Epilepsy surgery in patients with bilateral temporal lobe seizures: A systematic review

We explored the association between magnetic resonance imaging (MRI) lesion, degree of seizure laterality on intracranial electroencephalography (iEEG), and seizure outcome in patients with ambiguous or presumed bilateral temporal lobe epilepsy (BiTLE) on scalp EEG. We systematically reviewed the literature using Embase and MEDLINE up to May 31, 2012. Patients with bilateral iEEG, temporal lobe surgery, and follow‐up ≥1 year were included. We undertook three separate analyses on patients whose scalp EEG showed ambiguous onset or BiTLE (1) group data of those whose iEEG demonstrated unilateral TLE, (2) group data of those whose iEEG demonstrated BiTLE, (3) individual patient analysis in those with BiTLE for whom iEEG seizure laterality data were provided. Of 1,403 patients with ambiguous or presumed BiTLE on scalp EEG, 1,027 (73%) proved to have unilateral TLE on iEEG and contributed to the first analysis. Of these, 58% had Engel class I and 9% Engel class II outcomes. Of 132 patients in the second analysis (true BiTLE), Engel class I and II outcomes were achieved in 23% and 14%, respectively. Of 41 patients in the third analysis, 66% and 2% had Engel class I and II outcomes, respectively. The median proportion of seizures ipsilateral to the resection on iEEG did not differ between BiTLE patients with Engel class I–II (76%) and Engel III–IV (78%) outcomes (p = 0.87). Patients with ambiguous or independent bitemporal seizure onset on scalp EEG achieved good surgical outcomes. Overall, a significantly higher proportion of patients achieved good outcomes when iEEG showed unilateral TLE (67%) than when it showed true BiTLE (45%). However, the degree of seizure lateralization in those with BiTLE was not associated with seizure outcome, and it has a limited role in selecting the side of surgery.     

Standardized Computer‐based Organized Reporting of EEG: SCORE

The electroencephalography (EEG) signal has a high complexity, and the process of extracting clinically relevant features is achieved by visual analysis of the recordings. The interobserver agreement in EEG interpretation is only moderate. This is partly due to the method of reporting the findings in free‐text format. The purpose of our endeavor was to create a computer‐based system for EEG assessment and reporting, where the physicians would construct the reports by choosing from predefined elements for each relevant EEG feature, as well as the clinical phenomena (for video‐EEG recordings). A working group of EEG experts took part in consensus workshops in Dianalund, Denmark, in 2010 and 2011. The faculty was approved by the Commission on European Affairs of the International League Against Epilepsy (ILAE). The working group produced a consensus proposal that went through a pan‐European review process, organized by the European Chapter of the International Federation of Clinical Neurophysiology. The Standardised Computer‐based Organised Reporting of EEG (SCORE) software was constructed based on the terms and features of the consensus statement and it was tested in the clinical practice. The main elements of SCORE are the following: personal data of the patient, referral data, recording conditions, modulators, background activity, drowsiness and sleep, interictal findings, “episodes” (clinical or subclinical events), physiologic patterns, patterns of uncertain significance, artifacts, polygraphic channels, and diagnostic significance. The following specific aspects of the neonatal EEGs are scored: alertness, temporal organization, and spatial organization. For each EEG finding, relevant features are scored using predefined terms. Definitions are provided for all EEG terms and features. SCORE can potentially improve the quality of EEG assessment and reporting; it will help incorporate the results of computer‐assisted analysis into the report, it will make possible the build‐up of a multinational database, and it will help in training young neurophysiologists.     

视频脑电图与发作期SPECT对痫灶定位的对比研究

目的 探讨视频脑电图(VEEG)、发作期SPECT在术前痫灶定位中的作用.方法 回顾性对比分析48例难治性癫痫患者术前所行长程VEEG与发作期SPECT定位的情况,比较两者定位的一致性.结果 发作期SPECT定位阳性率为94%,VEEG为96%.两者完全一致占46%,部分一致占29%,完全不一致占25%.阳性率及定侧率差异无统计学意义(P＞0.05),局灶定位差异有统计学意义(P＜0.01).随访结果显示48例患者中Engel Ⅰ级27例,Ⅱ级10例,Ⅲ级8例,Ⅳ级3例;其中EngelⅠ～Ⅱ级的37例中33例来自两者定位一致的患者.结论 发作期SPECT与VEEG检查有较高的一致性,两者联合应用优势互补,可提高定位准确性,获得良好的手术疗效.     

Cross‐sensory modulation of alpha oscillatory activity: suppression,idling, and default resource allocation

Alpha oscillations (~10 Hz) have been suggested to have an inhibitory influence on stimulus processing within the context of attention being coordinated across space, with an increase in the power of alpha activity occurring in spatially irrelevant regions. However, with respect to cross‐sensory attention (distribution of attention to different sensory modalities) an increase in alpha activity from baseline has not yet been definitively linked to active inhibition of distraction. In the current study, we examined the role of top‐down alpha modulation in facilitating and suppressing stimulus processing between the visual and auditory domain. We utilized two cross‐sensory paradigms, one containing distractors while the other paradigm only contained targets, in order to separate distractor related activity. We found a cue induced increase from baseline for the power of occipital alpha activity in posterior cortex when participants anticipated the occurrence of auditory targets combined with visual distractors. Interestingly, there was no increase in alpha power observed in the condition where auditory targets occurred without distractors. These findings suggest that the increase in alpha activity from baseline reflects top‐down drive processes serving to inhibit distracting input. However, we found that there was no significant difference in the absolute occipital alpha power between when participants were expecting a visual distractor, and the session where no visual distractors were present. We account for these findings by suggesting that an increase in alpha power in the anticipation of visual distractors, rather than being exclusively inhibitory, could also signal the re‐allocation of resources in the sensory systems.     

Functional brain mapping of ictal activity in gelastic epilepsy associated with hypothalamic hamartoma: A case report

Hypothalamic hamartomas (HHs) have been demonstrated as the cause of gelastic epilepsy, both by intracranial electrodes and functional imaging. The neocortex becomes secondarily involved, through poorly characterized propagation pathways. The detailed dynamics of seizure spread have not yet been demonstrated, owing to the limited spatial–temporal resolution of available functional mapping. We studied a patient with epilepsy associated with HH and gelastic epilepsy. Simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) of several seizure events were obtained, with blood oxygen level dependent (BOLD) activation of the hamartoma, and left hemisphere hypothalamus, hippocampus, parietal–occipital area, cingulate gyrus, and dorsal–lateral frontal area. Integration of regional BOLD kinetics and EEG power dynamics strongly suggests propagation of the epileptic activity from the HH through the left fornix to the temporal lobe, and later through the cingulate fasciculus to the left frontal lobe. The EEG/fMRI method has the spatial–temporal resolution to study the dynamics of seizure activity, with detailed demonstration of origin and propagation pathways.