patients with intractable TLE. A continuous source analysis technique with multiple fixed dipoles (Focus 1.1) decomposed the EEG into source components representing the activity of major cortical sublobar surfaces. For the temporal lobe, these were basal, anterior tip, anterolateral, and posterolateral cortex. Ictal EEG onset was categorized according to its most prominent and leading source component. All patients underwent intracranial EEG studies before epilepsy surgery, and all had a successful surgical outcome (follow-up >1 year).
Results : Most patients with ictal rhythms having a predominant basal source component had hippocampal-onset seizures, whereas those with seizures with prominent lateral source activity had predominantly temporal neocortical seizure origins. Seizures with a prominent anterior temporal tip source component mostly had onset in entorhinal cortex. Seizures in some patients had several equally large and nearly synchronous source components. These seizures, which could be modeled equally well by a single oblique dipole, had onset predominantly in either entorhinal or lateral temporal cortex.
Conclusions : Multiple fixed dipole analysis of scalp EEG can provide information about the origin of temporal lobe seizures that is useful in presurgical planning. In particular, it can reliably distinguish seizures of mesial temporal origin from those of lateral temporal origin.     

颅内电极埋藏在枕叶癫痫中的作用

目的探讨运用颅内电极埋藏进行视频脑电图监测在定位困难的枕叶癫痫中的作用。方法通过对9例枕叶癫痫但定侧定位困难的患者,向颅内可疑部位植入硬膜下条状电极,进行视频脑电图监测,记录发作间期及发作期脑电图变化,确定癫痫病灶起始区。通过手术切除致痫灶。结果本组9例埋藏时间为3～9d,平均5d,均记录到间歇期痫样放电及发作期脑电图情况。行枕叶局部皮层切除6例及枕叶切除3例。术后按照Engel评分,I级7例,II级2例。所有病例均未出现埋藏电极引起的并发症。结论在致痫灶定位困难的顽固性枕叶癫痫中,采用颅内电极埋藏进行脑电图监测,可以精确定位致痫灶,从而提高癫痫的治愈率。     

Speech During Partial Seizures: Intracranial EEG Correlates

Vocalization during a seizure may help predict the location of seizure onset or identify structures ultimately involved in the seizure. Spontaneous vocalization during seizures was studied retrospectively in 22 patients with refractory complex partial seizures evaluated with bilateral intracranial electrodes. Of 22 patients, 12 vocalized during seizures. Seizures were as likely to originate from language-dominant (6/12) as from language-nondominant mesial temporal cortex (6/12). Fluent speech frequently occurred as seizure activity was recorded from language-dominant temporal lobe neocortex (6/12 seizures). Of the patients with well-localized seizure onsets who did not speak (6/10), seizures arose from both language-dominant and -nondominant mesial temporal cortex. We conclude that the presence or absence of vocalizations during a seizure does not reliably indicate the anatomic regions in which the seizure begins or spreads.     

Surgically proven coexistence of focal and generalized epilepsy: A case report

The coexistence of focal and idiopathic generalized epilepsy (IGE) is rarely observed, and the mechanism underlying this situation remains unknown. We report a 13-year-old girl with well-controlled generalized epilepsy and medically-refractory left temporal lobe epilepsy.She underwent intracranial EEG recording, which demonstrated two characteristic seizure patterns of generalized ictal onset and left mesial temporal onset. In addition, two types of interictal spike distribution, including the left mesial temporal region and generalized spikes, were also supportive of the coexistence of left mesial temporal lobe epilepsy and IGE. Thereafter, a left anterior temporal lobectomy and post-surgical medication significantly improved her seizure outcome. This case illustrates the importance of considering surgical management for patients with medically-intractable focal epilepsy coexisting with generalized epilepsy.     

影响手术治疗难治性颞叶癫痫预后的危险因素探讨

目的探讨影响手术治疗难治性颞叶癫痫预后的危险因素.方法以手术方法治疗难治性颞叶癫痫患者42例,经至少1年随访,以术后癫痫发作频率系统对疗效进行评分,分析术前发作频率,婴儿期热性惊厥、脑炎、围产期脑损伤、颅内肿瘤、颅脑外伤等可能病因,可能病因发生年龄,发病年龄,手术年龄,病程和手术疗效的关系.结果发作频率≥1次/周者较＜1次/周者疗效差,两组间差异有显著性意义.有婴儿期热性惊厥患者与无婴儿期热性惊厥患者的疗效差异有显著性意义,前者优于后者.脑炎,围产期脑损伤,颅内肿瘤,颅脑外伤等可能病因,可能病因发生年龄,发病年龄,手术年龄,病程两组间差异无显著性意义.但经多重回归分析发现发作频率高是影响手术疗效的唯一危险因素.结论发作频率高是影响手术治疗难治性颞叶癫痫预后的唯一危险因素.     

Clinical features of seizures associated with parahippocampal/inferior temporal lesions compared to those with hippocampal sclerosis

Temporal lobe epilepsy (TLE) is not a unitary electroclinical imaging syndrome. We asked if seizures arising from the parahippocampal‐inferior temporal (PIT) region differ from those associated with hippocampal sclerosis (HS). The electroclinical features of 22 patients with HS and 14 patients with lesions in the PIT region who underwent epilepsy surgery and were seizure free for at least 2 years postoperatively were analyzed retrospectively. Patients with PIT lesions had a higher frequency of hypermotor and bilateral features and a lower frequency of behavioral arrest at the onset of seizure compared to cases with HS, suggesting that TLE originating in the PIT area can mimic frontal lobe epilepsy or contralateral mesial TLE.     

Intracranial electrographic analysis of preictal spiking and ictal onset in uni‐ and bitemporal epilepsy

Aim. Ictal onset patterns in bilateral mesial temporal lobe epilepsy have not been comprehensively studied. A retrospective review of intracranial electrographic data was undertaken to establish whether it is possible to distinguish between unilateral and bilateral mesial temporal lobe epilepsy based on ictal onset patterns, including periodic preictal spiking. Methods. A total of 470 ictal onset patterns were analyzed by bitemporal extraoperative electrocorticography in 13 patients with medically intractable mesial temporal lobe epilepsy. Ictal onset patterns were categorized, by frequency, as type A (<12 Hz), type B (12–40 Hz) and type C (>40 Hz). Preictal rhythmic spiking, of at least five seconds duration, and time to contralateral propagation were also measured with each ictal event. We determined if the proportion of “ictal onset pattern frequencies” or “incidence of preictal spiking” differed between unilateral and bilateral mesial temporal lobe epilepsy. Results. Seven patients with unilateral mesial temporal lobe epilepsy received surgery and achieved Engel class I outcomes, while the remaining six did not undergo resective surgery, due to the bilateral ictal onsets in extraoperative electrocorticography. The proportion of patients experiencing any preictal spikes was higher in unitemporal than in bitemporal cases (100% vs 50%; p=0.069). Of the 470 ictal onset patterns analyzed (174 unitemporal and 296 bitemporal), a significant greater percentage of preictal spikes was found in unilateral cases (78% unitemporal vs 14% bitemporal; p=0.002). Low‐frequency patterns were more evident in bitemporal cases (45%) than in unitemporal (10%), although the difference was not statistically significant (p=0.129). No differences were detected between the unitemporal and bitemporal groups regarding age at onset or at presentation. Conclusion. A greater proportion of preictal spiking, based on extraoperative electrocorticography, was present in unilateral, compared to bilateral, mesial temporal lobe epilepsy. Further studies are warranted to determine the causal significance of preictal spiking in mesial temporal lobe epilepsy.     

Lateralizing and localizing values of ictal onset recorded on the scalp: evidence from simultaneous recordings with intracranial foramen ovale electrodes

PURPOSE: The value of scalp recordings to localize and lateralize seizure onset in temporal lobe epilepsy has been assessed by comparing simultaneous scalp and intracranial foramen ovale (FO) recordings during presurgical assessment. The sensitivity of scalp recordings for detecting mesial temporal ictal onset has been compared with a "gold standard" provided by simultaneous deep intracranial FO recordings from the mesial aspect of the temporal lobe. As FO electrodes are introduced via anatomic holes, they provide a unique opportunity to record simultaneously from scalp and mesial temporal structures without disrupting the conducting properties of the brain coverings by burr holes and wounds, which can otherwise make simultaneous scalp and intracranial recordings unrepresentative of the habitual EEG. METHODS: Simultaneous FO and scalp recordings from 314 seizures have been studied in 110 patients under telemetric presurgical assessment for temporal lobe epilepsy. Seizure onset was identified on scalp records while blind to recordings from FO electrodes and vice versa. RESULTS: Bilateral onset (symmetric or asymmetric) was more commonly found in scalp than in FO recordings. The contrary was true for unilateral seizure onset. In seizures with bilateral asymmetric onset on the scalp, the topography of largest-amplitude scalp changes at onset does not have localizing or lateralizing value. However, 75-76% of seizures showing unilateral scalp onset with largest amplitude at T1/T2 or T3/T4 had mesial temporal onset. This proportion dropped to 42% among all seizures with a unilateral scalp onset at other locations. Of those seizures with unilateral onset on the scalp at T1/T2, 65.2% showed an ipsilateral mesial temporal onset, and 10.9% had scalp onset incorrectly lateralized with respect to the mesial temporal onset seen on FO recordings. In seizures with a unilateral onset on the scalp at electrodes other than T1/T2, the proportions of seizures with correctly and incorrectly lateralized mesial temporal onset were 37.5 and 4.2%, respectively. Thus the ratio between incorrectly and correctly lateralized mesial temporal onsets is largely similar for seizures with unilateral scalp onset at T1/T2 (16.7%) and for seizures with unilateral scalp onset at electrodes other than T1/T2 (11.2%). The onset of scalp changes before the onset of clinical manifestations is not associated with a lower proportion of seizures with bilateral onset on the scalp, or with a higher percentage of mesial temporal seizures or of mesial temporal seizures starting ipsilateral to the side of scalp onset. In contrast, the majority (78.4%) of mesial temporal seizures showed clinical manifestations starting after ictal onset on FO recordings. CONCLUSIONS: A bilateral scalp onset (symmetric or asymmetric) is compatible with a mesial temporal onset, and should not deter further surgical assessment. Although a unilateral scalp onset at T1/T2 or T3/T4 is associated with a higher probability of mesial temporal onset, a unilateral onset at other scalp electrodes does not exclude mesial temporal onset. A unilateral scalp onset at electrodes other than T1/T2 is less likely to be associated with mesial temporal onset, but its lateralizing value is similar to that of unilateral scalp onset at T1/T2. The presence of clinical manifestations preceding scalp onset does not reduce the localizing or lateralizing values of scalp recordings.     

儿童难治性颞叶癫痫的手术治疗

目的 探讨儿童难治性颞叶癫痫术前评估和手术方法 及影响癫痫预后的因素.方法 回顾性分析2007年7月至2009年2月手术治疗的21例儿童难治性癫痫患者中得到随访的19例临床资料,主要为复杂部分性发作.多数患者有腹部不适等发作先兆和咂嘴等发作时伴随自动动作.MRI扫描15例异常.6例行PET扫描均异常.头皮脑电图示局灶痫性放电7例,多灶痫性放电12例.施行一侧颞前叶+海马、杏仁核切除术15例,一侧颞前叶、海马、杏仁核+部分额叶皮层切除术4例.结果 随访12-30个月,癫痫发作结果 ,Engel Ⅰ级13例;Ⅱ级3例;Ⅲ级1例;Ⅳ级2例.随访期间对4例进行神经心理学评估,2例明显好于术前.无永久性神经缺损并发症.术后切除标本病理诊断结果 为颞叶皮层发育不良和颞叶内侧硬化等.结论 颞叶切除治疗儿童难治性癫痫多数预后良好.该手术安全、并发症少.发作表现、EEG以及神经影像学检查对致痫灶定位相互符合时,预示预后良好.早期手术可能对患儿的神经心理学改善有帮助.     

Localized Cerebellar Hypometabolism in Patients with Complex Partial Seizures

Summary: Purpose : We sought to determine the cause of cerebellar dysfunction in epilepsy and whether this dysfunction was directly related to seizures.
Methods : Cerebellar metabolism was evaluated in 48 patients with a well-defined region of seizure onset and with corresponding hypometabolism. Regions of interest (ROI) were drawn according to a standardized template. If the ROI/honepileptogenic cortex count rate ratio was outside the 95% confidence interval (CI) of controls, the ROI was defined as abnormal. The ratios from cerebellar hemispheres (defined as ipsi- or contralateral to the seizure onset region), were compared among controls (n = 8); patients who had seizure onsets and corresponding hypometabolism mesially in a temporal lobe (patient group 1, n = 19); patients whose seizures had onset mesially in a temporal lobe but spread rapidly to the ipsilateral frontal lobe and who had hypometabolism both in the affected temporal lobe and frontal lobe (patient group 2, n = 23); and patients who had seizure onsets and corresponding hypometabolism in the frontal lobe (patient group 3, n = 6).
Results : Significant hypometabolism was noted in the contralateral cerebellum of patients in groups 2 and 3 [p = 0.007 and p = 0.008, respectively; two-way analysis of variance (ANOVA)]. In contrast, patients in group 1 tended to have lower values in the ipsilateral cerebellum (p = 0.057).
Conclusions : The observed cerebellar changes are consistent with animal data showing that cerebellar connections to frontal lobes are numerous and crossed, whereas the connections to mesial temporal lobes are less abundant, bilateral, with an ipsilateral predominance. The difference between the two groups of patients with mesial temporal seizures suggests that cerebellar dysfunction in partial epilepsy, at least to a certain extent, is related to mechanisms involved in seizure generation and spread.     

Paediatric epilepsy surgery in the posterior cortex: a study of 62 cases

Past surgical series have emphasized the diagnostic complexity of posterior cortex epilepsy. Available data are sparse, especially in children, and most published series report a high number of surgical failures and post‐operative neurological deficits. In this article, we present a paediatric cohort of 62 children who underwent surgery for drug resistant posterior cortex epilepsy before the age of 16 years with a mean post‐operative follow‐up of 6.94 years (range: 2–16). Mean age at epilepsy onset was 3.2 years and 28 children (45%) had onset before 1 year of age. The mean age at surgery was 7.9 years (range: 1–16). Daily seizures were present in 63% of children. MRI was positive in 58 cases (93.5%) and invasive stereo‐EEG was judged mandatory in 24/62 (39%) of patients. Surgery was confined to the parietal lobe in 11 children, the occipital lobe in 8, the occipito‐parietal region in four, the occipito‐temporal region in 18, and involved both the temporal and parietal lobes in the remaining 21. Following surgery, 53 subjects (85.5%) remained seizure‐free and among those who underwent a SEEG procedure, 75% achieved seizure freedom. Focal cortical dysplasia was the most frequent histopathological diagnosis (50%), followed by tumoural (24%) and gliotic lesions (14.5%). An older age at epilepsy onset, the presence of a rather restricted epileptogenic area, and a complete resection of the epileptogenic zone were predictive of a favourable surgical outcome. These results demonstrate that a good surgical outcome is possible in children with drug resistant posterior cortex epilepsy. Accurate analysis of the chronology of ictal semiology and electrophysiological features, viewed in the context of the complete electroclinical pattern, provides a topographical orientation for posterior cortex epilepsy and, together with the presence of a lesion detectable on imaging, may improve the rate of surgical success of posterior cortex epilepsy at paediatric age.     

长程颅内电极监测定位技术在癫痫外科中的应用(附19例临床分析)

目的分析长程颅内电极对难治性癫痫患者的癫痫发作起源区定位作用,评估采用这一技术后的癫痫发作控制以及手术并发症的发生情况。方法19例难治性癫痫患者,采用常规脑电图及其它检查不能明确癫痫发作起源区位置,或癫痫发作起源区与重要功能区关系密切,对怀疑脑区进行颅内电极埋置术,术后进行长程颅内脑电监测,根据脑电情况,确定发作起源区,明确与功能区的部位后,进行切除术或多处软膜下横切术。结果19例患者中,核磁共振有双侧病变者5例,单侧病变9例,核磁共振阴性的患者5例。非侵袭性的术前评估方法结论不一致的有11例。手术后15例患者发作消失,3例患者发作频率减少90%以上,1例癫痫发作控制无效。1例患者发生永久性局限视野缺损,缺损为左上视野区,1例患者电极埋置术后出现一过性失语,切除术后未发生失语。结论对于采用常规脑电图及其它检查不能明确癫痫发作起源区位置,或癫痫发作起源区与重要功能区关系密切的患者,长程颅内脑电图监测能够准确定位发作起源区位置,回避功能皮质区,有效降低并发症的发生率。     

Intracranial EEG findings in patients with lesional lateral temporal lobe epilepsy

PURPOSE: Intracranial EEG in patients with lesional lateral temporal lobe epilepsy is rarely reported. Therefore, the number of patients with seizures arising independently from ipsilateral mesial structures or contralateral hemisphere has not been clarified. We analyzed the intracranial EEG of cases with localized lesion in the lateral temporal cortex. METHODS: We studied 15 patients who satisfied the following criteria: (1) MRI depicted a lesion less than 4cm in diameter located lateral to the collateral sulcus and at least 3cm posterior to the temporal pole; (2) intracranial EEG with electrodes placed on bilateral temporal lobes captured at least one complex partial seizure; and (3) postoperative follow-up period of 2 years or longer. The mean age of seizure onset was 16.6 years (range, 11-25) and that at surgery was 26.7 years (range, 16-36). RESULTS: A total of 147 complex partial seizures, 51 simple partial seizures, 16 secondarily generalized seizures, and over 80 subclinical seizures were recorded. On the lesional side, many clinical seizures were recorded from the lateral cortex. Independent of the lateral temporal onset seizures, ictal discharges originating from the mesial temporal structures were recorded in 7 of 15 patients (47%). Moreover, onset of ictal discharges from the contralateral temporal lobe was recorded in 7 of 15 patients (47%). Interictal spikes from ipsilateral mesial structures were recorded in all patients. The presence of ipsilateral mesial onset seizures was not associated with hippocampal neuron losses. CONCLUSION: Intracranial EEG analysis revealed that approximately one-half of the patients with structural lesions in the lateral cortex showed independent epileptogenic areas in ipsilateral mesial structures. Although ictal discharges originating from the contralateral temporal lobe were recorded in a half of these patients, this finding does not constitute a contraindication of resective surgery. Interictal spike is not an indicator of whether mesial structures should be resected.     

Entorhinal cortex MRI assessment in temporal,extratemporal, and idiopathic generalized epilepsy

PURPOSE: We previously showed a reduction in the volume of the entorhinal cortex (EC) ipsilateral to the seizure focus in patients with intractable temporal lobe epilepsy (TLE). The purpose of this study was to examine the specificity of EC atrophy in epilepsy. METHODS: We performed volumetric measurement of the EC on high-resolution magnetic resonance imaging (MRI) in patients with TLE (n = 70), extratemporal lobe epilepsy (ETE; n = 18), and idiopathic generalized epilepsy (IGE; n = 20). EC volumes of epilepsy patients were compared with those of 48 age- and sex-matched normal controls. Within the TLE group, 63 patients were selected prospectively with hippocampal atrophy ipsilateral to the seizure focus. The remaining seven patients were chosen retrospectively based on normal volumetric MRI of the hippocampus and amygdale, as well as normal histopathologic examination of the resected tissue. RESULTS: Compared with normal controls, EC volume was smaller ipsilateral but not contralateral to the seizure focus in patients with TLE (p < 0.001). No difference in the EC volumes ipsilateral and contralateral to the seizure focus was seen in patients with ETE and IGE compared with normal controls. The individual analysis showed that the EC was atrophic in 73% of TLE patients with hippocampal atrophy. Three of the seven TLE patients with normal volumetric MRI of the hippocampus and amygdala and normal histopathologic examination had EC atrophy ipsilateral to the seizure focus. In no patient with ETE or IGE was the EC found to be atrophic. CONCLUSIONS: EC atrophy ipsilateral to the seizure focus appears to be specific to mesial temporal lobe structural damage associated with TLE.     

Interictal regional delta slowing is an EEG marker of epileptic network in temporal lobe epilepsy

Purpose: Several studies have suggested that interictal regional delta slowing (IRDS) carries a lateralizing and localizing value similar to interictal spikes and is associated with favorable surgical outcomes in patients with temporal lobe epilepsy (TLE). However, whether IRDS reflects structural dysfunction or underlying epileptic activity remains controversial. The objective of this study is to determine the cortical electroencephalography (EEG) correlates of scalp‐recorded IRDS, in so doing, to further understand its clinical and biologic significances. Methods: We examined the cortical EEG substrates of IRDS with electrocorticography (ECoG‐IRDS) and delineated the spatiotemporal relationship between ECoG‐IRDS and both interictal and ictal discharges by recording simultaneously scalp and intracranial EEG in 18 presurgical candidates with TLE. Key Findings: Our results demonstrated that ECoG‐IRDS is typically a mixture of delta/theta slowing and spike‐wave potentials. ECoG‐IRDS was predominantly recorded from basal and anterolateral temporal cortex, occasionally in mesial, posterior temporal, and extratemporal regions. Abundant IRDS was most commonly observed in patients with neocortical temporal lobe epilepsy (NTLE), whereas infrequent to moderate IRDS was usually observed in patients with mesial temporal lobe epilepsy (MTLE). The anatomic distribution of ECoG‐IRDS was highly correlated with the irritative and seizure‐onset zones in 10 patients with NTLE. However, it was poorly correlated with the irritative and seizure‐onset zones in the 8 patients with MTLE. Significance: These findings demonstrate that IRDS is an EEG marker of epileptic network in patients with TLE. Although IRDS and interictal/ictal discharges likely arise from the same neocortical generator in patients with NTLE, IRDS in patients with MTLE may reflect a network disease that involves temporal neocortex.     

Propagation of seizures in a case of lesional mid‐cingulate gyrus epilepsy studied by stereo‐EEG

Little is known about the propagation of seizures arising from the cingulate gyrus, as cingulate coverage with interhemispheric subdural electrodes is usually challenging and incomplete due to inherent anatomical and vascular limitations. We present a case of lesional mid‐cingulate epilepsy confirmed by stereotactically implanted intracranial depth electrodes and subsequent surgical resection. Hypermotor symptomatology was seen during the first seven seconds of seizure onset while the seizure was still confined to the mid‐cingulate gyrus contacts. The patient had brief contralateral clonic movements as seizure propagated to the primary motor cortex. There was a high concordance between the primary propagation contacts, as delineated by intracranial EEG, and the contacts, with higher coherence values in the connectivity matrix. Interestingly, cingulate‐extra‐cingulate connectivity and spread to the primary motor, premotor, and prefrontal cortex was seen preceding spread to other cingulate contacts, of which one was less than 15 mm from the onset contact. This report is one of a few published, documenting propagation of seizures arising from the mid‐cingulate cortex. As illustrated by these data, hypermotor semiology correlated with direct activation of the cingulate cortex. Subsequent seizure propagation activated an extensive extra‐cingulate rather than an intra‐cingulate epileptogenic network. Interestingly, had the region of onset not sampled, the seizure onset would have appeared as non‐localizing widespread rhythms over the fronto‐parietal convexities. Further studies to explore the propagation of seizures arising from the cingulate gyrus and the physiological and pathological connectivity patterns within the cingulate gyrus in humans are needed, preferably using stereotactic implantation. Specific targets to be investigated are also discussed.