Surgical outcomes in lesional and non-lesional epilepsy: a systematic review and meta-analysis

Automated segmentation of epilepsy surgical resection cavities: Comparison of four methods to manual segmentation

Accurate resection cavity segmentation on MRI is important for neuroimaging research involving epilepsy surgical outcomes. Manual segmentation, the gold standard, is highly labour intensive. Automated pipelines are an efficient potential solution; however, most have been developed for use following temporal epilepsy surgery. Our aim was to compare the accuracy of four automated segmentation pipelines following surgical resection in a mixed cohort of subjects following temporal or extra temporal epilepsy surgery. We identified 4 open-source automated segmentation pipelines. Epic-CHOP and ResectVol utilise SPM-12 within MATLAB, while Resseg and Deep Resection utilise 3D U-net convolutional neural networks. We manually segmented the resection cavity of 50 consecutive subjects who underwent epilepsy surgery (30 temporal, 20 extratemporal). We calculated Dice similarity coefficient (DSC) for each algorithm compared to the manual segmentation. No algorithm identified all resection cavities. ResectVol (n = 44, 88 %) and Epic-CHOP (n = 42, 84 %) were able to detect more resection cavities than Resseg (n = 22, 44 %, P < 0.001) and Deep Resection (n = 23, 46 %, P < 0.001). The SPM-based pipelines (Epic-CHOP and ResectVol) performed better than the deep learning-based pipelines in the overall and extratemporal surgery cohorts. In the temporal cohort, the SPM-based pipelines had higher detection rates, however there was no difference in the accuracy between methods. These pipelines could be applied to machine learning studies of outcome prediction to improve efficiency in pre-processing data, however human quality control is still required.

Non-lesional epilepsy does not necessarily convey poor outcomes after invasive monitoring followed by resection or thermal ablation

OBJECTIVE

We aimed to compare outcomes including seizure-free status at the last follow-up in adult patients with medically refractory focal epilepsy identified as lesional vs. non-lesional based on their magnetic resonance imaging (MRI) findings who underwent invasive evaluation followed by subsequent resection or thermal ablation (LiTT).

METHODS

We identified 88 adult patients who underwent intracranial monitoring between 2014 and 2021. Of those, 40 received resection or LiTT, and they were dichotomized based on MRI findings, as lesional (N = 28) and non-lesional (N = 12). Patient demographics, seizure characteristics, non-invasive interventions, intracranial monitoring, and surgical variables were compared between the groups. Postsurgical seizure outcome at the last follow-up was rated according to the Engel classification, and postoperative seizure freedom was determined by Kaplan-Meyer survival analysis. Statistical analyses employed Fisher's exact test to compare categorical variables, while a t-test was used for continuous variables.

RESULTS

There were no differences in baseline characteristics between groups except for more often noted PET abnormality in the lesional group (p = 0.0003). 64% of the lesional group and 57% of the non-lesional group received surgical resection or LiTT (p = 0.78). At the last follow-up, 78.5% of the patients with lesional MRI findings achieved Engel I outcomes compared to 66.7% of non-lesional patients (p = 0.45). Kaplan-Meier curves did not show a significant difference in seizure-free duration between both groups after surgical intervention (p = 0.49).

SIGNIFICANCE

In our sample, the absence of lesion on brain MRI was not associated with worse seizure outcomes in adult patients who underwent invasive intracranial monitoring followed by resection or thermal ablation.

Treatment odyssey to epilepsy surgery in children with focal cortical dysplasia: Risk factors for delayed surgical intervention

OBJECTIVE

To elucidate the patient's journey to epilepsy surgery and identify the risk factors contributing to surgical delay in pediatric patients with drug-resistant epilepsy (DRE) due to focal cortical dysplasia (FCD).

METHODS

A retrospective review was conducted of 93 pediatric patients who underwent curative epilepsy surgery for FCD between January 2012 and March 2023 at a tertiary epilepsy center. The Odyssey plot demonstrated the treatment process before epilepsy surgery, including key milestones of epilepsy onset, first hospital visit, epilepsy diagnosis, MRI diagnosis, DRE diagnosis, and surgery. The primary outcome was surgical delay; the duration from DRE to surgery. Multivariate linear regression models were used to examine the association between surgical delay and clinical, investigative, and treatment characteristics.

RESULTS

The median age at seizure onset was 1.3 years (interquartile range [IQR] 0.14-3.1), and at the time of surgery, it was 6 years (range 1-11). Notably, 46% experienced surgical delays exceeding two years. The Odyssey plot visually highlighted that surgical delay comprised a significant portion of the patient journey. Although most patients underwent MRI before referral, MRI abnormalities were identified before referral only in 39% of the prolonged group, compared to 70% of the non-prolonged group. Multivariate analyses showed that delayed notification of MRI abnormalities, longer duration from epilepsy onset to DRE, older age at onset, number of antiseizure medications tried, and moderate to severe intellectual disability were significantly associated with prolonged surgical delay.

CONCLUSION

Pediatric DRE patients with FCD experienced a long journey until surgery. Early and accurate identification of MRI abnormalities is important to minimize surgical delays.

WONOEP 2022: Neurotechnology for the diagnosis of epilepsy

Epilepsy's myriad causes and clinical presentations ensure that accurate diagnoses and targeted treatments remain a challenge. Advanced neurotechnologies are needed to better characterize individual patients across multiple modalities and analytical techniques. At the XVIth Workshop on Neurobiology of Epilepsy: Early Onset Epilepsies: Neurobiology and Novel Therapeutic Strategies (WONOEP 2022), the session on "advanced tools" highlighted a range of approaches, from molecular phenotyping of genetic epilepsy models and resected tissue samples to imaging-guided localization of epileptogenic tissue for surgical resection of focal malformations. These tools integrate cutting edge research, clinical data acquisition, and advanced computational methods to leverage the rich information contained within increasingly large datasets. A number of common challenges and opportunities emerged, including the need for multidisciplinary collaboration, multimodal integration, potential ethical challenges, and the multistage path to clinical translation. Despite these challenges, advanced epilepsy neurotechnologies offer the potential to improve our understanding of the underlying causes of epilepsy and our capacity to provide patient-specific treatment.

Spatial and temporal properties of intra-operatively recorded spikes and high frequency oscillations in focal cortical dysplasia

OBJECTIVE

Focal cortical dysplasias (FCD) are characterized by distinct interictal spike patterns and high frequency oscillations (HFOs; ripples: 80-250 Hz; fast ripples: 250-500 Hz) in the intra-operative electrocorticogram (ioECoG). We studied the temporal relation between intra-operative spikes and HFOs and their relation to resected tissue in people with FCD with a favorable outcome.

METHODS

We included patients who underwent ioECoG-tailored epilepsy surgery with pathology confirmed FCD and long-term Engel 1A outcome. Spikes and HFOs were automatically detected and visually checked in 1-minute pre-resection-ioECoG. Channels covering resected and non-resected tissue were compared using a logistic mixed model, assessing event numbers, co-occurrence ratios, and time-based properties.

RESULTS

We found pre-resection spikes, ripples in respectively 21 and 20 out of 22 patients. Channels covering resected tissue showed high numbers of spikes and HFOs, and high ratios of co-occurring events. Spikes, especially with ripples, have a relatively sharp rising flank with a long descending flank and early ripple onset over resected tissue.

CONCLUSIONS

A combined analysis of event numbers, ratios, and temporal relationships between spikes and HFOs may aid identifying epileptic tissue in epilepsy surgery.

SIGNIFICANCE

This study shows a promising method for clinically relevant properties of events, closely associated with FCD.

Updates from the International League Against Epilepsy Classification of Epilepsy (2017) and Focal Cortical Dysplasias (2022): Imaging Phenotype and Genetic Characterization

The International League Against Epilepsy (ILAE) is an organization of 120 national chapters providing the most widely accepted and updated guidelines on epilepsy. In 2022, the ILAE Task Force revised the prior (2011) classification of focal cortical dysplasias to incorporate and update clinicopathologic and genetic information, with the aim to provide an objective classification scheme. New molecular-genetic information has led to the concept of "integrated diagnosis" on the same lines as brain tumors, with a multilayered diagnostic model providing a phenotype-genotype integration. Major changes in the new update were made to type II focal cortical dysplasias, apart from identification of new entities, such as mild malformations of cortical development and cortical malformation with oligodendroglial hyperplasia. No major changes were made to type I and III focal cortical dysplasias, given the lack of significant new genetic information. This review provides the latest update on changes to the classification of focal cortical dysplasias with discussion about the new entities. The ILAE in 2017 updated the classification of seizure and epilepsy with 3 levels of diagnosis, including seizure type, epilepsy type, and epilepsy syndrome, which are also briefly discussed here.

Association of Localizing 18F-FDG-PET Hypometabolism and Outcome Following Epilepsy Surgery: Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVES

Although commonly used in the evaluation of patients for epilepsy surgery, the association between the detection of localizing 18fluorine fluorodeoxyglucose PET (18F-FDG-PET) hypometabolism and epilepsy surgery outcome is uncertain. We conducted a systematic review and meta-analysis to determine whether localizing 18F-FDG-PET hypometabolism is associated with favorable outcome after epilepsy surgery.

METHODS

A systematic literature search was undertaken. Eligible publications included evaluation with 18F-FDG-PET before epilepsy surgery, with ≥10 participants, and those that reported surgical outcome at ≥12 months. Random-effects meta-analysis was used to calculate the odds of achieving a favorable outcome, defined as Engel class I, International League Against Epilepsy class 1-2, or seizure-free, with localizing 18F-FDG-PET hypometabolism, defined as concordant with the epilepsy surgery resection zone. Meta-regression was used to characterize sources of heterogeneity.

RESULTS

The database search identified 8,916 studies, of which 98 were included (total patients n = 4,104). Localizing 18F-FDG-PET hypometabolism was associated with favorable outcome after epilepsy surgery for all patients with odds ratio (OR) 2.68 (95% CI 2.08-3.45). Subgroup analysis yielded similar findings for those with (OR 2.64, 95% CI 1.54-4.52) and without epileptogenic lesion detected on MRI (OR 2.49, 95% CI 1.80-3.44). Concordance with EEG (OR 2.34, 95% CI 1.43-3.83), MRI (OR 1.69, 95% CI 1.19-2.40), and triple concordance with both (OR 2.20, 95% CI 1.32-3.64) was associated with higher odds of favorable outcome. By contrast, diffuse 18F-FDG-PET hypometabolism was associated with worse outcomes compared with focal hypometabolism (OR 0.34, 95% CI 0.22-0.54).

DISCUSSION

Localizing 18F-FDG-PET hypometabolism is associated with favorable outcome after epilepsy surgery, irrespective of the presence of an epileptogenic lesion on MRI. The extent of 18F-FDG-PET hypometabolism provides additional information, with diffuse hypometabolism associated with worse surgical outcome than focal 18F-FDG-PET hypometabolism. These findings support the incorporation of 18F-FDG-PET into routine noninvasive investigations for patients being evaluated for epilepsy surgery to improve epileptogenic zone localization and to aid patient selection for surgery.

Specific consistency score for rational selection of epilepsy resection surgery candidates

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

SIGNIFICANCE

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.

The use of automated and AI-driven algorithms for the detection of hippocampal sclerosis and focal cortical dysplasia

In drug-resistant epilepsy, magnetic resonance imaging (MRI) plays a central role in detecting lesions as it offers unmatched spatial resolution and whole-brain coverage. In addition, the last decade has witnessed continued developments in MRI-based computer-aided machine-learning techniques for improved diagnosis and prognosis. In this review, we focus on automated algorithms for the detection of hippocampal sclerosis and focal cortical dysplasia, particularly in cases deemed as MRI negative, with an emphasis on studies with histologically validated data. In addition, we discuss imaging-derived prognostic markers, including response to anti-seizure medication, post-surgical seizure outcome, and cognitive reserves. We also highlight the advantages and limitations of these approaches and discuss future directions toward person-centered care.

Global Assessment of Palliative Care Need: Serious Health-Related Suffering Measurement Methodology

CONTEXT

Inequities and gaps in palliative care access are a serious impediment to health systems especially in low- and middle-income countries and the accurate measurement of need across health conditions is a critical step to understanding and addressing the issue. Serious Health-related Suffering (SHS) is a novel methodology to measure the palliative care need and was originally developed by The Lancet Commission on Global Access to Palliative Care and Pain Relief. In 2015, the first iteration - SHS 1.0 - was estimated at over 61 million people worldwide experiencing at least 6 billion days of SHS annually as a result of life-limiting and life-threatening conditions.

OBJECTIVES

In this paper, an updated methodology - SHS 2.0 - is presented building on the work of the Lancet Commission and detailing calculations, data requirements, limitations, and assumptions.

METHODS AND RESULTS

The updates to the original methodology focus on measuring the number of people who die with (decedents) or live with (non-decedents) SHS in a given year to assess the number of people in need of palliative care across health conditions and populations. Detail on the methodology for measuring the number of days of SHS that was pioneered by the Lancet Commission, is also shared, as this second measure is essential for determining the health system responses that are necessary to address palliative care need and must be a priority for future methodological work on SHS.

CONCLUSIONS

The methodology encompasses opportunities for applying SHS to future policy making assessment of future research priorities particularly in light of the dearth of data from low- and middle-income countries, and sharing of directions for future work to develop SHS 3.0.

Evidence based noninvasive presurgical evaluation for patients with drug resistant epilepsies

PURPOSE OF REVIEW

To review the current practices and evidence for the diagnostic accuracy and the benefits of presurgical evaluation.

RECENT FINDINGS

Preoperative evaluation of patients with drug-resistant focal epilepsies and subsequent epilepsy surgery leads to a significant proportion of seizure-free patients. Even those who are not completely seizure free postoperatively often experience improved quality of life with better social integration. Systematic reviews and meta-analysis on the diagnostic accuracy are available for Video-electroencephalographic (EEG) monitoring, magnetic resonance imaging (MRI), electric and magnetic source imaging, and functional MRI for lateralization of language and memory. There are currently no evidence-based international guidelines for presurgical evaluation and epilepsy surgery.

SUMMARY

Presurgical evaluation is a complex multidisciplinary and multiprofessional clinical pathway. We rely on limited consensus-based recommendations regarding the required staffing or methodological expertise in epilepsy centers.

Multimodal non-invasive evaluation in MRI-negative epilepsy patients

Presurgical evaluation is still challenging for MRI-negative epilepsy patients. As non-invasive modalities are the easiest acceptable and economic methods in determining the epileptogenic zone, we analyzed the localization value of common non-invasive methods in MRI-negative epilepsy patients. In this study, we included epilepsy patients undergoing presurgical evaluation with presurgical negative MRI. MRI post-processing was performed using a Morphometric Analysis Program (MAP) on T1-weighted volumetric MRI. The relationship between MAP, magnetoencephalography (MEG), scalp electroencephalogram (EEG), and seizure outcomes was analyzed to figure out the localization value of different non-invasive methods. Eighty-six patients were included in this study. Complete resection of the MAP-positive regions or the MEG-positive regions was positively associated with seizure freedom (p = 0.028 and 0.007, respectively). When an area is co-localized by MAP and MEG, the resection of the area was significantly associated with seizure freedom (p = 0.006). However, neither the EEG lateralization nor the EEG localization showed statistical association with the surgical outcome (p = 0.683 and 0.505, respectively). In conclusion, scalp EEG had a limited role in presurgical localization and predicting seizure outcome, combining MAP and MEG results can significantly improve the localization of epileptogenic lesions and have a positive association with seizure-free outcome. PLAIN LANGUAGE SUMMARY: Due to the lack of obvious structure abnormalities on neuroimaging examinations, the identification of epilepsy lesions in MRI-negative epilepsy patients can be difficult. In this study, we intended to use non-invasive examinations to explore the potential epileptic lesions in MRI-negative epilepsy patients and to determine the results accuracy by comparing the neuroimaging results with the epilepsy surgery outcomes. A total of 86 epilepsy patients without obvious structure lesions on MRI were included, and we found that the combinations of different non-invasive examinations and neuroimaging post-processing methods are significantly associated with the seizure freedom results of epilepsy surgery.

Neurostimulation targeting the epileptic focus: Current understanding and perspectives for treatment

For the one third of people with epilepsy whose seizures are not controlled with medications, targeting the seizure focus with neurostimulation can be an effective therapeutic strategy. In this focused review, we summarize a discussion of targeted neurostimulation modalities during a workshop held in Frankfurt, Germany in September 2023. Topics covered include: available devices for seizure focus stimulation; alternating current (AC) and direct current (DC) stimulation to reduce focal cortical excitability; modeling approaches to simulate DC stimulation; reconciling the efficacy of focal stimulation with the network theory of epilepsy; and the emerging concept of 'neurostimulation zones,' which are defined as cortical regions where focal stimulation is most effective for reducing seizures and which may or may not directly involve the seizure onset zone. By combining experimental data, modeling results, and clinical outcome analysis, rational selection of target regions and stimulation parameters is increasingly feasible, paving the way for a broader use of neurostimulation for epilepsy in the future.

Detection of somatic and germline pathogenic variants in adult cohort of drug-resistant focal epilepsies

OBJECTIVE

This study investigates the prevalence of pathogenic variants in the mechanistic target of rapamycin (mTOR) pathway in surgical specimens of malformations of cortical development (MCDs) and cases with negative histology. The study also aims to evaluate the predictive value of genotype-histotype findings on the surgical outcome.

METHODS

The study included patients with drug-resistant focal epilepsy who underwent epilepsy surgery. Cases were selected based on histopathological diagnosis, focusing on MCDs and negative findings. We included brain tissues both as formalin-fixed, paraffin-embedded (FFPE) or fresh frozen (FF) samples. Single-molecule molecular inversion probes (smMIPs) analysis was conducted, targeting the MTOR gene in FFPE samples and 10 genes within the mTOR pathway in FF samples. Correlations between genotype-histotype and surgical outcome were examined.

RESULTS

We included 78 patients for whom we obtained 28 FFPE samples and 50 FF tissues. Seventeen pathogenic variants (22 %) were identified and validated, with 13 being somatic within the MTOR gene and 4 germlines (2 DEPDC5, 1 TSC1, 1 TSC2). Pathogenic variants in mTOR pathway genes were exclusively found in FCDII and TSC cases, with a significant association between FCD type IIb and MTOR genotype (P = 0.003). Patients carrying mutations had a slightly better surgical outcome than the overall cohort, however it results not significant. The FCDII diagnosed cases more frequently had normal neuropsychological test, a higher incidence of auras, fewer multiple seizure types, lower occurrence of seizures with awareness impairment, less ictal automatisms, fewer Stereo-EEG investigations, and a longer period long-life of seizure freedom before surgery.

SIGNIFICANCE

This study confirms that somatic MTOR variants represent the primary genetic alteration detected in brain specimens from FCDII/TSC cases, while germline DEPDC5, TSC1/TSC2 variants are relatively rare. Systematic screening for these mutations in surgically treated patients' brain specimens can aid histopathological diagnoses and serve as a biomarker for positive surgical outcomes. Certain clinical features associated with pathogenic variants in mTOR pathway genes may suggest a genetic etiology in FCDII patients.

Intraoperative electrocorticography-guided resection of the epileptogenic zone in an unusual porencephalic cyst: case report and literature review

Introduction

Porencephalic cysts resulting from perinatal artery infarctions typically manifest as large cysts accompanied by pre-existing neurological deficits. A small porencephalic cyst without any neurological deficit is a rare cause of medically refractory epilepsy.

Case presentation

A 23-year-old female presented with a history of medically refractory epilepsy secondary to a small right parieto-temporal porencephalic cyst. Despite optimal anti-seizure medications, seizures persisted. Surgical intervention was planned, and intraoperative electrocorticography (ioECoG) was used to delineate the epileptogenic zone (EZ), which was found to be two gyri posterior to the cyst.

Discussion

Very focal ischaemia resulting in a small porencephalic cyst from perinatal artery infarction exhibits a distinct organization of the EZ involving wider area posteriorly indicating involvement of arterial territory distal to the cyst. This contrasts with the typical perilesional EZ observed in other lesional epilepsy causes.

Conclusion

Our findings emphasize the need to consider aetiology during interpretation of ioECoG to better define the electrophysiological border between the normal and epileptogenic brain, aiding in achieving a better surgical outcome.

Impact of intracranial subclinical seizures on seizure outcomes after SLAH in patients with mesial temporal lobe epilepsy

OBJECTIVE

To investigate the association between subclinical seizures detected on intracranial electroencephalographic (i-SCSs)recordings and mesial temporal sclerosis (MTS), as well as their impact on surgical outcomes of stereotactic laser amygdalohippocampotomy (SLAH).

METHODS

A retrospective review was conducted on 27 patients with drug-resistant mesial temporal lobe epilepsy (MTLE) who underwent SLAH. The number of seizures detected on scalp EEG and iEEG was assessed. Patients were followed for a minimum of 3 years after SLAH.

RESULTS

Of the 1715 seizures recorded from mesial temporal regions, 1640 were identified as i-SCSs. Patients with MTS were associated with favorable short- and long-term surgical outcomes. Patients with MTS had a higher number of i-SCSs compared to patients without MTS. The numbers of i-SCSs were higher in patients with Engel I-II outcomes, but no significant statistical difference was found. However, it was observed that patients with MTS who achieved Engel I-II classification had higher numbers of i-SCSs than patients without MTS (P < 0.05).

CONCLUSION

Patients with MTS exhibited favorable short-term and long-term surgical outcome after SLAH. A higher number of i-SCSs was significantly associated with MTS in patients with MTLE. The number of i-SCSs tended to be higher in patients with Engel Ⅰ-Ⅱ surgical outcomes.

SIGNIFICANCE

The association between i-SCSs, MTS, and surgical outcomes in MTLE patients undergoing SLAH has significant implications for understanding the underlying mechanisms and identifying potential therapeutic targets to enhance surgical outcomes.

Outcome of Epilepsy Surgery in MRI-Negative Patients Without Histopathologic Abnormalities in the Resected Tissue

BACKGROUND AND OBJECTIVE

Patients with presumed nonlesional focal epilepsy-based on either MRI or histopathologic findings-have a lower success rate of epilepsy surgery compared with lesional patients. In this study, we aimed to characterize a large group of patients with focal epilepsy who underwent epilepsy surgery despite a normal MRI and had no lesion on histopathology. Determinants of their postoperative seizure outcomes were further studied.

METHODS

We designed an observational multicenter cohort study of MRI-negative and histopathology-negative patients who were derived from the European Epilepsy Brain Bank and underwent epilepsy surgery between 2000 and 2012 in 34 epilepsy surgery centers within Europe. We collected data on clinical characteristics, presurgical assessment, including genetic testing, surgery characteristics, postoperative outcome, and treatment regimen.

RESULTS

Of the 217 included patients, 40% were seizure-free (Engel I) 2 years after surgery and one-third of patients remained seizure-free after 5 years. Temporal lobe surgery (adjusted odds ratio [AOR]: 2.62; 95% CI 1.19-5.76), shorter epilepsy duration (AOR for duration: 0.94; 95% CI 0.89-0.99), and completely normal histopathologic findings-versus nonspecific reactive gliosis-(AOR: 4.69; 95% CI 1.79-11.27) were significantly associated with favorable seizure outcome at 2 years after surgery. Of patients who underwent invasive monitoring, only 35% reached seizure freedom at 2 years. Patients with parietal lobe resections had lowest seizure freedom rates (12.5%). Among temporal lobe surgery patients, there was a trend toward favorable outcome if hippocampectomy was part of the resection strategy (OR: 2.94; 95% CI 0.98-8.80). Genetic testing was only sporadically performed.

DISCUSSION

This study shows that seizure freedom can be reached in 40% of nonlesional patients with both normal MRI and histopathology findings. In particular, nonlesional temporal lobe epilepsy should be regarded as a relatively favorable group, with almost half of patients achieving seizure freedom at 2 years after surgery-even more if the hippocampus is resected-compared with only 1 in 5 nonlesional patients who underwent extratemporal surgery. Patients with an electroclinically identified focus, who are nonlesional, will be a promising group for advanced molecular-genetic analysis of brain tissue specimens to identify new brain somatic epilepsy genes or epilepsy-associated molecular pathways.

Simultaneous high-resolution whole-brain MR spectroscopy and [18F]FDG PET for temporal lobe epilepsy

PURPOSE

Precise lateralizing the epileptogenic zone in patients with drug-resistant mesial temporal lobe epilepsy (mTLE) remains challenging, particularly when routine MRI scans are inconclusive (MRI-negative). This study aimed to investigate the synergy of fast, high-resolution, whole-brain MRSI in conjunction with simultaneous [18F]FDG PET for the lateralization of mTLE.

METHODS

Forty-eight drug-resistant mTLE patients (M/F 31/17, age 12-58) underwent MRSI and [18F]FDG PET on a hybrid PET/MR scanner. Lateralization of mTLE was evaluated by visual inspection and statistical classifiers of metabolic mappings against routine MRI. Additionally, this study explored how disease status influences the associations between altered N-acetyl aspartate (NAA) and FDG uptake using hierarchical moderated multiple regression.

RESULTS

The high-resolution whole-brain MRSI data offers metabolite maps at comparable resolution to [18F]FDG PET. Visual examinations of combined MRSI and [18F]FDG PET showed an mTLE lateralization accuracy rate of 91.7% in a 48-patient cohort, surpassing routine MRI (52.1%). Notably, out of 23 MRI-negative mTLE, combined MRSI and [18F]FDG PET helped detect 19 cases. Logistical regression models combining hippocampal NAA level and FDG uptake improved lateralization performance (AUC=0.856), while further incorporating extrahippocampal regions such as amygdala, thalamus, and superior temporal gyrus increased the AUC to 0.939. Concurrent MRSI/PET revealed a moderating influence of disease duration and hippocampal atrophy on the association between hippocampal NAA and glucose uptake, providing significant new insights into the disease's trajectory.

CONCLUSION

This paper reports the first metabolic imaging study using simultaneous high-resolution MRSI and [18F]FDG PET, which help visualize MRI-unidentifiable lesions and may thus advance diagnostic tools and management strategies for drug-resistant mTLE.

Yield of non-invasive imaging in MRI-negative focal epilepsy

OBJECTIVE

The absence of MRI-lesion reduces considerably the probability of having an excellent outcome (International League Against Epilepsies [ILAE] class I-II) after epilepsy surgery. Surgical success in magnetic-resonance imaging (MRI)-negative cases relies therefore mainly on non-invasive techniques such as positron-emission tomography (PET), subtraction ictal/inter-ictal single-photon-emission-computed-tomography co-registered to MRI (SISCOM), electric source imaging (ESI) and morphometric MRI analysis (MAP). We were interested in identifying the optimal imaging technique or combination to achieve post-operative class I-II in patients with MRI-negative focal epilepsy.

METHODS

We identified 168 epileptic patients without MRI lesion. Thirty-three (19.6%) were diagnosed with unifocal epilepsy, underwent surgical resection and follow-up ⩾ 2 years. Sensitivity, specificity, predictive values, and diagnostic odds ratio (OR) were calculated for each technique individually and in combination (after co-registration).

RESULTS

23/33 (70%) were free of disabling seizures (75.0% with temporal and 61.5% extratemporal lobe epilepsy). None of the individual modalities presented an OR > 1.5, except ESI if only patients with interictal epileptiform discharges (IEDs) were considered (OR 3.2). On a dual combination, SISCOM with ESI presented the highest outcome (OR = 6). MAP contributed to detecting indistinguishable focal cortical dysplasia in particular in extratemporal epilepsies with a sensitivity of 75%. Concordance of PET, ESI on interictal epileptic discharges, and SISCOM was associated with the highest chance for post-operative seizure control (OR = 11).

CONCLUSION

If MRI is negative, the chances to benefit from epilepsy surgery are almost as high as in lesional epilepsy, provided that multiple established non-invasive imaging tools are rigorously applied and co-registered together.

The impact of a history of status epilepticus for epilepsy surgery outcome

OBJECTIVE

Patients with focal drug resistant epilepsy are excellent candidates for epilepsy surgery. Status epilepticus (SE) and seizure clusters (SC), described in a subset of patients, have both been associated with extended epileptogenic cerebral networks within one or both hemispheres. In this retrospective study, we were interested to determine if a history of SE or SC is associated with a worse surgical outcome.

METHODS

Data of 244 patients operated between 2000 to 2018 were reviewed, with a follow-up of at least 2 years. Patients with a previous history of SE or SC were compared to operated patients without these conditions (control group, CG).

RESULTS

We identified 27 (11%) and 38 (15.5%) patients with history of SE or SC, respectively. No difference in post-operative outcome was found for SE and SC patients. Compared to the control group, patients with a history of SE were diagnosed and operated significantly at earlier age(p = 0.01), and after a shorter duration of the disease (p = 0.027), but with a similar age of onset.

SIGNIFICANCE

A history of SE or SC was not associated with a worse post-operative prognosis. Earlier referral of SE patients for surgery suggests a heightened awareness regarding serious complications of recurrent SE by the referring neurologist or neuropediatrician. While the danger of SE is evident, policies to underline the impact for SC or very frequent seizures might be an efficient approach to accelerate patient referral also for this patient group.

Implementation of a 7T Epilepsy Task Force consensus imaging protocol for routine presurgical epilepsy work-up: effect on diagnostic yield and lesion delineation

OBJECTIVE

Recently, the 7 Tesla (7 T) Epilepsy Task Force published recommendations for 7 T magnetic resonance imaging (MRI) in patients with pharmaco-resistant focal epilepsy in pre-surgical evaluation. The objective of this study was to implement and evaluate this consensus protocol with respect to both its practicability and its diagnostic value/potential lesion delineation surplus effect over 3 T MRI in the pre-surgical work-up of patients with pharmaco-resistant focal onset epilepsy.

METHODS

The 7 T MRI protocol consisted of T1-weighted, T2-weighted, high-resolution-coronal T2-weighted, fluid-suppressed, fluid-and-white-matter-suppressed, and susceptibility-weighted imaging, with an overall duration of 50 min. Two neuroradiologists independently evaluated the ability of lesion identification, the detection confidence for these identified lesions, and the lesion border delineation at 7 T compared to 3 T MRI.

RESULTS

Of 41 recruited patients > 12 years of age, 38 were successfully measured and analyzed. Mean detection confidence scores were non-significantly higher at 7 T (1.95 ± 0.84 out of 3 versus 1.64 ± 1.19 out of 3 at 3 T, p = 0.050). In 50% of epilepsy patients measured at 7 T, additional findings compared to 3 T MRI were observed. Furthermore, we found improved border delineation at 7 T in 88% of patients with 3 T-visible lesions. In 19% of 3 T MR-negative cases a new potential epileptogenic lesion was detected at 7 T.

CONCLUSIONS

The diagnostic yield was beneficial, but with 19% new 7 T over 3 T findings, not major. Our evaluation revealed epilepsy outcomes worse than ILAE Class 1 in two out of the four operated cases with new 7 T findings.

Ultrasound-Navigated Multiple Hippocampal Transections: An Anatomical Study

BACKGROUND

 Multiple hippocampal transection (MHT) is a surgical technique used for the treatment of drug-resistant mesial temporal lobe epilepsy in situations where standard procedures would pose a high risk for memory deterioration. During MHT, the longitudinal fibers of the hippocampus, implicated in epilepsy spreading, are interrupted, while the transverse memory circuits are spared. The extent of MHT is governed by intraoperative electrocorticography; abolition of epileptic discharges serves as an end point to terminate the transection. In other words, the aim of MHT is not the anatomical completeness of hippocampal transection. In contrast, we hypothesize that only the complete transection of hippocampal cross-section is needed to durably terminate epilepsy, avoiding possible postoperative reorganization of longitudinal pathways. Here, we report an anatomical study designed to evaluate the feasibility of complete transection of hippocampus with the aid of ultrasound neuronavigation and we propose new instruments to reach this goal.

METHODS

 Five cadaveric brains were analyzed in this study. MHT was performed on both sides of each brain either with or without ultrasound neuronavigation. The percentage of transected cross-section of the hippocampus was measured using magnetic resonance imaging (MRI) and both sides were compared.

RESULTS

 The ultrasound-guided MHTs were more likely to achieve complete hippocampal transection compared with the nonnavigated MHT transection (73 vs 58%; p < 0.01). Our study also allowed us to propose specialized transectors to minimize invasivity of this procedure.

CONCLUSION

 Completeness of MHT can be better reached with the aid of an ultrasound neuronavigation system; modified instruments for this procedure were also designed.

Imaging and Stereotactic Electroencephalography Functional Networks to Guide Epilepsy Surgery

Epilepsy surgery is a potentially curative treatment of drug-resistant epilepsy that has remained underutilized both due to inadequate referrals and incomplete localization hypotheses. The complexity of patients evaluated for epilepsy surgery has increased, thus new approaches are necessary to treat these patients. The paradigm of epilepsy surgery has evolved to match this challenge, now considering the entire seizure network with the goal of disrupting it through resection, ablation, neuromodulation, or a combination. The network paradigm has the potential to aid in identification of the seizure network as well as treatment selection.

Interictal Electrical Source Imaging

SUMMARY

Interictal electrical source imaging (ESI) determines the neuronal generators of epileptic activity in EEG occurring outside of seizures. It uses computational models to take anatomic and neuronal characteristics of the individual patient into account. The presented article provides an overview of application and clinical value of interictal ESI in patients with pharmacoresistant focal epilepsies undergoing evaluation for surgery. Neurophysiological constraints of interictal data are discussed and technical considerations are summarized. Typical indications are covered as well as issues of integration into clinical routine. Finally, an outlook on novel markers of epilepsy for interictal source analysis is presented. Interictal ESI provides diagnostic performance on par with other established methods, such as MRI, PET, or SPECT. Although its accuracy benefits from high-density recordings, it provides valuable information already when applied to EEG with only a limited number of electrodes with complete coverage. Novel oscillatory markers and the integration of frequency coupling and connectivity may further improve accuracy and efficiency.

Imaging biomarkers of sleep-related hypermotor epilepsy and sudden unexpected death in epilepsy: a review

In recent years, imaging has emerged as a promising source of several intriguing biomarkers in epilepsy, due to the impressive growth of imaging technology, supported by methodological advances and integrations of post-processing techniques. Bearing in mind the mutually influencing connection between sleep and epilepsy, we focused on sleep-related hypermotor epilepsy (SHE) and sudden unexpected death in epilepsy (SUDEP), aiming to make order and clarify possible clinical utility of emerging multimodal imaging biomarkers of these two epilepsy-related entities commonly occurring during sleep. Regarding SHE, advanced structural techniques might soon emerge as a promising source of diagnostic and predictive biomarkers, tailoring a targeted therapeutic (surgical) approach for MRI-negative subjects. Functional and metabolic imaging may instead unveil SHE's extensive and night-related altered brain networks, providing insights into distinctions and similarities with non-epileptic sleep phenomena, such as parasomnias. SUDEP is considered a storm that strikes without warning signals, but objective subtle structural and functional alterations in autonomic, cardiorespiratory, and arousal centers are present in patients eventually experiencing SUDEP. These alterations could be seen both as susceptibility and diagnostic biomarkers of the underlying pathological ongoing loop ultimately ending in death. Finally, given that SHE and SUDEP are rare phenomena, most evidence on the topic is derived from small single-center experiences with scarcely comparable results, hampering the possibility of performing any meta-analytic approach. Multicenter, longitudinal, well-designed studies are strongly encouraged.

Deep learning and radiomics based automatic diagnosis of hippocampal sclerosis

Accurate and rapid segmentation of the hippocampus can help doctors perform intractable temporal lobe epilepsy (TLE) preoperative evaluations to identify good surgical candidates. This study aims to establish a radiomics system for the automatic diagnosis of hippocampal sclerosis with the help of machine learning. A total of 240 cases were analysed to develop a diagnostic model. First, an automatic hippocampal segmentation process was established that exploits a priori knowledge of the relatively fixed location of the hippocampus in brain partitions, as well as a deep-learning segmentation network based on an Attention U-net. Then, we extracted 527 radiomics features from each side of the segmented hippocampus. The iterative sparse representation based on feature selection and a support vector machine classifier were finally used to establish the diagnostic model of hippocampal sclerosis. The diagnostic model consists of two consecutive steps: distinguish hippocampal sclerosis (HS) from normal control (NC) and detect whether the HS is located on the left or right side. When the automatic diagnosis model identified HS and NC, the sensitivity and specificity reached 0.941 and 0.917 in the 10-fold cross-validation set and 0.920 and 0.909 in the independent testing set. When the diagnostic model detected HS lateralization, the sensitivity and specificity reached 0.923 and 0.920 in cross-validation and 0.909 and 0.929 in independent testing. Our results show that the developed radiomics model can help detect TLE patients with hippocampal sclerosis and has the potential to simplify preoperative evaluations and select surgical candidates.

Feasibility and limitations of head MRI in patients with cochlear implants

OBJECTIVE

Cochlear implants (CIs) were noncompatible with magnetic resonance imaging (MRI) initially; however, recently, implants have become available that are compatible with MRI without the need for magnet removal or bandage fixation. The images produced by MRI scans are sometimes deteriorated by artifacts and are not clinically useful. In this study, we discussed the size differences of such artifacts with respect to the imaging modality and sequences with their clinical validity.

METHODS

We performed a head MRI, using a head bandage and without magnet removal in five patients who underwent cochlear implantation at our department and analyzed the MRI findings.

RESULTS

Without magnet removal, diffusion-weighted images and T2 star-weighted images had larger artifacts and less useful images. T1-weighted images, T2-weighted images (T2WIs), T2-weighted fluid-attenuated inversion recovery (T2-FLAIR) images, and heavy T2WIs could evaluate the unimplanted side and middle of the head but had limited applicability on the CI side.

CONCLUSION

The characteristic features of MRI scan images vary with the method used as well as with the sequence, suggesting that the choice of MRI is largely determined on the basis of clinical feasibility and the requirement. Accordingly, we need to judge well in advance of imaging whether the images would be clinically relevant.

Enhanced focal cortical dysplasia detection in pediatric frontal lobe epilepsy with asymmetric radiomic and morphological features

Objective

Focal cortical dysplasia (FCD) is the most common pathological cause for pediatric epilepsy, with frontal lobe epilepsy (FLE) being the most prevalent in the pediatric population. We attempted to utilize radiomic and morphological methods on MRI and PET to detect FCD in children with FLE.

Methods

Thirty-seven children with FLE and 20 controls were included in the primary cohort, and a five-fold cross-validation was performed. In addition, we validated the performance in an independent site of 12 FLE children. A two-stage experiments including frontal lobe and subregions were employed to detect the lesion area of FCD, incorporating the asymmetric feature between the left and right hemispheres. Specifically, for the radiomics approach, we used gray matter (GM), white matter (WM), GM and WM, and the gray-white matter boundary regions of interest to extract features. Then, we employed a Multi-Layer Perceptron classifier to achieve FCD lesion localization based on both radiomic and morphological methods.

Results

The Multi-Layer Perceptron model based on the asymmetric feature exhibited excellent performance both in the frontal lobe and subregions. In the primary cohort and independent site, the radiomics analysis with GM and WM asymmetric features had the highest sensitivity (89.2 and 91.7%) and AUC (98.9 and 99.3%) in frontal lobe. While in the subregions, the GM asymmetric features had the highest sensitivity (85.6 and 79.7%). Furthermore, relying on the highest sensitivity of GM and WM asymmetric features in frontal lobe, when integrated with the subregions results, our approach exhibited overlaps with GM asymmetric features (55.4 and 52.4%), as well as morphological asymmetric features (54.4 and 53.8%), both in the primary cohort and at the independent site.

Significance

This study demonstrates that a two-stage design based on the asymmetry of radiomic and morphological features can improve FCD detection. Specifically, incorporating regions of interest for GM, WM, GM, and WM, and the gray-white matter boundary significantly enhances the localization capabilities for lesion detection within the radiomics approach.

Interictal invasive very high-frequency oscillations in resting awake state and sleep

Interictal very high-frequency oscillations (VHFOs, 500-2000 Hz) in a resting awake state seem to be, according to a precedent study of our team, a more specific predictor of a good outcome of the epilepsy surgery compared to traditional interictal high-frequency oscillations (HFOs, 80-500 Hz). In this study, we retested this hypothesis on a larger cohort of patients. In addition, we also collected patients' sleep data and hypothesized that the occurrence of VHFOs in sleep will be greater than in resting state. We recorded interictal invasive electroencephalographic (iEEG) oscillations in 104 patients with drug-resistant epilepsy in a resting state and in 35 patients during sleep. 21 patients in the rest study and 11 patients in the sleep study met the inclusion criteria (interictal HFOs and VHFOs present in iEEG recordings, a surgical intervention and a postoperative follow-up of at least 1 year) for further evaluation of iEEG data. In the rest study, patients with good postoperative outcomes had significantly higher ratio of resected contacts with VHFOs compared to HFOs. In sleep, VHFOs were more abundant than in rest and the percentage of resected contacts in patients with good and poor outcomes did not considerably differ in any type of oscillations. In conclusion, (1) our results confirm, in a larger patient cohort, our previous work about VHFOs being a specific predictor of the area which needs to be resected; and (2) that more frequent sleep VHFOs do not further improve the results.

The clinical application of neuro-robot in the resection of epileptic foci: a novel method assisting epilepsy surgery

During surgery for foci-related epilepsy, neurosurgeons face significant difficulties in identifying and resecting MRI-negative or deep-seated epileptic foci. Here, we present a neuro-robotic navigation system that is specifically designed for resection of MRI negative epileptic foci. We recruited 52 epileptic patients, and randomly assigned them to treatment group with either neuro-robotic navigation or conventional neuronavigation system. For each patient, in the neuro-robotic navigation group, we integrated multimodality imaging including MRI and PET-CT into the robotic workstation and marked the boundary of foci from the fused image. During surgery, this boundary was delineated by the robotic laser device with high accuracy, guiding resection for the surgeon. For deeply seated foci, we exploited the neuro-robotic navigation system to localize the deepest point with biopsy needle insertion and methylene dye application to locate the boundary of the foci. Our results show that, compared with the conventional neuronavigation, the neuro-robotic navigation system performs equally well in MRI positive epilepsy patients (ENGEL I ratio: 71.4% vs 100%, p = 0.255) systems and show better performance in patients with MRI-negative focal cortical dysplasia (ENGEL I ratio: 88.2% vs 50%, p = 0.0439). At present, there are no documented neurosurgery robots with similar function and application in the field of epilepsy. Our research highlights the added value of using neuro-robotic navigation systems in resection surgery for epilepsy, particularly in cases that involve MRI-negative or deep-seated epileptic foci.

Brain vascularization in deep brain stimulation surgeries: epilepsy, Parkinson's disease, and obsessive-compulsive disorder

BACKGROUND

In our experience, we encountered more blood vessels during deep brain stimulation (DBS) surgeries in epilepsy. In this study, we have quantified and compared the cerebral vascularization in epilepsy, Parkinson's disease (PD) and obsessive-compulsive disorder (OCD).

METHODS

A retrospective observational study in 15 epilepsy and 15 PD patients was performed. The amount, location, and size of blood vessels within 5 millimeters (mm) of all DBS electrode trajectories (N.=120) for both targets (anterior nucleus of the thalamus: ANT and subthalamic nucleus: STN) in both patient groups were quantified and compared on a Medtronic workstation (Dublin, Ireland). Additionally, blood vessels in the trajectories (N.=120) of another group of 15 PD (STN) and 15 OCD (ventral capsule-ventral striatum [VC-VS]) patients were quantified and compared (trajectories N.=120), also to the first group. Statistical analyses were performed with SPSS version 27.0 (descriptive statistics, independent samples t-tests, Mann Whitney U Test, ANOVA Test and post-hoc Tukey Test). A P value <0.05 was considered statistically significant.

RESULTS

Our results showed a significant greater amount of cerebral blood vessels in epilepsy patients (10 SD±4) compared to PD (PD1 6 SD±1 and PD2 5 SD±3) and OCD (5 SD±1) with P<0.0001. Also, all other subanalyses showed more vascularization in the epilepsy group.

CONCLUSIONS

Our results show that the brain of epilepsy patients seems to be more vascularized compared to PD and OCD patients. This can make the surgical planning for DBS more challenging, and the use of multiple trajectories limited.

Radiomics features from 3D-MPRAGE imaging can differentiate temporal-plus epilepsy from temporal lobe epilepsy

OBJECTIVE

This study aimed to differentiate temporal-plus epilepsy (TPE) from temporal lobe epilepsy (TLE) using extraction of radiomics features from three-dimensional magnetization-prepared rapid acquisition gradient echo (3D-MPRAGE) imaging data.

METHODS

Data from patients with TLE or TPE who underwent epilepsy surgery between January 2019 and January 2021 were retrospectively analyzed. Thirty-three regions of interest in the affected hemisphere of each patient were defined on 3D-MPRAGE images. A total of 3531 image features were extracted from each patient. Four feature selection methods and 10 machine learning algorithms were used to build 40 differentiation models. Model performance was evaluated using receiver operating characteristic analysis.

RESULTS

Eighty-two patients were included for analysis, 47 with TLE and 35 with TPE. The model combining logistic regression and the relief selection method had the best performance (area under the receiver operating characteristic curve, .779; accuracy, .875; sensitivity, .800; specificity, .929; positive predictive value, .889; negative predictive value, .867).

SIGNIFICANCE

Radiomics analysis can differentiate TPE from TLE. The logistic regression classifier trained with radiomics features extracted from 3D-MPRAGE images had the highest accuracy and best performance.

Utility of Gadolinium-Based Contrast in Initial Evaluation of Seizures in Children Presenting Emergently

BACKGROUND AND PURPOSE

The frequency and utility of gadolinium in evaluation of acute pediatric seizure presentation is not well known. The purpose of this study was to assess the utility of gadolinium-based contrast agents in MR imaging performed for the evaluation of acute pediatric seizure presentation.

MATERIALS AND METHODS

We identified consecutive pediatric patients with new-onset seizures from October 1, 2016, to September 30, 2021, who presented to the emergency department and/or were admitted to the inpatient unit and had an MR imaging of the brain for the evaluation of seizures. The clinical and imaging data were recorded, including the patient's age and sex, the use of IV gadolinium, and the underlying cause of epilepsy when available.

RESULTS

A total of 1884 patients were identified for inclusion. Five hundred twenty-four (28%) patients had potential epileptogenic findings on brain MR imaging, while 1153 (61%) patients had studies with normal findings and 207 (11%) patients had nonspecific signal changes. Epileptogenic findings were subclassified as the following: neurodevelopmental lesions, 142 (27%); intracranial hemorrhage (traumatic or germinal matrix), 89 (17%); ischemic/hypoxic, 62 (12%); hippocampal sclerosis, 44 (8%); neoplastic, 38 (7%); immune/infectious, 20 (4%); phakomatoses, 19 (4%); vascular anomalies, 17 (3%); metabolic, 3 (<1%); and other, 90 (17%). Eight hundred seventy-four (46%) patients received IV gadolinium. Of those, only 48 (5%) cases were retrospectively deemed to have necessitated the use of IV gadolinium: Fifteen of 48 (31%) cases were subclassified as immune/infectious, while 33 (69%) were neoplastic. Of the 1010 patients with an initial noncontrast study, 15 (1.5%) required repeat MR imaging with IV contrast to further evaluate the findings.

CONCLUSIONS

Gadolinium contrast is of limited additive benefit in the imaging of patients with an acute onset of pediatric seizures in most instances.

Drug-resistant epilepsy: Definition, pathophysiology, and management

There are currently >51 million people with epilepsy (PWE) in the world and every year >4.9 million people develop new-onset epilepsy. The cornerstone of treatment in PWE is drug therapy with antiseizure medications (ASMs). However, about one-third of PWE do not achieve seizure control and do not respond well to drug therapy despite the use of appropriate ASMs [drug-resistant epilepsy (DRE)]. The aims of the current narrative review are to discuss the definition of DRE, explain the biological underpinnings and clinical biomarkers of this condition, and finally to suggest practical management strategies to tackle this issue appropriately, in a concise manner.

Seizure features and outcomes in 50 children with GATOR1 variants: A retrospective study, more favorable for epilepsy surgery

OBJECTIVES

To summarize the clinical features of epilepsy related to DEPDC5, NPRL2, and NPRL3 genes encoding the GATOR1 complex in children and to evaluate the factors affecting the prognosis of these epilepsies.

METHODS

In this retrospective study, we reviewed the clinical and genetic characteristics of children with epilepsy related to GATOR1 variants who were admitted to the Peking University First Hospital between January 2016 and December 2021. Potential prognostic factors were assessed by comparing children with and without ongoing seizures.

RESULTS

Fifty probands, including 31 boys and 19 girls were recruited. The median age at onset of epilepsy was 4 months, and 64% of patients had early-onset epilepsy (≤1 year). The most frequent epileptic seizure type was focal seizure (86%). Among the 50 patients, only six were with de novo variants. According to the novel classification framework for GATOR1 variants, 36 patients were with pathogenic variants and 14 with likely pathogenic variants. DEPDC5 variants were found in 37 patients, NPRL3 in 9, and NPRL2 in 4. The phenotype was similar among the probands, with variants in DEPDC5, NRPL2, or NPRL3. 76% (38/50) of epilepsy related to GATOR1 variants was neuroimaging positive, including brain MRI positive in 31 patients, and MRI combined F-18-fluorodeoxyglucose positron emission tomography positive in the other seven patients. Twenty-seven patients underwent epilepsy surgery. In total, after initial antiseizure medications alone, 92% (46/50) of patients were drug-resistant epilepsies, only 8% (4/50) of the probands became seizure-free but seizure-free (≥6 m) occurred in 92.6% (25/27) of patients with drug-resistant epilepsy after epilepsy surgery at the last follow-up. Patients undergoing epilepsy surgery had better epilepsy prognosis.

SIGNIFICANCE

Epilepsy related to GATOR1 variants had high possibility to be drug-resistant epilepsy and to have positive neuroimaging finding. Epilepsy surgery is the only favorable factor for better seizure prognosis in this kind epilepsy.

Seizure outcomes after resection of primary brain tumors in pediatric patients: a systematic review and meta-analysis

PURPOSE

Primary brain neoplasms are the most common solid tumors in pediatric patients and seizures are a common presenting symptom. Surgical intervention improves oncologic outcomes and seizure burden. A better understanding of factors that influence seizure outcomes in the surgical management of primary brain tumors of childhood can guide treatment approach thereby improving patient quality of life.

METHODS

We performed a systematic analysis using articles queried from PubMed, EMBASE, and Cochrane published from January 1990 to August 2022 to determine predictors of seizure outcomes in pediatric patients undergoing resection of primary brain tumors.

RESULTS

We identified 24 retrospective cohort studies, one prospective cohort study, and one mixed retrospective and prospective study for the systematic analysis. A total of 831 pediatric patients were available for analysis. 668 (80.4%) patients achieved seizure freedom after surgery. Complete tumor resection increased the likelihood of a seizure-free (Engel I) outcome compared to subtotal resection (OR 7.1, 95% CI 2.3-21.9). Rates of Engel I seizure outcomes did not significantly differ based on factors such as age at seizure onset, duration of epilepsy, gender, tumor laterality, or age at surgery, but trended towards significance for improved outcomes in temporal lobe tumors.

CONCLUSION

Primary brain tumors in the pediatric population are commonly associated with seizures. Resection of these lesions reduces seizure burden and is associated with high rates of seizure freedom. Complete resection, compared to subtotal resection, significantly increases the likelihood of seizure-free outcomes.

An open presurgery MRI dataset of people with epilepsy and focal cortical dysplasia type II

Automated detection of lesions using artificial intelligence creates new standards in medical imaging. For people with epilepsy, automated detection of focal cortical dysplasias (FCDs) is widely used because subtle FCDs often escape conventional neuroradiological diagnosis. Accurate recognition of FCDs, however, is of outstanding importance for affected people, as surgical resection of the dysplastic cortex is associated with a high chance of postsurgical seizure freedom. Here, we make publicly available a dataset of 85 people affected by epilepsy due to FCD type II and 85 healthy control persons. We publish 3D-T1 and 3D-FLAIR, manually labeled regions of interest, and carefully selected clinical features. The open presurgery MRI dataset may be used to validate existing automated algorithms of FCD detection as well as to create new approaches. Most importantly, it will enable comparability of already existing approaches and support a more widespread use of automated lesion detection tools.

Impact of epilepsy surgery on quality of life: Systematic review and meta-analysis

Improved quality of life (QoL) is an important outcome goal following epilepsy surgery. This study aims to quantify change in QoL for adults with drug-resistant epilepsy (DRE) who undergo epilepsy surgery, and to explore clinicodemographic factors associated with these changes. We conducted a systematic review and meta-analysis using Medline, Embase, and Cochrane Central Register of Controlled Trials. All studies reporting pre- and post-epilepsy surgery QoL scores in adults with DRE via validated instruments were included. Meta-analysis assessed the postsurgery change in QoL. Meta-regression assessed the effect of postoperative seizure outcomes on postoperative QoL as well as change in pre- and postoperative QoL scores. A total of 3774 titles and abstracts were reviewed, and ultimately 16 studies, comprising 1182 unique patients, were included. Quality of Life in Epilepsy Inventory-31 item (QOLIE-31) meta-analysis included six studies, and QOLIE-89 meta-analysis included four studies. Postoperative change in raw score was 20.5 for QOLIE-31 (95% confidence interval [CI] = 10.9-30.1, I2  = 95.5) and 12.1 for QOLIE-89 (95% CI = 8.0-16.1, I2  = 55.0%). This corresponds to clinically meaningful QOL improvements. Meta-regression demonstrated a higher postoperative QOLIE-31 score as well as change in pre- and postoperative QOLIE-31 score among studies of cohorts with higher proportions of patients with favorable seizure outcomes. At an individual study level, preoperative absence of mood disorders, better preoperative cognition, fewer trials of antiseizure medications before surgery, high levels of conscientiousness and openness to experience at the baseline, engagement in paid employment before and after surgery, and not being on antidepressants following surgery were associated with improved postoperative QoL. This study demonstrates the potential for epilepsy surgery to provide clinically meaningful improvements in QoL, as well as identifies clinicodemographic factors associated with this outcome. Limitations include substantial heterogeneity between individual studies and high risk of bias.

Advances in Image Processing for Epileptogenic Zone Detection with MRI

Focal epilepsy is a common and severe neurologic disorder. Neuroimaging aims to identify the epileptogenic zone (EZ), preferably as a macroscopic structural lesion. For approximately a third of patients with chronic drug-resistant focal epilepsy, the EZ cannot be precisely identified using standard 3.0-T MRI. This may be due to either the EZ being undetectable at imaging or the seizure activity being caused by a physiologic abnormality rather than a structural lesion. Computational image processing has recently been shown to aid radiologic assessments and increase the success rate of uncovering suspicious regions by enhancing their visual conspicuity. While structural image analysis is at the forefront of EZ detection, physiologic image analysis has also been shown to provide valuable information about EZ location. This narrative review summarizes and explains the current state-of-the-art computational approaches for image analysis and presents their potential for EZ detection. Current limitations of the methods and possible future directions to augment EZ detection are discussed.

Is intracranial electroencephalography mandatory for MRI-negative neocortical epilepsy surgery?

OBJECTIVE

MRI-negative focal epilepsy is one of the most challenging cases in surgical epilepsy treatment. Many epilepsy centers recommend intracranial electroencephalography (EEG) for MRI-negative cases, especially neocortical epilepsy. This retrospective study aimed to explore whether intracranial monitoring is mandatory in MRI-negative neocortical epilepsy surgery and the factors that significantly influence the decision on whether to perform intracranial recording.

METHODS

In this study, consecutive surgical patients with focal MRI-negative neocortical epilepsy were recruited. All patients underwent routine preoperative evaluation according to the dedicated protocol of the authors' epilepsy center to determine the treatment strategy. Patients were divided into two groups according to the surgical strategy, i.e., a direct group and a stereo-EEG (SEEG)-guided group. History of epilepsy, seizure frequency, interictal and ictal EEG data, PET data, PET/MRI coregistration data, neuropathological findings, and surgical outcomes were compared between the two groups. Multivariate analysis was performed to identify factors influencing the decision to perform SEEG monitoring.

RESULTS

Sixty-four patients were included in this study, 19 and 45 of whom underwent direct and SEEG-guided cortical resection, respectively. At an average follow-up of 3.9 years postoperatively, 56 patients (87.5%) had Engel class I results without permanent neurological deficits. Surgical outcomes were not significantly different between the direct and SEEG-guided groups (94.7% vs 84.4%). PET hypometabolic abnormalities were detected in all patients. There were significant differences between the two groups in the extent of hypometabolism (focal vs nonfocal, p < 0.01) and pathological subtype (focal cortical dysplasia type II vs others, p = 0.03). Multivariate analysis revealed that the extent of hypometabolism (OR 0.01, 95% CI 0.00-0.15; p = 0.001) was the only independent factor affecting the treatment strategy.

CONCLUSIONS

Careful selection of patients with MRI-negative neocortical epilepsy may yield favorable outcomes after direct cortical resection without intracranial monitoring. PET/MRI coregistration plays an essential role in the preoperative evaluation and subsequent resection of these patients. Intracranial monitoring is not a mandatory requirement for surgery if the focal hypometabolic areas are consistent with the findings of semiology and scalp EEG.

Lateralization of interictal temporal lobe hypoperfusion in lesional and non-lesional temporal lobe epilepsy using arterial spin labeling MRI

PURPOSE

Non-invasive imaging studies play a critical role in the presurgical evaluation of patients with drug-resistant temporal lobe epilepsy (TLE), particularly in helping to lateralize the seizure focus. Arterial Spin Labeling (ASL) MRI has been widely used to non-invasively study cerebral blood flow (CBF), with somewhat variable interictal alterations reported in TLE. Here, we compare temporal lobe subregional interictal perfusion and symmetry in lesional (MRI+) and non-lesional (MRI-) TLE compared to healthy volunteers (HVs).

METHODS

Twenty TLE patients (9 MRI+, 11 MRI-) and 14 HVs under went 3 T Pseudo-Continuous ASL MRI through an epilepsy imaging research protocol at the NIH Clinical Center. We compared normalized CBF and absolute asymmetry indices in multiple temporal lobe subregions.

RESULTS

Compared to HVs, both MRI+ and MRI- TLE groups demonstrated significant ipsilateral mesial and lateral temporal hypoperfusion, specifically in the hippocampal and anterior temporal neocortical subregions, with additional hypoperfusion in the ipsilateral parahippocampal gyrus in the MRI+ and contralateral hippocampus in the MRI- TLE groups. Contralateral to the seizure focus, there was significant relative hypoperfusion in multiple subregions in the MRI- compared to the MRI+ TLE groups. The MRI+ group therefore had significantly greater asymmetry across multiple temporal subregions compared to the MRI- TLE and HV groups. No significant differences in asymmetry were found between the MRI- TLE and HV groups.

CONCLUSION

We found a similar extent of interictal ipsilateral temporal hypoperfusion in MRI+ and MRI- TLE. However, significantly increased asymmetries were found only in the MRI+ group due to differences in perfusion contralateral to the seizure focus between the patient groups. The lack of asymmetry in the MRI- group may negatively impact the utility of interictal ASL for seizure focus lateralization in this patient population.

Clinical added value of interictal automated electrical source imaging in the presurgical evaluation of MRI-negative epilepsy: A real-life experience in 29 consecutive patients

OBJECTIVE

During the presurgical evaluation, manual electrical source imaging (ESI) provides clinically useful information in one-third of the patients but it is time-consuming and requires specific expertise. This prospective study aims to assess the clinical added value of a fully automated ESI analysis in a cohort of patients with MRI-negative epilepsy and describe its diagnostic performance, by evaluating sublobar concordance with stereo-electroencephalography (SEEG) results and surgical resection and outcome.

METHODS

All consecutive patients referred to the Center for Refractory Epilepsy (CRE) of St-Luc University Hospital (Brussels, Belgium) for presurgical evaluation between 15/01/2019 and 31/12/2020 meeting the inclusion criteria, were recruited to the study. Interictal ESI was realized on low-density long-term EEG monitoring (LD-ESI) and, whenever available, high-density EEG (HD-ESI), using a fully automated analysis (Epilog PreOp, Epilog NV, Ghent, Belgium). The multidisciplinary team (MDT) was asked to formulate hypotheses about the epileptogenic zone (EZ) location at sublobar level and make a decision on further management for each patient at two distinct moments: i) blinded to ESI and ii) after the presentation and clinical interpretation of ESI. Results leading to a change in clinical management were considered contributive. Patients were followed up to assess whether these changes lead to concordant results on stereo-EEG (SEEG) or successful epilepsy surgery.

RESULTS

Data from all included 29 patients were analyzed. ESI led to a change in the management plan in 12/29 patients (41%). In 9/12 (75%), modifications were related to a change in the plan of the invasive recording. In 8/9 patients, invasive recording was performed. In 6/8 (75%), the intracranial EEG recording confirmed the localization of the ESI at a sublobar level. So far, 5/12 patients, for whom the management plan was changed after ESI, were operated on and have at least one-year postoperative follow-up. In all cases, the EZ identified by ESI was included in the resection zone. Among these patients, 4/5 (80%) are seizure-free (ILAE 1) and one patient experienced a seizure reduction of more than 50% (ILAE 4).

CONCLUSIONS

In this single-center prospective study, we demonstrated the added value of automated ESI in the presurgical evaluation of MRI-negative cases, especially in helping to plan the implantation of depth electrodes for SEEG, provided that ESI results are integrated into the whole multimodal evaluation and clinically interpreted.

Deep Brain Stimulation of the Anterior Nucleus of the Thalamus in Drug-Resistant Epilepsy in the MORE Multicenter Patient Registry

BACKGROUND AND OBJECTIVES

The efficacy of deep brain stimulation of the anterior nucleus of the thalamus (ANT DBS) in patients with drug-resistant epilepsy (DRE) was demonstrated in the double-blind Stimulation of the Anterior Nucleus of the Thalamus for Epilepsy randomized controlled trial. The Medtronic Registry for Epilepsy (MORE) aims to understand the safety and longer-term effectiveness of ANT DBS therapy in routine clinical practice.

METHODS

MORE is an observational registry collecting prospective and retrospective clinical data. Participants were at least 18 years old, with focal DRE recruited across 25 centers from 13 countries. They were followed for at least 2 years in terms of seizure frequency (SF), responder rate (RR), health-related quality of life (Quality of Life in Epilepsy Inventory 31), depression, and safety outcomes.

RESULTS

Of the 191 patients recruited, 170 (mean [SD] age of 35.6 [10.7] years, 43% female) were implanted with DBS therapy and met all eligibility criteria. At baseline, 38% of patients reported cognitive impairment. The median monthly SF decreased by 33.1% from 15.8 at baseline to 8.8 at 2 years (p < 0.0001) with 32.3% RR. In the subgroup of 47 patients who completed 5 years of follow-up, the median monthly SF decreased by 55.1% from 16 at baseline to 7.9 at 5 years (p < 0.0001) with 53.2% RR. High-volume centers (>10 implantations) had 42.8% reduction in median monthly SF by 2 years in comparison with 25.8% in low-volume center. In patients with cognitive impairment, the reduction in median monthly SF was 26.0% by 2 years compared with 36.1% in patients without cognitive impairment. The most frequently reported adverse events were changes (e.g., increased frequency/severity) in seizure (16%), memory impairment (patient-reported complaint, 15%), depressive mood (patient-reported complaint, 13%), and epilepsy (12%). One definite sudden unexpected death in epilepsy case was reported.

DISCUSSION

The MORE registry supports the effectiveness and safety of ANT DBS therapy in a real-world setting in the 2 years following implantation.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that ANT DBS reduces the frequency of seizures in patients with drug-resistant focal epilepsy.

TRIAL REGISTRATION INFORMATION

MORE ClinicalTrials.gov Identifier: NCT01521754, first posted on January 31, 2012.

Seizure Outcome After Surgery for Refractory Epilepsy Diagnosed by 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET/MRI): A Systematic Review and Meta-Analysis

OBJECTIVE

When magnetic resonance imaging (MRI) fails to detect an underlying epileptogenic lesion, the odds of a good outcome after epilepsy surgery are significantly lower (20%-65% compared with 60%-90% if a lesion is detected). We investigated the possible effects of introducing hybrid 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET)/MRI into the decision algorithm for patients with lesioned and nonlesioned drug-resistant epilepsy.

METHODS

Three databases were searched from January 1990 to October 2022. We registered the protocol with International Platform of Registered Systematic Review and Meta-analysis Protocols. Studies in which 18F-FDG PET/MRI was conducted with ≥12 months of postsurgical follow-up in patients with refractory epilepsy. Random-effects meta-analysis was used to calculate the proportion of patients with good outcomes. Metaregression was used to investigate sources of heterogeneity.

RESULTS

We identified 8105 studies, of which 23 (1292 patients in total) were included. The overall good postoperative outcome rate was 71% (95% confidence interval 63.6-74.9). Good outcome was associated with the location of the refractory epileptic lesion (temporal lobe or extratemporal; risk ratio 1.27 [95% confidence interval 1.01-1.52], P = 0.009); Length of postoperative follow-up ≥40 months included in the same study accounted for 0.6% of the observed heterogeneity.

CONCLUSIONS

Seventy-one percent of patients with refractory epilepsy and 18F-FDG PET/MRI epileptogenic lesion features had a good outcome of epilepsy after surgery. Our findings can be incorporated into routine preoperative consultations and emphasize the importance of the complete resection of the temporal lobe epileptogenic zone for 18F-FDG PET/MRI detection when safe and feasible.

Quantitative analysis of the morphometric analysis program MAP in patients with truly MRI-negative focal epilepsy

OBJECTIVE

In the presurgical evaluation of epilepsy, identifying the epileptogenic zone is challenging if magnetic resonance imaging (MRI) is negative. Several studies have shown the benefit of using a morphometric analysis program (MAP) on T1-weighted MRI scans to detect subtle lesions. MAP can guide a focused re-evaluation of MRI to ultimately identify structural lesions that were previously overlooked. Data on patients where this additional review after MAP analysis did not reveal any lesions is limited. Here we evaluate the diagnostic yield of MAP in a large group of truly MRI-negative patients.

METHODS

We identified 68 patients with MRI-negative focal epilepsy and clear localization of the epileptogenic zone by intracranial EEG or postoperative seizure freedom. High resolution 3D T1 data of patients and 73 healthy controls were acquired on a 3 T scanner. Morphometric analysis was performed with MAP software, creating five z-score maps, reflecting different structural properties of the brain and a patient's deviation from the control population, and a neural network-based focal cortical dysplasia probability map. Ten brain regions were specified to quantify whether MAP findings were located in the correct region. Receiver operating characteristic (ROC) analyses were performed to identify the optimal thresholds for each map.

RESULTS

MAP-guided visual re-evaluation of the original MRI revealed overlooked lesions in three patients. The remaining 65 truly MRI-negative patients were included in the statistical analysis. At the optimal thresholds, maximum sensitivity was 84 %, with 35 % specificity. Balanced accuracy (arithmetic mean of sensitivity and specificity) of the respective maps ranged from 51 % to 60 %, creating three to six times more false positive than true positive findings.

CONCLUSION

This study confirms that MAP is useful in detecting previously overlooked subtle structural lesions. However, in truly MRI-negative patients, the additional diagnostic yield is very limited.

Pearls & Oy-sters: Salt and Pepper Sign, PLNTY for Drug-Resistant Epilepsy

Drug-resistant epilepsy, defined as the failure of 2 or more antiseizure medications to achieve seizure freedom, is responsible for 2/3 of epilepsy cases. Tumors are responsible for up to 15% of all adult onset and up to 6% of childhood onset epilepsies. Among these tumors, commonly known subtypes DNET, ganglioglioma, and low-grade astrocytoma are often suspected. New advances in tumor classification have been made, with genetics playing a key role in tumor classification. Polymorphic low-grade neuroepithelial tumor of the young (PLNTY) is a highly epileptogenic subtype of tumors that may mimic low-grade gliomas but offer pathologic and genetic clues: oligodendroglioma-like cellular components and infiltration patterns and strong CD34-immunopositive stain. In addition, a key finding is radiologic: a unifocal abnormality best seen on MRI brain in FLAIR sequence as the "salt and pepper sign" and calcifications appreciated on CT head.

Laser Interstitial Thermal Therapy for Epilepsy

Laser interstitial thermal therapy is an important new technique with a diverse use in epilepsy. This article gives an up-to-date evaluation of the current use of the technique within epilepsy, as well as provides some guidance to novice users appropriate clinical cases for its use.

Recent advances in epilepsy surgery

PURPOSE OF REVIEW

Technological innovations in the preoperative evaluation, surgical techniques and outcome prediction in epilepsy surgery have grown exponentially over the last decade. This review highlights and emphasizes relevant updates in techniques and diagnostic tools, discussing their context within standard practice at comprehensive epilepsy centres.

RECENT FINDINGS

High-resolution structural imaging has set an unprecedented opportunity to detect previously unrecognized subtle abnormalities. Machine learning and computer science are impacting the methodologies to analyse presurgical and surgical outcome data, building more accurate prediction models to tailor treatment strategies. Robotic-assisted placement of depth electrodes has increased the safety and ability to sample epileptogenic nodes within deep structures, improving our understanding of the seizure networks in drug-resistant epilepsy. The current available minimally invasive techniques are reasonable surgical alternatives to ablate or disrupt epileptogenic regions, although their sustained efficacy is still an active area of research.

SUMMARY

Epilepsy surgery is still underutilized worldwide. Every patient who continues with seizures despite adequate trials of two well selected and tolerated antiseizure medications should be evaluated for surgical candidacy. Collaboration between academic epilepsy centres is of paramount importance to answer long-standing questions in epilepsy surgery regarding the understanding of spatio-temporal dynamics in epileptogenic networks and its impact on surgical outcomes.

The influence of disease course and surgery on quality of life in children with focal cortical dysplasia and long-term epilepsy-associated tumours: A systematic review and meta-analysis

INTRODUCTION

Carefully selected patients with lesional epilepsy, including focal cortical dysplasia (FCD) and long-term epilepsy-associated tumours (LEAT), can benefit from epilepsy surgery. The influence of disease course and subsequent epilepsy surgery on quality of life (QoL) and intelligence quotient (IQ) is not well understood.

METHODS

A systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies reporting QoL or IQ measures in paediatric patients with FCD and LEAT at epilepsy onset, at establishment of drug resistance (pre-operative/non-surgically managed) and post-operatively were included. To evaluate the "effect size" and clinical significance of surgery, a meta-analysis of the data was conducted using fixed effects models for weighted mean differences, 95% confidence intervals and sensitivity analyses.

RESULTS

Nineteen eligible studies (911 patients) were included, 17 assessing IQ and 2 evaluating QoL. Twelve studies reported preoperative and postoperative IQ measures and five reported IQ in non-surgically managed cohorts after drug resistance was established; no papers reported IQ at epilepsy onset. No significant IQ/DQ changes were detected after surgery (pre-operative pooled mean 69.32; post-operative pooled mean 69.98; p = 0.32). Age at epilepsy surgery, type of surgery and epilepsy-related pathology did not influence the post-operative IQ. QoL was reported in 2 studies with the pooled mean estimates for pre- and post-operative QoL being 42.52 and 55.50, respectively.

CONCLUSIONS

The present study demonstrated no statistical change in IQ and QoL following surgery in paediatric patients with FCD and LEAT. There was no data on IQ and QoL at disease onset. Attempting to understand the impact of epilepsy, ongoing seizures and surgery on IQ and QoL will facilitate planning of future studies that aim to optimise quality of life and developmental outcomes in these children. Studies assessing children at epilepsy onset with longitudinal follow-up are required to optimise the timing of epilepsy surgery on QoL and IQ.

New insights for predicting surgery outcome in patients with temporal lobe epilepsy. A systematic review

Resective surgery is the treatment of choice for one-third of adult patients with focal, drug-resistant epilepsy. This procedure is associated with substantial clinical and cognitive risks. In clinical practice, there is no validated model for epilepsy surgery outcome prediction (ESOP). Meta-analyses on ESOP studies assessing prognostic factors report discrepancies in terms of study design. Our review aims to systematically investigate methodological and analytical aspects of studies predicting clinical and cognitive outcomes after temporal lobe epilepsy surgery. A systematic review of ESOP studies published between 2000 and 2022 from three databases (MEDLINE, Web of Science, and PsycINFO) was completed by following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. It yielded 4867 articles. Among them, 21 corresponded to our inclusion criteria and were therefore retained in the final review. The risk of bias was assessed using A Tool to Assess Risk of Bias and Applicability of Prediction Model Studies (PROBAST). Data extracted from the 21 studies were analyzed using narrative synthesis and descriptive statistics. Our findings show an increase in the use of multimodal datasets and machine learning analyses in recent ESOP studies, although regression remained the most frequently used approach. We also identified a more frequent use of network notions in recent ESOP studies. Nevertheless, several methodological issues were noted, such as small sample sizes, lack of information on the follow-up period, variability in seizure outcome, and the definition of neuropsychological postoperative change. Of 21 studies, only one provided a clinical tool to anticipate the cognitive outcome after epilepsy surgery. We conclude that methodological issues should be overcome before we move towards more complete models to better predict clinical and cognitive outcomes after epilepsy surgery. Recommendations for future studies to harness the possibilities of multimodal datasets and data fusion, are provided. A stronger bridge between fundamental and clinical research may result in developing accessible clinical tools.