Epileptic-network-based prediction and control of seizures in humans

Epilepsy is now conceptualized as a network disease. The epileptic brain network comprises structurally and functionally connected cortical and subcortical brain regions - spanning lobes and hemispheres -, whose connections and dynamics evolve in time. With this concept, focal and generalized seizures as well as other related pathophysiological phenomena are thought to emerge from, spread via, and be terminated by network vertices and edges that also generate and sustain normal, physiological brain dynamics. Research over the last years has advanced concepts and techniques to identify and characterize the evolving epileptic brain network and its constituents on various spatial and temporal scales. Network-based approaches further our understanding of how seizures emerge from the evolving epileptic brain network, and they provide both novel insights into pre-seizure dynamics and important clues for success or failure of measures for network-based seizure control and prevention. In this review, we summarize the current state of knowledge and address several important challenges that would need to be addressed to move network-based prediction and control of seizures closer to clinical translation.

Serum Proteins Associated with Blood-Brain Barrier as Potential Biomarkers for Seizure Prediction

As 30% of epileptic patients remain drug-resistant, seizure prediction is vital. Induction of epileptic seizure is a complex process that can depend on factors such as intrinsic neuronal excitability, changes in extracellular ion concentration, glial cell activity, presence of inflammation and activation of the blood−brain barrier (BBB). In this study, we aimed to assess if levels of serum proteins associated with BBB can predict seizures. Serum levels of MMP-9, MMP-2, TIMP-1, TIMP-2, S100B, CCL-2, ICAM-1, P-selectin, and TSP-2 were examined in a group of 49 patients with epilepsy who were seizure-free for a minimum of seven days and measured by ELISA. The examination was repeated after 12 months. An extensive medical history was taken, and patients were subjected to a follow-up, including a detailed history of seizures. Serum levels of MMP-2, MMP-9, TIMP-1, CCL-2, and P-selectin differed between the two time points (p < 0.0001, p < 0.0001, p < 0.0001, p < 0.0001, p = 0.0035, respectively). General linear model analyses determined the predictors of seizures. Levels of MMP-2, MMP-9, and CCL-2 were found to influence seizure count in 1, 3, 6, and 12 months of observation. Serum levels of MMP-2, MMP-9, and CCL-2 may be considered potential biomarkers for seizure prediction and may indicate BBB activation.

The long-term prognosis and predictors of epilepsy: a retrospective study in 820 patients

Background

To investigate the prognosis and predictors for seizure control in epileptic patients in China.

Methods

Eight hundred and twenty patients with epilepsy who visited Xuanwu Hospital from October 2017 to January 2020, were enrolled. The clinical information of the patients was obtained by retrospectively reviewing medical records. Prognostic measures of seizure control included remission, relapse and occurrence of drug resistance. The relationship of prognosis of seizure control with factors such as demographics, clinical characteristics and initial electroencephalography (EEG) features was investigated.

Results

A total of 503 (61.3%) patients experienced a 1-year remission and 330 (49.3% of 669) had a 2-year remission. Idiopathic type of epilepsy (P <  0.001), normal EEG (P <  0.05), number of antiepileptic drugs (P <  0.05) and seizure frequency of < 1 /month (P <  0.001) at the first arrival predicted a remission independently. Of the 503 patients who achieved a 1-year remission, 184 (36.6%) experienced a relapse, due to external reversible causes (58 patients) or with unknown reversible triggers (126 patients). No factors were found to be associated with a relapse (P > 0.05). At the end of the study, 322 patients (39.3%) developed drug resistance. The development of drug resistance was associated with the following factors: symptomatic aetiology of epilepsy, epileptiform abnormality in EEG, number of antiepileptic drugs and seizure frequency of ≥1 /month at first arrival (P <  0.001). For symptomatic epilepsy, patients with meningitis/encephalitis (P = 0.007) were more likely to develop drug-resistant epilepsy than these with other causes.

Conclusions

Remission is a common process. The type of epilepsy (idiopathic or symptomatic), EEG features, seizure frequency and treatment history at first arrival are related to both remission and terminal drug resistance. Among various causes of symptomatic epilepsy, meningitis/encephalitis is associated with the worst prognosis of epilepsy.

DNA Methylation Signature of Epileptic Encephalopathy-Related Pathogenic Genes Encoding Ion Channels in Temporal Lobe Epilepsy

Epilepsy is characterized by highly abnormal synchronous discharge of brain neurons, and ion channels are fundamental in the generation and modulation of neural excitability. Considering that abnormal methylation can either activate or repress genes, this study was designed to explore the DNA methylation signature of pathogenic genes encoding ion channels in temporal lobe epilepsy (TLE). In total, 38 TLE patients and 38 healthy controls were enrolled in the study, and genomic DNA and total protein of the lymphocytes were extracted from peripheral blood samples to assess methylation and protein levels. The DNA methylation levels of all 12 genes examined were significantly lower in the TLE group than in the control group. After false-positive correction, 83.3% (10/12) of these genes, namely, gamma-aminobutyric acid type A receptor subunit beta1 (GABRB1), gamma-aminobutyric acid type A receptor subunit beta2 (GABRB2), gamma-aminobutyric acid type A receptor subunit beta1 (GABRB3), glutamate ionotropic receptor NMDA type subunit 1 (GRIN1), glutamate ionotropic receptor NMDA type subunit 2A (GRIN2A), glutamate ionotropic receptor NMDA type subunit 2B (GRIN2B), hyperpolarization activated cyclic nucleotide gated potassium channel 1 (HCN1), potassium voltage-gated channel subfamily A member 2 (KCNA2), potassium voltage-gated channel subfamily B member 1 (KCNB1), and potassium sodium-activated channel subfamily T member 1 (KCNT1), were still differentially expressed. Among these ion channels, HCN1 and KCNA2 were selected to evaluate the effects of DNA methylation, and the levels of these proteins were inversely upregulated in the TLE group compared to the control group. As the genes identified as having differential methylation levels are involved in both excitatory and inhibitory ion channels, this study observed by binary logistic regression that hypermethylated GARAB1 was an independent risk factor for TLE, indicating that the overwhelming effect of ion channels on TLE is probably inhibitory from the perspective of DNA methylation. All these findings support the involvement of DNA methylation in TLE pathologies, but the mechanisms need to be further investigated.

Predictive factors of Status Epilepticus and its recurrence in patients with adult-onset seizures: A multicenter, long follow-up cohort study

PURPOSE

Status epilepticus (SE) is associated with high morbidity and mortality. This multicenter retrospective cohort study aims to identify the factors associated with the occurrence of SE and the predictors of its recurrence in patients with adult-onset seizures.

METHODS

We retrospectively analyzed data of 1115 patients with seizure onset>18 years, observed from 1983 to 2020 in 7 Italian Centers (median follow-up 2.1 years). Data were collected from the databases of the Centers. Patients with SE were consecutively recruited, and patients without SE history were randomly selected in a 2:1 ratio. To assess determinants of SE, different clinical-demographic variables were evaluated and included in univariate and multivariate logistic regression model.

RESULTS

Three hundred forty-seven patients had a SE history, whereas the remaining 768 patients had either isolated seizures or epilepsy without SE history. The occurrence of SE was independently associated with increasing age at onset of disease (OR 1.02, 95% CI 1.01--1.03, p<0.001), female sex (OR 1.39, 95% CI 1.05--1.83, p=0.02) and known etiology (OR 3.58, 95% CI 2.61--4.93, p<0.001). SE recurred in 21% of patients with adult-onset SE and recurrence was associated with increasing number of anti-seizure medications taken at last follow-up (OR 1.88, 95% CI 1.31--2.71, p<0.001).

CONCLUSIONS

In patients with adult-onset seizures, SE occurrence is associated with known etiologies, advanced age and female sex. Patients with recurrent SE are likely to have a refractory epilepsy, deserving careful treatment to prevent potentially fatal events.

Incidence and Prevalence of Drug-Resistant Epilepsy: A Systematic Review and Meta-analysis

OBJECTIVE

To evaluate the incidence and prevalence of drug-resistant epilepsy (DRE) as well as its predictors and correlates, we conducted a systematic review and meta-analysis of observational studies.

METHODS

Our protocol was registered with PROSPERO, and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses and Meta-analysis of Observational Studies in Epidemiology reporting standards were followed. We searched MEDLINE, Embase, and Web of Science. We used a double arcsine transformation and random-effects models to perform our meta-analyses. We performed random-effects meta-regressions using study-level data.

RESULTS

Our search strategy identified 10,794 abstracts. Of these, 103 articles met our eligibility criteria. There was high interstudy heterogeneity and risk of bias. The cumulative incidence of DRE was 25.0% (95% confidence interval [CI]: 16.8-34.3) in child studies but 14.6% (95% CI: 8.8-21.6) in adult/mixed age studies. The prevalence of DRE was 13.7% (95% CI: 9.2-19.0) in population/community-based populations but 36.3% (95% CI: 30.4-42.4) in clinic-based cohorts. Meta-regression confirmed that the prevalence of DRE was higher in clinic-based populations and in focal epilepsy. Multiple predictors and correlates of DRE were identified. The most reported of these were having a neurologic deficit, an abnormal EEG, and symptomatic epilepsy. The most reported genetic predictors of DRE were polymorphisms of the ABCB1 gene.

CONCLUSIONS

Our observations provide a basis for estimating the incidence and prevalence of DRE, which vary between populations. We identified numerous putative DRE predictors and correlates. These findings are important to plan epilepsy services, including epilepsy surgery, a crucial treatment option for people with disabling seizures and DRE.

Understanding the challenge of comparative effectiveness research in focal epilepsy: A review of network meta-analyses and real-world evidence on antiepileptic drugs

OBJECTIVE

Head-to-head randomized controlled trials (RCTs) are the gold standard for assessing comparative treatment effects. In the absence of direct comparisons between all possible antiepileptic drugs (AEDs), however, clinical decision-making in focal (partial onset) epilepsy relies on alternative evidence borne from indirect comparisons including network meta-analyses (NMAs) and from real-world evidence (RWE) studies. We review NMAs and observational RWE studies comparing AEDs in the adjunctive setting to compare the robustness of these methods and to formulate recommendations for future evidence development.

METHODS

A literature review identified NMAs and RWE studies comparing AEDs for the adjunctive treatment of focal seizures published between January 2008 and October 2018. NMAs were evaluated for robustness using a framework based on guidelines from the National Institute for Health and Care Excellence Decision Support Unit and the International Society for Pharmacoeconomics and Outcomes Research. RWE studies were evaluated using the GRACE checklist.

RESULTS

From a total of 1993 records, 11 NMAs and six RWE studies were eligible. Key limitations identified in the NMAs include nonsystematic selection of RCTs, unexplored heterogeneity between included RCTs in terms of study and patient characteristics, and selection of AEDs and AED doses or dosing strategies that are not reflective of clinical practice. The main limitations of RWE studies concern sample size, design, and analysis methods. Approximately 90% of comparisons between individual AEDs were nonsignificant in the NMAs. None of the RWE studies adjusted for baseline differences between comparator groups; therefore, they lack the validity to make comparative conclusions.

SIGNIFICANCE

Current NMAs and RWE studies provide only nominal comparative evidence for AED treatments in focal epilepsy, and should be used with caution for decision-making due to their methodological limitations. To overcome these hurdles, adherence to methodological guidelines and concerted efforts to collect relevant outcome data in the real world are needed.

Treatment response and predictors in patients with newly diagnosed epilepsy in Ethiopia: a retrospective cohort study

Epilepsy is a chronic neurological disease with a variable therapeutic response. To design effective treatment strategies for epilepsy, it is important to understand treatment responses and predictive factors. However, limited data are available in Africa, including Ethiopia. The aim of this study was therefore to assess treatment response and identify prognostic predictors among patients with epilepsy at Jimma university medical center, Ethiopia. We conducted a retrospective cohort study of 404 newly diagnosed adult epilepsy patients receiving antiepileptic treatment between May 2010 and May 2015. Demographic, clinical, and outcome data were collected for all patients with a minimum follow-up of two years. Cox proportional hazards model was used to identify predictors of poor seizure remission. Overall, 261 (64.6%) of the patients achieved seizure remission for at least one year. High number of pre-treatment seizures (adjusted hazard ratios (AHR) = 0.64, 95% CI: 0.49–0.83) and poor adherence (AHR = 0.57, 95% CI: 0.44–0.75) were significant predictors of poor seizure remission. In conclusion, our study showed that only about two-thirds of patients had achieved seizure remission. The high number of pre-treatment seizures and non-adherence to antiepileptic medications were predictors of poor seizure remission. Patients with these characteristics should be given special attention.

Prognostic patterns and predictors in epilepsy: a multicentre study (PRO-LONG)

OBJECTIVES

To describe the long-term prognosis of epilepsy and prognostic patterns in a large cohort of newly diagnosed patients and identify prognostic factors.

METHODS

Study participants were 13 Italian epilepsy centres with accessible records dating back to 2005 or earlier, complete data on seizure outcome and treatments, precise epilepsy diagnosis, and follow-up of at least 10 years. Records were examined by trained neurology residents for demographics, seizure characteristics, neurological signs, psychiatric comorbidity, first electroencephalogram (EEG) and MRI/CT, epilepsy type and aetiology, antiepileptic drugs (AEDs), and 1-year, 2-year, 5-year and 10-year seizure remissions. Five predefined prognostic patterns were identified: early remission, late remission, relapsing-remitting course, worsening course and no remission. Prognostic factors were assessed using multinomial logistic regression models.

RESULTS

1006 children and adults were followed for 17 892 person-years (median 16 years; range 10-57). During follow-up, 923 patients (91.7%) experienced 1-year remission. 2-year, 5-year and 10-year remissions were present in 89.5%, 77.1% and 44.4% of cases. 5-year remission was associated with one to two seizures at diagnosis, generalised epilepsy, no psychiatric comorbidity, and treatment with one or two AEDs during follow-up. 10-year remission was associated with one or two AEDs. The most common prognostic pattern was relapsing-remitting (52.2%), followed by early remission (24.5%). 8.3% of cases experienced no remission. Predictors of a relapsing-remitting course were <6 seizures at diagnosis, (presumed) genetic aetiology and no psychiatric comorbidity.

CONCLUSIONS

Few seizures at diagnosis, generalised epilepsy and no psychiatric comorbidity predict early or late seizure freedom in epilepsy. Achieving remission at any time after the diagnosis does not exclude further relapses.

Seizure outcome and epilepsy patterns in patients with cerebral palsy

PURPOSE

The aim of the present study was to investigate epilepsy patterns and outcomes in patients with cerebral palsy (CP) and identify the variables that determine remission.

METHODS

This was a retrospective cohort study. We followed 107 CP patients aged 1-16 years with newly diagnosed epilepsy. The patients were categorized according to their remission outcome, uninterrupted freedom of seizure for 2 years or longer, and 4 epilepsy patterns: A) sustained freedom from seizures before 6 months of treatment; B) delayed but sustained seizure freedom; C) relapsing-remitting course; and D) seizure freedom never attained. The variables were analysed for their prognostic relevance to the outcomes RESULTS: A total of 107 patients were included; their mean age at epilepsy diagnosis was 4.2 years (SD 2.5). By the end of the 8-year follow up, 19.6% 26.1%, 31.7%, and 22.4% were in sustained remission, terminal remission, relapse, and no remission respectively. Pattern A was identified in 6.5% of the patients, pattern B in 27.1%, pattern C in 43.9%, and pattern Din 22.4%. Univariate analysis revealed that the type of CP, mobility, and number of seizure types, are among the other factors that significantly affected remission.

CONCLUSION

A total of 45% of patients with CP and epilepsy achieved remission (with and without antiepileptics) but after a relatively long treatment duration. Remission was affected by patient- and epilepsy-related factors. More studies are required to further evaluate these factors.

Is there a place for surgical treatment of nonpharmacoresistant epilepsy?

Epilepsy surgery has been shown to be the best possible treatment in well-defined and difficult-to-treat epilepsy syndromes, such as mesial temporal lobe epilepsy with unilateral hippocampal sclerosis, even early in the course of the disease if pharmacoresistance is proven. This review addresses the question if epilepsy surgery may be justified today even in nonpharmacoresistant cases. There are two possible groups of patients: first, there are epilepsy syndromes with a benign spontaneous course or with a potentially good treatment prognosis under appropriate antiepileptic drug (AED) treatment. Second, there are epilepsies with potentially worse AED treatment prognosis in which appropriate AED treatment has not yet been applied because of the short course of the disease, tolerability problems that prevented usually effective dosing, or adherence issues. In group one, the good spontaneous prognosis or the usually satisfying course under AED treatment in line with the commonly generalized underlying epileptogenesis does not suggest that epilepsy surgery is a realistic alternative, not even in cases with distinct focal clinical and/or electroencephalography (EEG) patterns like in Rolandic epilepsy with centrotemporal spikes. In the second group, the recent International League Against Epilepsy (ILAE) definition should allow assessment of individual pharmacoresistance early after the onset of the disease in order to avoid any delay. Concerns about a potential disease-specific or drug-specific cognitive decline that could be avoided in early surgery are speculative, a matter of controversial discussion, and certainly not relevant, if pharmacoresistance is consequently addressed in time according to the ILAE recommendations. One should also not forget that even in typically pharmacoresistant epilepsy syndromes that are suitable for surgical procedures, satisfying courses do exist that would not require early or any epilepsy surgery. Therefore, in almost any instance, epilepsy surgery as initial treatment or immediately after a first AED is still not recommended although, especially in cases with nonadherence to AEDs, it may be occasionally considered in order to outweigh the risks of ongoing seizures and epilepsy if surgery is not performed.

Epilepsy with auditory features: Long-term outcome and predictors of terminal remission

OBJECTIVE

To assess the long-term outcome of epilepsy with auditory features (EAF) and to identify the clinical predictors for prognosis.

METHODS

The study involved consecutive EAF patients with a follow-up of ≥5 years. Terminal remission (TR) was defined as a period of ≥5 consecutive years of seizure freedom at the last follow-up. We used Kaplan-Meier estimate to calculate the cumulative time-dependent probability of conversion to TR. Log-rank test and multivariate Cox regression analyses were performed to study the association between time to TR and prognostic determinants.

RESULTS

We included 123 EAF patients (male/female = 58/65) with a median follow-up of 11 years (1626.9 person-years). Most were sporadic cases (68.3%), whereas 31.7% reported a family history of epilepsy. At last assessment, 42 patients had achieved TR (34.1%). Of the remaining 81 cases with no TR (65.9%), 37% had been in remission for 1-4 years and 62.9% still had seizures within the past year. The cumulative rates of TR were 26.6%, 35.7%, and 51.6% at 10, 20, and 30 years from inclusion. On multivariate analysis, age at onset > 10 years (hazard ratio [HR] = 3.2, P = .028), auditory aura characterized by distortions only versus simple/complex hallucinations (HR = 2.9, P = .041), and unremarkable scalp electroencephalogram (EEG) versus EEG with focal epileptiform activity (HR = 3.5, P = .041) were associated with TR.

SIGNIFICANCE

Our data show a wide prognostic spectrum of EAF, ranging from mild forms with spontaneous remission, to severely refractory epilepsy addressed to surgery. The outcome, less favorable than expected from previous studies, appears to be primarily a function of 3 prognostic negative risk factors: age at onset < 10 years, auditory aura characterized by complex auditory hallucinations, and focal epileptiform abnormalities on scalp EEG. These predictors, easy to collect even at the first visit, may inform both clinicians and patients about the long-term prognosis and aid patient management.

Pharmacoresistance with newer anti-epileptic drugs in mesial temporal lobe epilepsy with hippocampal sclerosis

This study aims to evaluate the overall prognosis, prognostic factors, and efficacy of treatment in patients with mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) who have access to third generation anti-epileptic drugs but not to epilepsy surgery. Eighty-five MTLE-HS patients were retrospectively placed into a seizure-free (seizure-free for >1year) or drug-resistant group, and the two groups were compared on the basis of age, sex, age at onset of seizures, duration of epilepsy, side of lesion, handedness, EEG findings, history of CNS infection, history of febrile convulsions, history of head trauma, history of cognitive impairment, family history of seizures, number of current anti-epileptic drugs (AEDs), total number of AED trials, and presence of individual AEDs. Only 24.7% of MTLE-HS patients had achieved seizure freedom for >1 year. Poor prognosis and drug-resistance were associated with younger age at onset of seizures (p=0.002), longer duration of epilepsy (p=0.018), greater number of current AEDs (p<0.001), and greater total number of AED trials (p<0.001). In addition, regimens with newer AEDs had no greater efficacy than regimens with older AEDs. Most medically managed MTLE-HS patients do not achieve seizure freedom despite multiple AED trials, and treatment with third generation AEDs should not preclude evaluation for epilepsy surgery.

Antiepileptic drug discontinuation by people with epilepsy in the general population

OBJECTIVE

Rate, reasons, and predictors of antiepileptic drug (AED) discontinuation were investigated in a well-defined cohort of people with epilepsy to verify efficacy and tolerability of treatment up to 20 years from treatment initiation.

METHODS

The history of AED usage in children and adults with epilepsy registered with 123 family physicians in an area of Northern Italy between 2000 and 2008 was recorded. Cumulative probabilities of AED withdrawal for specific reasons were estimated using cumulative incidence functions. The probabilities of withdrawing for terminal remission, and of achieving sustained remission while still on treatment, were also evaluated. The roles of sex, age at diagnosis, seizure types, duration at diagnosis, and syndrome were assessed with hazard ratios and 95% confidence intervals.

RESULTS

Seven hundred thirty-one of 747 individuals were treated with one or more AEDs during the disease course. The three commonest drugs were valproate, carbamazepine, and phenobarbital. Reported reasons for AED withdrawal were, in decreasing order, terminal remission, ineffectiveness, and adverse events. The probability of withdrawing the first AED for terminal remission was 1.0% at 1 year and increased to 20.0% at 20 years. Corresponding rates were 2.9% and 12.6% for ineffectiveness and 0.5% and 3.3% for adverse events. Reasons for withdrawal varied with individuals' age, sex, disease characteristics, and drugs.

SIGNIFICANCE

The initial AED given was retained in the majority of cases. Terminal remission, lack of efficacy, and adverse effects were, in decreasing order, the commonest reasons for AED discontinuation. Withdrawal could be predicted by age at diagnosis, sex, and clinical characteristics and varies among drugs.

Remission in epilepsy: How long is enough?

OBJECTIVE

The International League Against Epilepsy (ILAE) has proposed to expand the definition of remission to 10 years seizure-free with the last 5 years off antiepileptic drugs (AEDs). We examined if a 10-year remission is needed to predict the lowest recurrence risk.

METHODS

The population-based study cohort consisted of 148 patients with new-onset childhood epilepsy living in the catchment area of Turku University Hospital. They were prospectively followed for 44 years (median). Patients in first remission were prospectively followed for the duration of remission or possible relapse at 2 years in remission with the last year without antiepileptic drugs (AEDs), at 5 years in remission with the last 2 years without AEDs, and at 10 years with the last 5 years without AEDs. For comparison of the proportions of relapsed patients within each remission category exact Clopper Pearson 95% confidence intervals were used.

RESULTS

The magnitude of the relapse rate estimates off AEDs did not significantly improve when remission increased from 2 years (2YR) to 5 years (5YR) and further to 10 years (10YR). However, 10YR was a more sensitive measure of no relapse than 2YR. Among patients with remission on or off AEDs, the ability to predict lower relapse rate increased markedly from 2 to 5 years, and again from 5 to 10 years. The risk of relapse was virtually the same estimated after 2YR off AEDs as after 10YR on or off AEDs, except for patients with generalized epilepsy whose 2YR off AEDs was a weaker predictor than 10YR on or off AEDs.

SIGNIFICANCE

Given the modest differences in relapse rates between the 5 years seizure-free with last 2 years off medications definition and the 10 years seizure-free with last 5 years off medications, and the adverse impact of not being considered in remission, we propose that a return to the 5-year definition may be warranted.