Epilepsy surgery for pharmacoresistant temporal lobe epilepsy: a decision analysis

High-precision stereotactic irradiation for focal drug-resistant epilepsy versus standard treatment: a randomized waitlist-controlled trial (the PRECISION trial)

INTRODUCTION

The standard treatment for patients with focal drug-resistant epilepsy (DRE) who are not eligible for open brain surgery is the continuation of anti-seizure medication (ASM) and neuromodulation. This treatment does not cure epilepsy but only decreases severity. The PRECISION trial offers a non-invasive, possibly curative intervention for these patients, which consist of a single stereotactic radiotherapy (SRT) treatment. Previous studies have shown promising results of SRT in this patient population. Nevertheless, this intervention is not yet available and reimbursed in the Netherlands. We hypothesize that: SRT is a superior treatment option compared to palliative standard of care, for patients with focal DRE, not eligible for open surgery, resulting in a higher reduction of seizure frequency (with 50% of the patients reaching a 75% seizure frequency reduction at 2 years follow-up).

METHODS

In this waitlist-controlled phase 3 clinical trial, participants are randomly assigned in a 1:1 ratio to either receive SRT as the intervention, while the standard treatments consist of ASM continuation and neuromodulation. After 2-year follow-up, patients randomized for the standard treatment (waitlist-control group) are offered SRT. Patients aged ≥ 18 years with focal DRE and a pretreatment defined epileptogenic zone (EZ) not eligible for open surgery will be included. The intervention is a LINAC-based single fraction (24 Gy) SRT treatment. The target volume is defined as the epileptogenic zone (EZ) on all (non) invasive examinations. The seizure frequency will be monitored on a daily basis using an electronic diary and an automatic seizure detection system during the night. Potential side effects are evaluated using advanced MRI, cognitive evaluation, Common Toxicity Criteria, and patient-reported outcome questionnaires. In addition, the cost-effectiveness of the SRT treatment will be evaluated.

DISCUSSION

This is the first randomized trial comparing SRT with standard of care in patients with DRE, non-eligible for open surgery. The primary objective is to determine whether SRT significantly reduces the seizure frequency 2 years after treatment. The results of this trial can influence the current clinical practice and medical cost reimbursement in the Netherlands for patients with focal DRE who are not eligible for open surgery, providing a non-invasive curative treatment option.

TRIAL REGISTRATION

Clinicaltrials.gov Identifier: NCT05182437. Registered on September 27, 2021.

Patient, parent and carer perspectives surrounding expedited paediatric epilepsy surgery

OBJECTIVE

Most paediatric epilepsies with MRI visible lesions do not respond to antiseizure pharmacotherapy. Such medication resistance, which often takes years to become formally defined, is commonly required for surgical candidacy. Expedited surgical referral at lesional epilepsy diagnosis may result in better seizure, cognitive and developmental prognoses. This study explored the views of patients, parents and carers regarding epilepsy surgery, treatment priorities, and participation in a proposed expedited surgery trial.

METHODS

205 patients, parents and carers (61% UK-based, 26% North American) responded to electronic surveys from February to May 2022. Participants were recruited through social media sites, epilepsy charities and societies. Categorical choice and free-text questions were used to investigate participant perspectives, and Pearson's chi-squared test was utilised to detect meaningful differences amongst respondent subgroups.

RESULTS

Almost 90% of respondents who had experienced epilepsy surgery (either themselves or their child) reported seizure cessation or reduction. Postoperative outcome measures prioritised most frequently were seizure freedom (66%), quality of life (47%), seizure severity (30%), seizure frequency (28%) and independence (27%). Most participants support expedited surgery in suitable patients (65%), with just over half (51%) willing to participate in the proposed trial. Many participants (37%) were undecided, often due to fears surrounding neurosurgery. Subgroup perspectives were broadly similar, with more parents and caregivers favouring expedited surgery compared to patients (p = .016) and more UK-based participants willing to take part in an expedited surgery trial compared to those from North America (p = .01).

CONCLUSIONS

Patients, parents and carers are open to considering expedited surgery for lesional epilepsies and would support a trial exploring this approach. Priorities from treatment were largely similar between participant subgroups, with seizure, quality of life and neuropsychological outcomes ranked highly. Accounting for these preferences will facilitate the delivery of a trial that is patient- and caregiver-focused, enhancing feasibility, satisfaction and benefit for prospective participants.

Effect of Race and Insurance Type on Access to, and Outcomes of, Epilepsy Surgery: A Literature Review

BACKGROUND

Despite higher rates of seizure freedom, a large proportion of patients with medically refractory seizures who could benefit from epilepsy surgery do not receive surgical treatment. This literature review describes the association of race and insurance status with epilepsy surgery access and outcomes.

METHODS

Searches in Scopus and PubMed databases related to disparities in epilepsy surgery were conducted. The inclusion criteria consisted of data that could be used to compare epilepsy surgery patient access and outcomes by insurance or race in the United States. Two independent reviewers determined article eligibility.

RESULTS

Of the 289 studies reviewed, 26 were included. Most of the studies were retrospective cohort studies (23 of 26) and national admissions database studies (13 of 26). Of the 17 studies that evaluated epilepsy surgery patient demographics, 11 showed that Black patients were less likely to receive surgery than were White patients or had an increased time to surgery from seizure onset. Nine studies showed that patients with private insurance were more likely to undergo epilepsy surgery and have shorter time to surgery compared with patients with public insurance. No significant association was found between the seizure recurrence rate after surgery with insurance or race.

CONCLUSIONS

Black patients and patients with public insurance are receiving epilepsy surgery at lower rates after a prolonged waiting period compared with other patients with medically refractory epilepsy. These results are consistent across the current reported literature. Future efforts should focus on additional characterization and potential causes of these disparities to develop successful interventions.

Aromatherapy for the brain: Lavender's healing effect on epilepsy, depression, anxiety, migraine, and Alzheimer's disease: A review article

Neurological diseases affect the nervous system, including the brain, spinal cord, cranial nerves, nerve roots, autonomic nervous system, neuromuscular junctions, and muscles. Herbal medicine has long been used to cure these diseases. One of these plants is lavender, which is composed of various compounds, including terpenes, such as linalool, limonene, triterpenes, linalyl acetate, alcohols, ketones, polyphenols, coumarins, cineole, and flavonoids. In this review, the literature was searched using scientific search engines and databases (Google Scholar, Science Direct, Scopus, and PubMed) for papers published between 1982 and 2020 via keywords, including review, lavender, and neurological disorders. This plant exerts its healing effect on many diseases, such as anxiety and depression through an inhibitory effect on GABA. The anti-inflammatory effects of this plant have also been documented. It improves depression by regulating glutamate receptors and inhibiting calcium channels and serotonergic factors, such as SERT. Its antiepileptic mechanism is due to an increase in the inhibitory effect of GABA and potassium current and a decrease in sodium current. Therefore, many vegetable oils are also used in herbal medicine. In this review, the healing effect of lavender on several neurological disorders, including epilepsy, depression, anxiety, migraine, and Alzheimer's disease was investigated. All findings strongly support the traditional uses of lavender. More clinical studies are needed to investigate the effect of the plants' pharmacological active constituents on the treatment of life-threatening diseases in humans. The limitations of this study are the low quality and the limited number of clinical studies. Different administration methods of lavender are one of the limitations of this review.

Predictors and reasons for epilepsy patients to decline surgery: a prospective study

BACKGROUND

In patients with drug-resistant focal epilepsy, resective surgery is the most successful treatment option to achieve seizure freedom. However, a surprisingly high rate of patients declines their physicians' recommendation to undergo removal of the seizure focus or-if necessary-further video-EEG monitoring (VEM).

METHODS

In this prospective study, consecutive patients in presurgical assessment with at least one scalp VEM between 2016 and 2018 were included. We assessed both epilepsy-related and psychosocial variables as well as decision-making of physicians and patients, including reasons for decline in the latter.

RESULTS

Out of 116 patients with a total of 165 VEM, 20 patients were eventually found to be ineligible for resection, 51 declined, and 45 agreed on recommendations for resection or further VEM diagnostics. Patients most frequently declined due to general fear of brain surgery (n = 30, 59%) and currently lower seizure frequency (n = 11, 22%). An independent predictor of patients' decline was less epilepsy-related fear (OR 0.43; p = 0.02) assessed in a standardised questionnaire.

CONCLUSION

Half of the patients potentially eligible for resective surgery decline the operation or further VEM procedures. Patients who decline are more fearful of brain surgery than of ongoing disabling seizures. More insight is needed to improve counselling of patients.

A procedure for predicting, illustrating, communicating, and optimizing patient-centered outcomes of epilepsy surgery using nomograms and Bayes' theorem

Clinicians have an ethical obligation to obtain and convey relevant information about possible treatment outcomes in a manner that can be comprehended by patients. This contributes to the processes of informed consent and shared prospective decision-making. In epilepsy neurosurgery, there has historically been an emphasis on studying clinician-centered (e.g., seizure- and cognition-related) outcomes and using these data to inform recommendations and, by extension, to frame pre-surgical counseling with respect to patients' decisions about elective neurosurgery. In contrast, there is a relative dearth of available data related to patient-centered outcomes of epilepsy neurosurgery, such as functional (e.g., employment) status, and there is also a lack of methods to communicate these data to patients. Here, illustrated using a hypothetical case scenario, we present a potential solution to the latter of these problems using principles of evidence-based neuropsychology; published data on patient employment status before and after epilepsy neurosurgery; and Bayes' theorem. First, we reviewed existing literature on employment outcomes following epilepsy neurosurgery to identify and extract data relevant to our hypothetical patient, clinical question, and setting. Then, we used the base rate (prior probability) of post-surgical unemployment, contingency tables (to derive likelihood ratios), and Bayes' theorem to compute the conditional (posterior) probability of post-surgical employment status for our hypothetical patient scenario. Finally, we translated this information to an intuitive visual format (Bayesian nomogram) that can support evidence-based pre-surgical counseling. We propose that the application of our patient-centered decision-support process and visual aid will improve clinician-patient communication about prospective risks and benefits of epilepsy neurosurgery and will empower clinicians and patients to make informed decisions about whether or not to pursue elective neurosurgery with a greater degree of confidence and with more realistic and concrete expectations about possible outcomes. We further propose that clinicians and patients would benefit from incorporating this evidence-based framework into a broader sequence of function-focused epilepsy treatment that includes pre-surgical assessments and interventions ("prehabilitation"), neurosurgery, and post-surgical cognitive/vocational rehabilitation.

Health care resource utilization and costs before and after epilepsy surgery

OBJECTIVE

To describe the demographics of epilepsy surgery utilization and its impact on health care resource use.

METHODS

Retrospective descriptive study using the MarketScan commercial claims database. We studied children and adults who underwent epilepsy surgery in the USA in the period 2006-2019. Our main outcome was health care resource utilization.

RESULTS

Among the 87,368 patients with refractory epilepsy, 2,011 (2.3%) patients underwent resective epilepsy surgery, 188 (0.2%) patients underwent partial or total hemispherectomy, and 183 (0.2%) patients underwent corpus callosotomy. The proportion of patients undergoing epilepsy surgery has barely increased in the period 2006 to 2019. The year of resective epilepsy surgery was associated with high healthcare costs per person-year [median (p₂₅-p₇₅): $140,322 ($88,749-$225,862)], but healthcare costs per person-year substantially decreased in the 5 years after compared to the 5 years before the year of resective epilepsy surgery [$7,691 ($2,738-$22,092) versus $18,750 ($7,361-$47,082), p-value < 0.0001]. This result held in all resective epilepsy surgery subgroups: children, adults, temporal, extratemporal, subdural EEG monitoring, stereoEEG monitoring, and no intracranial monitoring. Similarly, the year of hemispherectomy was associated with high healthcare costs per person-year [$260,983 ($154,791-$453,986)], but healthcare costs per person-year substantially decreased in the 5 years after compared to the 5 years before the year of hemispherectomy [$26,834 ($12,842-$52,627) versus $54,596 ($19,547-$136,412), p-value < 0.0001]. In contrast, the year of corpus callosotomy was associated with high healthcare costs per person-year [$162,399 ($108,150-$253,156)], but healthcare costs per person-year did not substantially decrease in the 5 years after than in the 5 years before the year of corpus callosotomy [$25,464 ($10,764-$69,338) versus $36,221 ($12,841-$85,747), p-value = 0.2142].

CONCLUSION

In privately insured patients in the USA, resective epilepsy surgery and hemispherectomy substantially decrease healthcare utilization in subsequent years. Epilepsy surgery may help contain costs in the field of epilepsy.

Implementation of Machine Learning Pipelines for Clinical Practice: Development and Validation Study

BACKGROUND

Artificial intelligence (AI) technologies, such as machine learning and natural language processing, have the potential to provide new insights into complex health data. Although powerful, these algorithms rarely move from experimental studies to direct clinical care implementation.

OBJECTIVE

We aimed to describe the key components for successful development and integration of two AI technology-based research pipelines for clinical practice.

METHODS

We summarized the approach, results, and key learnings from the implementation of the following two systems implemented at a large, tertiary care children's hospital: (1) epilepsy surgical candidate identification (or epilepsy ID) in an ambulatory neurology clinic; and (2) an automated clinical trial eligibility screener (ACTES) for the real-time identification of patients for research studies in a pediatric emergency department.

RESULTS

The epilepsy ID system performed as well as board-certified neurologists in identifying surgical candidates (with a sensitivity of 71% and positive predictive value of 77%). The ACTES system decreased coordinator screening time by 12.9%. The success of each project was largely dependent upon the collaboration between machine learning experts, research and operational information technology professionals, longitudinal support from clinical providers, and institutional leadership.

CONCLUSIONS

These projects showcase novel interactions between machine learning recommendations and providers during clinical care. Our deployment provides seamless, real-time integration of AI technology to provide decision support and improve patient care.

Localizing targets for neuromodulation in drug-resistant epilepsy using intracranial EEG and computational model

Neuromodulation has emerged as a promising technique for the treatment of epilepsy. The target for neuromodulation is critical for the effectiveness of seizure control. About 30% of patients with drug-resistant epilepsy (DRE) fail to achieve seizure freedom after surgical intervention. It is difficult to find effective brain targets for neuromodulation in these patients because brain regions are damaged during surgery. In this study, we propose a novel approach for localizing neuromodulatory targets, which uses intracranial EEG and multi-unit computational models to simulate the dynamic behavior of epileptic networks through external stimulation. First, we validate our method on a multivariate autoregressive model and compare nine different methods of constructing brain networks. Our results show that the directed transfer function with surrogate analysis achieves the best performance. Intracranial EEGs of 11 DRE patients are further analyzed. These patients all underwent surgery. In three seizure-free patients, the localized targets are concordant with the resected regions. For the eight patients without seizure-free outcome, the localized targets in three of them are outside the resected regions. Finally, we provide candidate targets for neuromodulation in these patients without seizure-free outcome based on virtual resected epileptic network. We demonstrate the ability of our approach to locate optimal targets for neuromodulation. We hope that our approach can provide a new tool for localizing patient-specific targets for neuromodulation therapy in DRE.

Testing an Adapted Auditory Verbal Learning Test Paradigm for fMRI to Lateralize Verbal Memory in Patients with Epilepsy

BACKGROUND AND PURPOSE

fMRI is a noninvasive tool for predicting postsurgical deficits in candidates with pharmacoresistant temporal lobe epilepsy. We aimed to test an adapted paradigm of the Rey Auditory Verbal Learning Test to evaluate differences in memory laterality indexes between patients and healthy controls and its association with neuropsychological scores.

MATERIALS AND METHODS

We performed a prospective study of 50 patients with temporal lobe epilepsy and 22 healthy controls. Participants underwent a block design language and memory fMRI. Laterality indexes and the hippocampal anterior-posterior index were calculated. Language and memory lateralization was organized into typical and atypical on the basis of laterality indexes. A neuropsychological assessment was performed with a median time from fMRI of 8 months and was compared with fMRI performance.

RESULTS

We studied 40 patients with left temporal lobe epilepsy and 10 with right temporal lobe epilepsy. Typical language occurred in 65.3% of patients and 90.9% of healthy controls (P = .04). The memory fMRI laterality index was obtained in all healthy controls and 92% of patients. The verbal memory laterality index was bilateral (24.3%) more frequently than the language laterality index (7.69%) in patients with left temporal lobe epilepsy. Atypical verbal memory was greater in patients with left temporal lobe epilepsy (56.8%) than in healthy controls (36.4%), and the proportion of bilateral laterality indexes (53.3%) was larger than right laterality indexes (46.7%). Atypical verbal memory might be associated with higher cognitive scores in patients. No relevant differences were seen in the hippocampal anterior-posterior index according to memory impairment.

CONCLUSIONS

The adapted Rey Auditory Verbal Learning Test paradigm fMRI might support verbal memory lateralization. Temporal lobe epilepsy laterality influences hippocampal memory laterality indexes. Left temporal lobe epilepsy has shown a higher proportion of atypical verbal memory compared with language, potentially to memory functional reorganization.

Can intraoperative electrocorticography be used to minimize the extent of resection in patients with temporal lobe epilepsy associated with hippocampal sclerosis?

OBJECTIVE

Tailored surgery to extensively resect epileptogenic lesions using intraoperative electrocorticography (ioECoG) may improve seizure outcomes. However, resection of large areas is associated with decreased memory function postoperatively. The authors assessed whether ioECoG could provide useful information on how to minimize the focus resection and obtain better seizure outcomes without memory deterioration. They examined the postoperative seizure-free period and memory alteration in a retrospective cohort of patients with mesial temporal lobe epilepsy (TLE) due to hippocampal sclerosis (HS) in whom the extent of removal was determined using ioECoG findings.

METHODS

The authors enrolled 82 patients with TLE associated with HS who were treated surgically. Transsylvian amygdalohippocampectomy was indicated as the first step. When visual inspection identified interictal epileptic discharges from the lateral temporal lobe on ioECoG, anterior temporal lobectomy (ATL) was eventually performed. The patients were divided into the selective amygdalohippocampectomy (SA, n = 40) and ATL (n = 42) groups. Postoperative seizure outcomes were assessed at 1, 2, 3, 5, and 7 years postoperatively using the International League Against Epilepsy classification. The Kaplan-Meier survival analysis was applied to evaluate the period of seizure recurrence between the SA and ATL groups. Factors attributed to seizure recurrence were analyzed using the Cox proportional hazards model, and they were as follows: epileptic focal laterality; age at seizure onset (< 10 or ≥ 10 years old); seizure frequency (more than weekly or less than weekly seizures); history of focal to bilateral tonic-clonic seizure; infectious etiology; and surgical procedure. The Wechsler Memory Scale-Revised was used to evaluate memory function pre- and postoperatively.

RESULTS

Seizure outcomes were significantly worse in the SA group than in the ATL group at 2 years postoperatively (p = 0.045). The International League Against Epilepsy class 1 outcomes at 7 years postoperatively in the SA and ATL groups were 63% and 81%, respectively. Kaplan-Meier analysis showed that seizure recurred significantly earlier in the SA group than in the ATL group (p = 0.031). The 2-way ANOVA analysis was used to compare the SA and ATL groups in each memory category, and revealed that there was no significant difference regardless of the side of surgery.

CONCLUSIONS

Visual assessment of ioECoG cannot be used as an indicator to minimize epileptic focus resection in patients with TLE associated with HS. ATL is more effective in obtaining seizure-free outcomes; however, both ATL and SA can preserve memory function.

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.

Temporal lobe epilepsy surgery: Piriform cortex resection impacts seizure control in the long-term

Objective

Recently, we showed that resection of at least 27% of the temporal part of piriform cortex (PiC) strongly correlated with seizure freedom 1 year following selective amygdalo‐hippocampectomy (tsSAHE) in patients with mesial temporal lobe epilepsy (mTLE). However, the impact of PiC resection on long‐term seizure outcome following tsSAHE is currently unknown. The aim of this study was to evaluate the impact of PiC resection on long‐term seizure outcome in patients with mTLE treated with tsSAHE.

Methods

Between 2012 and 2017, 64 patients were included in the retrospective analysis. Long‐term follow‐up (FU) was defined as at least 2 years postoperatively. Seizure outcome was assessed according to the International League against Epilepsy (ILAE). The resected proportions of hippocampus, amygdala, and PiC were volumetrically assessed.

Results

The mean FU duration was 3.75 ± 1.61 years. Patients with ILAE class 1 revealed a significantly larger median proportion of resected PiC compared to patients with ILAE class 2–6 [46% (IQR 31–57) vs. 16% (IQR 6–38), p = 0.001]. Resected proportions of hippocampus and amygdala did not significantly differ for these groups. Among those patients with at least 27% resected proportion of PiC, there were significantly more patients with seizure freedom compared to the patients with <27% resected proportion of PiC (83% vs. 39%, p = 0.0007).

Conclusions

Our results show a strong impact of the extent of PiC resection on long‐term seizure outcome following tsSAHE in mTLE. The authors suggest the PiC to constitute a key target volume in tsSAHE to achieve seizure freedom in the long term.

What is a clinical practice guideline? A roadmap to their development. Special report from the Guidelines Task Force of the International League Against Epilepsy

Clinical practice guidelines (CPGs) are statements that provide evidence-based recommendations aimed at optimizing patient care. However, many other documents are often published as "guidelines" when they are not; these documents, although also important in clinical practice, are usually not systematically produced following rigorous processes linking the evidence to the recommendations. Specifically, the International League Against Epilepsy (ILAE) guideline development toolkit aims to ensure that high-quality CPGs are developed to fill knowledge gaps and optimize the management of epilepsy. In addition to adhering to key methodological processes, guideline developers need to consider that effective CPGs should lead to improvements in clinical processes of care and health care outcomes. This requires monitoring the effectiveness of epilepsy-related CPGs and interventions to remove the barriers to epilepsy CPG implementation. This article provides an overview of what distinguishes quality CPGs from other documents and discusses their benefits and limitations. We summarize the recently revised ILAE CPG development process and elaborate on the barriers and facilitators to guideline dissemination, implementation, and adaptation.

Structure and function of language networks in temporal lobe epilepsy

Individuals with temporal lobe epilepsy (TLE) may have significant language deficits. Language capabilities may further decline following temporal lobe resections. The language network, comprising dispersed gray matter regions interconnected with white matter fibers, may be atypical in individuals with TLE. This review explores the structural changes to the language network and the functional reorganization of language abilities in TLE. We discuss the importance of detailed reporting of patient's characteristics, such as, left- and right-sided focal epilepsies as well as lesional and nonlesional pathological subtypes. These factors can affect the healthy functioning of gray and/or white matter. Dysfunction of white matter and displacement of gray matter function could concurrently impact their ability, in turn, producing an interactive effect on typical language organization and function. Surgical intervention can result in impairment of function if the resection includes parts of this structure-function network that are critical to language. In addition, impairment may occur if language function has been reorganized and is included in a resection. Conversely, resection of an epileptogenic zone may be associated with recovery of cortical function and thus improvement in language function. We explore the abnormality of functional regions in a clinically applicable framework and highlight the differences in the underlying language network. Avoidance of language decline following surgical intervention may depend on tailored resections to avoid critical areas of gray matter and their white matter connections. Further work is required to elucidate the plasticity of the language network in TLE and to identify sub-types of language representation, both of which will be useful in planning surgery to spare language function.

Informed MEG/EEG source imaging reveals the locations of interictal spikes missed by SEEG

Determining the accurate locations of interictal spikes has been fundamental in the presurgical evaluation of epilepsy surgery. Stereo-electroencephalography (SEEG) is able to directly record cortical activity and localize interictal spikes. However, the main caveat of SEEG techniques is that they have limited spatial sampling (covering <5% of the whole brain), which may lead to missed spikes originating from brain regions that were not covered by SEEG. To address this problem, we propose a SEEG-informed minimum-norm estimates (SIMNE) method by combining SEEG with magnetoencephalography (MEG) or EEG. Specifically, the spike locations determined by SEEG offer as a priori information to guide MEG source reconstruction. Both computer simulations and experiments using data from five epilepsy patients were conducted to evaluate the performance of SIMNE. Our results demonstrate that SIMNE generates more accurate source estimation than a traditional minimum-norm estimates method and reveals the locations of spikes missed by SEEG, which would improve presurgical evaluation of the epileptogenic zone.

The American Society for Stereotactic and Functional Neurosurgery Position Statement on Laser Interstitial Thermal Therapy for the Treatment of Drug-Resistant Epilepsy

Magnetic resonance image-guided laser interstitial thermal therapy (MRgLITT) is a novel tool in the neurosurgical armamentarium for the management of drug-resistant epilepsy. Given the recent introduction of this technology, the American Society for Stereotactic and Functional Neurosurgery (ASSFN), which acts as the joint section representing the field of stereotactic and functional neurosurgery on behalf of the Congress of Neurological Surgeons and the American Association of Neurological Surgeons, provides here the expert consensus opinion on evidence-based best practices for the use and implementation of this treatment modality. Indications for treatment are outlined, consisting of failure to respond to, or intolerance of, at least 2 appropriately chosen medications at appropriate doses for disabling, localization-related epilepsy in the setting of well-defined epileptogenic foci, or critical pathways of seizure propagation accessible by MRgLITT. Applications of MRgLITT in mesial temporal lobe epilepsy and hypothalamic hamartoma, along with its contraindications in the treatment of epilepsy, are discussed based on current evidence. To put this position statement in perspective, we detail the evidence and authority on which this ASSFN position statement is based.

Patient preferences pertaining to treatment options for drug-resistant focal epilepsy

OBJECTIVE

To determine patient acceptability of benefit-risk trade-offs in selecting treatment options for drug-resistant mesial temporal lobe epilepsy, including open brain surgery, laser ablation (laser interstitial thermal therapy [LITT]), and continued medications.

METHODS

A discrete-choice experiment survey was developed, consisting of 20 versions that were randomly assigned to respondents. Each version had 8 sets of constructed treatment alternatives, representing open brain surgery, LITT, or continued medical management. For each set, respondents indicated the treatment alternative they would choose first. Treatment alternatives were characterized by varying levels of chance of seizure freedom for at least 2 years (20-70%), risk of 30-day mortality (0-10%), and risk of neurological deficits (0-40%). Respondents' choices were analyzed using random-parameters logit models to quantify acceptable benefit-risk trade-offs. Preference heterogeneity was evaluated using latent-class analysis.

RESULTS

The survey was administered to 2 cohorts of adult patients with drug-resistant epilepsy: a Duke cohort identified using diagnostic codes (n = 106) and a web-recruited panel with a self-reported physician diagnosis of drug-resistant epilepsy (n = 300). Based on mean preference weights, respondents who indicated a willingness to consider surgical intervention would accept a reduction in chance of seizure freedom from 70% to a minimum-acceptable benefit (MAB) of 23% if they could undergo LITT rather than open brain surgery. For a reduction in 30-day mortality from 1% to 0%, MAB was 52%. For a reduction in risk of long-term deficits from 10% to 0%, MAB was 39%. Latent-class analysis revealed additional choice patterns identifying respondent groups that more strongly favored continuing medications or undergoing surgery.

CONCLUSION

Patients who are receptive to surgery would accept significantly lower treatment effectiveness to undergo a minimally invasive procedure relative to open brain surgery. They also were willing to accept lower treatment benefit to reduce risks of mortality or neurological deficits.

The role of the piriform cortex in temporal lobe epilepsy: A current literature review

Temporal lobe epilepsy is the most common form of focal epilepsy and can have various detrimental consequences within many neurologic domains. Recent evidence suggests that the piriform cortex may also be implicated in seizure physiology. The piriform cortex is a primary component of the olfactory network and is located at the junction of the frontal and temporal lobes, wrapping around the entorhinal sulcus. Similar to the hippocampus, it is a tri-layered allocortical structure, with connections to many adjacent regions including the orbitofrontal cortex, amygdala, peri- and entorhinal cortices, and insula. Both animal and human studies have implicated the piriform cortex as a critical node in the temporal lobe epilepsy network. It has additionally been shown that resection of greater than half of the piriform cortex may significantly increase the odds of achieving seizure freedom. Laser interstitial thermal therapy has also been shown to be an effective treatment strategy with recent evidence hinting that ablation of the piriform cortex may be important for seizure control as well. We propose that sampling piriform cortex in intracranial stereoelectroencephalography (sEEG) procedures with the use of a temporal pole or amygdalar electrode would be beneficial for further understanding the role of the piriform cortex in temporal lobe epilepsy.

Network connectivity predicts effectiveness of responsive neurostimulation in focal epilepsy

Responsive neurostimulation is a promising treatment for drug-resistant focal epilepsy; however, clinical outcomes are highly variable across individuals. The therapeutic mechanism of responsive neurostimulation likely involves modulatory effects on brain networks; however, with no known biomarkers that predict clinical response, patient selection remains empiric. This study aimed to determine whether functional brain connectivity measured non-invasively prior to device implantation predicts clinical response to responsive neurostimulation therapy. Resting-state magnetoencephalography was obtained in 31 participants with subsequent responsive neurostimulation device implantation between 15 August 2014 and 1 October 2020. Functional connectivity was computed across multiple spatial scales (global, hemispheric, and lobar) using pre-implantation magnetoencephalography and normalized to maps of healthy controls. Normalized functional connectivity was investigated as a predictor of clinical response, defined as percent change in self-reported seizure frequency in the most recent year of clinic visits relative to pre-responsive neurostimulation baseline. Area under the receiver operating characteristic curve quantified the performance of functional connectivity in predicting responders (≥50% reduction in seizure frequency) and non-responders (<50%). Leave-one-out cross-validation was furthermore performed to characterize model performance. The relationship between seizure frequency reduction and frequency-specific functional connectivity was further assessed as a continuous measure. Across participants, stimulation was enabled for a median duration of 52.2 (interquartile range, 27.0-62.3) months. Demographics, seizure characteristics, and responsive neurostimulation lead configurations were matched across 22 responders and 9 non-responders. Global functional connectivity in the alpha and beta bands were lower in non-responders as compared with responders (alpha, p_fdr < 0.001; beta, p_fdr < 0.001). The classification of responsive neurostimulation outcome was improved by combining feature inputs; the best model incorporated four features (i.e. mean and dispersion of alpha and beta bands) and yielded an area under the receiver operating characteristic curve of 0.970 (0.919-1.00). The leave-one-out cross-validation analysis of this four-feature model yielded a sensitivity of 86.3%, specificity of 77.8%, positive predictive value of 90.5%, and negative predictive value of 70%. Global functional connectivity in alpha band correlated with seizure frequency reduction (alpha, P = 0.010). Global functional connectivity predicted responder status more strongly, as compared with hemispheric predictors. Lobar functional connectivity was not a predictor. These findings suggest that non-invasive functional connectivity may be a candidate personalized biomarker that has the potential to predict responsive neurostimulation effectiveness and to identify patients most likely to benefit from responsive neurostimulation therapy. Follow-up large-cohort, prospective studies are required to validate this biomarker. These findings furthermore support an emerging view that the therapeutic mechanism of responsive neurostimulation involves network-level effects in the brain.

Dollars and Sense: Cost-Effectiveness of Epilepsy Surgery

Cost Effectiveness of Surgery for Drug-Resistant Temporal Lobe Epilepsy in the US Neurology

Sheikh SR, Kattan MW, Steinmetz M, Singer ME, Udeh BL, Jehi L. Neurology. 2020;95(1):e1404-e1416. doi:10.1212/WNL.0000000000010185

Objective:

Surgery is an effective but costly treatment for many patients with drug-resistant temporal lobe epilepsy (DR-TLE). We aim to evaluate whether, in the United States, surgery is cost-effective compared to medical management for patients deemed surgical candidates and whether surgical evaluation is cost-effective for patients with DR-TLE in general.

Methods:

We use a semi-Markov model to assess the cost-effectiveness of surgery and surgical evaluation over a lifetime horizon. We use second-order Monte Carlo simulations to conduct probabilistic sensitivity analyses to estimate variation in model output. We adopt both health care and societal perspectives, including direct health care costs (eg, surgery, antiepileptic drugs) and indirect costs (eg, lost earnings by patients and care providers). We compare the incremental cost-effectiveness ratio to societal willingness to pay (∼US$100 000 per quality-adjusted life-year [QALY]) to determine whether surgery is cost-effective.

Results:

Epilepsy surgery is cost-effective compared to medical management in surgically eligible patients by virtue of being cost-saving (US$328 000 vs US$423 000) and more effective (16.6 vs 13.6 QALY) than medical management in the long run. Surgical evaluation is cost-effective in patients with DR-TLE even if the probability of being deemed a surgical candidate is only 5%. From a societal perspective, surgery becomes cost-effective within 3 years, and 89% of simulations favor surgery over the lifetime horizon.

Conclusion:

For surgically eligible patients with DR-TLE, surgery is cost-effective. For patients with DR-TLE in general, referral for surgical evaluation (and possible subsequent surgery) is cost-effective. Patients with DR-TLE should be referred for surgical evaluation without hesitation on cost-effectiveness grounds.

Imaging the extent and location of spatiotemporally distributed epileptiform sources from MEG measurements

Non-invasive MEG/EEG source imaging provides valuable information about the epileptogenic brain areas which can be used to aid presurgical planning in focal epilepsy patients suffering from drug-resistant seizures. However, the source extent estimation for electrophysiological source imaging remains to be a challenge and is usually largely dependent on subjective choice. Our recently developed algorithm, fast spatiotemporal iteratively reweighted edge sparsity minimization (FAST-IRES) strategy, has been shown to objectively estimate extended sources from EEG recording, while it has not been applied to MEG recordings. In this work, through extensive numerical experiments and real data analysis in a group of focal drug-resistant epilepsy patients' interictal spikes, we demonstrated the ability of FAST-IRES algorithm to image the location and extent of underlying epilepsy sources from MEG measurements. Our results indicate the merits of FAST-IRES in imaging the location and extent of epilepsy sources for pre-surgical evaluation from MEG measurements.

Efficacy of cathodal transcranial direct current stimulation on electroencephalographic functional networks in patients with focal epilepsy: Preliminary findings

BACKGROUND

Neuromodulation is a promising therapeutic alternative for epilepsy. We aimed to explore the efficacy and safety of cathodal transcranial current direct stimulation (ctDCS) on electroencephalographic functional networks in focal epilepsy.

METHODS

A sham-controlled, double-blinded, randomized study was conducted on 25 participants with focal epilepsy who underwent a 5-day, -1.0 mA, 20 min ctDCS, which targeted at the most active interictal epileptiform discharge (IED) region. We examined the electroencephalograms (EEGs) at baseline, immediately and at 4 weeks following ctDCS. The graph theory-based brain networks were established through time-variant partial directed coherence (TVPDC), and were calculated between each pair of EEG signals. The functional networks were characterized using average clustering coefficient, characteristic path length, and small-worldness index. The seizure frequencies, IEDs, graph-theory metrics and cognitive tests were compared.

RESULTS

Preliminary findings indicated an IED reduction of 30.2% at the end of 5-day active ctDCS compared to baseline (p < 0.10) and a significant IED reduction of 33.4% 4 weeks later (p < 0.05). In terms of the EEG functional network, the small-worldness index significantly reduced by 3.5% (p < 0.05) and the characteristic path length increased by 1.8% (p < 0.10) at the end of the session compared to the baseline. No obvious change was found in the seizure frequency during follow-up (p > 0.05). The Mini-Mental State Examination (MMSE) showed no difference between the active and sham groups (p > 0.05). No severe adverse reactions were observed.

CONCLUSIONS

In focal epilepsy, the 5-day consecutive ctDCS may potentially decrease the IEDs and ameliorate the EEG functional network, proposing a novel personalized therapeutic scenario for epilepsy.

Seizure Prophylaxis After Spontaneous Intracerebral Hemorrhage

Importance

Limited evidence is available concerning optimal seizure prophylaxis after spontaneous intracerebral hemorrhage (sICH).

Objective

To evaluate which of 4 seizure prophylaxis strategies provides the greatest net benefit for patients with sICH.

Design, Setting, and Participants

This decision analysis used models to simulate the following 4 common scenarios: (1) a 60-year-old man with low risk of early (≤7 days after stroke) (10%) and late (3.6% or 9.8%) seizures and average risk of short- (9%) and long-term (30%) adverse drug reaction (ADR); (2) an 80-year-old woman with low risk of early (10%) and late (3.6% or 9.8%) seizures and high short- (24%) and long-term (80%) ADR risks; (3) a 55-year-old man with high risk of early (19%) and late (34.8% or 46.2%) seizures and low short- (9%) and long-term (30%) ADR risks; and (4) a 45-year-old woman with high risk of early (19%) and late (34.8% or 46.2%) seizures and high short- (18%) and long-term (60%) ADR risks.

Interventions

The following 4 antiseizure drug strategies were included: (1) conservative, consisting of short-term (7-day) secondary early-seizure prophylaxis with long-term therapy after late seizure; (2) moderate, consisting of long-term secondary early-seizure prophylaxis or late-seizure therapy; (3) aggressive, consisting of long-term primary prophylaxis; and (4) risk guided, consisting of short-term secondary early-seizure prophylaxis among low-risk patients (2HELPS2B score, 0), short-term primary prophylaxis among patients at higher risk (2HELPS2B score, ≥1), and long-term secondary therapy for late seizure.

Main Outcomes and Measures

Quality-adjusted life-years (QALYs).

Results

For scenario 1, the risk-guided strategy (8.13 QALYs) was preferred over the conservative (8.08 QALYs), moderate (8.07 QALYs), and aggressive (7.88 QALYs) strategies. For scenario 2, the conservative strategy (2.18 QALYs) was preferred over the risk-guided (2.17 QALYs), moderate (2.09 QALYs), and aggressive (1.15 QALYs) strategies. For scenario 3, the aggressive strategy (9.21 QALYs) was preferred over the risk-guided (8.98 QALYs), moderate (8.93 QALYs), and conservative (8.77 QALYs) strategies. For scenario 4, the risk-guided strategy (11.53 QALYs) was preferred over the conservative (11.23 QALYs), moderate (10.93 QALYs), and aggressive (8.08 QALYs) strategies. Sensitivity analyses suggested that short-term strategies (conservative and risk guided) are preferred under most scenarios, and the risk-guided strategy performs comparably to or better than alternative strategies in most settings.

Conclusions and Relevance

This decision analytical model suggests that short-term (7-day) prophylaxis dominates longer-term therapy after sICH. Use of the 2HELPS2B score to guide clinical decisions for initiation of short-term primary vs secondary early-seizure prophylaxis should be considered for all patients after sICH.

Anticonvulsant Primary and Secondary Prophylaxis for Acute Ischemic Stroke Patients: A Decision Analysis

Background and Purpose

We examined the impact of 3 anticonvulsant prophylaxis strategies on quality-adjusted life-years (QALYs) among patients with an incident acute ischemic stroke.

Methods

We created a decision tree to evaluate 3 strategies: (1) long-term primary prophylaxis; (2) short-term secondary prophylaxis after an early seizure with lifetime prophylaxis if persistent or late seizures (LSs) developed; and (3) long-term secondary prophylaxis if either early, late, or persistent seizures developed. The outcome was quality-adjusted life expectancy (QALY). We created 4 base cases to simulate common clinical scenarios: (1) female patient aged 40 years with a 2% or 11% lifetime risk of an LS and a 33% lifetime risk of an adverse drug reaction (ADR); (2) male patient aged 65 years with a 6% or 29% LS risk and 60% ADR risk; (3) male patient aged 50 years with an 18% or 65% LS risk and 33% ADR risk; and (4) female patient aged 80 years with a 29% or 83% LS risk and 80% ADR risk. In sensitivity analyses, we altered the parameters and assumptions.

Results

Across all 4 base cases, primary prophylaxis yielded the fewest QALYs when compared with secondary prophylaxis. For example, under scenario 1, strategies 2 and 3 resulted in 7.17 QALYs each, but strategy 1 yielded only 6.91 QALYs. Under scenario 4, strategies 2 and 3 yielded 2.85 QALYs compared with 1.40 QALYs for strategy 1. Under scenarios in which patients had higher ADR risks, strategy 2 led to the most QALYs.

Conclusions

Short-term therapy with continued anticonvulsant prophylaxis only after postischemic stroke seizures arise dominates lifetime primary prophylaxis in all scenarios examined. Our findings reinforce the necessity of close follow-up and discontinuation of anticonvulsant seizure prophylaxis started during acute ischemic stroke hospitalization.

Does etiology really matter for epilepsy surgery outcome?

Multiple factors influence the outcomes of epilepsy surgery. Prognostic indicators varying from clinical characteristics, imaging findings, ictal, and interictal electrophysiological activity have been linked to surgical outcomes. In this review, we focus on the relatively under‐studied role of the underlying epilepsy histopathology in driving post‐surgical outcomes, specifically focusing on the broad categories of seizure outcomes and cognitive outcomes. For each of these two outcomes of interest, we answer two questions: 1)‐ does etiology matter? and 2)‐ how could it matter? The goal is to review the existing literature on the relationship between etiology and surgical outcomes to provide the best possible judgment as to whether a causal relationship exists between histopathology and the ultimate surgical outcome as an initial step. Then, we delve into the possible mechanisms via which such relationships can be explained. We conclude with a call to action to the epilepsy surgery and histopathology research community to push the mechanistic understanding of the pathology‐outcome interaction and identify actionable knowledge and biomarkers that could inform patient care in a timely fashion.

In this review, we focus on the relatively under‐studied role of the underlying epilepsy histopathology in driving post‐surgical outcomes, specifically focusing on the broad categories of seizure outcomes and cognitive outcomes. For each of these two outcomes of interest, we answer two questions: (1) does etiology matter? and (2) how could it matter? We then delve into the mechanisms of these answers.

Early identification of epilepsy surgery candidates: A multicenter, machine learning study

OBJECTIVES

Epilepsy surgery is underutilized. Automating the identification of potential surgical candidates may facilitate earlier intervention. Our objective was to develop site-specific machine learning (ML) algorithms to identify candidates before they undergo surgery.

MATERIALS & METHODS

In this multicenter, retrospective, longitudinal cohort study, ML algorithms were trained on n-grams extracted from free-text neurology notes, EEG and MRI reports, visit codes, medications, procedures, laboratories, and demographic information. Site-specific algorithms were developed at two epilepsy centers: one pediatric and one adult. Cases were defined as patients who underwent resective epilepsy surgery, and controls were patients with epilepsy with no history of surgery. The output of the ML algorithms was the estimated likelihood of candidacy for resective epilepsy surgery. Model performance was assessed using 10-fold cross-validation.

RESULTS

There were 5880 children (n = 137 had surgery [2.3%]) and 7604 adults with epilepsy (n = 56 had surgery [0.7%]) included in the study. Pediatric surgical patients could be identified 2.0 years (range: 0-8.6 years) before beginning their presurgical evaluation with AUC =0.76 (95% CI: 0.70-0.82) and PR-AUC =0.13 (95% CI: 0.07-0.18). Adult surgical patients could be identified 1.0 year (range: 0-5.4 years) before beginning their presurgical evaluation with AUC =0.85 (95% CI: 0.78-0.93) and PR-AUC =0.31 (95% CI: 0.14-0.48). By the time patients began their presurgical evaluation, the ML algorithms identified pediatric and adult surgical patients with AUC =0.93 and 0.95, respectively. The mean squared error of the predicted probability of surgical candidacy (Brier scores) was 0.018 in pediatrics and 0.006 in adults.

CONCLUSIONS

Site-specific machine learning algorithms can identify candidates for epilepsy surgery early in the disease course in diverse practice settings.

Budget Impact Analysis of Treatment Flow Optimization in Epilepsy Patients: Estimating Potential Impacts with Increased Referral Rate to Specialized Care

Objectives: We developed a Markov model to simulate a treatment flow of epilepsy patients who refer to specialized care from non-specialized care, and to surgery from specialized care for estimation of patient distributions and expenditures caused by increasing the referral rate for specialized care. Methods: This budget impact analysis of treatment flow optimization in epilepsy patients was performed as a long-term simulation using the Markov model by comparing the current treatment flow and the optimized treatment flow. In the model, we simulated the prognosis of new onset 5-year-old epilepsy patients (assuming to represent epilepsy occurring between 0 and 10 years of age) treated over a lifetime period. Direct costs of pharmacotherapies, management fees and surgeries are included in the analysis to evaluate the annual budget impact in Japan. Results: In the current treatment flow, the number of refractory patients treated with four drugs by non-specialized care were estimated as 8766 and yielded JPY5.8 billion annually. However, in the optimized treatment flow, the number of patients treated with four drugs by non-specialized care significantly decreased and who continued the monotherapy increased. The costs for the four-drug therapy by non-specialized care were eliminated. Hence cost-saving of JPY9.5 billion (-5% of the current treatment flow) in total national expenditures would be expected. Conclusion: This study highlights that any policy decision-making for referral optimization to specialized care in appropriate epilepsy patients would be feasible with a cost-savings or very few budget impacts. However, important information in the decision-making such as transition probability to the next therapy or excuse for sensitive limitations is not available currently. Therefore, further research with reliable data such as big data analysis or a national survey with real-world treatment patterns is needed.

Cost-effectiveness analysis of invasive EEG monitoring in drug-resistant epilepsy

PURPOSE

Our aim was to determine the cost-effectiveness of two intracranial electroencephalography (iEEG) interventions: 1) stereoelectroencephalography (SEEG) and 2) placement of subdural grid electrodes (SDGs) both followed by resective surgery in patients with drug-resistant, partial-onset epilepsy, compared with medical management (MM) in Hungary from payer's perspective.

METHODS

The incremental health gains and costs of iEEG interventions have been determined with a combination of a decision tree and prevalence Markov process model over a 30-year time horizon in a cost-utility analysis (CUA). To address the effect of parameter uncertainty on the incremental cost-effectiveness ratio (ICER), deterministic and probabilistic sensitivity analyses were performed.

RESULTS

Our results showed that both SEEG and SDG interventions represent a more expensive but more effective strategy than MM representing the current standard of care. The total discounted cost of SEEG and SDG were € 32,760 and € 25,028 representing € 18,108 and € 10,375 additional cost compared with MM, respectively. However, they provide an additional 3.931 (in SEEG group) and 3.444 quality-adjusted life years (QALYs; in SDG group), correspondingly. Thus, the ICER of SEEG is € 4607 per QALY gain, while the ICER for SDG is € 3013 per QALY gain, compared with MM. At a cost-effectiveness threshold of € 41,058 per QALY in Hungary, both subtypes of iEEG interventions are cost-effective and provide good value for money.

SIGNIFICANCE

Because of the high cost of implanting electrodes and monitoring, the invasive EEG for patients with refractory epilepsy is currently not available in the Hungarian national healthcare system. Our study demonstrated that these procedures in Hungary are cost-effective compared with the MM. As a result, the introduction of iEEG interventions to the reimbursement list of the National Health Insurance Fund Administration was initiated.

Effect of Long-Term Treatment with Vagus Nerve Stimulation on Mood and Quality of Life in Korean Patients with Drug-Resistant Epilepsy

BACKGROUND AND PURPOSE

This study aimed to determine the long-term effects of vagus nerve stimulation (VNS) treatment on suicidality, mood-related symptoms, and quality of life (QOL) in patients with drug-resistant epilepsy (DRE). We also investigated the relationships among these main effects, clinical characteristics, and VNS parameters.

METHODS

Among 35 epilepsy patients who underwent VNS implantation consecutively in our epilepsy center, 25 patients were recruited to this study for assessing the effects of VNS on suicidality, mood-related symptoms, and QOL. The differences in these variables between before and after VNS treatment were analyzed statistically using paired t-tests. Multiple linear regression analyses were also performed to determine how the patients' demographic and clinical characteristics influenced the variables that showed statistically significant changes after long-term VNS treatment.

RESULTS

After VNS, our patients showed significant improvements not only in the mean seizure frequency but also in suicidality, depression, and QOL. The reduction in depression was associated with the improvement in QOL and more-severe depression at baseline. The reduction in suicidality was associated with higher suicidality at baseline, smaller changes in depression, and less-severe depression at baseline. Improved QOL was associated with lower suicidality at baseline.

CONCLUSIONS

This study found that VNS decreased the mean seizure frequency in patients with DRE, and also improved their depression, suicidality, and QOL. These results provide further evidence for therapeutic effect of VNS on psychological comorbidities of patients with DRE.

A Theoretical Paradigm for Evaluating Risk-Benefit of Status Epilepticus Treatment

Aggressive treatment of status epilepticus with anesthetic drugs can provide rapid seizure control, but it might lead to serious medical complications and worse outcomes. Using a decision analysis approach, this concise review provides a framework for individualized decision making about aggressive and nonaggressive treatment in status epilepticus. The authors propose and review the most relevant parameters guiding the risk-benefit analysis of treatment aggressiveness in status epilepticus and present real-world-based case examples to illustrate how these tools could be used at the bedside and serve to guide future research in refractory status epilepticus treatment.

Resection of piriform cortex predicts seizure freedom in temporal lobe epilepsy

Objective

Transsylvian selective amygdalo‐hippocampectomy (tsSAHE) represents a generally recognized surgical procedure for drug‐resistant mesial temporal lobe epilepsy (mTLE). Although postoperative seizure freedom can be achieved in about 70% of tsSAHE, there is a considerable amount of patients with persisting postoperative seizures. This might partly be explained by differing extents of resection of various tsSAHE target volumes. In this study we analyzed the resected proportions of hippocampus, amygdala as well as piriform cortex in regard of postoperative seizure outcome.

Methods

Between 2012 and 2017, 82 of 103 patients with mTLE who underwent tsSAHE at the authors’ institution were included in the analysis. Resected proportions of hippocampus, amygdala and temporal piriform cortex as target structures of tsSAHE were volumetrically assessed and stratified according to favorable (International League Against Epilepsy (ILAE) class 1) and unfavorable (ILAE class 2–6) seizure outcome.

Results

Patients with favorable seizure outcome revealed a significantly larger proportion of resected temporal piriform cortex volumes compared to patients with unfavorable seizure outcome (median resected proportional volumes were 51% (IQR 42–61) versus (vs.) 13 (IQR 11–18), P = 0.0001). Resected proportions of hippocampus and amygdala did not significantly differ for these groups (hippocampus: 81% (IQR 73–88) vs. 80% (IQR 74–92) (P = 0.7); amygdala: 100% (IQR 100–100) vs. 100% (IQR 100–100) (P = 0.7)).

Interpretation

These results strongly suggest temporal piriform cortex to constitute a key target resection volume to achieve seizure freedom following tsSAHE.

Lost in Transition: The Long and Winding Road Toward Epilepsy Surgery—An Analysis of Obstacles Prior to Surgery and Call for Orchestrated Health Care Efforts in Epilepsy

Difficult-to-treat epilepsy is defined as ongoing seizures despite adequate pharmacological treatment. This condition is affecting a significant percentage of epilepsy patients and is estimated to be as high as one-third of all patients. Epilepsy surgery, targeting the removal of the key parts of cerebral convolutions responsible for seizure generation and often including a structural lesion, can be a very successful approach. However, this necessitates careful patient selection by comprehensive investigations, proving the localization of the epileptogenic zone as well as measures to make such surgeries safe. With careful selection as a prerequisite, the percentage of patients achieving seizure freedom by neurosurgical intervention is high, approximating two-thirds of all epilepsy surgeries performed. In contrast, the average duration of a patient's pharmacoresistant focal epilepsy prior to surgery anywhere around the globe is around 20 years. Given that typical patients are ∼30 to 40 years of age at the time of surgery, many patients have been living with chronic seizures since childhood or adolescence. This means that most of these patients have been going through several stages of medical care for years or even decades, both as children and adults, without ever being fully investigated and/or selected for surgery which is concerning. Yet, there is no set standard for a timeline leading toward successful surgery in epilepsy. It is obvious that the average transit period from the moment of first seizure manifestation until the day of successful surgery takes much too long. This is the reason why we see these patients lost in transition.

Long-term outcomes after epilepsy surgery, a retrospective cohort study linking patient-reported outcomes and routine healthcare data

OBJECTIVE

The objective of the study was to assess the long-term outcomes of epilepsy surgery between 1995 and 2015 in South Wales, UK, linking case note review, postal questionnaire, and routinely collected healthcare data.

METHOD

We identified patients from a departmental database and collected outcome data from patient case notes, a postal questionnaire, and the QOLIE-31-P and linked with Welsh routinely collected data in the Secure Anonymised Information Linkage (SAIL) databank.

RESULTS

Fifty-seven patients were included. Median age at surgery was 34 years (11-70), median: 24 years (2-56) after onset of habitual seizures. Median follow-up was 7 years (2-19). Twenty-eight (49%) patients were free from disabling seizures (Engel Class 1), 9 (16%) experienced rare disabling seizures (Class 2), 13 (23%) had worthwhile improvements (Class 3), and 7 (12%) had no improvement (Class 4). There was a 30% mean reduction in total antiepileptic drug (AED) load at five years postsurgery. Thirty-eight (66.7%) patients experienced tonic-clonic seizures presurgery verses 8 (14%) at last review. Seizure-free patients self-reported a greater overall quality of life (QOL; QOLIE-31-P) when compared with those not achieving seizure freedom. Seizure-free individuals scored a mean of 67.6/100 (100 is best), whereas those with continuing seizures scored 46.0/100 (p < 0.006). There was a significant decrease in the median rate of hospital admissions for any cause after epilepsy surgery (9.8 days per 1000 patient days before surgery compared with 3.9 after p < 0.005).

SIGNIFICANCE

Epilepsy surgery was associated with significant improvements in seizures, a reduced AED load, and an improved QOL that closely correlated with seizure outcomes and reduced hospital admission rates following surgery. Despite this, there was a long delay from onset of habitual seizures to surgery. The importance of long-term follow-up is emphasized in terms of evolving medical needs and health and social care outcomes.

Prediction of seizure freedom after epilepsy surgery - Critical reappraisal of significance of intracranial EEG parameters

OBJECTIVE

To analyze the significance of intracranial electroencephalography (iEEG) parameters such as seizure onset patterns (SOP) and size of seizure onset zone (SOZ) with respect to prediction of seizure freedom after resective epilepsy surgery.

METHODS

All patients who underwent iEEG with subdural electrodes between January 2006 and December 2015 in our epilepsy-center were included. Various iEEG parameters were retrospectively analyzed regarding their predictive value to post-operative seizure freedom. Furthermore, associations of specific SOPs with underlying histopathology and brain regions of the SOZ were examined.

RESULTS

Eighty-one patients (34 female) with 324 seizures were assessed. Low-voltage fast activity (37%) and sharp activity <13 Hz (30%) were the most frequent SOPs. Focal SOZ (≤2 cm) was the only iEEG parameter independently associated with 1-year post-operative seizure freedom (OR 4.1, 95% CI 1.433-11.679). While no SOP was linked to specific histopathologies, some associations between SOPs and anatomical regions of SOZ were found.

CONCLUSIONS

A circumscribed SOZ, but no specific SOP was predictive for seizure freedom after epilepsy surgery.

SIGNIFICANCE

Intracranial EEG may be helpful to predict post-operative seizure freedom. Multicenter studies with larger numbers of patients are required to reliably assess the significance of specific SOPs for successful resective epilepsy surgery.

Brainstem Functional Connectivity Disturbances in Epilepsy may Recover After Successful Surgery

BACKGROUND

Focal seizures in temporal lobe epilepsy (TLE) are associated with widespread brain network perturbations and neurocognitive problems.

OBJECTIVE

To determine whether brainstem connectivity disturbances improve with successful epilepsy surgery, as recent work has demonstrated decreased brainstem connectivity in TLE that is related to disease severity and neurocognitive profile.

METHODS

We evaluated 15 adult TLE patients before and after (>1 yr; mean, 3.4 yr) surgery, and 15 matched control subjects using magnetic resonance imaging to measure functional and structural connectivity of ascending reticular activating system (ARAS) structures, including cuneiform/subcuneiform nuclei (CSC), pedunculopontine nucleus (PPN), and ventral tegmental area (VTA).

RESULTS

TLE patients who achieved long-term postoperative seizure freedom (10 of 15) demonstrated increases in functional connectivity between ARAS structures and fronto-parietal-insular neocortex compared to preoperative baseline (P = .01, Kruskal-Wallis), with postoperative connectivity patterns resembling controls' connectivity. No functional connectivity changes were detected in 5 patients with persistent seizures after surgery (P = .9, Kruskal-Wallis). Among seizure-free postoperative patients, larger increases in CSC, PPN, and VTA functional connectivity were observed in individuals with more frequent seizures before surgery (P < .05 for each, Spearman's rho). Larger postoperative increases in PPN functional connectivity were seen in patients with lower baseline verbal IQ (P = .03, Spearman's rho) or verbal memory (P = .04, Mann-Whitney U). No changes in ARAS structural connectivity were detected after successful surgery.

CONCLUSION

ARAS functional connectivity disturbances are present in TLE but may recover after successful epilepsy surgery. Larger increases in postoperative connectivity may be seen in individuals with more severe disease at baseline.

The Effectiveness of Medical and Surgical Treatment for Children With Refractory Epilepsy

BACKGROUND

Pediatric refractory epilepsy affects quality of life, clinical disability, and healthcare costs for patients and families.

OBJECTIVE

To show the impact of surgical treatment for pediatric epilepsy on healthcare utilization compared to medically treated pediatric epilepsy over 5 yr.

METHODS

The Pediatric Health Information System database was used to conduct a cohort study using 5 published algorithms. Refractory epilepsy patients treated with antiepileptic medications (AEDs) only or AEDs plus epilepsy surgery between 1/1/2008 and 12/31/2014 were included. Healthcare utilization following the index date at 2 and 5 yr including inpatient, emergency department (ED), and all epilepsy-related visits were evaluated. The propensity scores (PS) method was used to match surgically and medically treated patients. PS. SAS® 9.4 and Stata 14.0 were used for data management and statistical analysis.

RESULTS

A total of 2106 (17.1%) and 10186 (82.9%) were surgically and medically treated. A total of 4050 matched cases, 2025 per each treated group, were included. Compared to medically treated patients, utilization was reduced in the surgical group: at 2 and 5 yr postindex date, there was a reduction of 36% to 37% of inpatient visits and 47% to 50% of ED visits. The total number (inpatient, ED, ambulatory visits) of epilepsy-associated visits were reduced by 39% to 43% in the surgical group compared to the medically treated group. In those who had surgery, the average reduction in AEDs was 16% at 2 and 5 yr after treatment.

CONCLUSION

Patients with refractory epilepsy treated with surgery had significant reductions in healthcare utilization compared with patients treated only with medications.

Cost-effectiveness of surgery for drug-resistant temporal lobe epilepsy in the US

OBJECTIVE

Surgery is an effective but costly treatment for many patients with drug-resistant temporal lobe epilepsy (DR-TLE). We aim to evaluate whether, in the United States, surgery is cost-effective compared to medical management for patients deemed surgical candidates and whether surgical evaluation is cost-effective for patients with DR-TLE in general.

METHODS

We use a semi-Markov model to assess the cost-effectiveness of surgery and surgical evaluation over a lifetime horizon. We use second-order Monte Carlo simulations to conduct probabilistic sensitivity analyses to estimate variation in model output. We adopt both health care and societal perspectives, including direct health care costs (e.g., surgery, antiepileptic drugs) and indirect costs (e.g., lost earnings by patients and care providers.) We compare the incremental cost-effectiveness ratio to societal willingness to pay (∼$100,000 per quality-adjusted life-year [QALY]) to determine whether surgery is cost-effective.

RESULTS

Epilepsy surgery is cost-effective compared to medical management in surgically eligible patients by virtue of being cost-saving ($328,000 vs $423,000) and more effective (16.6 vs 13.6 QALY) than medical management in the long run. Surgical evaluation is cost-effective in patients with DR-TLE even if the probability of being deemed a surgical candidate is only 5%. From a societal perspective, surgery becomes cost-effective within 3 years, and 89% of simulations favor surgery over the lifetime horizon.

CONCLUSION

For surgically eligible patients with DR-TLE, surgery is cost-effective. For patients with DR-TLE in general, referral for surgical evaluation (and possible subsequent surgery) is cost-effective. Patients with DR-TLE should be referred for surgical evaluation without hesitation on cost-effectiveness grounds.

All-cause mortality and SUDEP in a surgical epilepsy population

Epilepsy surgery is considered to reduce the risk of epilepsy-related mortality, including sudden unexpected death in epilepsy (SUDEP), though data from existing surgical series are conflicting. We retrospectively examined all-cause mortality and SUDEP in a population of 590 epilepsy surgery patients and a comparison group of 122 patients with pharmacoresistant focal epilepsy who did not undergo surgery, treated at Columbia University Medical Center between 1977 and 2014. There were 34 deaths in the surgery group, including 14 cases of SUDEP. Standardized mortality ratio (SMR) for the surgery group was 1.6, and SUDEP rate was 1.9 per 1000 patient-years. There were 13 deaths in the comparison group, including 5 cases of SUDEP. Standardized mortality ratio for the comparison group was 3.6, and SUDEP rate was 4.6 per 1000 patient-years. Both were significantly greater than in the surgery group (p < 0.05). All but one of the surgical SUDEP cases, and all of the comparison group SUDEP cases, had a history of bilateral tonic-clonic seizures (BTCS). Of postoperative SUDEP cases, one was seizure-free, and two were free of BTCS at last clinical follow-up. Time to SUDEP in the surgery group was longer than in the comparison group (10.1 vs 5.9 years, p = 0.013), with 10 of the 14 cases occurring >10 years after surgery. All-cause mortality was reduced after epilepsy surgery relative to the comparison group. There was an early benefit of surgery on the occurrence of SUDEP, which was reduced after 10 years. A larger, multicenter study is needed to further investigate the time course of postsurgical SUDEP.

Merging Magnetoencephalography into Epilepsy Presurgical Work-up Under the Framework of Multimodal Integration

Multimodal image integration is the procedure that puts together imaging data from multiple sources into the same space by a computerized registration process. This procedure is relevant to patients with difficult-to-localize epilepsy undergoing presurgical evaluation, who typically have many tests performed, including MR imaging, PET, ictal single-photon emission computed tomography, magnetoencephalography (MEG), and intracranial electroencephalogram (EEG). This article describes the methodology of such integration, focusing on integration of MEG. Also discussed is the clinical value of integration of MEG, in terms of planning of intracranial EEG implantation, interpretation of intracranial EEG data, planning of final resection, and addressing surgical failures.

Prognostic factors of postoperative seizure outcomes in older patients with temporal lobe epilepsy

OBJECTIVE

The authors of this study aimed to investigate surgical outcomes and prognostic factors in older patients with drug-resistant temporal lobe epilepsy (TLE) who had undergone resective surgery.

METHODS

Data on patients older than 45 years of age with drug-resistant TLE who had undergone resective surgery at Sanbo Brain Hospital, Capital Medical University, between January 2009 and August 2017 were retrospectively collected. Postoperative seizure outcomes were evaluated according to the International League Against Epilepsy (ILAE) classification. Patients belonging to ILAE classes 1 and 2 were classified as having a favorable outcome, whereas patients belonging to ILAE classes 3-6 were classified as having an unfavorable outcome. Univariate analysis and multivariate logistic regression analysis were used to identify the potential predictors of seizure outcomes.

RESULTS

A total of 45 patients older than 45 years of age who had undergone resective epilepsy surgery for TLE were included in the present study. Eight (17.8%) of 45 patients had preoperative comorbidity in addition to seizures. The average age at the time of surgery was 51.76 years, and the average duration of epilepsy at the time surgery was 18.01 years. After an average follow-up period of 4.53 ± 2.82 years (range 2-10 years), 73.3% (33/45) of patients were seizure free. Surgical complications were observed in 13.3% of patients. Univariate and multivariate analyses revealed that an MRI-negative finding is the only independent predictor of unfavorable seizure outcomes (OR 0.06, 95% CI 0.01-0.67, p = 0.023).

CONCLUSIONS

Resective surgery is a safe and effective treatment for older patients with drug-resistant TLE. An MRI-negative finding independently predicts unfavorable seizure outcomes.

Epileptogenic zone localization using a new automatic quantitative analysis based on normal brain glucose metabolism database

OBJECTIVES

To assess the clinical value of voxel-based automatic quantitative analysis using a normal brain glucose metabolism database in the preoperative localization of focal intractable temporal lobe epilepsy patients.

METHODS

Patients with refractory temporal lobe epilepsy who underwent 18F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) imaging were retrospectively enrolled from January to June 2017. Visual analysis was performed by two nuclear medicine radiologists, and the automatic quantitative analysis was carried out using MIMneuro software based the age- and gender-stratified normal brain glucose metabolism database. Setting postoperative outcomes as reference, the consistency between visual analysis and automatic quantitative analysis was tested by Cohen's kappa coefficient, and differences in localization of epileptic foci of the two methods were compared by Chi-square test.

RESULTS

A total of 32 patients intractable temporal lobe epilepsy were included in this study. There was a moderate agreement between the automatic quantitative analysis based on MIMneuro software and visual analysis (kappa coefficient = 0.472, p = 0.002). In terms of the efficiency of focus localization, the voxel-based automatic quantitative analysis was higher than that of visual analysis (Chi-square value = 6.969, p = 0.008).

CONCLUSIONS

The voxel-based automatic quantitative analysis combined with normal brain glucose metabolism database had a certain clinical application value for detection temporal lobe epilepsy.

Missed opportunities for epilepsy surgery referrals in Bhutan: A cohort study

OBJECTIVE

To quantify the missed opportunities for epilepsy surgery referral and operationalize the Canadian Appropriateness of Epilepsy Surgery (CASES) tool for use in a lower income country without neurologists.

METHODS

People with epilepsy were recruited from the Jigme Dorji Wangchuck National Referral Hospital from 2014-2016. Each participant was clinically evaluated, underwent at least one standard EEG, and was invited to undergo a free 1.5 T brain MRI. Clinical variables required for CASES were operationalized for use in lower-income populations and entered into the free, anonymous website tool.

FINDINGS

There were 209 eligible participants (mean age 28.4 years, 56 % female, 179 with brain MRI data). Of the 179 participants with brain MRI, 43 (24.0 %) were appropriate for an epilepsy surgery referral, 21 (11.7 %) were uncertain, and 115 (64.3 %) were inappropriate for referral. Among the 43 appropriate referral cases, 36 (83.7 %) were "very high" and 7 (16.3 %) were "high" priorities for referral. For every unit increase in surgical appropriateness, quality of life (QoL) dropped by 2.3 points (p-value <0.001). Among the 68 patients who took >1 antiepileptic drug prior to enrollment, 42 (61.8 %) were appropriate referrals, 14 (20.6 %) were uncertain, and 12 (17.6 %) were inappropriate.

CONCLUSION

Approximately a quarter of Bhutanese epilepsy patients who completed evaluation in this national referral-based hospital should have been evaluated for epilepsy surgery, sometimes urgently. Surgical services for epilepsy are an emerging priority for improving global epilepsy care and should be scaled up through international partnerships and clinician support algorithms like CASES to avoid missed opportunities.

Early economic evaluation of MRI-guided laser interstitial thermal therapy (MRgLITT) and epilepsy surgery for mesial temporal lobe epilepsy

Background

MRI-guided laser interstitial thermal therapy (MRgLITT) is a new minimally invasive treatment for temporal lobe epilepsy (TLE), with limited effectiveness data. It is unknown if the cost savings associated with shorter hospitalization could offset the high equipment cost of MRgLITT. We examined the cost-utility of MRgLITT versus surgery for TLE from healthcare payer perspective, and the value of additional research to inform policy decision on MRgLITT.

Methods

We developed a microsimulation model to evaluate quality adjusted life years (QALYs), costs, and incremental cost-effectiveness ratio (ICER) of MRgLITT versus surgery in TLE, assuming life-time horizon and 1.5% discount rate. Model inputs were derived from the literature. We conducted threshold and sensitivity analyses to examine parameter uncertainties, and expected value of partial perfect information analyses to evaluate the expected monetary benefit of eliminating uncertainty on probabilities associated with MRgLITT.

Results

MRgLITT yielded 0.08 more QALYs and cost $7,821 higher than surgery, with ICER of $94,350/QALY. Influential parameters that could change model outcomes include probabilities of becoming seizure-free from disabling seizures state and returning to disabling seizures from seizure-free state 5 years after surgery and MRgLITT, cost of MRgLITT disposable equipment, and utilities of disabling seizures and seizure-free states of surgery and MRgLITT. The cost-effectiveness acceptability curve showed surgery was preferred in more than 50% of iterations. The expected monetary benefit of eliminating uncertainty for probabilities associated with MRgLITT was higher than for utilities associated with MRgLITT.

Conclusions

MRgLITT resulted in more QALYs gained and higher costs compared to surgery in the base-case. The model was sensitive to variations in the cost of MRgLITT disposable equipment. There is value in conducting more research to reduce uncertainty on the probabilities and utilities of MRgLITT, but priority should be given to research focusing on improving the precision of estimates on effectiveness of MRgLITT.

Magnetoencephalography imaging of high frequency oscillations strengthens presurgical localization and outcome prediction

In patients with medically refractory epilepsy, resective surgery is the mainstay of therapy to achieve seizure freedom. However, ∼20-50% of cases have intractable seizures post-surgery due to the imprecise determination of epileptogenic zone. Recent intracranial studies suggest that high frequency oscillations between 80 and 200 Hz could serve as one of the consistent epileptogenicity biomarkers for localization of the epileptogenic zone. However, these high frequency oscillations are not adopted in the clinical setting because of difficult non-invasive detection. Here, we investigated non-invasive detection and localization of high frequency oscillations and its clinical utility in accurate pre-surgical assessment and post-surgical outcome prediction. We prospectively recruited 52 patients with medically refractory epilepsy who underwent standard pre-surgical workup including magnetoencephalography (MEG) followed by resective surgery after determination of the epileptogenic zone. The post-surgical outcome was assessed after 22.14 ± 10.05 months. Interictal epileptic spikes were expertly identified, and interictal epileptic oscillations across the neural activity frequency spectrum from 8 to 200 Hz were localized using adaptive spatial filtering methods. Localization results were compared with epileptogenic zone and resected cortex for congruence assessment and validated against the clinical outcome. The concordance rate of high frequency oscillations sources (80-200 Hz) with the presumed epileptogenic zone and the resected cortex were 75.0% and 78.8%, respectively, which is superior to that of other frequency bands and standard dipole fitting methods. High frequency oscillation sources corresponding with the resected cortex, had the best sensitivity of 78.0%, positive predictive value of 100% and an accuracy of 78.84% to predict the patient's surgical outcome, among all other frequency bands. If high frequency oscillation sources were spatially congruent with resected cortex, patients had an odds ratio of 5.67 and 82.4% probability of achieving a favourable surgical outcome. If high frequency oscillations sources were discordant with the epileptogenic zone or resection area, patient has an odds ratio of 0.18 and only 14.3% probability of achieving good outcome, and mostly tended to have an unfavourable outcome (χ2 = 5.22; P = 0.02; φ = -0.317). In receiver operating characteristic curve analyses, only sources of high-frequency oscillations demonstrated the best sensitivity and specificity profile in determining the patient's surgical outcome with area under the curve of 0.76, whereas other frequency bands indicate a poor predictive performance. Our study is the first non-invasive study to detect high frequency oscillations, address the efficacy of high frequency oscillations over the different neural oscillatory frequencies, localize them and clinically validate them with the post-surgical outcome in patients with medically refractory epilepsy. The evidence presented in the current study supports the fact that HFOs might significantly improve the presurgical assessment, and post-surgical outcome prediction, where it could widely be used in a clinical setting as a non-invasive biomarker.

Strategic hospital partnerships: improved access to care and increased epilepsy surgical volume

OBJECTIVE Surgical treatment of patients with medically refractory focal epilepsy is underutilized. Patients may lack access to surgically proficient centers. The University of California, Irvine (UCI) entered strategic partnerships with 2 epilepsy centers with limited surgical capabilities. A formal memorandum of understanding (MOU) was created to provide epilepsy surgery to patients from these centers. METHODS The authors analyzed UCI surgical and financial data associated with patients undergoing epilepsy surgery between September 2012 and June 2016, before and after institution of the MOU. Variables collected included the length of stay, patient age, seizure semiology, use of invasive monitoring, and site of surgery as well as the monthly number of single-surgery cases, complex cases (i.e., staged surgeries), and overall number of surgery cases. RESULTS Over the 46 months of the study, a total of 104 patients underwent a total of 200 operations; 71 operations were performed in 39 patients during the pre-MOU period (28 months) and 129 operations were performed in 200 patients during the post-MOU period (18 months). There was a significant difference in the use of invasive monitoring, the site of surgery, the final therapy, and the type of insurance. The number of single-surgery cases, complex-surgery cases, and the overall number of cases increased significantly. CONCLUSIONS Partnerships with outside epilepsy centers are a means to increase access to surgical care. These partnerships are likely reproducible, can be mutually beneficial to all centers involved, and ultimately improve patient access to care.