"Time is Brain"-How early should surgery be done in drug-resistant TLE?

Epilepsy surgery education and practice around the globe: An ILAE taskforce report

Up to 80% of the world's population with epilepsy lives in low and middle-income countries. Around one-third of these patients will have drug-resistant epilepsy, for which epilepsy surgery is an option. Unfortunately, many of these regions, as well as some more developed nations, lack sufficient epilepsy surgery units and trained neurosurgeons. With this in mind, the International League Against Epilepsy (ILAE) formed the Epilepsy Surgery Education Taskforce to address the shortage of further educational opportunities for surgeons and neurologists and to promote the creation of more epilepsy surgery units around the world. In this article, we publish our findings from a web-based international survey, in which we investigated the global distribution and experience of neurosurgeons who perform epilepsy surgery, their educational paths, and opinions on the further need for epilepsy surgery education, as well as the resources available to them. We report a detailed analysis of the 202 survey replies received from 35 different countries across six continents. The lack of adequate numbers of epilepsy surgery units in the Southern Hemisphere is notable, and the aim of this task force with other ILAE committees, is to improve access to epilepsy surgery for patients and to enhance training for their health care providers.

Molecular subtypes of epilepsy associated with post-surgical seizure recurrence

Approximately 50% of individuals who undergo resective epilepsy surgery experience seizure recurrence. The heterogenous post-operative outcomes are not fully explained by clinical, imaging and electrophysiological variables. We hypothesized that molecular features may be useful in understanding surgical response, and that individuals with epilepsy can be classified into molecular subtypes that are associated with seizure freedom or recurrence after surgical resection. Pre-operative blood samples, brain tissue and post-operative seizure outcomes were collected from a cohort of 40 individuals with temporal lobe epilepsy, 23 of whom experienced post-operative seizure recurrence. Messenger RNA and microRNA extracted from the blood and tissue samples were sequenced. The messenger RNA and microRNA expression levels from the blood and brain were each subjected to a novel clustering approach combined with multiple logistic regression to separate individuals into genetic clusters that identify novel subtypes associated with post-operative seizure outcomes. We then compared the microRNAs and messenger RNAs from patient blood and brain tissue that were significantly associated with each subtype to identify signatures that are similarly over- or under-represented for an outcome and more likely to represent endophenotypes with common molecular aetiology. These target microRNAs and messenger RNAs were further characterized by pathway analysis to assess their functional role in epilepsy. Using blood-derived microRNA and messenger RNA expression levels, we identified two subtypes of epilepsy that were significantly associated with seizure recurrence (clusters A1 and B4) (adjusted P < 0.20). A total of 551 microRNAs and 2486 messenger RNAs were associated with clusters A1 and B4, respectively (adjusted P < 0.05). Clustering of brain-tissue messenger RNA expression levels revealed an additional subtype (C2) associated with seizure recurrence that had high overlap of dysregulated messenger RNA transcripts with cluster B4. Clusters A1, B4 and C2 also shared significant overlap of subjects, which altogether suggests a coordinated mechanism by which microRNA and messenger RNA transcripts may be related to seizure recurrence. Epileptic subtypes A1, B4 and C2 reveal both known and novel microRNA and messenger RNA targets in seizure recurrence. Furthermore, targets identified in A1 and B4 are quantifiable in pre-operative blood samples and could potentially serve as biomarkers for surgical resection outcomes.

The Missed Value of Underutilizing Pediatric Epilepsy Surgery: A Systematic Review

Pediatric epilepsy surgery is underutilized. Only 1%-11% of children with drug resistant epilepsy (DRE) undergo surgical treatment, or less than half of those estimated to benefit. We conducted a systematic review of articles published in PubMed, EMBASE, and Web of Science in order to study the factors related to surgery underutilization as well as the impact on both the individual and the healthcare system. Our review demonstrates multiple factors leading to underutilization, including family misconceptions about epilepsy surgery, lack of provider knowledge, as well as systemic health disparities. While the upfront cost of epilepsy surgery is significant, the long-term financial benefits and reduced health resource utilization tilt the economic advantage in favor of surgery in children with DRE. Additionally, timely interventions improve seizure and cognitive outcomes with low risk of complications. Further interventions are needed at the levels of family, provider, and the healthcare system to increase access to pediatric epilepsy surgery.

Outcome of epilepsy surgery in lesional epilepsy: Experiences from a developing country

BACKGROUND

Our aim was to report the postoperative seizure outcome and associated factors in patients with lesional epilepsy, in a low-income setting.

METHODS

This longitudinal prospective study included patients who underwent epilepsy surgery at Kashani Comprehensive Epilepsy Center between 2014 and 2019. Post-surgical outcomes were reported according to the Engel score, and patients were classified into two groups of seizure free (SF) and not-seizure free (NSF).

RESULTS

A total of 148 adult patients, with a mean age of 30.45 ± 9.23 years were included. The SF outcome was reported in 86.5% of patients and antiepileptic drugs (AEDs) were reduced or discontinued in 45.9%. The mean follow-up duration was 26.7 ± 14.9 months. Temporal lobe lesions (76.3%) and mesial temporal sclerosis (MTS) (56.7%) were the most frequent etiologies. Temporal lesion (Incidence relative risk (IRR): 1.76, 95% CI [1.08-2.87], p = 0.023), prior history of CNS infection (IRR:1.18, 95% CI [1.03-1.35], p = 0.019), use of intra-operative ECoG (IRR:1.73, 95% CI [1.06-2.81], p = 0.028), and absence of IEDs in postoperative EEG (IRR: 1.41, 95% CI [1.18-1.70], p < 0.001) were positive predictors for a favorable outcome.

CONCLUSION

Many patients with drug-resistant lesional epilepsy showed a favorable response to surgery. We believe that resective epilepsy surgery in low-income settings is a major treatment option. The high frequency of patients with drug-resistant epilepsy in developing countries is associated with high rates of morbidity and mortality. Hence, strategies to increase access to epilepsy surgery in these settings are urgently needed.

Surgical candidates in children with epileptic spasms can be selected without invasive monitoring: A report of 70 cases

OBJECTIVE

Prior surgical series in children with drug-resistant epileptic spasms have reported use of intracranial EEG monitoring in up to two-third of patients. We report outcome after epilepsy surgery for drug-resistant epileptic spasms in a cohort of children without the use of intracranial EEG monitoring in any of the patients.

METHODS

Medical records of all consecutive children aged 5 years or under who had epilepsy surgery for epileptic spasms at Cleveland Clinic between 2000 and 2018 were reviewed. Post-operative seizure outcome and predictors of prognosis of seizure outcome were analyzed.

RESULTS

Seventy children with active epileptic spasms underwent surgical resections during the study period. Mean age at seizure onset was 6.8 (+9.31) months and median age at surgery was 18.5 months. An epileptogenic lesion was identified on brain MRI in all patients; 17 (24%) had bilateral abnormalities. Etiologies included malformations of cortical development (58%), perinatal infarct/encephalomalacia (39%), and tumor (3%). None of the patients had intracranial EEG. Surgical procedures included hemispherectomy (44%), lobectomy/ lesionectomy (33%), and multilobar resections (23%). Twelve children needed repeat surgery; six (50%) became seizure free after the second surgery. At six months follow-up, 73% (51/70) were seizure-free since surgery. At a mean follow-up of 4.7 years, 60% (42/70) had Engel 1 outcome. In those with seizure recurrence, 17 (60%) reported improvement. Shorter epilepsy duration (p = 0.05) and lobar or sub-lobar epileptogenic lesions (p = 0.02) predicted favorable seizure outcome at 6 months after surgery. For long term outcome, patients with bilateral abnormalities on MRI (p = 0.001), and multilobar extent on MRI (p = 0.02) were at higher risk for recurrence.

SIGNIFICANCE

Children with drug-resistant epileptic spasms secondary to an epileptogenic lesion detected on MRI could be selected for epilepsy surgery without undergoing intracranial EEG monitoring. A surgical selection paradigm without intracranial monitoring may allow early surgery without the risks of invasive monitoring.

Trends in pediatric epilepsy surgery: A lower-middle-income country perspective

OBJECTIVE

To study the trends for pediatric epilepsy surgery between 2000 and 2014 in a tertiary epilepsy surgery center in India in order to gain a lower- and middle-income country (LMIC) perspective.

METHODS

Children aged <18 years and undergoing epilepsy surgery were divided into three groups based on the year that they underwent surgery-group 1: year 2000-2004; group 2: year 2005-2009; and group 3: year 2010-2014. Data including the rate of surgery, type of surgery, and duration of epilepsy before referral were analyzed from the medical records and compared.

RESULTS

Between 2000 and 2014, 463 pediatric epilepsy surgeries were performed. The proportion of pediatric epilepsy surgeries showed an increasing trend-218 (total 510 surgeries, 42.74%) in group 3, compared with 115 (total 375 surgeries, 30.66%) in group 1 and 130 (total 466 surgeries, 27.9%) in group 2. A significant decrease in the age at evaluation and duration of epilepsy before referral was noted between 2000 and 2014, particularly in patients belonging to the lowest income group. There was a two-fold increase in the number of extratemporal surgeries over time. The proportion of children undergoing surgery for benign tumors, cortical malformations, and gliosis/atrophy showed an upward trend while that for mesial temporal sclerosis did not show an increase.

SIGNIFICANCE

Promising trends in pediatric epilepsy surgery were noted with increasing number of surgeries and decreasing age at presurgical evaluation. Seen from an LMIC perspective, this reflects an evolution in the practice of pediatric epilepsy surgery, mirroring trends in high-income countries.

MicroRNAs in temporal lobe epilepsy: a systematic review

OBJECTIVE

About 30% of patients with epilepsy have drug-resistant seizures. The aim of the current endeavor was to systematically review the existing evidence on the potential applications of microRNAs as biomarkers in people with difficult to treat temporal lobe epilepsy (TLE).

METHODS

MEDLINE (accessed from PubMed) and Scopus from inception to March 18, 2020 were systematically searched for related published articles. In both electronic databases, the following search strategy was implemented, and these keywords (in the title/abstract) were used: "microRNA" AND "temporal lobe epilepsy." Articles written in English that were human studies in people with epilepsy were all included in this search.

RESULTS

We could identify 16 articles about different aspects of microRNAs in the serum of patients with TLE. However, only three studies robustly investigated microRNAs as potential biomarkers in the diagnosis of drug-resistant TLE (microRNA-155 (upregulated), microRNA-129-2-3p (upregulated), microRNA-153 (downregulated)). One small study provided class II, and two small studies provided class III evidence.

CONCLUSION

While this systematic review identified three studies that provided some evidence on the potential applications of circulating serum microRNAs as biomarkers in people with drug-resistant TLE, the evidence is not robust yet. While these findings provide a new horizon, substantial challenges remain before the roles of microRNAs as biomarkers in the diagnosis of drug-resistant TLE can be translated into clinical practice.

Temporal lobe epilepsy surgery in children and adults: A multicenter study

OBJECTIVE

To assess seizure and cognitive outcomes and their predictors in children (<16 years at surgery) and adults undergoing temporal lobe epilepsy (TLE) surgery in eight Italian centers.

METHODS

This is a retrospective multicenter study. We performed a descriptive analysis and subsequently carried out multivariable mixed-effect models corrected for multiple comparisons.

RESULTS

We analyzed data from 511 patients (114 children) and observed significant differences in several clinical features between adults and children. The possibility of achieving Engel class IA outcome and discontinuing antiepileptic drugs (AEDs) at last follow-up (FU) was significantly higher in children (P = .006 and < .0001). However, percentages of children and adults in Engel class I at last FU (mean ± SD, 45.9 ± 17 months in children; 45.9 ± 20.6 months in adults) did not differ significantly. We identified different predictors of seizure outcome in children vs adults and at short- vs long-term FU. The only variables consistently associated with class I outcome over time were postoperative electroencephalography (EEG) in adults (abnormal, improved,odds ratio [OR] = 0.414, P = .023, Q = 0.046 vs normal, at 2-year FU and abnormal, improved, OR = 0.301, P = .001, Q = 0.002 vs normal, at last FU) and the completeness of resection of temporal magnetic resonance (MR) abnormalities other than hippocampal sclerosis in children (OR = 7.93, P = .001, Q = 0.003, at 2-year FU and OR = 45.03, P < .0001, Q < 0.0001, at last FU). Cognitive outcome was best predicted by preoperative performances in either age group.

SIGNIFICANCE

Clinical differences between adult and pediatric patients undergoing TLE surgery are reflected in differences in long-term outcomes and predictors of failures. Children are more likely to achieve sustained seizure freedom and withdraw AEDs after TLE surgery. Earlier referral should be encouraged as it can improve surgical outcome.

Addressing the epilepsy surgery gap: Impact of community/tertiary epilepsy center collaboration

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Collaboration agreements can improve epilepsy surgery referral volumes.

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Standardized referral pathways may help address epilepsy surgery gap.

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Internal and external process changes can improve referral process.

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Sociodemographic variables continue to influence referral completion.

To assess whether a formal collaboration between a non-surgical, community epilepsy center and a surgical, tertiary-care epilepsy center can improve patient progress throughout the pre-surgical referral process, and to elucidate predictors of referral completion among inter-center referrals.

The inter-center referral process was tracked, and the number of patients completing surgical conference (primary outcome) and epilepsy surgery at the tertiary center were collected and compared in the 45-month immediate pre/post-collaboration periods. Demographic and clinical variables were collected on post-collaboration inter-center patient referrals to explore factors associated with completion of the referral process.

Compared to the pre-collaboration period, the proportion of tertiary center epilepsy surgery conference patients referred from the community epilepsy center increased from 3/88 to 14/113 (263% increase, p = .01) during the post-collaboration period. The proportion of patients completing surgery via the community to tertiary referral process increased from 2/63 pre-collaboration to 8/71 post-collaboration (254% increase, p = .04). Referral completion was associated with higher seizure frequency, shorter travel distance, private insurance status and positive employment status (p < 0.05).

Collaboration agreements between community and tertiary-care epilepsy centers may improve patient completion of the epilepsy surgery referral process. Implementation of similar programs at other centers may be beneficial in reducing the epilepsy surgery gap.

Seizure outcome and use of antiepileptic drugs after epilepsy surgery according to histopathological diagnosis: a retrospective multicentre cohort study

BACKGROUND

Surgery is a widely accepted treatment option for drug-resistant focal epilepsy. A detailed analysis of longitudinal postoperative seizure outcomes and use of antiepileptic drugs for different brain lesions causing epilepsy is not available. We aimed to analyse the association between histopathology and seizure outcome and drug freedom up to 5 years after epilepsy surgery, to improve presurgical decision making and counselling.

METHODS

In this retrospective, multicentre, longitudinal, cohort study, patients who had epilepsy surgery between Jan 1, 2000, and Dec 31, 2012, at 37 collaborating tertiary referral centres across 18 European countries of the European Epilepsy Brain Bank consortium were assessed. We included patients of all ages with histopathology available after epilepsy surgery. Histopathological diagnoses and a minimal dataset of clinical variables were collected from existing local databases and patient records. The primary outcomes were freedom from disabling seizures (Engel class 1) and drug freedom at 1, 2, and 5 years after surgery. Proportions of individuals who were Engel class 1 and drug-free were reported for the 11 main categories of histopathological diagnosis. We analysed the association between histopathology, duration of epilepsy, and age at surgery, and the primary outcomes using random effects multivariable logistic regression to control for confounding.

FINDINGS

9147 patients were included, of whom seizure outcomes were available for 8191 (89·5%) participants at 2 years, and for 5577 (61·0%) at 5 years. The diagnoses of low-grade epilepsy associated neuroepithelial tumour (LEAT), vascular malformation, and hippocampal sclerosis had the best seizure outcome at 2 years after surgery, with 77·5% (1027 of 1325) of patients free from disabling seizures for LEAT, 74·0% (328 of 443) for vascular malformation, and 71·5% (2108 of 2948) for hippocampal sclerosis. The worst seizure outcomes at 2 years were seen for patients with focal cortical dysplasia type I or mild malformation of cortical development (50·0%, 213 of 426 free from disabling seizures), those with malformation of cortical development-other (52·3%, 212 of 405 free from disabling seizures), and for those with no histopathological lesion (53·5%, 396 of 740 free from disabling seizures). The proportion of patients being both Engel class 1 and drug-free was 0-14% at 1 year and increased to 14-51% at 5 years. Children were more often drug-free; temporal lobe surgeries had the best seizure outcomes; and a longer duration of epilepsy was associated with reduced chance of favourable seizure outcomes and drug freedom. This effect of duration was evident for all lesions, except for hippocampal sclerosis.

INTERPRETATION

Histopathological diagnosis, age at surgery, and duration of epilepsy are important prognostic factors for outcomes of epilepsy surgery. In every patient with refractory focal epilepsy presumed to be lesional, evaluation for surgery should be considered.

FUNDING

None.

Referral trends for temporal lobe epilepsy surgery between 2000 and 2014 in India

BACKGROUND

We conducted a retrospective study examining the trends in referral to a tertiary epilepsy surgery center in India over 2 decades.

METHODS

Data of patients who underwent long-term video electro encephalography monitoring for presurgical evaluation were retrospectively analyzed. Patients aged >16 years and diagnosed to have drug-resistant temporal lobe epilepsy (TLE) were included. They were divided into 3 groups comprising 5-year periods each during which they underwent presurgical evaluation, group 1: year 2000-2004; group 2: year 2005-2009; and group 3: year 2010-2014. Referral data with particular reference to duration of epilepsy before referral, age at onset of seizures, and number of antiepileptic drugs tried before referral were analyzed.

RESULTS

A total of 1362 patients fulfilled the inclusion criteria. There were 385 referrals in group 1, 488 in group 2, and 489 in group 3. The mean duration of epilepsy before referral was 18.10 ± 9.44 years; there was no change in the duration of epilepsy before referral (p = 0.638). A significant increase in the age at onset of seizures and age at presurgical evaluation was noted over time.

CONCLUSION

There is evidence for delayed referral of patients with refractory TLE to a surgical epilepsy center in this study. Renewed efforts to confront challenges beholding epilepsy surgery and steps to ensure timely referral are desirable.

Effects of surgical targeting in laser interstitial thermal therapy for mesial temporal lobe epilepsy: A multicenter study of 234 patients

OBJECTIVE

Laser interstitial thermal therapy (LITT) for mesial temporal lobe epilepsy (mTLE) has reported seizure freedom rates between 36% and 78% with at least 1 year of follow-up. Unfortunately, the lack of robust methods capable of incorporating the inherent variability of patient anatomy, the variability of the ablated volumes, and clinical outcomes have limited three-dimensional quantitative analysis of surgical targeting and its impact on seizure outcomes. We therefore aimed to leverage a novel image-based methodology for normalizing surgical therapies across a large multicenter cohort to quantify the effects of surgical targeting on seizure outcomes in LITT for mTLE.

METHODS

This multicenter, retrospective cohort study included 234 patients from 11 centers who underwent LITT for mTLE. To investigate therapy location, all ablation cavities were manually traced on postoperative magnetic resonance imaging (MRI), which were subsequently nonlinearly normalized to a common atlas space. The association of clinical variables and ablation location to seizure outcome was calculated using multivariate regression and Bayesian models, respectively.

RESULTS

Ablations including more anterior, medial, and inferior temporal lobe structures, which involved greater amygdalar volume, were more likely to be associated with Engel class I outcomes. At both 1 and 2 years after LITT, 58.0% achieved Engel I outcomes. A history of bilateral tonic-clonic seizures decreased chances of Engel I outcome. Radiographic hippocampal sclerosis was not associated with seizure outcome.

SIGNIFICANCE

LITT is a viable treatment for mTLE in patients who have been properly evaluated at a comprehensive epilepsy center. Consideration of surgical factors is imperative to the complete assessment of LITT. Based on our model, ablations must prioritize the amygdala and also include the hippocampal head, parahippocampal gyrus, and rhinal cortices to maximize chances of seizure freedom. Extending the ablation posteriorly has diminishing returns. Further work is necessary to refine this analysis and define the minimal zone of ablation necessary for seizure control.