Candidates For Epilepsy Surgery Research Articles

Clinical Applicability and Safety of Conventional Frame-Based Stereotactic Techniques for Stereoelectroencephalography.

Stereoelectroencephalography (SEEG) is increasingly being recognized as an important invasive modality for presurgical evaluation of epilepsy. This study focuses on the clinical and technical considerations of SEEG investigations when using conventional frame-based stereotaxy, drawing on institutional experience and a comprehensive review of relevant literature. This retrospective observational study encompassed the surgical implantation of 201 SEEG electrodes in 16 epilepsy patients using a frame-based stereotactic instrument at a single tertiary-level center. We provide detailed descriptions of the operative procedures and technical nuances for bilateral and multiple SEEG insertions, along with several illustrative cases. Additionally, we present a literature review on the technical aspects of the SEEG procedure, discussing its clinical implications and potential risks. Frame-based SEEG electrode placements were successfully performed through sagittal arc application, with the majority (81.2%) of cases being bilateral and involving up to 18 electrodes in a single operation. The median skin-to-skin operation time was 162 minutes (interquartile range [IQR], 145-200), with a median of 13 minutes (IQR, 12-15) per electrode placement for time efficiency. There were two occurrences (1.0%) of electrode misplacement and one instance (0.5%) of a postoperative complication, which manifested as a delayed intraparenchymal hemorrhage. Following SEEG investigation, 11 patients proceeded with surgical intervention, resulting in favorable seizure outcomes for nine (81.8%) and complete remission for eight cases (72.7%). Conventional frame-based stereotactic techniques remain a reliable and effective option for bilateral and multiple SEEG electrode placements. While SEEG is a suitable approach for selected patients who are strong candidates for epilepsy surgery, it is important to remain vigilant concerning the potential risks of electrode misplacement and hemorrhagic complications.

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.

SPECT postprocessing for epileptogenic focus localization: SISCOM versus ISAS.

Ictal SPECT can be used as an estimate for the epileptogenic zone in people with focal epilepsy. Subtraction of ictal and interictal SPECT scans reveals the area with significant ictal hyperperfusion. Some methods use a control database to also correct for physiological variance. This control database is ideally scanner specific, but it is not trivial to obtain such a database because of ethical issues. In this study, we used a publicly available control database to compare ictal-interictal SPECT analyzed by SPM (ISAS) with the most commonly used subtraction ictal SPECT co-registered to MRI (SISCOM). Ictal and interictal SPECTs of 26 patients (age range: 7-50 years, 15 adults, 11 children) with focal drug resistant epilepsy in workup for epilepsy surgery were retrospectively analyzed using both SISCOM and ISAS. The control database for ISAS was obtained from the ISAS website. Two groups of blinded reviewers determined the location of ictal hyperperfusion in all datasets. Results were compared between subtraction algorithms and with the resected area (if available) or the suspected epileptogenic zone. The number of significant clusters and the locations of maximum hyperperfusion were compared between algorithms. The location of ISAS and SISCOM hyperperfusion was the same in 14 patients (54%). ISAS localized in 6 patients where SISCOM did not. Compared to the resected area or suspected epileptogenic zone, SISCOM correctly localized in 55%, while ISAS did in 65% (not significantly different). ISAS shows significantly less clusters than SISCOM. The maximum hyperperfusion was in the reviewer's location in 65% for ISAS and 38% for SISCOM. ISAS using a publicly available control database gives comparable or better results than SISCOM. ISAS results are easier to interpret than SISCOM results. We show that ISAS is a reliable alternative for SISCOM, which could easily be implemented in epilepsy surgery clinics. We explored the effectiveness of ISAS as an alternative to the widely used SISCOM for assessing SPECT scans in epilepsy surgery candidates. Utilizing a publicly available control database, we compared the two methods in 26 patients. The results indicate that ISAS might offer increased accuracy and interpretability, making it a promising option, especially for centers without access to a specific control dataset.

Identifying epilepsy surgery referral candidates with natural language processing in an Australian context.

Epilepsy surgery is known to be underutilized. Machine learning-natural language processing (ML-NLP) may be able to assist with identifying patients suitable for referral for epilepsy surgery evaluation. Data were collected from two tertiary hospitals for patients seen in neurology outpatients for whom the diagnosis of "epilepsy" was mentioned. Individual case note review was undertaken to characterize the nature of the diagnoses discussed in these notes, and whether those with epilepsy fulfilled prespecified criteria for epilepsy surgery workup (namely focal drug refractory epilepsy without contraindications). ML-NLP algorithms were then developed using fivefold cross-validation on the first free-text clinic note for each patient to identify these criteria. There were 457 notes included in the study, of which 250 patients had epilepsy. There were 37 (14.8%) individuals who fulfilled the prespecified criteria for epilepsy surgery referral without described contraindications, 32 (12.8%) of whom were not referred for epilepsy surgical evaluation in the given clinic visit. In the prediction of suitability for epilepsy surgery workup using the prespecified criteria, the tested models performed similarly. For example, the random forest model returned an area under the receiver operator characteristic curve of 0.97 (95% confidence interval 0.93-1.0) for this task, sensitivity of 1.0, and specificity of 0.93. This study has shown that there are patients in tertiary hospitals in South Australia who fulfill prespecified criteria for epilepsy surgery evaluation who may not have been referred for such evaluation. ML-NLP may assist with the identification of patients suitable for such referral. Epilepsy surgery is a beneficial treatment for selected individuals with drug-resistant epilepsy. However, it is vastly underutilized. One reason for this underutilization is a lack of prompt referral of possible epilepsy surgery candidates to comprehensive epilepsy centers. Natural language processing, coupled with machine learning, may be able to identify possible epilepsy surgery candidates through the analysis of unstructured clinic notes. This study, conducted in two tertiary hospitals in South Australia, demonstrated that there are individuals who fulfill criteria for epilepsy surgery evaluation referral but have not yet been referred. Machine learning-natural language processing demonstrates promising results in assisting with the identification of such suitable candidates in Australia.

Memory and language risk assessment with Wada test in patients candidates for epilepsy surgery.

To determine post-surgical cognitive risk and associated factors according to lesion location in a sample of patients evaluated for epilepsy surgery with Wada test at the Fundacion Instituto Neurologico de Colombia. An observational, retrospective, analytical study was completed in patients with drug-resistant temporal lobe epilepsy candidates for epilepsy surgery treated from 2001 to 2021, who completed the Wada test as part of the pre-surgical evaluation. A descriptive analysis of sociodemographic, clinical, imaging and neuropsychological variables was completed; a multivariate logistic regression was performed analyzing factors associated with resection risk in patients with left lesions. RESULTS A total of 369 patients were included, 54.74% of the cases were women, with a median age of seizure onset of 11 years. 92.66% of the cases had lesional epilepsy and 68.56% were secondary to hippocampal sclerosis. Left hemisphere was the most frequently affected (65.68%) being dominant for memory and language in most of the patients with a proportion of 42.82% and 81.3%, respectively. The median functional adequacy was 43.75 (IQR 0-75) and the functional reserve was 75 (IQR 25 -93.75). In 104 patients, the Wada test determined a resection risk. In patients with a left lesion, it was found that functional reserve (PRadjusted 0.99, CI 95% 0.9997-0.9998) and having a right hemispheric dominance for memory (PRadjusted 0.92, CI 95% 0.547-0.999) were protective factors for post-surgical resection risk. Wada test is a useful tool for surgical decision-making in patients with drug-resistant temporal lobe epilepsy. When considering cognitive risk, components such as memory dominance and functional reserve should be considered as protective factors for postsurgical cognitive function preservation in patients with left lesions.

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.

The impact of referring patients with drug-resistant focal epilepsy to an epilepsy center for presurgical diagnosis

BackgroundEpilepsy surgery is an established treatment for drug-resistant focal epilepsy (DRFE) that results in seizure freedom in about 60% of patients. Correctly identifying an epileptogenic lesion in magnetic resonance imaging (MRI) is challenging but highly relevant since it improves the likelihood of being referred for presurgical diagnosis. The epileptogenic lesion’s etiology directly relates to the surgical intervention’s indication and outcome. Therefore, it is vital to correctly identify epileptogenic lesions and their etiology presurgically.MethodsWe compared the final histopathological diagnoses of all patients with DRFE undergoing epilepsy surgery at our center between 2015 and 2021 with their MRI diagnoses before and after presurgical diagnosis at our epilepsy center, including MRI evaluations by expert epilepsy neuroradiologists. Additionally, we analyzed the outcome of different subgroups.ResultsThis study included 132 patients. The discordance between histopathology and MRI diagnoses significantly decreased from 61.3% for non-expert MRI evaluations (NEMRIs) to 22.1% for epilepsy center MRI evaluations (ECMRIs; p < 0.0001). The MRI-sensitivity improved significantly from 68.6% for NEMRIs to 97.7% for ECMRIs (p < 0.0001). Identifying focal cortical dysplasia (FCD) and amygdala dysplasia was the most challenging for both subgroups. 65.5% of patients with negative NEMRI were seizure-free 12 months postoperatively, no patient with negative ECMRI achieved seizure-freedom. The mean duration of epilepsy until surgical intervention was 13.6 years in patients with an initial negative NEMRI and 9.5 years in patients with a recognized lesion in NEMRI.ConclusionsThis study provides evidence that for patients with DRFE—especially those with initial negative findings in a non-expert MRI—an early consultation at an epilepsy center, including an ECMRI, is important for identifying candidates for epilepsy surgery. NEMRI-negative findings preoperatively do not preclude seizure freedom postoperatively. Therefore, patients with DRFE that remain MRI-negative after initial NEMRI should be referred to an epilepsy center for presurgical evaluation. Nonreferral based on NEMRI negativity may harm such patients and delay surgical intervention. However, ECMRI-negative patients have a reduced chance of becoming seizure-free after epilepsy surgery. Further improvements in MRI technique and evaluation are needed and should be directed towards improving sensitivity for FCDs and amygdala dysplasias.

Sex differences in the pre and postoperative neuropsychological function of epilepsy surgery candidates

Objective: As programs expand globally, epilepsy surgery is becoming increasingly available as an effective treatment for some people with medically intractable seizures. Prospective candidates require careful neuropsychological evaluation and follow-up. The aim of this study was to examine the sex differences in neuropsychological function in presurgical presentation and postoperative outcomes in people with temporal lobe epilepsy referred for epilepsy surgery. Methods: Three hundred and seventy-two patients (202 Female; 170 Male) with a homogenous underlying pathology (hippocampal sclerosis) underwent a preoperative assessment on tests of intellectual, language, and memory function and were followed up one year after undergoing a unilateral temporal lobe resection; n = 169 Right (RTL), n = 203 Left (LTL). Results: There was no impact of sex or laterality of surgery on seizure outcome; 84% of males and 80% of females were seizure free at follow-up. Before surgery, sex effects were evident on tests of verbal memory with females performing better than males. Declines in verbal memory function following surgery were greater in females than males. Being female had a stronger association with postoperative decline on immediate prose recall (partial eta squared η 2 = 0.029), than side of surgery (η 2 = 0.018) albeit with a small effect size. Conclusions: There are subtle but significant sex differences in the neuropsychological profiles of people with temporal lobe epilepsy, before and following surgery. Whilst females generally perform better than males on tests of verbal memory function before surgery they demonstrate greater post-operative declines on these measures following surgery.

Long-term outcomes after responsive neurostimulation for treatment of refractory epilepsy: a single-center experience of 100 cases.

Despite antiepileptic drugs, more than 30% of people with epilepsy continue to have seizures. Patients with such drug-resistant epilepsy (DRE) may undergo invasive treatment such as resection, laser ablation of the epileptogenic focus, or vagus nerve stimulation, but many are not candidates for epilepsy surgery or fail to respond to such interventions. Responsive neurostimulation (RNS) provides a neuromodulatory option. In this study, the authors present a single-center experience with the use of RNS over the last 5 years to provide long-term control of seizures in patients with DRE with at least 1 year of follow-up. The authors performed a retrospective analysis of a prospectively collected single-center database of consecutive DRE patients who underwent RNS system implantation from September 2015 to December 2020. Patients were followed-up postoperatively to evaluate seizure freedom and complications. One hundred patients underwent RNS placement. Seven patients developed infections: 2 responded to intravenous antibiotic therapy, 3 required partial removal and salvaging of the system, and 2 required complete removal of the RNS device. No postoperative tract hemorrhages, strokes, device migrations, or malfunctions were documented in this cohort. The average follow-up period was 26.3 months (range 1-5.2 years). In terms of seizure reduction, 8 patients had 0%-24% improvement, 14 had 25%-49% improvement, 29 experienced 50%-74% improvement, 30 had 75%-99% improvement, and 19 achieved seizure freedom. RNS showed significantly better outcomes over time: patients with more than 3 years of RNS therapy had 1.8 higher odds of achieving 75% or more seizure reduction (95% CI 1.07-3.09, p = 0.02). Also, patients who had undergone resective or ablative surgery prior to RNS implantation had 8.25 higher odds of experiencing 50% or more seizure reduction (95% CI 1.05-65.1, p = 0.04). Responsive neurostimulator implantation achieved 50% or more seizure reduction in approximately 80% of patients. Even in patients who did not achieve seizure freedom, significant improvement in seizure duration, severity, or postictal state was reported in more than 68% of cases. Infection (7%) was the most common complication. Patients with prior resective or ablative procedures and those who had been treated with RNS for more than 3 years achieved better outcomes.

40 Performance validity in a presurgical epilepsy population

Objective:To examine whether suboptimal performance as determined by formal validity testing would predict neurocognitive scores in a sample of 83 pre-surgical, non-litigating epilepsy patients.Participants and Methods:Participants were 83 patients who underwent comprehensive outpatient neuropsychological testing as part as their evaluation as epilepsy surgery candidates. The sample consisted of 41 females and 42 males, with 72 patients identifying as White, 5 as Black, 2 as Hispanic, 1 as Asian, and 2 as other. Mean age was 36 (SD=12.4) mean FSIQ was 87 (SD=12.7), mean years of education of 12.9 (SD=2.1). Each patient’s assessment included a stand-alone performance validity test (PVTs)— Word Memory Test (WMT), the Test of Memory Malingering (TOMM), or the Medical Symptom Validity Test (MSVT)—as well as two embedded measures of validity—the California Verbal Learning Test Forced Choice (CVLT FC) and WAIS-IV Reliable Digit Span (RDS). Pass/fail rates were analyzed, with valid performance being defined as pass score on at least two of the completed PVTs (N=73 Pass Effort group 86.9%; N=10 Failed Effort group 11.9%). Point-biserial Pearson correlations were conducted to determine the relationship between validity pass/fail status and WAIS-IV FSIQ, VCI, and PRI scores, CVLT-II Trials 1-5 Total T scores, CVLT-II Long Delay Free Recall z scores, WMS-III Logical Memory II T scores, BVMT Total Recall T scores, BVMT Delayed Recall T scores, and Trail Making Test (TMT) B T scores.Results:Significant relationships were found between Failed Effort group and all neurocognitive scores except BVMT Total Recall. On average, the Failed Effort group obtained significantly lower FSIQ (M=76.57, SD=10.94), VCI (M=80.89, SD=16.03), PRI (M=81.00, SD=14.91), CVLT-II Trials 1-5 Total (M =34, SD=6.89), CVLT-II Long Delay Free Recall (M =-2.44, SD=1.43), WMS-IV Logical Memory II (M =4.83, SD=2.79), BVMT Delayed Recall (M=26.38, SD=6.41), and TMT B (M=29.70, SD=11.46) standard scores compared to the Pass Effort group (FSIQ M=88.09, SD=12.52; VCI M=92.13, SD=13.61; PRI M=91.14, SD=12.06; CVLT-II Trials 1-5 Total M=47.86, SD=12.02; CVLT- II Long Delay Free Recall M=-.44, SD=1.11; WMS-III Logical Memory II M=8.41, SD=3.17; BVMT Delayed Recall M=39.19, SD=12.66; TMT B M=39.34, SD=13.18). Correlation coefficients were r=-.266* (FSIQ), r=-.255* (VCI), r=-.271* (PRI), r=.361**(CVLT-II Total), r=-.474** (CVLT-II LDFR), r=-.298** (WMS-IV LM II), r=-.308** (BVMT DR), and r=-.240* (TMTB). All coefficients were significant at the .05 (*) or .01 (**) level.Conclusions:Results suggest that pass/fail status on formal validity testing predicts depressed performance on a variety of neurocognitive measures. Therefore, predicting surgical outcome of resection/ablation (e.g., compensation of contralateral hemisphere) should not be based upon neuropsychological memory performance alone when there are failures on tests of engagement as memory scores have strong correlations to pass/fail status on formal validity testing. Overall, this emphasizes the importance of routinely integrating PVTs as part of pre-epilepsy surgery neuropsychological evaluations.

29 Quality of Life in Younger and Older Adults with Epilepsy

Objective:Epilepsy is the third most common neurological disorder among older adults, and as adults are living longer, the incidence of epilepsy is increasing (Kun Lee, 2019). The purpose of this study is to examine 1. differences in quality of life (QOL) between older and younger adults with medically intractable epilepsy and 2. the impact of seizure frequency, seizure duration, depression, sex, and marital status on QOL. Given differences in the prevalence rates of depression between men and women and importance of depression in QOL, we predicted that sex and marital status would moderate the effect of depression on total QOL (TQOL).Hypothesis I: Compared to younger adults, older adults with epilepsy will report lower TQOL scores and lower scores on subscales measuring energy/fatigue, cognition, and medication effects. Hypothesis II: Seizure variables and depression will significantly account for TQOL scores in both groups (younger and older) above demographic variables (sex, marital status, and education). Hypothesis III: Sex will moderate the effect of depression in both groups and marital status will moderate the effect of depression only in the older adults.Participants and Methods:Participants were 607 adults (&gt; 18 years old) who were prospective candidates for epilepsy surgery and underwent a comprehensive neuropsychological evaluation including QOL assessment using the Quality of Life in Epilepsy Scale-31 (QOLIE-31). Individuals were grouped by older (&gt; 50 years old; N = 122) and younger adults (&lt; 50 years old; N = 485). Hierarchical regression was used to examine the proposed associations.Results:Hypothesis I: In contrast to our hypothesis, a one-way ANOVA did not reveal significant differences between the older and younger groups on the QOL subscales, TQOL, or depression.Hypothesis II: For older adults, longer seizure duration was associated with better TQOL; bivariate correlations showed no evidence of statistical suppression. Higher depression scores were associated with worse TQOL. Overall, the model accounted for 39.6% of variance among older adults. For younger adults, only depression was a significant predictor of TQOL wherein higher depression scores were associated with worse TQOL. Overall, the model accounted for 36.1% of the variance among younger adults. Hypothesis III: There was no moderation between depression and marital status in older or younger adults (b = -.009, p &gt; .05). There was multicollinearity evidenced by VIF (variance inflation factor) greater than 10, so the associations between depression and sex could not be examined.Conclusions:Overall, there were no significant differences between QOL in younger versus older adults. Greater depression symptoms were associated with lower TQOL in both groups. Longer seizure duration was a significant predictor of better TQOL in older adults only, perhaps indicating better adjustment to having a seizure disorder with longer duration of epilepsy. Lastly, marital status did not moderate the effects of depression on TQOL and the moderating effects of sex on TQOL could not be assessed due to multicollinearity. Study limitations include dichotomizing the sample into these particular age groups and the heterogeneity of seizure types.

Vagus nerve stimulation for treating developmental and epileptic encephalopathy in young children.

To investigate the clinical variables that might predict the outcome of developmental and epileptic encephalopathy (DEE) after vagus nerve stimulation (VNS) therapy and identify the risk factors for poor long-term outcome. We retrospectively studied 32 consecutive children with drug-resistant DEE who had undergone VNS surgery from April 2019 to July 2021, which were not suitable for corpus callosotomy. In spite of combining valproic acid, levetiracetam, lamotrigine, topiramate, etc. (standard anti-seizure medicine available in China) it has not been possible to effectively reduce seizures in the population we investigate (Cannabidiol and brivaracetam were not available in China). A responder was defined as a frequency reduction decrease > 50%. Seizure freedom was defined as freedom from seizures for at least 6 months. Sex, electroencephalograph (EEG) group, neurodevelopment, time lag, gene mutation, magnetic resonance imaging (MRI), and epilepsy syndrome were analyzed with Fisher's exact test, The age at onset and age at VNS therapy were analyzed with Kruskal-Wallis test, statistical significance was defined as p < 0.05. And used the effect size to correction. Among the 32 patients, the median age at VNS implantation was 4.7 years (range: 1-12 years). At the most recent follow-up, five children (15.6%) were seizure-free and 22 (68.8%) were responders. Univariate analysis demonstrated that the responders were significantly associated with mild development delay/intellectual disability (p = 0.044; phi coefficient = 0.357) and a multifocal EEG pattern (p = 0.022; phi coefficient = -0.405). Kaplan-Meier survival analyses demonstrated that a multifocal EEG pattern (p = 0.049) and DEE without epileptic spasm (ES) (p = 0.012) were statistically significant (p = 0.030). Multivariate analysis demonstrated that DEE with ES had significant predictive value for poor long-term outcome (p = 0.014, hazard ratio = 5.433, confidence interval = 1.402-21.058). Our study suggested that VNS was a generally effective adjunct treatment for DEE. Although the predictive factors for VNS efficacy remain unclear, it should be emphasized that patients with ES are not suitable candidates for epilepsy surgery. Further investigations are needed to validate the present results.

Ictal EEG Source Imaging With Supplemental Electrodes.

Noninvasive brain imaging tests play a major role in guiding decision-making and the usage of invasive, costly intracranial electroencephalogram (ICEEG) in the presurgical epilepsy evaluation. This study prospectively examined the concordance in localization between ictal EEG source imaging (ESI) and ICEEG as a reference standard. Between August 2014 and April 2019, patients during video monitoring with scalp EEG were screened for those with intractable focal epilepsy believed to be amenable to surgical treatment. Additional 10-10 electrodes (total = 31-38 per patient, "31+") were placed over suspected regions of seizure onset in 104 patients. Of 42 patients requiring ICEEG, 30 (mean age 30, range 19-59) had sufficiently localized subsequent intracranial studies to allow comparison of localization between tests. ESI was performed using realistic forward boundary element models used in dipole and distributed source analyses. At least partial sublobar concordance between ESI and ICEEG solutions was obtained in 97% of cases, with 73% achieving complete agreement. Median Euclidean distances between ESI and ICEEG solutions ranged from 25 to 30 mm (dipole) and 23 to 38 mm (distributed source). The latter was significantly more accurate with 31+ compared with 21 electrodes (P < 0.01). A difference of ≤25 mm was present in two thirds of the cases. No significant difference was found between dipole and distributed source analyses. A practical method of ictal ESI (nonuniform placement of 31-38 electrodes) yields high accuracy for seizure localization in epilepsy surgery candidates. These results support routine clinical application of ESI in the presurgical evaluation.

Candidate Selection for Implantation: Noninvasive Predictors of Seizure Onset Zone Focality and Surgical Outcome in People with Drug-Resistant Epilepsy Evaluated by Intracranial Video-EEG Monitoring—A Retrospective Cohort Study

Objectives. People with drug-resistant epilepsy are potential candidates for epilepsy surgery, a subset of whom requires intracranial video-EEG monitoring (IVEM) to determine the seizure onset zone (SOZ). The purpose of this study is to investigate noninvasive predictors of SOZ focality and surgical outcome in order to optimise case selection for this procedure. Materials and Methods. We performed a retrospective cohort study of patients who underwent IVEM at our centre from January 2006 to July 2021. We applied a multivariate logistic regression model to estimate the effect of potential noninvasive data as influencing factors for both SOZ focality and surgical outcome. A focal SOZ included a sublobar onset on IVEM, and a good surgical outcome was defined as Engel class I. Results. A total of 783 underwent a presurgical evaluation, 102 of them with IVEM. Ninety-seven patients were included in the SOZ focality analysis, and 64 were included in the surgical outcome analysis. The presence of focal to bilateral tonic-clonic seizures ( p = 0.03 ) and generalised interictal epileptiform discharges (IEDs) during scalp EEG ( p = 0.02 ) predicted a nonfocal SOZ. A weekly ( p = 0.01 ) or daily seizure frequency ( p &lt; 0.01 ), focal to bilateral tonic-clonic seizures ( p = 0.01 ), nonlesional MRI ( p &lt; 0.01 ), and multifocal ( p = 0.02 ) or generalised IEDs ( p &lt; 0.01 ) were associated with a poor surgical outcome. Conclusions. A high seizure frequency, positive history of focal to bilateral tonic-clonic seizures, nonlesional MRI, and generalised and multifocal IEDs are noninvasive factors that may aid in selecting candidates for IVEM.

An in–vivo validation of ESI methods with focal sources

Electrophysiological source imaging (ESI) aims at reconstructing the precise origin of brain activity from measurements of the electric field on the scalp. Across laboratories/research centers/hospitals, ESI is performed with different methods, partly due to the ill-posedness of the underlying mathematical problem. However, it is difficult to find systematic comparisons involving a wide variety of methods. Further, existing comparisons rarely take into account the variability of the results with respect to the input parameters. Finally, comparisons are typically performed using either synthetic data, or in-vivo data where the ground-truth is only roughly known. We use an in-vivo high-density EEG dataset recorded during intracranial single pulse electrical stimulation, in which the true sources are substantially dipolar and their locations are precisely known. We compare ten different ESI methods, using their implementation in the MNE-Python package: MNE, dSPM, LORETA, sLORETA, eLORETA, LCMV beamformers, irMxNE, Gamma Map, SESAME and dipole fitting. We perform comparisons under multiple choices of input parameters, to assess the accuracy of the best reconstruction, as well as the impact of such parameters on the localization performance. Best reconstructions often fall within 1 cm from the true source, with most accurate methods hitting an average localization error of 1.2 cm and outperforming least accurate ones erring by 2.5 cm. As expected, dipolar and sparsity-promoting methods tend to outperform distributed methods. For several distributed methods, the best regularization parameter turned out to be the one in principle associated with low SNR, despite the high SNR of the available dataset. Depth weighting played no role for two out of the six methods implementing it. Sensitivity to input parameters varied widely between methods. While one would expect high variability being associated with low localization error at the best solution, this is not always the case, with some methods producing highly variable results and high localization error, and other methods producing stable results with low localization error. In particular, recent dipolar and sparsity-promoting methods provide significantly better results than older distributed methods. As we repeated the tests with “conventional” (32 channels) and dense (64, 128, 256 channels) EEG recordings, we observed little impact of the number of channels on localization accuracy; however, for distributed methods denser montages provide smaller spatial dispersion. Overall findings confirm that EEG is a reliable technique for localization of point sources and therefore reinforce the importance that ESI may have in the clinical context, especially when applied to identify the surgical target in potential candidates for epilepsy surgery.

Short and long term prediction of seizure freedom in drug-resistant focal epilepsy surgery

BackgroundThe selection of candidates for drug-resistant focal epilepsy surgery is essential to achieve the best post-surgical outcomes. Objective: To develop two prediction models for seizure freedom in the short and long-term follow-up and from them to create a risk calculator in order to individualize the selection of candidates for surgery and future therapies in each patients. MethodsA sample of 64 consecutive patients who underwent epilepsy surgery at two Cuban tertiary health institutions between 2012 and 2020 constituted the basis for the prediction models. Two models were obtained through the novel methodology, based on biomarker selection reached by resampling methods, cross-validation and high-accuracy index measured through the area under the receiving operating curve (ROC) procedure. ResultsThe first, to pre-operative model included five predictors: epilepsy type, seizures per month, ictal pattern, interictal EEG topography and normal or abnormal magnetic resonance imaging,. it's precision was 0.77 at one year, and with four years and more 0.63. The second model including variables from the trans-surgical and post-surgical stages: the interictal discharges in the post-surgical EEG, incomplete or complete resection of the epileptogenic zone, the surgical techniques employed and disappearance of the discharge in post-resection electrocorticography; the precision of this model was 0.82 at one year, and with four years and more 0.97. ConclusionsThe introduction of trans-surgical and post-surgical variables increase the prediction of the pre-surgical model. A risk calculator was developed using these prediction models, which could be useful as an accurate tool to improve the prediction in epilepsy surgery.

Corpus Callosotomy for Drug Resistant Epilepsy. Long Term Outcome in Adult Population. (S44.005)

<h3>Objective:</h3> Favorable outcome of corpus callosotomy is reported in pediatric population with intractable epilepsy and it is considered standard of care for patients with drop attacks. Our objective is to compare the long term outcome of corpus callosotomy for drug resistant epilepsy in adult population. <h3>Background:</h3> Corpus callosotomy is a palliative neurosurgical procedure for patients with medically drug-resistant epilepsy who are not candidates for resective epilepsy surgery. Corpus callosotomy is most commonly performed in children with epilepsy, either as an anterior two-thirds disconnection of corpus callosum or as a complete disconnection. Good long-term outcomes against drop attacks have been reported in a population-based prospective study and the risk of a persistent complication is low. <h3>Design/Methods:</h3> 17 adults with idiopathic generalized epilepsy, frontal lobe epilepsy and Lennox Gastaut Syndrome (LGS) were followed for the outcome measures of seizure and antiepileptic drug (AED) burden and quality of life (QoL). Data was extracted from patients registered in our RedCap database. <h3>Results:</h3> 17 patients fulfill the inclusion criteria. 4 underwent conventional corpus callsotomy and 14 had laser interstitial thermal therapy (LITT). 7 had failed prior Vagal Nerve Stimulator and 10 did not have VNS. All patients who had conventional procedure had complications and none from the LITT group reported complications. 11 patients reported presence of seizures and 6 were seizure free. None of the patients had persistent drop attacks, while 4 had convulsive seizures and 11 had mild focal impaired awareness seizures. More than 70 % of the patients reported improvement in speech, social abilities and activities of daily living. <h3>Conclusions:</h3> Corpus callosotomy for drug resistant epilepsy in adults provide significant improvement when observed for decreasing in seizure burden, reduction in medication and improvement of quality of life. LITT carries a low risk for complication and similar efficacy when compared with conventional one and should be utilize more frequently. <b>Disclosure:</b> Miss Proteasa has nothing to disclose. Dr. Proteasa has nothing to disclose. Dr. Lado has a non-compensated relationship as a Board Member with American Epilepsy Society that is relevant to AAN interests or activities. Dr. Lado has a non-compensated relationship as a Officer with National Association of Epilepsy Centers that is relevant to AAN interests or activities.

Spike-microstates correlate with interictal epileptogenic discharges: a marker for hidden epileptic activity.

Objectively estimating disease severity and treatment success is a main problem in outpatient managing of epilepsy. Self-reported seizures diaries are well-known to underestimate the actual seizure count, and repeated EEGs might not show interictal epileptiform discharges (IEDs), although patients suffer from seizures. In this prospective study, we investigate the potential of microstate analysis to monitor epilepsy patients independently of their IED count. From our databank of candidates for epilepsy surgery, we included 18 patients who underwent controlled resting EEG sessions (with eyes closed, 30 min), at around the same time of the day, during at least four days (range: 4-8 days; mean: 5). Nine patients with temporal foci, six with extratemporal foci, and three with generalized epilepsy were included. Each patient's IEDs were marked and the topographic voltage maps of the IED peaks were averaged, and an individual average spike topography (AST) was created. The AST was then backfitted to each timepoint of the whole EEG resulting in the Spike-Microstate (SMS). The presence of the SMS in the residual EEG outside of the short IEDs epochs was determined for each recording session in each patient and correlated with the occurrence of the IEDs across all recording session, as well as with the drug charge of each day. Overall, SMS was much more represented in the routine EEG than the IEDs: they were identified 262 times more often than IEDs. The SMS time coverage correlated significantly with the IED occurrence rate (rho = 0.56; P < 0.001). If only patients with focal epilepsy were considered, this correlation was even higher rho = 0.69 (P < 0.001). Drug charge per day did not correlate with SMS. In this proof-of-concept study, the time coverage of SMS correlated strongly with the occurrence rate of the IEDs, they can be retrieved in the scalp EEG at a much higher occurrence rate. We conclude that SMS, once obtained for a given patient, are a more abundant marker of hidden epileptic activity than IEDs, in particular in focal epilepsy, and can be used also in absence of IEDs. Future larger studies are needed to verify its potential as monitoring tool and to determine cut-off values when drug protection becomes imperfect.

Seizures as a Struggle between Life and Death: An Existential Approach to the Psychosocial Impact of Seizures in Candidates for Epilepsy Surgery

Introduction: Mental health comorbidities such as depression and anxiety are common in epilepsy, especially among people with pharmacoresistant epilepsy who are candidates for epilepsy surgery. The Psychology Task Force of the International League Against Epilepsy advised that psychological interventions should be integrated into comprehensive epilepsy care. Methods: To better understand the psychological impact of epilepsy and epileptic seizures in epilepsy surgery candidates, we analysed interviews with this subgroup of patients using Karl Jaspers’ concept of limit situations, which are characterised by a confrontation with the limits and challenges of life. These are especially chance, randomness, and unpredictability, death and finitude of life, struggle and self-assertion, guilt, failure, and falling short of one’s aspirations. Results: In 43 interviews conducted with 15 people with drug-resistant epilepsy who were candidates for epilepsy surgery, we found that these themes are recurrent and have a large psychosocial impact, which can result in depression and anxiety. For some people, epileptic seizures appear to meet the criteria for traumatic events. Conclusion: Understanding epilepsy and seizures as existential challenges complements the neurobiological explanations for psychological comorbidities and can help tailor psychological interventions to the specific needs of people with epilepsy, especially those who are candidates for surgical treatment.

Are AI language models such as ChatGPT ready to improve the care of individuals with epilepsy?

Are AI language models such as ChatGPT ready to improve the care of individuals with epilepsy?