Resective Epilepsy Surgery Research Articles

Determinants of health-related quality of life of patients with focal epilepsy: A systematic literature review.

Focal epilepsy can have significant negative impacts on a person's health-related quality of life (HRQoL). Although studies have been published on HRQoL in persons with focal epilepsy (PWFE), determinants of HRQoL have not been comprehensively examined. This systematic literature review (SLR) queried existing literature to identify aspects associated with HRQoL in PWFE without focus on resective epilepsy surgery, with an interest in identifying modifiable determinants for medical/nonmedical interventions. This SLR was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Searches were conducted in PubMed and Google Scholar for articles published from January 1, 1900, to February 19, 2023, reporting on the association between HRQoL or employability and a range of demographic, psychosocial, or epilepsy-related factors and comorbidities in PWFE. A total of 879 abstracts were identified, with 126 manuscripts reviewed and 37 studies selected for inclusion that quantified the relationship between HRQoL and the variable of interest by multivariate (N = 21) or univariate only (N = 15) methods; 10 multivariate models also included univariate data. In adjusted models, the most commonly examined determinants of HRQoL included depression (n = 15/21), number of antiseizure medications (ASMs; n = 13/21), seizure frequency (continuous seizure count, n = 11/21; seizure freedom, n = 5/21), anxiety (n = 10/21), duration of disease (n = 9/21), and cognition (n = 9/21). Depression, anxiety, and cognition were frequently seen as significant contributors to HRQoL when studied (14/15 [93%], 9/10 [90%], and 7/9 [78%], respectively). Among concepts studied less frequently, ASM severity/adverse event burden was significant each time examined (in 5/19 studies). Attainment of seizure freedom and employability was significant 75% (n = 3/4) and 72% (n = 5/7) of the time, respectively. Poor HRQoL in PWFE can be attributed to a multitude of factors, including depression, anxiety, factors in disease management, and employability. An unmet need remains in addressing elements associated with poor HRQoL in this population.

Combination Resective or Ablative Epilepsy Surgery with Neurostimulation for Complex Epilepsy Networks: A Case Series

Introduction: Complex epilepsy networks with multifocal onset zones that overlap with eloquent cortex may benefit from combined surgical approaches. However, limited data exist on outcomes associated with performing these therapies in tandem. In this case series, we report on 6 patients who underwent combination surgery with either resection or laser interstitial thermal therapy (LITT) and neuromodulation with responsive neurostimulation (RNS) or deep brain stimulation (DBS). Methods: We performed a retrospective review of adult patients with medically refractory epilepsy who underwent staged combination epilepsy surgeries during the same admission at our institution. Six cases treated between 2019 and 2023 were identified. All patients underwent a presurgical work-up including invasive intracranial monitoring and underwent a combined approach with either surgical resection, LITT, RNS, or DBS. We extracted data on demographic, clinical, and surgical characteristics. The primary outcome was change in seizure frequency from baseline. Results: The mean age was 42.7 years old (4 female). All patients had at least one epileptogenic zone in the temporal lobe, two in extratemporal neocortex, two in periventricular nodular heterotopia. For the staged combination approach, 3 patients underwent LITT followed by RNS, two underwent resection and RNS, and one received LITT and DBS. The mean reduction in seizure frequency per month at last follow-up was 90%. Postoperatively, 1 patient experienced superior visual field deficits related to LITT, and another had postoperative deep vein thrombosis. Conclusion: All patients experienced at least an 83% reduction in seizures. This case series demonstrates the potential benefits of a combined surgical approach in patients with multifocal seizures and at least one lesion that can be safely resected or ablated. Future prospective studies are warranted.

Resective epilepsy surgery and its impact on depression in adults: a systematic review, meta-analysis, and implications for future research

BackgroundHow epilepsy surgery influences the bidirectional relationship of epilepsy and depression remains poorly defined.MethodFor a better understanding of this question, we conducted a systematic review and meta-analysis of risk ratio...

Resective surgery for mesial temporal lobe epilepsy associated with hippocampal sclerosis in patients over 50 years: a case-control study.

Mesial temporal lobe epilepsy associated with hippocampal sclerosis (MTLE/HS) is the most common cause of drug-resistant focal seizures and surgical resection is the primary treatment option, with seizure-free rates ranging from 60 to 80%. However, data on postsurgical seizure outcomes in patients ≥ 50years of age are limited. This study aimed to assess the efficacy and safety of surgery in this age group compared to younger patients. We performed a retrospective analysis of data from resective surgeries conducted in patients with MTLE/HS between 1990 and 2022. We focused on patients aged ≥ 50years and compared the surgical safety and efficacy variables between this group and a control group of patients aged < 50years through a case-control study. Among the 450 MTLE/HS patients who underwent surgery during the inclusion period, 61 (13.6%) were aged ≥ 50years and matched with 183 younger patients, totaling 244 study participants. The two groups had similar characteristics. At the last follow-up (median 5.7years), Engel I outcomes were achieved in 80.3% of the older patients and 81.4% of the younger patients, with no significant difference (p = 0.85). Postoperative cognitive and psychiatric outcomes did not differ between the groups. Major complication rates were also comparable, at 3.3% in the older group and 2.7% in the younger group (p = 0.83). The extratemporal ictal abnormalities observed on video-EEG were the only variable that demonstrated a significant association with an unfavorable seizure outcome in the older group (OR 9.3, 95% CI [1.8-47.6], p = 0.005). This study provides grade 3 evidence that resective surgery for MTLE/HS patients aged ≥ 50years is as effective and safe as it is for younger patients, and thus should be considered as the primary treatment option for drug-resistant cases.

The Fingerprint of Scalp-EEG in Drug-Resistant Frontal Lobe Epilepsies.

Scalp-EEG incompletely covers the frontal lobe cortex. Underrepresentation of frontobasal or frontomesial structures, fast ictal spreading, and false lateralization impede scalp-EEG interpretation. Hence, we investigated the significance of scalp-EEG in the presurgical workup of frontal lobe epilepsy. Using descriptive statistical methods and Pearson chi-squared test for group comparisons, we retrospectively investigated postsurgical outcome, interictal epileptiform discharges (iiEDs), and electrographic seizure patterns on scalp-EEG in 81 consecutive patients undergoing resective epilepsy surgery within the margins of the frontal lobe. Postoperatively, patients with frontopolar iiEDs (n = 7) or concordant frontopolar iiED focus and seizure-onset (n = 2) were seizure free (n = 7/7, Engel Ia). MRI-positive patients with frontopolar iiEDs or frontopolar seizure-onset (n = 1/8 Engel Id, n = 7/8 Engel Ia) underwent surgery without stereo-EEG. Thirteen of 16 patients with frontolateral (n = 8/10, Engel Ia), or left frontobasal (n = 5/6, Engel Ia) seizure-onset undergoing further stereo-EEG, were seizure-free postoperatively. Seizure-onset prevalent over one electrode (n = 37/44 Engel I, p = 0.02), fast activity (FA)/flattening at seizure-onset (n = 29/33 Engel I, p = 0.02), FA/flattening during the seizure (n = 38/46 Engel I, p = 0.05), or focal rhythmic sharp-/spike-/polyspike-and-slow waves during the seizure (n = 24/31, Engel Ia, p = 0.05) were favorable prognostic markers. Interictal polyspike waves (p = 0.006 for Engel Ia) and interictal paroxysmal FA (p = 0.02 for Engel I) were unfavorable prognostic markers. Frontopolar scalp-EEG findings serve as biomarkers for predicting favorable surgical outcome in lesional frontal lobe epilepsy. Consequently, careful analysis of scalp-EEG assists in bypassing stereo-EEG in these patients.

Minimally Invasive Epilepsy Surgery.

Surgery remains a critical and often necessary intervention for a subset of patients with epilepsy. The overarching objective of surgical treatment has consistently been to enhance the quality of life for these individuals, either by achieving seizure freedom or by eliminating debilitating seizure types. This review specifically examines minimally invasive surgical approaches for epilepsy. Contemporary advancements have introduced a range of treatments that offer increased safety and efficacy compared to traditional open resective epilepsy surgeries. This manuscript provides a comprehensive review of these techniques and technologies.

Predictors of SOZ localization, subsequent surgical intervention, and seizure outcomes in iEEG.

A third of the patients who undergo intracranial EEG (iEEG) for seizure-onset zone (SOZ) localization do not proceed to resective surgery for epilepsy, and over half of those who do continue to have seizures following treatment. To better identify candidates who are more likely to see benefits from undergoing iEEG, we investigated preoperative and iEEG peri-operative features associated with the localization of a putative SOZ, undergoing subsequent surgical treatment, and seizure outcomes. We conducted a retrospective cohort study of consecutive patients who underwent iEEG from 2001 to 2022 at two institutions. Outcomes included SOZ identification, proceeding to surgical treatment (resection vs. neuromodulation), and subsequent seizure freedom. We identified 329 unique patients who were followed for a median of 3.9 (IQR:7) years, with a minimum of 2-year follow-up for seizure outcomes analyses. Multivariate analysis identified lateralized and lobar localization on scalp EEG (OR 3.8, p = 0.001) to be associated with SOZ localization. Patients with unilateral localization on scalp EEG (OR 3.0, p = 0.003), unilateral preimplantation hypothesis (OR 3.1, p = 0.001), and lesional preoperative MRI (OR 2.1, p = 0.033) were more likely to undergo resection than neuromodulation. Similarly, a unilateral pre-implantation hypothesis (OR 2.6, p < 0.001) favored seizure freedom, whereas prior neuromodulation (OR 0.3, p = 0.013) decreased the odds. Larger number of preoperative anti-seizure medications (ASMs) did not influence seizure freedom rates but did decrease favorable (Engel I, II) seizure outcomes (OR 0.7, p = 0.026). Non-invasive localization data prior to iEEG are associated with subsequent resection and seizure freedom, independent of iEEG localization. Factors predictive of SOZ localization are not necessarily predictive of post-operative seizure freedom.

Seizure freedom but not epilepsy surgery is associated with fewer neuropsychiatric difficulties in patients with tuberous sclerosis

BackgroundDrug-resistant epilepsy (DRE) in selected individuals with the rare tuberous sclerosis complex (TSC) may benefit from resective epilepsy surgery. Furthermore, associated neuropsychiatric disorders (TAND) are common in patients with TSC; however, long-term data on how surgery affects neuropsychiatric comorbidities are sparse. Materials and methodsTwo retrospective approaches were used to identify children with TSC and DRE with onset at < 18 years of age. The study group (surgical) was identified through the Swedish National Epilepsy Surgery Registry (n = 17), a registry with complete national coverage since 1990 and prospective patient enrolment since 1995. The reference group (non-surgical) was identified by searching medical records retrieved from the tertiary hospital of Southern Sweden (n = 52). Eligible participants were invited to complete the validated TAND lifetime checklist. Those who did not complete the checklist, never had DRE, or were aged < 7 years old were excluded from the study. The reference group was balanced with the study group for putative confounders, in the following hierarchical order: DRE at the survey, age at seizure onset, age at follow-up, and sex. ResultsAfter the balancing procedure, both groups comprised 13 participants. The median time from epilepsy onset to the survey was 18.5 (range: 7.75–40.25) and 16.0 (7.33–33.5) years in the study and reference groups, respectively. The median time from surgery to the survey was 13 years (range: 4–22). No significant differences were found in behavioural problems, autism spectrum disorder diagnosis or symptoms, or intellectual disability between the groups, regardless of surgery. Seizure-free individuals (n = 11) performed better in social skills (p = 0.016), intellectual skills (p = 0.029), and overall TAND scores (p = 0.005) than the non-seizure-free group (n = 15). ConclusionThis is the first study to evaluate TAND comorbidities during the long-term follow-up after epilepsy surgery in patients with TSC. We found no evidence of the adverse effects of TAND comorbidities after tuberectomy. However, a larger study that allows for a better adjustment for confounders is needed. Following previous studies, seizure-free individuals had fewer symptoms within most TAND domains compared with the group with uncontrolled epilepsy, indicating less severe symptomatology.

Changes in overlap of subjective and objective cognition over time in epilepsy surgery candidates

PurposeSubjective and objective cognition often show weak overlap in persons with epilepsy (PWE). Over- as well as underestimation may occur. In particular after epilepsy surgery, objective memory decline is often not subjectively reported. Additionally, studies on how concordance of subjective and objective cognition changes over time are missing. Therefore, we study the extent of concordance in operated and non-operated PWE over time. MethodsCandidates for resective epilepsy surgery were assessed between 03/18 and 12/20 (T1) with self-report questionnaires and underwent a neuropsychological examination. For 21 operated as well as 27 non-operated PWE follow-up data was obtained one to three years later (T2). Concordance of attention and memory were compared between groups and time points. Moreover, reliable change was calculated and compared between groups. ResultsOf the total sample, 42 % rated their attention performance realistically and 25 % showed memory concordance. Differences in patterns of over- and underestimation between groups and over time occurred for attention, but not for memory. Overestimation of memory was more frequent in operated than non-operated PWE, especially at T2 (67% vs. 11 %). In the operated group, we mainly observed reliable improvement in subjective cognition and decline in objective memory, whereas non-operated PWE showed more frequently decline of simple attention. Reliable subjective and objective change did not co-occur. ConclusionConcordance of subjective and objective cognition is low. Over- as well as underestimation may persist over time. Domain-specific perspectives are necessary. Tendencies of operated PWE to develop overestimation of memory after surgery should be considered in neuropsychological interventions.

Outcomes of stereoelectroencephalography following failed epilepsy surgery in children.

Stereoelectroencephalography (SEEG) is valuable for delineating the seizure onset zone (SOZ) in pharmacoresistant epilepsy when non-invasive presurgical techniques are inconclusive. Secondary epilepsy surgery after initial failure is challenging and there is limited research on SEEG following failed epilepsy surgery in children. The objective of this manuscript is to present the outcomes of children who underwent SEEG after failed epilepsy surgery. In this single-institution retrospective study, demographics, previous surgery data, SEEG characteristics, management, and follow-up were analyzed for pediatric patients who underwent SEEG after unsuccessful epilepsy surgery between August 2016 and February 2023. Fifty three patients underwent SEEG investigation during this period. Of this, 13 patients were identified who had unsuccessful initial epilepsy surgery (24%). Of these 13 patients, six patients (46%) experienced unsuccessful resective epilepsy surgery that targeted the temporal lobe, six patients (46%) underwent surgery involving the frontal lobe, and one patient (8%) had laser interstitial thermal therapy (LITT) of the right insula. SEEG in two thirds of patients (4/6) with initial failed temporal resections revealed expanded SOZ to include the insula. All 13 patients (100%) had a subsequent surgery after SEEG which was either LITT (54%) or surgical resection (46%). After the subsequent surgery, a favorable outcome (Engel class I/II) was achieved by eight patients (62%), while five patients experienced an unfavorable outcome (Engel class III/IV, 38%). Of the six patients with secondary surgical resection, four patients (67%) had favorable outcomes, while of the seven patients with LITT, two patients (29%) had favorable outcomes (Engel I/II). Average follow-up after the subsequent surgery was 37 months ±23 months. SEEG following initial failed resective epilepsy surgery may help guide next steps at identifying residual epileptogenic cortex and is associated with favorable seizure control outcomes.

150 Backbone Spiking Sequence as a Basis for Preplay, Replay, and Default States in Human Cortex

INTRODUCTION: Sequences of spiking activity are a fundamental feature of many neural systems, and recent evidence suggests that they play an important role in information coding in the human brain. A parallel set of studies also asserts that sequential activity may in part derive from a pre-existing network structure. Sequential spiking activity therefore may arise as a natural property of the neurophysiologic properties of the human cortex. METHODS: We measured single unit spiking activity in the human cortex by implanting Utah micro-electrode arrays into participants who performed an episodic memory task while undergoing invasive monitoring for potential resective epilepsy surgery. RESULTS: We confirm the presence of an average backbone spiking sequence identified during pre-task rest that is stable over time and different cognitive states. These resting backbone sequences served as a scaffold for cognitively relevant sequential spiking activity occurring later in the recording session. We further demonstrate that backbone sequences are composed of both rigid and flexible sequence elements, and that flexible elements serve to promote memory specificity when forming and retrieving new memories. CONCLUSIONS: Here we demonstrate that backbone sequences can be measured in the human cortex and that they persist over time and through different cognitive states. Our data show that backbone sequences are composed of both rigid and flexible elements, and flexibility around the backbone allows for the formation of memory specific spiking sequences. Taken together, our results provide the first evidence for backbone spiking sequences in the human cortex, and more generally suggest a cognitive role of predetermined spiking network dynamics in the human brain.

Monopolar stereoelectroencephalography-guided radiofrequency thermocoagulation.

Stereoelectroencephalography (SEEG)-guided radiofrequency thermocoagulation (RFTC) has the advantage of producing a lesion in the epileptogenic zone (EZ) at the end of SEEG. The majority of published SEEG-guided RFTCs have been bipolar and usually performed between contiguous contacts of the same electrode. In the present study, the authors evaluate the safety, efficacy, and benefits of monopolar RFTC at the end of SEEG. This study included a series of 31 consecutive patients who had undergone RFTC at the end of SEEG for drug-resistant focal epilepsy in the period of January 2013-December 2019. Post-RFTC seizure control was assessed after 2 months and at the last follow-up visit. Twenty-one patients underwent resective epilepsy surgery after the SEEG-guided RFTC, and the postoperative seizure outcome among these patients was compared with the post-RFTC seizure outcome. Four hundred forty-six monopolar RFTCs were done in the 31 patients. Monopolar RFTCs were performed in all cortical areas, including the insular cortex in 11 patients (56 insular RFTCs). There were 31 noncontiguous lesions (7.0%) because of vascular constraints. The volume of one monopolar RFTC, as measured on T2-weighted MRI immediately after the procedure, was between 44 and 56 mm3 (mean 50 mm3). The 2-month post-RFTC seizure outcomes were as follows: seizure freedom in 13 patients (41.9%), ≥ 50% reduced seizure frequency in 11 (35.5%), and no significant change in 7 (22.6%). Seizure outcome at the last follow-up visit (mean 18 months, range 2-54 months) showed seizure freedom in 2 patients (6.5%) and ≥ 50% reduced seizure frequency in 20 patients (64.5%). Seizure freedom after monopolar RFTC was not significantly associated with the number or location of coagulated contacts. Seizure response after monopolar RFTC had a high positive predictive value (93.8%) but a low negative predictive value (40%) for seizure outcome after subsequent resective surgery. In this series, the only complication (3.2%) was a limited intraventricular hematoma following RFTC performed in the hippocampal head, with spontaneous resolution and no sequelae. The use of monopolar SEEG-guided RFTC provides more freedom in terms of choosing the SEEG contacts for thermocoagulation and a larger thermolesion volume. Monopolar thermocoagulation seems particularly beneficial in cases with an insular EZ, in which vascular constraints could be partially avoided by making noncontiguous lesions within the EZ.

Specific consistency score for rational selection of epilepsy resection surgery candidates.

Degree of indication for epilepsy surgery is determined by taking multiple factors into account. This study aimed to investigate the usefulness of the Specific Consistency Score (SCS), a proposed score for focal epilepsy to rate the indication for epilepsy focal resection. This retrospective cohort study included patients considered for resective epilepsy surgery in Kyoto University Hospital from 2011 to 2022. Plausible epileptic focus was tentatively defined. Cardinal findings were scored based on specificity and consistency with the estimated laterality and lobe. The total points represented SCS. The association between SCS and the following clinical parameters was assessed by univariate and multivariate analysis: (1) probability of undergoing resective epilepsy surgery, (2) good postoperative seizure outcome (Engel I and II or Engel I only), and (3) lobar concordance between the noninvasively estimated focus and intracranial electroencephalographic (EEG) recordings. A total of 131 patients were evaluated. Univariate analysis revealed higher SCS in the (1) epilepsy surgery group (8.4 [95% confidence interval (CI) = 7.8-8.9] vs. 4.9 [95% CI = 4.3-5.5] points; p < .001), (2) good postoperative seizure outcome group (Engel I and II; 8.7 [95% CI = 8.2-9.3] vs. 6.4 [95% CI = 4.5-8.3] points; p = .008), and (3) patients whose focus defined by intracranial EEG matched the noninvasively estimated focus (8.3 [95% CI = 7.3-9.2] vs. 5.4 [95% CI = 3.5-7.3] points; p = .004). Multivariate analysis revealed areas under the curve of .843, .825, and .881 for Parameters 1, 2, and 3, respectively. SCS provides a reliable index of good indication for resective epilepsy surgery and can be easily available in many institutions not necessarily specializing in epilepsy.

Measurable transitions during seizures in intracranial EEG: A stereoelectroencephalography and SPECT study

ObjectiveIctal Single Photon Emission Computed Tomography (SPECT) and stereo-electroencephalography (SEEG) are diagnostic techniques used for the management of patients with drug-resistant focal epilepsies. While hyperperfusion patterns in ictal SPECT studies reveal seizure onset and propagation pathways, the role of ictal hypoperfusion remains poorly understood. The goal of this study was to systematically characterize the spatio-temporal information flow dynamics between differently perfused brain regions using stereo-EEG recordings. MethodsWe identified seizure-free patients after resective epilepsy surgery who had prior ictal SPECT and SEEG investigations. We estimated directional connectivity between the epileptogenic-zone (EZ), non-resected areas of hyperperfusion, hypoperfusion, and baseline perfusion during the interictal, preictal, ictal, and postictal periods. ResultsCompared to the background, we noted significant information flow (1) during the preictal period from the EZ to the baseline and hyperperfused regions, (2) during the ictal onset from the EZ to all three regions, and (3) during the period of seizure evolution from the area of hypoperfusion to all three regions. ConclusionsHypoperfused brain regions were found to indirectly interact with the EZ during the ictal period. SignificanceOur unique study, combining intracranial electrophysiology and perfusion imaging, presents compelling evidence of dynamic changes in directional connectivity between brain regions during the transition from interictal to ictal states.

Stereoelectroencephalography-Guided Radiofrequency Thermocoagulation: Diagnostic and Therapeutic Implications.

Despite recent medical therapeutic advances, approximately one third of patients do not attain seizure freedom with medications. This drug-resistant epilepsy population suffers from heightened morbidity and mortality. In appropriate patients, resective epilepsy surgery is far superior to continued medical therapy. Despite this efficacy, there remain drawbacks to traditional epilepsy surgery, such as the morbidity of open neurosurgical procedures as well as neuropsychological adverse effects. SEEG-guided Radiofrequency Thermocoagulation (SgRFTC) is a minimally invasive, electrophysiology-guided intervention with both diagnostic and therapeutic implications for drug-resistant epilepsy that offers a convenient adjunct or alternative to ablative and resective approaches. We review the international experience with this procedure, including methodologies, diagnostic benefit, therapeutic benefit, and safety considerations. We propose a framework in which SgRFTC may be incorporated into intracranial EEG evaluations alongside passive recording. Lastly, we discuss the potential role of SgRFTC in both delineating and reorganizing epilepsy networks.

Triggered Seizures for Ictal SPECT Imaging: A Case Series and Feasibility Study.

Ictal SPECT is an informative seizure imaging technique to tailor epilepsy surgery. However, capturing the onset of unpredictable seizures is a medical and logistic challenge. Here, we sought to image planned seizures triggered by direct stimulation of epileptic networks via stereotactic electroencephalography (sEEG) electrodes. Methods: In this case series of 3 adult participants with left temporal epilepsy, we identified and stimulated sEEG contacts able to trigger patient-typical seizures. We administered 99mTc-HMPAO within 12 s of ictal onset and acquired SPECT images within 40 min without any adverse events. Results: Ictal hyperperfusion maps partially overlapped concomitant sEEG seizure activity. In both participants known for periictal aphasia, SPECT imaging revealed hyperperfusion in the speech cortex lacking sEEG coverage. Conclusion: Triggering of seizures for ictal SPECT complements discrete sEEG sampling with spatially complete images of early seizure propagation. This readily implementable method revives interest in seizure imaging to guide resective epilepsy surgery.

Association Between Magnetoencephalography-Localized Epileptogenic Zone, Surgical Resection Volume, and Postsurgical Seizure Outcome.

Surgical resection of magnetoencephalography (MEG) dipole clusters, reconstructed from interictal epileptiform discharges, is associated with favorable seizure outcomes. However, the relation of MEG cluster resection to the surgical resection volume is not known nor is it clear whether this association is direct and causal, or it may be mediated by the resection volume or other predictive factors. This study aims to clarify these open questions and assess the diagnostic accuracy of MEG in our center. We performed a retrospective cohort study of 68 patients with drug-resistant epilepsy who underwent MEG followed by resective epilepsy surgery and had at least 12 months of postsurgical follow-up. Good seizure outcomes were associated with monofocal localization (χ2 = 6.94, P = 0.001; diagnostic odds ratio = 10.2) and complete resection of MEG clusters (χ2 = 22.1, P < 0.001; diagnostic odds ratio = 42.5). Resection volumes in patients with and without removal of MEG clusters were not significantly different (t = 0.18, P = 0.86; removed: M = 20,118 mm3, SD = 10,257; not removed: M = 19,566 mm3, SD = 10,703). Logistic regression showed that removal of MEG clusters predicts seizure-free outcome independent of the resection volume and other prognostic factors (P < 0.001). Complete resection of MEG clusters leads to favorable seizure outcomes without affecting the volume of surgical resection and independent of other prognostic factors. MEG can localize the epileptogenic zone with high accuracy. MEG interictal epileptiform discharges mapping should be used whenever feasible to improve postsurgical seizure outcomes.

Resective Epilepsy Surgery after Corpus Callosotomy in Children with Lennox-Gastaut Syndrome

Purpose: This study examined the characteristics and outcomes of resective epilepsy surgery following corpus callosotomy (CC) in children with Lennox-Gastaut syndrome (LGS).Methods: We retrospectively analyzed 17 children with LGS who underwent resective surgery (RS) after CC over a span of 10 years, with a minimum of 2 years of follow-up, at a single tertiary epilepsy center in Korea.Results: Of the 17 patients, 13 (73.5%) demonstrated favorable surgical outcomes (Engel class I or II) at 1 year after RS, and eight (47.1%) were ultimately free of seizures 2 years after surgery. A significantly larger decrease in the number of anti-seizure medications taken from before to 2 years after the final surgical procedure was observed in the group that became seizure-free than in the group with persistent seizures (&lt;i&gt;P&lt;/i&gt;=0.062). Furthermore, a significantly greater decline in daily adaptive function was found in the persistent seizure group (&lt;i&gt;P&lt;/i&gt;=0.059). The baseline characteristics, results of presurgical evaluation, and treatment-related factors assessed prior to surgery showed no significant differences between the seizure-free group and the group with persistent seizures.Conclusion: In conclusion, RS may be a viable option for patients with LGS who exhibit lateralization and/or localization on presurgical evaluation after CC, as the procedure may reveal a concealed primary focus. The proactive implementation of two-stage epilepsy surgery could provide significant seizure reduction and preservation of cognitive function in carefully selected patients with LGS.

Who are the Better Candidates for Epilepsy Surgery?

The resective epilepsy surgery can be the effective procedure to get seizure-free outcome in these drug resistant epilepsy (DRE) patients. Class I evidence firmly establishes the superiority of epilepsy surgery over medical treatments in both seizure control and quality of life for DRE patients. For the effective identification of optimal surgical candidates, it's essential to understand the prognostic factors of epilepsy surgery based on the surgical methods employed. Established positive prognostic indicators for temporal resection include the presence of hippocampal sclerosis on magnetic resonance imaging (MRI), focal lesions on MRI, unilateral temporal spikes, concordant ictal electroencephalography (EEG), and a history of prolonged febrile convulsion. Potential negative predictors encompass preoperative secondary generalized tonic-clonic seizures, a normal MRI, postoperative EEG spikes, and age at the time of surgery. For neocortical epilepsy, the prognostic factors identified through multivariate analysis were the presence of a discrete lesion, localized hypometabolism on Fluorodeoxyglucose positron emission tomography (FDG-PET), and localized ictal EEG. A significant correlation was found between achieving a seizure-free outcome in no visible lesion on MRI (MR-negative) epilepsy patients and having concordance in two or more presurgical evaluations, specifically in interictal EEG, ictal EEG, FDG-PET, and ictal single-photon emission computed tomography. There was a marked improvement in the seizure-free outcome in MR-negative temporal lobe epilepsy (TLE) by the application of this strategy. The better surgical candidates for epilepsy surgery are the followings: patients displaying a discrete lesion on MRI with concordant video-EEG monitoring (VEM) results, patients diagnosed with unilateral hippocampal sclerosis who have concordant VEM results, patients with unilateral hippocampal sclerosis but discordant VEM results, patients with focal cortical dysplasia and concordant VEM results, and patients diagnosed with MR-negative TLE who exhibit two or more consistent results from presurgical evaluations.

High frequency oscillations in relation to interictal spikes in predicting postsurgical seizure freedom

We evaluate whether interictal spikes, epileptiform HFOs and their co-occurrence (Spike + HFO) were included in the resection area with respect to seizure outcome. We also characterise the relationship between high frequency oscillations (HFOs) and propagating spikes. We analysed intracranial EEG of 20 patients that underwent resective epilepsy surgery. The co-occurrence of ripples and fast ripples was considered an HFO event; the co-occurrence of an interictal spike and HFO was considered a Spike + HFO event. HFO distribution and spike onset were compared in cases of spike propagation. Accuracy in predicting seizure outcome was 85% for HFO, 60% for Spikes, and 79% for Spike + HFO. Sensitivity was 57% for HFO, 71% for Spikes and 67% for Spikes + HFO. Specificity was 100% for HFO, 54% for Spikes and 85% for Spikes + HFO. In 2/2 patients with spike propagation, the spike onset included the HFO area. Combining interictal spikes with HFO had comparable accuracy to HFO. In patients with propagating spikes, HFO rate was maximal at the onset of spike propagation.