(Re)Defining success in epilepsy surgery: The importance of relative seizure reduction in patient‐reported quality of life

Stereo-electroencephalographic seizure localization in patients with mesial temporal sclerosis: A single center experience

Objective

Epilepsy patients with mesial temporal sclerosis (MTS) on imaging who are drug-resistant usually undergo epilepsy surgery without previous invasive evaluation. However, up to one-third of patients are not seizure-free after surgery. Prior studies have identified risk factors for surgical failure, but it is unclear if they are associated with bilateral or discordant seizure onset.

Methods

In this retrospective case series, we identified 17 epilepsy patients who had MRI-confirmed MTS but received invasive stereo-EEG (SEEG) evaluation before definitive intervention. We analyzed their presurgical risk factors in relation to SEEG seizure onset localization and MRI/SEEG concordance.

Results

SEEG ictal onset was concordant with MTS localization (i.e. seizures started only from the hippocampus with MTS) in 5 out of 13 patients with unilateral MTS (UMTS) and in 3 out of 4 patients with bilateral MTS.No statistically significant association regarding concordance of SEEG ictal onset and MTS location was found in patients with such risk factors as a history of non-mesial temporal aura, frequent focal to bilateral tonic-clonic seizures, prior viral brain infection, or family history of epilepsy. Nine out of 13 UMTS patients had resective surgery only, 5 out of 9 (56 %) have Engel class I outcome at most recent follow-up (median 46.5 months, range 22-91 months). In Engel class I cohort, the SEEG ictal onset was concordant with MTS location in 3 out of 5 patients, and 2 patients had ipsilateral temporal neocortical ictal onset.

Conclusions

Our findings suggest that patients with MTS might have discordant SEEG ictal onset (in 61.5% patients with UMTS in presented cohort), which may explain poor surgical outcome after destructive surgery in these cases.

Significance

Although no statistically significant association was found in this under-powered study, these findings could be potentially valuable for future meta-analyses.

Epilepsy Surgery for Cognitive Improvement in Epileptic Encephalopathy

Epileptic encephalopathies are defined by the presence of frequent epileptiform activity that causes neurodevelopmental slowing or regression. Here, we review evidence that epilepsy surgery improves neurodevelopment in children with epileptic encephalopathies. We describe an example patient with epileptic encephalopathy without drug refractory seizures, who underwent successful diagnostic and therapeutic surgeries. In patients with epileptic encephalopathy, cognitive improvement alone is a sufficient indication to recommend surgical intervention in experienced centers.

Low IQ predicts worse long-term seizure outcome after resective epilepsy surgery - A propensity score matched analysis

OBJECTIVE

To describe long-term seizure outcomes in patients with IQ < 70 undergoing resective epilepsy surgery and to analyse whether baseline IQ predicts seizure outcome.

METHODS

Patients undergoing focal resective epilepsy surgery 1995-2017 at age ≥ 4 years were identified in the population-based Swedish National Epilepsy Surgery Register. Two-year, five-year and long-term (10-20-year follow-up) outcomes were analysed. Seizure outcomes of patients with IQ ≥ 70 and IQ < 70 at baseline were compared in the full cohort and between propensity score matched groups.

RESULTS

Follow-up data were available for 884 patients, 79 of whom had IQ < 70. Matched controls were found for 74 of the IQ < 70 patients. Preoperative MRI pathology was unifocal in 54 % and 79 % of IQ < 70 and IQ ≥ 70 patients before matching compared to 58 % and 62 % after matching, respectively. Patients with IQ < 70 achieved significantly worse seizure outcomes at all time points both when analysing the full cohort and the matched groups. After matching, the proportions of seizure-free patients in the IQ < 70 group were 28 %, 32 % and 32 % at the 2-year, 5-year and long-term follow-ups, respectively. Corresponding figures in the IQ ≥ 70 group were 54 %, 62 % and 60 % (p for difference between IQ groups 0.004, 0.002 and 0.049). In the IQ < 70 group, 36 %, 29 % and 45 % had a ≥ 75 % reduction in seizure frequency at the respective three follow-ups.

CONCLUSION

Low preoperative IQ predicts lower chances of seizure freedom after resective epilepsy surgery and few patients with IQ < 70 remain completely seizure-free in the long term. Nevertheless, a significant proportion had a reduction in seizure frequency of at least 75 % at long-term follow-up, indicating an important palliative potential of resective surgery for epilepsy patients with intellectual disability.

Cognitive decline and quality of life after resective epilepsy surgery

OBJECTIVES

The objectives of this study were to examine the association between cognitive decline and quality of life (QoL) change in a large sample of individuals with drug-resistant epilepsy who underwent resective surgery and to examine whether the association between cognitive decline and QoL is differentially affected by seizure classification outcome (Engel Class 1 vs. 2-4) or side of surgery (left vs. right hemisphere).

MATERIALS AND METHODS

The sample comprised 224 adults (ages ≥ 18) with drug-resistant focal epilepsy treated with resective surgery who underwent comprehensive pre-operative and post-operative evaluations including neuropsychological testing and the Quality of Life in Epilepsy Inventory - 31 between 1991 and 2020. Linear mixed-effects models were fit to examine subject-specific trajectories and assess the effects of time (pre- to post-operative), cognitive decline (number of measures that meaningfully declined), and the interaction between time and cognitive decline on pre- to post-operative change in QoL.

RESULTS

Increases in QoL following resection were observed (B = -10.72 [SE = 1.22], p < .001; mean difference between time point 1 and time point 2 QoL rating = 8.11). There was also a main effect of cognitive decline on QoL (B = -.85 [SE = .27], p = .002). Follow-up analyses showed that the number of cognitive measures that declined was significantly associated with post-surgical QoL, (r = -.20 p = .003), but not pre-surgical QoL, (r = -.04 p = .594), and with pre-to post-surgery raw change in QoL score, (r = -.18 p = .009). A cognitive decline by time point interaction was observed, such that those who had greater cognitive decline had less improvement in overall QoL following resection (B = .72 [SE = .27], p = .009). Similar results were observed within the Engel Class 1 outcome subgroup. However, within the Engel Class 2-4 outcome subgroup, QoL improved following resection, but there was no main effect of cognitive decline or interaction between cognitive decline and time point on QoL change. There was no main effect of resection hemisphere on overall QoL, nor were there interactions with hemisphere by time, hemisphere by cognitive decline, or hemisphere by time by cognitive decline.

CONCLUSIONS

Quality of life improves following epilepsy surgery. Participants who had cognitive decline across a greater number of measures experienced less improvement in QoL post-operatively overall, but there was no clear pattern of domain-specific cognitive decline associated with change in QoL. Our results indicate that cognitive decline in a diffuse set of cognitive domains negatively influences post-operative QoL, particularly for those who experience good seizure outcomes (i.e., seizure freedom), regardless of the site or side of resection.

Quality of life of children with residual seizures after epileptic resection surgery

Objective

Epilepsy dramatically affects the quality of life (QoL) of children, and resection surgery can improve their QoL by reducing seizures or completely controlling them. Children who have postoperative seizures tend to show a poorer QoL. The aim of the present study was to investigate the QoL of children with seizures after resection surgery and its influencing factors.

Methods

In the present study, we retrospectively reviewed 151 consecutive children who underwent resection surgery. We then divided them into two groups, seizure and seizure-free groups, according to the seizure outcomes 1 year after surgery. Variables were categorized into a number of factor types such as preoperative factors, surgery-related factors, postoperative factors, and family factors. QoL and seizure outcomes more than 3 years after surgery were assessed according to the ILAE seizure outcome classification and the CHEQOL-25 scale.

Results

Forty-three (28.5%) of the 151 children had seizures 1 year after surgery, and two children died during the follow-up period. The mean CHEQOL-25 scale for children with seizures was 63.5 ± 18.2, and 20 (48.8%) patients had poor QoL. Surgery-related factors, such as surgical complications and surgical sequelae, were not statistically associated with QoL. Preoperative language development retardation or language dysfunction [odds ratio (OR) = 29.3, P = 0.012) and postoperative ILAE seizure outcome classification (OR = 1.9, P = 0.045)] were significantly associated with QoL.

Significance

Children with seizures after resection surgery had a relatively poor QoL. Surgery-related factors, such as surgical complications and surgical sequelae, cannot predict the QoL. Preoperative language development retardation or language dysfunction and postoperative ILAE seizure outcome classification were independent predictors of the quality of life (QoL). For children who could not achieve the expected freedom from seizure after surgery, a lower ILAE grade (ILAE 1-3) is also an acceptable outcome since it predicts a higher QoL.

A Pilot Study on the Use of Low Doses of CBD to Control Seizures in Rare and Severe Forms of Drug-Resistant Epilepsy

Due to its anticonvulsant properties, cannabidiol can be supportive as an adjuvant therapy in the management of drug resistant epilepsy. This retrospective observational study evaluates the intensity and frequency of the seizures of patients with drug-resistant epilepsy that have been treated with antiepileptic medication associated with CBD in low doses for at least 12 months. Thirty-four patients were included in the study. The most frequent diagnosis of epilepsy was focal symptomatic epilepsy and Lennox−Gastaut syndrome (35.2%). During the follow-up, there was a statistically significant decrease in the seizure frequency (t student p < 0.001). A high proportion of patients, 16, concluded the study with a total control of the seizures reaching a 100% improvement, 12 reported ≥ 75% improvement, 3 ≥ 50%, and 2 ≥ 25%; only 1 patient had an improvement of less than 25%. This is the first Latin American study that demonstrates that long-term CBD added to the usual drugs significantly reduces the frequency, duration, and type of seizures in the different etiologies of epilepsy, being especially effective on the seizures that are the most incapacitating, improving the quality of life of the individual and their family.

Source-sink connectivity: a novel interictal EEG marker for seizure localization

Over 15 million epilepsy patients worldwide have drug-resistant epilepsy. Successful surgery is a standard of care treatment but can only be achieved through complete resection or disconnection of the epileptogenic zone, the brain region(s) where seizures originate. Surgical success rates vary between 20% and 80%, because no clinically validated biological markers of the epileptogenic zone exist. Localizing the epileptogenic zone is a costly and time-consuming process, which often requires days to weeks of intracranial EEG (iEEG) monitoring. Clinicians visually inspect iEEG data to identify abnormal activity on individual channels occurring immediately before seizures or spikes that occur interictally (i.e. between seizures). In the end, the clinical standard mainly relies on a small proportion of the iEEG data captured to assist in epileptogenic zone localization (minutes of seizure data versus days of recordings), missing opportunities to leverage these largely ignored interictal data to better diagnose and treat patients. IEEG offers a unique opportunity to observe epileptic cortical network dynamics but waiting for seizures increases patient risks associated with invasive monitoring. In this study, we aimed to leverage interictal iEEG data by developing a new network-based interictal iEEG marker of the epileptogenic zone. We hypothesized that when a patient is not clinically seizing, it is because the epileptogenic zone is inhibited by other regions. We developed an algorithm that identifies two groups of nodes from the interictal iEEG network: those that are continuously inhibiting a set of neighbouring nodes ('sources') and the inhibited nodes themselves ('sinks'). Specifically, patient-specific dynamical network models were estimated from minutes of iEEG and their connectivity properties revealed top sources and sinks in the network, with each node being quantified by source-sink metrics. We validated the algorithm in a retrospective analysis of 65 patients. The source-sink metrics identified epileptogenic regions with 73% accuracy and clinicians agreed with the algorithm in 93% of seizure-free patients. The algorithm was further validated by using the metrics of the annotated epileptogenic zone to predict surgical outcomes. The source-sink metrics predicted outcomes with an accuracy of 79% compared to an accuracy of 43% for clinicians' predictions (surgical success rate of this dataset). In failed outcomes, we identified brain regions with high metrics that were untreated. When compared with high frequency oscillations, the most commonly proposed interictal iEEG feature for epileptogenic zone localization, source-sink metrics outperformed in predictive power (by a factor of 1.2), suggesting they may be an interictal iEEG fingerprint of the epileptogenic zone.

Factors Predicting Outcome After Intracranial EEG Evaluation in Patients With Medically Refractory Epilepsy

BACKGROUND AND OBJECTIVES

The aim of this study was to identify predictors of a resective surgery and subsequent seizure freedom following intracranial EEG (ICEEG) for seizure-onset localization.

METHODS

This is a retrospective chart review of 178 consecutive patients with medically refractory epilepsy who underwent ICEEG monitoring from 2002 to 2015. Univariable and multivariable regression analysis identified independent predictors of resection vs other options. Stepwise Akaike information criteria with the aid of clinical consideration were used to select the best multivariable model for predicting resection and outcome. Discrete time survival analysis was used to analyze the factors predicting seizure-free outcome. Cumulative probability of seizure freedom was analyzed using Kaplan-Meier curves and compared between resection and nonresection groups. Additional univariate analysis was performed on 8 select clinical scenarios commonly encountered during epilepsy surgical evaluations.

RESULTS

Multivariable analysis identified the presence of a lesional MRI, presurgical hypothesis suggesting temporal lobe onset, and a nondominant hemisphere implant as independent predictors of resection (p < 0.0001, area under the receiver operating characteristic curve 0.80, 95% CI 0.73-0.87). Focal ICEEG onset and undergoing a resective surgery predicted absolute seizure freedom at the 5-year follow-up. Patients who underwent resective surgery were more likely to be seizure-free at 5 years compared with continued medical treatment or neuromodulation (60% vs 7%; p < 0.0001, hazard ratio 0.16, 95% CI 0.09-0.28). Even patients thought to have unfavorable predictors (nonlesional MRI or extratemporal lobe hypothesis or dominant hemisphere implant) had ≥50% chance of seizure freedom at 5 years if they underwent resection.

DISCUSSION

Unfavorable predictors, including having nonlesional extratemporal epilepsy, should not deter a thorough presurgical evaluation, including with invasive recordings in many cases. Resective surgery without functional impairment offers the best chance for sustained seizure freedom and should always be considered first.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that the presence of a lesional MRI, presurgical hypothesis suggesting temporal lobe onset, and a nondominant hemisphere implant are independent predictors of resection. Focal ICEEG onset and undergoing resection are independent predictors of 5-year seizure freedom.

Noninvasive disconnection of targeted neuronal circuitry sparing axons of passage and nonneuronal cells

OBJECTIVE

Surgery can be highly effective for the treatment of medically intractable, neurological disorders, such as drug-resistant focal epilepsy. However, despite its benefits, surgery remains substantially underutilized due to both surgical concerns and nonsurgical impediments. In this work, the authors characterized a noninvasive, nonablative strategy to focally destroy neurons in the brain parenchyma with the goal of limiting collateral damage to nontarget structures, such as axons of passage.

METHODS

Low-intensity MR-guided focused ultrasound (MRgFUS), together with intravenous microbubbles, was used to open the blood-brain barrier (BBB) in a transient and focal manner in rats. The period of BBB opening was exploited to focally deliver to the brain parenchyma a systemically administered neurotoxin (quinolinic acid) that is well tolerated peripherally and otherwise impermeable to the BBB.

RESULTS

Focal neuronal loss was observed in targeted areas of BBB opening, including brain regions that are prime objectives for epilepsy surgery. Notably, other structures in the area of neuronal loss, including axons of passage, glial cells, vasculature, and the ventricular wall, were spared with this procedure.

CONCLUSIONS

These findings identify a noninvasive, nonablative approach capable of disconnecting neural circuitry while limiting the neuropathological consequences that attend other surgical procedures. Moreover, this strategy allows conformal targeting, which could enhance the precision and expand the treatment envelope for treating irregularly shaped surgical objectives located in difficult-to-reach sites. Finally, if this strategy translates to the clinic, the noninvasive nature and specificity of the procedure could positively influence both physician referrals for and patient confidence in surgery for medically intractable neurological disorders.

Neural fragility as an EEG marker of the seizure onset zone

Over 15 million patients with epilepsy worldwide do not respond to drugs. Successful surgical treatment requires complete removal or disconnection of the seizure onset zone (SOZ), brain region(s) where seizures originate. Unfortunately, surgical success rates vary between 30 and 70% because no clinically validated biological marker of the SOZ exists. We develop and retrospectively validate a new electroencephalogram (EEG) marker-neural fragility-in a retrospective analysis of 91 patients by using neural fragility of the annotated SOZ as a metric to predict surgical outcomes. Fragility predicts 43 out of 47 surgical failures, with an overall prediction accuracy of 76% compared with the accuracy of clinicians at 48% (successful outcomes). In failed outcomes, we identify fragile regions that were untreated. When compared to 20 EEG features proposed as SOZ markers, fragility outperformed in predictive power and interpretability, which suggests neural fragility as an EEG biomarker of the SOZ.

Cost-effectiveness analysis of responsive neurostimulation for drug-resistant focal onset epilepsy

OBJECTIVE

We evaluated the incremental cost-effectiveness of responsive neurostimulation (RNS) therapy for management of medically refractory focal onset seizures compared to pharmacotherapy alone.

METHODS

We created and analyzed a decision model for treatment with RNS therapy versus pharmacotherapy using a semi-Markov process. We adopted a public payer perspective and used the maximum duration of 9 years in the RNS long-term follow-up study as the time horizon. We used seizure frequency data to model changes in quality of life and estimated the impact of RNS therapy on the annual direct costs of epilepsy care. The model also included expected mortality, adverse events, and costs related to system implantation, programming, and replacement. We interpreted our results against societal willingness-to-pay thresholds of $50 000, $100 000, and $200 000 per quality-adjusted life year (QALY).

RESULTS

Based on three different calculated utility value estimates, the incremental cost-effectiveness ratio (ICER) for RNS therapy (with continued pharmacotherapy) compared to pharmacotherapy alone ranged between $28 825 and $46 596. Multiple sensitivity analyses yielded ICERs often below $50 000 per QALY and consistently below $100 000/QALY.

SIGNIFICANCE

Modeling based on 9 years of available data demonstrates that RNS therapy for medically refractory epilepsy very likely falls within the range of cost-effectiveness, depending on method of utility estimation, variability in model inputs, and willingness-to-pay threshold. Several factors favor improved cost-effectiveness in the future. Given the increasing focus on delivering cost-effective care, we hope that this analysis will help inform clinical decision-making for this surgical option for refractory epilepsy.

sEEG for Expansion of a Surgical Epilepsy Program: Safety and Efficacy in 152 Consecutive Cases

Objective

Stereoelectroencephalography (sEEG) is an intracranial encephalography method of expanding use. The need for increased epilepsy surgery access has led to the consideration of sEEG adoption by new or expanding surgical epilepsy programs. Data regarding safety and efficacy are uncommon outside of high‐volume, well‐established centers, which may be less applicable to newer or low‐volume centers. The objective of this study was to add to the sEEG outcomes in the literature from the perspective of a rapidly expanding center.

Methods

A retrospective chart review of consecutive sEEG cases from January 2016 to December 2019 was performed. Data extraction included demographic data, surgical data, and outcome data, which pertinently examined surgical method, progression to therapeutic procedure, clinically significant adverse events, and Engel outcomes.

Results

One hundred and fifty‐two sEEG procedures were performed on 131 patients. Procedures averaged 10.5 electrodes for a total of 1603 electrodes. The majority (84%) of patients progressed to a therapeutic procedure. Six clinically significant complications occurred: three retained electrodes, two hemorrhages, and one failure to complete investigation. Only one complication resulted in a permanent deficit. Engel 1 outcome was achieved in 63.3% of patients reaching one‐year follow‐up after a curative procedure.

Significance

New or expanding epilepsy surgery centers can appropriately consider the use of sEEG. The complication rate is low and the majority of patients progress to therapeutic surgery. Procedural safety, progression to therapeutic intervention, and Engel outcomes are comparable to cohorts from long‐established epilepsy surgery programs.

Advantages of magnetoencephalography, neuronavigation and intraoperative MRI in epilepsy surgery re-operations

Objective: Management of patients after failed epilepsy surgery is still challenging. Advanced diagnostic and intraoperative tools including magneto-encephalography (MEG) as well as neuronavigation and intraoperative magnetic resonance imaging (iopMRI) may contribute to a better postoperative seizure outcome in this patient group.Methods: We retrospectively analyzed consecutive patients after reoperation of failed epilepsy surgery for medically refractory epilepsy at the University of Erlangen between 1988 and 2017. Inclusion criteria for patients were available MEG, neuronavigation and iopMRI data. The Engel scale was used to categorize seizure outcome.Results: We report on 27 consecutive patients (13 female/14 male mean age at first surgery 29.4 years) who had operative revision of the first resection after failed epilepsy surgery. An improved seizure outcome postoperatively was observed in 78% of patients (p < 0.001) with 55% seizure free (Engel I) patients after a mean follow-up time of 4.9 years. In detail, 80% of lesional cases were seizure free compared to 59% of MRI negative patients. Localizing MEG spike activity in the vicinity of the first resection cavity was present in 12 of 27 patients (44%) corresponding to 83% (10/12) of MEG localizing spike patients having advanced seizure outcome after operative revision.Conclusion: Re-operation after failed surgery in refractory epilepsy may lead to a better seizure outcome in the majority of patients. Preoperative MEG may support the decision for surgery and may facilitate targeting epileptogenic tissue for re-resection by employing navigation and iopMR imaging.

Transfer Function Models for the Localization of Seizure Onset Zone From Cortico-Cortical Evoked Potentials

Surgical resection of the seizure onset zone (SOZ) could potentially lead to seizure-freedom in medically refractory epilepsy patients. However, localizing the SOZ can be a time consuming and tedious process involving visual inspection of intracranial electroencephalographic (iEEG) recordings captured during passive patient monitoring. Cortical stimulation is currently performed on patients undergoing invasive EEG monitoring for the main purpose of mapping functional brain networks such as language and motor networks. We hypothesized that evoked responses from single pulse electrical stimulation (SPES) can also be used to localize the SOZ as they may express the natural frequencies and connectivity of the iEEG network. To test our hypothesis, we constructed patient specific transfer function models from the evoked responses recorded from 22 epilepsy patients that underwent SPES evaluation and iEEG monitoring. We then computed the frequency and connectivity dependent “peak gain” of the system as measured by the H∞  norm from systems theory. We found that in cases for which clinicians had high confidence in localizing the SOZ, the highest peak gain transfer functions with the smallest “floor gain” (gain at which the dipped H∞   3dB below DC gain) corresponded to when the clinically annotated SOZ and early spread regions were stimulated. In more complex cases, there was a large spread of the peak-to-floor (PF) ratios when the clinically annotated SOZ was stimulated. Interestingly for patients who had successful surgeries, our ratio of gains, agreed with clinical localization, no matter the complexity of the case. For patients with failed surgeries, the PF ratio did not match clinical annotations. Our findings suggest that transfer function gains and their corresponding frequency responses computed from SPES evoked responses may improve SOZ localization and thus surgical outcomes.

Quality of life before and after epilepsy surgery: Age is just a number

BACKGROUND

In a rapidly aging population, it is critical to analyze if the quality of life (QOL) in patients with drug-resistant epilepsy (DRE) and the change in it after epilepsy surgery is dependent on the age at operation.

METHODS

A prospective registry-based retrospective cohort study including adults with a completed pre- and post-surgery Quality of Life in Epilepsy 10 (QOLIE-10) survey. Multivariable linear regression models analyzed the baseline, postoperative, or change in QOLIE-10 score.

RESULTS

We analyzed 416 patients (51% females) with the mean age of 39.6 (SD = 12.6) years at the time of surgery, including 100 (24%) individuals 50 years or older. The younger and older adults (dichotomized as <50 vs. ≥50 and <60 vs. ≥60) had comparable pre- and post-surgery QOLIE 10 total scores. The change in total and individual QOLIE-10 items score were comparable between the groups as well. Within group improvements in total QOLIE-10 score post-surgery was in younger as well as older groups. The linear regression models showed that age, regardless of parameterization (linear or dichotomized), was not related to pre-surgery, post-surgery, and change in QOLIE-10 score, both before and after adjustment for covariates. The change in QOLIE-10 score did not show correlation with age, whether seizure freedom or relative seizure reduction was used in the model.

CONCLUSION

With QOL, before or after surgery, being independent of a patient's age, our findings suggest that well-selected older adults and the elderly should be offered epilepsy surgery without concern for an inferior improvement in QOL compared to their younger counterparts.

Localizing the seizure onset zone from single pulse electrical stimulation responses using transfer function models

Surgical resection of the seizure onset zone (SOZ) could potentially lead to seizure-freedom in medically refractory epilepsy patients. However, localizing the SOZ can be a time consuming and tedious process involving visual inspection of intracranial electroencephalographic (iEEG) recordings captured during passive patient monitoring. Single pulse electrical stimulation (SPES) is currently performed on patients undergoing invasive EEG monitoring for the main purposes of mapping functional brain networks such as language and motor networks. We hypothesize that evoked responses from SPES can also be used to localize the SOZ as they may express the natural frequencies and connectivity of the iEEG network. To test our hypothesis, we construct patient specific single-input multi-output transfer function models from the evoked responses recorded from five epilepsy patients that underwent SPES evaluation and iEEG monitoring. Our preliminary results suggest that the stimulation electrodes that produced the highest gain transfer functions, as measured by the ${\mathcal{H}_\infty }$ norm, correspond to those electrodes clinically defined in the SOZ in successfully treated patients.Clinical Relevance- This study creates an innovative tool that allows clinicians to identify the seizure onset zone in medically refractory epilepsy patients using quantitative metrics thereby increasing surgical success outcomes, mitigating patient risks, and decreasing costs.

Epilepsy surgery in tuberous sclerosis complex (TSC): emerging techniques and redefinition of treatment goals

Epilepsy occurs in nearly all patients with tuberous sclerosis and is often refractory to medical treatment. The definition of surgical candidacy in these patients has broadened in recent years due to philosophical and technological advances. The goals of surgery have shifted to focusing on quality of life and maximizing neurodevelopmental potential in patients unable to obtain seizure freedom. Novel diagnostic, ablative, and neuromodulatory techniques have been developed that may help patients that were previously considered inoperable to have an improved quality of life. In the coming years, it is expected that these techniques will be further refined and lead to an improvement of neurological prognosis in patients with tuberous sclerosis.

Quality of life, psychiatric symptoms, and stigma perception in three groups of persons with epilepsy

OBJECTIVE

The current study aimed to describe quality of life (QoL) levels, psychiatric symptoms prevalence, and perceived stigma levels in persons with either drug-resistant epilepsy (DRE) or drug-sensitive epilepsy (DSE) and in persons with epilepsy (PwE) with DRE that underwent epilepsy surgery (DREES).

METHODS

Persons with epilepsy diagnosed as having DRE according to International League Against Epilepsy (ILAE) criteria, DSE, and DREES were enrolled at the Epilepsy Unit of the Neurological Institute Carlo Besta of Milan. Sociodemographic and clinical data, Quality of Life in Epilepsy Inventory (QOLIE-31), Symptom Checklist-90 (SCL-90), and the Epilepsy Stigma Scale (ESS) were collected based on self-reported information and on medical records.

RESULTS

Sociodemographic, medical, and psychological data were obtained from 181 PwE: 80 with DRE, 31 with DSE, and 70 with DREES. We found that QoL is higher and psychiatric symptoms are lower in persons with DSE compared with DRE and that patients with DREES, who were drug-resistant before surgery, are in between DSE and DRE for both measures. Perceived stigma level is different in DSE and in DRE, that report the highest levels of stigma, and is between the other two groups in DREES.

SIGNIFICANCE

This study suggests that low QoL levels and high psychiatric symptoms prevalence in drug-resistant PwE may be significantly improved after epilepsy surgery and suggests the importance of a biopsychosocial approach when planning therapeutic intervention.

Quantifying the burden of generalized tonic-clonic seizures in patients with drug-resistant epilepsy

OBJECTIVE

Compared to other seizure types, generalized tonic-clonic (GTC) seizures may be disproportionately related to increased morbidity, and reducing seizure frequency could translate into improvements across measures of morbidity in medically treated patients with drug-resistant epilepsy (DRE). The primary objective of this analysis was to quantify the burden of patients with DRE who experience GTC seizures (GTC+) compared to patients with DRE who do not experience GTC seizures (GTC-).

METHODS

Adult patients from the Cleveland Clinic Epilepsy Center-Neurological Institute from 2012-2016 with DRE with epilepsy for at least 1 year were eligible for inclusion and were divided into GTC ± groups based on whether the patient had experienced a GTC seizure in the year preceding the first visit. Epilepsy duration, comorbidities, antiepileptic drug use, patient-reported outcomes (PROs) and seizure type, frequency, and etiology were captured. Generalized linear models, negative binomial regression, logistic regression, and linear regression were used as appropriate for multivariate analyses.

RESULTS

A total of 379 patients met inclusion criteria and had data at 1-year follow-up after their baseline visit (192 GTC+ and 187 GTC-). Although DRE patients experiencing GTC seizures had fewer seizures per day over the preceding 6 months than those not experiencing GTC seizures, seizure severity and levels of depression and anxiety were greater. GTC+ patients who reported five or more seizures in the preceding 4 weeks had 82% lower odds (1-0.18 = 0.82) of working than patients with no seizures.

SIGNIFICANCE

Patients with DRE experience a significant burden and decreased quality of life. Multivariate analysis is necessary to understand the complex relationship between seizure type, frequency, and impact on health-related quality of life (HRQoL) and changes over time. Effective treatments to reduce the burden for DRE patients who experience GTC seizures continue to be needed.

Social functioning and health-related quality of life trajectories in people with epilepsy after epilepsy surgery

OBJECTIVE

An improvement in quality of life (QoL) over time after epilepsy surgery has been demonstrated in people with epilepsy; however, social functioning has been less investigated. We conducted this study to examine whether postsurgical improvement is parallel between QoL and social functioning in patients with epilepsy.

METHODS

We retrospectively reviewed patients who underwent epilepsy surgery. All participants completed a comprehensive neuropsychological assessment, the Quality of Life in Epilepsy Inventory (QOLIE-89) questionnaire, and the Social and Occupational Functioning Scale for Epilepsy (SOFSE) before surgery and at 3 months, 6 months, and 1 year after surgery. Demographic and epilepsy-related information was also collected. Generalized estimating equations with identity links were used to model the QOLIE-89 and SOFSE over time and possible associated factors. A p < 0.05 was considered statistically significant.

RESULTS

A total of 76 patients, including 36 males and 43 females aged 18 to 62 years were collected. Both total QOLIE-89 and overall SOFSE improved over time after epilepsy surgery (adjusted p value < 0.001 and 0.002, respectively, with Bonferroni's correction). Total QOLIE-89 improved 3 months after surgery, while overall SOFSE showed no significant improvement until 6 months after surgery. The presurgical Full-Scale Intelligence Quotient (FSIQ) of the Wechsler Adult Intelligence Scale-III and years of education were significantly associated with time-dependent improvement for both total QOLIE-89 and overall SOFSE (p value < 0.001). At one year after surgery, overall SOFSE and total QOLIE-89 scores were significantly higher in the seizure-free group than in the nonseizure-free group (p value = 0.040 and 0.032, respectively).

CONCLUSION

Social functioning significantly improved in people with epilepsy after surgery as QoL, but it took more time to exhibit improvement. People with better FSIQ and more years of education had better improvement in social functioning over time. The early intervention of rehabilitation programs after epilepsy surgery might be necessary to facilitate the improvement in social functioning.