Epilepsy surgery: eligibility criteria and presurgical evaluation

Effectiveness of Seizure Dogs for People With Severe Refractory Epilepsy: Results From the EPISODE Study

BACKGROUND AND OBJECTIVES

The aim of this study was to evaluate whether people living with severe medically refractory epilepsy (PSRE) benefit from a seizure dog.

METHODS

An individual-level stepped-wedge randomized controlled trial was conducted. The study was conducted in the Netherlands among adults with daily to weekly seizures. All participants were included simultaneously (on June 1, 2019) while receiving usual care. Then, during the 36-month follow-up, they received a seizure dog in a randomized sequence. Participants kept a seizure diary and completed 3-monthly surveys. Seizure frequency was the primary outcome. Secondary outcomes included seizure-free days, seizure severity, health-related quality of life (HRQoL), and well-being. Data were analyzed using generalized linear mixed modeling (GLMM). The models assumed a delayed intervention effect, starting when the seizure dog reached an advanced stage of training. Effects were calculated as changes per 28-day period with the intervention.

RESULTS

Data were collected from 25 participants, of whom 20 crossed over to the intervention condition. The median follow-up was 19 months with usual care and 12 months with the intervention. On average, participants experienced 115 (SD 164) seizures per 28-day period in the usual care condition and 73 (SD 131) seizures in the intervention condition. Seven participants achieved a reduction of 50% or more at the end of follow-up. GLMM indicated a 3.1% decrease in seizure frequency for each consecutive 28-day period with the intervention (0.969, 95% CI 0.960-0.977). Furthermore, an increase in the number of seizure-free days was observed (1.012, 95% CI 1.009, 1.015), but no effect on seizure severity measured with the NHS3. Generic HRQoL scores improved, as reflected in the decrease in EQ-5D-5L utility decrement (0.975, 95% CI 0.954-0.997). Smaller improvements were observed on overall self-rated HRQoL, epilepsy-specific HRQoL, and well-being, measured with the EQ VAS, QOLIE-31-P, and ICECAP-A, respectively.

DISCUSSION

Seizure dogs reduce seizure frequency, increase the number of seizure-free days, and improve the quality of life of PSRE. The magnitude of the effect on generic HRQoL indicates that seizure dogs benefit PSRE beyond the impact on seizure frequency alone. Early discontinuation of seizure dog partnerships suggests that this intervention is not suitable for all PSRE and requires further study.

TRIAL REGISTRATION INFORMATION

This study was registered in the Dutch Trial Register (NL6682) on November 28, 2017. Participants were enrolled on June 1, 2019.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that seizure dogs are associated with a decrease in seizure frequency in adult patients with medically refractory epilepsy.

AMPK role in epilepsy: a promising therapeutic target?

Epilepsy is a complex and multifaceted neurological disorder characterized by spontaneous and recurring seizures. It poses significant therapeutic challenges due to its diverse etiology and often-refractory nature. This comprehensive review highlights the pivotal role of AMP-activated protein kinase (AMPK), a key metabolic regulator involved in cellular energy homeostasis, which may be a promising therapeutic target for epilepsy. Current therapeutic strategies such as antiseizure medication (ASMs) can alleviate seizures (up to 70%). However, 30% of epileptic patients may develop refractory epilepsy. Due to the complicated nature of refractory epilepsy, other treatment options such as ketogenic dieting, adjunctive therapy, and in limited cases, surgical interventions are employed. These therapy options are only suitable for a select group of patients and have limitations of their own. Current treatment options for epilepsy need to be improved. Emerging evidence underscores a potential association between impaired AMPK functionality in the brain and the onset of epilepsy, prompting an in-depth examination of AMPK's influence on neural excitability and ion channel regulation, both critical factors implicated in epileptic seizures. AMPK activation through agents such as metformin has shown promising antiepileptic effects in various preclinical and clinical settings. These effects are primarily mediated through the inhibition of the mTOR signaling pathway, activation of the AMPK-PI3K-c-Jun pathway, and stimulation of the PGC-1α pathway. Despite the potential of AMPK-targeted therapies, several aspects warrant further exploration, including the detailed mechanisms of AMPK's role in different brain regions, the impact of AMPK under various conditional circumstances such as neural injury and zinc toxicity, the long-term safety and efficacy of chronic metformin use in epilepsy treatment, and the potential benefits of combination therapy involving AMPK activators. Moreover, the efficacy of AMPK activators in refractory epilepsy remains an open question. This review sets the stage for further research with the aim of enhancing our understanding of the role of AMPK in epilepsy, potentially leading to the development of more effective, AMPK-targeted therapeutic strategies for this challenging and debilitating disorder.

Ultrasonic therapies for seizures and drug-resistant epilepsy

Ultrasonic therapy is an increasingly promising approach for the treatment of seizures and drug-resistant epilepsy (DRE). Therapeutic focused ultrasound (FUS) uses thermal or nonthermal energy to either ablate neural tissue or modulate neural activity through high- or low-intensity FUS (HIFU, LIFU), respectively. Both HIFU and LIFU approaches have been investigated for reducing seizure activity in DRE, and additional FUS applications include disrupting the blood-brain barrier in the presence of microbubbles for targeted-drug delivery to the seizure foci. Here, we review the preclinical and clinical studies that have used FUS to treat seizures. Additionally, we review effective FUS parameters and consider limitations and future directions of FUS with respect to the treatment of DRE. While detailed studies to optimize FUS applications are ongoing, FUS has established itself as a potential noninvasive alternative for the treatment of DRE and other neurological disorders.

Deep-learning predicted PET can be subtracted from the true clinical fluorodeoxyglucose PET co-registered to MRI to identify the epileptogenic zone in focal epilepsy

OBJECTIVE

Normal interictal [18 F]FDG-PET can be predicted from the corresponding T1w MRI with Generative Adversarial Networks (GANs). A technique we call SIPCOM (Subtraction Interictal PET Co-registered to MRI) can then be used to compare epilepsy patients' predicted and clinical PET. We assessed the ability of SIPCOM to identify the Resection Zone (RZ) in patients with drug-resistant epilepsy (DRE) with reference to visual and statistical parametric mapping (SPM) analysis.

METHODS

Patients with complete presurgical work-up and subsequent SEEG and cortectomy were included. RZ localisation, the reference region, was assigned to one of eighteen anatomical brain regions. SIPCOM was implemented using healthy controls to train a GAN. To compare, the clinical PET coregistered to MRI was visually assessed by two trained readers, and a standard SPM analysis was performed.

RESULTS

Twenty patients aged 17-50 (32 ± 7.8) years were included, 14 (70%) with temporal lobe epilepsy (TLE). Eight (40%) were MRI-negative. After surgery, 14 patients (70%) had a good outcome (Engel I-II). RZ localisation rate was 60% with SIPCOM vs 35% using SPM (P = 0.015) and vs 85% using visual analysis (P = 0.54). Results were similar for Engel I-II patients, the RZ localisation rate was 64% with SIPCOM vs 36% with SPM. With SIPCOM localisation was correct in 67% in MRI-positive vs 50% in MRI-negative patients, and 64% in TLE vs 43% in extra-TLE. The average number of false-positive clusters was 2.2 ± 1.3 using SIPCOM vs 2.3 ± 3.1 using SPM. All RZs localized with SPM were correctly localized with SIPCOM. In one case, PET and MRI were visually reported as negative, but both SIPCOM and SPM localized the RZ.

SIGNIFICANCE

SIPCOM performed better than the reference computer-assisted method (SPM) for RZ detection in a group of operated DRE patients. SIPCOM's impact on epilepsy management needs to be prospectively validated.

Multimodal imaging-based diagnostic approach for MRI-negative posterior cortex epilepsy

Background

Posterior cortex epilepsy (PCE) primarily comprises seizures originating from the occipital, parietal, and/or posterior edge of the temporal lobe. Electroclinical dissociation and subtle imaging representation render the diagnosis of PCE challenging. Improved methods for accurately identifying patients with PCE are necessary.

Objectives

To develop a novel voxel-based image postprocessing method for better visual identification of the neuroimaging abnormalities associated with PCE.

Design

Multicenter, retrospective study.

Methods

Clinical and imaging features of 165 patients with PCE were retrospectively reviewed and collected from five epilepsy centers. A total of 37 patients (32.4% female, 20.2 ± 8.9 years old) with magnetic resonance imaging (MRI)-negative PCE were finally included for analysis. Image postprocessing features were calculated over a neighborhood for each voxel in the multimodality data. The postprocessed maps comprised structural deformation, hyperintense signal, and hypometabolism. Five raters from three different centers were blinded to the clinical diagnosis and determined the neuroimaging abnormalities in the postprocessed maps.

Results

The average accuracy of correct identification was 55.7% (range from 43.2 to 62.2%) and correct lateralization was 74.1% (range from 64.9 to 81.1%). The Cronbach's alpha was 0.766 for the correct identification and 0.683 for the correct lateralization with similar results of the interclass correlation coefficient, thus indicating reliable agreement between the raters.

Conclusion

The image postprocessing method developed in this study can potentially improve the visual detection of MRI-negative PCE. The technique could lead to an increase in the number of patients with PCE who could benefit from the surgery.

PET image enhancement using artificial intelligence for better characterization of epilepsy lesions

INTRODUCTION

[18F]fluorodeoxyglucose ([18F]FDG) brain PET is used clinically to detect small areas of decreased uptake associated with epileptogenic lesions, e.g., Focal Cortical Dysplasias (FCD) but its performance is limited due to spatial resolution and low contrast. We aimed to develop a deep learning-based PET image enhancement method using simulated PET to improve lesion visualization.

METHODS

We created 210 numerical brain phantoms (MRI segmented into 9 regions) and assigned 10 different plausible activity values (e.g., GM/WM ratios) resulting in 2100 ground truth high quality (GT-HQ) PET phantoms. With a validated Monte-Carlo PET simulator, we then created 2100 simulated standard quality (S-SQ) [18F]FDG scans. We trained a ResNet on 80% of this dataset (10% used for validation) to learn the mapping between S-SQ and GT-HQ PET, outputting a predicted HQ (P-HQ) PET. For the remaining 10%, we assessed Peak Signal-to-Noise Ratio (PSNR), Structural Similarity Index Measure (SSIM), and Root Mean Squared Error (RMSE) against GT-HQ PET. For GM and WM, we computed recovery coefficients (RC) and coefficient of variation (COV). We also created lesioned GT-HQ phantoms, S-SQ PET and P-HQ PET with simulated small hypometabolic lesions characteristic of FCDs. We evaluated lesion detectability on S-SQ and P-HQ PET both visually and measuring the Relative Lesion Activity (RLA, measured activity in the reduced-activity ROI over the standard-activity ROI). Lastly, we applied our previously trained ResNet on 10 clinical epilepsy PETs to predict the corresponding HQ-PET and assessed image quality and confidence metrics.

RESULTS

Compared to S-SQ PET, P-HQ PET improved PNSR, SSIM and RMSE; significatively improved GM RCs (from 0.29 ± 0.03 to 0.79 ± 0.04) and WM RCs (from 0.49 ± 0.03 to 1 ± 0.05); mean COVs were not statistically different. Visual lesion detection improved from 38 to 75%, with average RLA decreasing from 0.83 ± 0.08 to 0.67 ± 0.14. Visual quality of P-HQ clinical PET improved as well as reader confidence.

CONCLUSION

P-HQ PET showed improved image quality compared to S-SQ PET across several objective quantitative metrics and increased detectability of simulated lesions. In addition, the model generalized to clinical data. Further evaluation is required to study generalization of our method and to assess clinical performance in larger cohorts.

Implementation of a Morphological Filter for Removing Spikes from the Epileptic Brain Signals to Improve Identification Ripples

Epilepsy is a very common disease affecting at least 1% of the population, comprising a number of over 50 million people. As many patients suffer from the drug-resistant version, the number of potential treatment methods is very small. However, since not only the treatment of epilepsy, but also its proper diagnosis or observation of brain signals from recordings are important research areas, in this paper, we address this very problem by developing a reliable technique for removing spikes and sharp transients from the baseline of the brain signal using a morphological filter. This allows much more precise identification of the so-called epileptic zone, which can then be resected, which is one of the methods of epilepsy treatment. We used eight patients with 5 KHz data set and depended upon the Staba 2002 algorithm as a reference to detect the ripples. We found that the average sensitivity and false detection rate of our technique are significant, and they are ∼94% and ∼14%, respectively.

Evidence supporting deep brain stimulation of the medial septum in the treatment of temporal lobe epilepsy

Electrical brain stimulation has become an essential treatment option for more than one third of epilepsy patients who are resistant to pharmacological therapy and are not candidates for surgical resection. However, currently approved stimulation paradigms achieve only moderate success, on average providing approximately 75% reduction in seizure frequency and extended periods of seizure freedom in nearly 20% of patients. Outcomes from electrical stimulation may be improved through the identification of novel anatomical targets, particularly those with significant anatomical and functional connectivity to the epileptogenic zone. Multiple studies have investigated the medial septal nucleus (i.e., medial septum) as such a target for the treatment of mesial temporal lobe epilepsy. The medial septum is a small midline nucleus that provides a critical functional role in modulating the hippocampal theta rhythm, a 4-7-Hz electrophysiological oscillation mechanistically associated with memory and higher order cognition in both rodents and humans. Elevated theta oscillations are thought to represent a seizure-resistant network activity state, suggesting that electrical neuromodulation of the medial septum and restoration of theta-rhythmic physiology may not only reduce seizure frequency, but also restore cognitive comorbidities associated with mesial temporal lobe epilepsy. Here, we review the anatomical and physiological function of the septohippocampal network, evidence for seizure-resistant effects of the theta rhythm, and the results of stimulation experiments across both rodent and human studies, to argue that deep brain stimulation of the medial septum holds potential to provide an effective neuromodulation treatment for mesial temporal lobe epilepsy. We conclude by discussing the considerations necessary for further evaluating this treatment paradigm with a clinical trial.

Drug resistant epilepsy of the insular lobe: A review and update article

Background:

Epilepsy is a chronic disease that affects millions of people around the world generating great expenses and psychosocial problems burdening the public health in different ways. A considerable number of patients are refractory to the drug treatment requiring a more detailed and specialized investigation to establish the most appropriate therapeutic option. Insular epilepsy is a rare form of focal epilepsy commonly drug resistant and has much of its investigation and treatment involved with the surgical management at some point. The insula or the insular lobe is a portion of the cerebral cortex located in the depth of the lateral sulcus of the brain; its triangular in shape and connects with the other adjacent lobes. The insular lobe is a very interesting and complex portion of the brain related with different functions. Insula in Latin means Island and was initially described in the 18^th century but its relation with epilepsy was first reported in the 1940–1950s. Insular lobe epilepsy is generally difficult to identify and confirm due to its depth and interconnections. Initial non-invasive studies generally demonstrate frustrating or incoherent information about the origin of the ictal event. Technological evolution made this pathology to be progressively better recognized and understood enabling professionals to perform the correct diagnosis and choose the ideal treatment for the affected population.

Methods:

A literature review was performed using MEDLINE/PubMed, Scopus, and Web of Science databases. The terms epilepsy/epileptic seizure of the insula and surgical treatment was used in various combinations. We included studies that were published in English, French, or Portuguese; performed in humans with insular epilepsy who underwent some surgical treatment (microsurgery, laser ablation, or radiofrequency thermocoagulation).

Results:

Initial search results in 1267 articles. After removing the duplicates 710 remaining articles were analyzed for titles and abstracts applying the inclusion and exclusion criteria. 70 studies met all inclusion criteria and were selected.

Conclusion:

At present, the main interests and efforts are in the attempt to achieve and standardize the adequate management of the patient with refractory epilepsy of the insular lobe and for that purpose several forms of investigation and treatment were developed. In this paper, we will discuss the characteristics and information regarding the pathology and gather data to identify and choose the best therapeutic option for each case.

Multimodal Presurgical Evaluation of Medically Refractory Focal Epilepsy in Adults: An Update for Radiologists

Surgery is a potentially curative treatment option for patients with medically refractory focal epilepsy. Advanced neuroimaging modalities often improve surgical outcomes by contributing key information during the highly individualized surgical planning process and intraoperative localization. Hence, neuroradiologists play an integral role as part of the multidisciplinary management team. In this review, we initially present the conceptual background and practical framework of the presurgical evaluation process, including a description of the surgical treatment approaches in medically refractory focal epilepsy in adults. This background is followed by an overview of the advanced modalities commonly used during the presurgical workup at level IV epilepsy centers including diffusion imaging techniques, blood oxygen level dependent (BOLD) functional MRI (fMRI), PET, SPECT, and subtraction ictal SPECT, as well as by introductions to 7-T MRI and electrophysiologic techniques including electroencephalography (EEG) and magnetoencephalography (MEG). We also provide illustrative case examples of multimodal neuroimaging including PET/MRI, PET/MRI-DTI, subtraction ictal SPECT, and image-guided stereotactic planning with fMRI-DTI.

Estimation of seizure onset zone from ictal scalp EEG using independent component analysis in extratemporal lobe epilepsy

OBJECTIVE

The purpose of this study is to localize the seizure onset zone of patients suffering from drug-resistant epilepsy. During the last two decades, multiple studies proposed the use of Independent Component Analysis (ICA) to analyze ictal electroencephalogram (EEG) recordings. This study aims at evaluating ICA potential with quantitative measurements. In particular, we address the challenging step where the components extracted by ICA of an ictal nature must be selected.

APPROACH

We considered a cohort of 10 patients suffering from extratemporal lobe epilepsy who were rendered seizure-free after surgery. Different sets of pre-processing parameters were compared and component features were explored to help distinguish ictal components from others. Quantitative measurements were implemented to determine whether some of the components returned by ICA were located within the resection zone and thus likely to be ictal. Finally, an assistance to the component selection was proposed based on the implemented features.

MAIN RESULTS

For every seizure, at least one component returned by ICA was localized within the resection zone, with the optimal pre-processing parameters. Three features were found to distinguish components localized within the resection zone: the dispersion of their active brain sources, the ictal rhythm power and the contribution to the EEG variance. Using the implemented component selection assistance based on the features, the probability that the first proposed component yields an accurate estimation reaches 51.43% (without assistance: 24.74%). The accuracy reaches 80% when considering the best result within the first five components.

SIGNIFICANCE

This study confirms the utility of ICA for ictal EEG analysis in extratemporal lobe epilepsy, and suggests relevant features to analyze the components returned by ICA. A component selection assistance is proposed to guide clinicians in their choice for ictal components.

Efficacy and safety of VNS therapy or continued medication management for treatment of adults with drug-resistant epilepsy: systematic review and meta-analysis

Vagus nerve stimulation (VNS) Therapy® is an adjunctive neurostimulation treatment for people with drug-resistant epilepsy (DRE) who are unwilling to undergo resective surgery, have had unsuccessful surgery or are unsuitable for surgery. A systematic review and meta-analysis were conducted to determine the treatment effects of VNS Therapy as an adjunct to anti-seizure medications (ASMs) for the management of adults with DRE. A literature search was performed in August 2020 of the Medline®, Medline® Epub Ahead of Print, Embase, and the Cochrane library databases. Outcomes examined included reduction in seizure frequency, seizure freedom, ASM load, discontinuations, and serious adverse events (SAEs). Comparators included best medical practice, ASMs, low-stimulation or sham VNS Therapy. Four RCTs and six comparative observational studies were identified for inclusion. Against comparators, individuals treated with VNS had a significantly better odds of experiencing a ≥ 50% reduction in seizure frequency (OR: 2.27 [95% CI 1.47, 3.51]; p = 0.0002), a ≥ 75% reduction in seizure frequency (OR: 3.56 [95% CI 1.59, 7.98]; p = 0.002) and a reduced risk for increased ASM load (risk ratio: 0.36 [95% CI 0.21, 0.62]; p = 0.0002). There was no difference in the odds of discontinuation or the rate of SAEs between VNS versus comparators. This meta-analysis demonstrated the benefits of VNS Therapy in people with DRE, which included improvement in seizure frequency without an increase in the rate of SAEs or discontinuations, thereby supporting the consideration of VNS Therapy for people who are not responding to ASMs and those unsuitable or unwilling to undergo surgery.

Genetic testing before epilepsy surgery - An exploratory survey and case collection from German epilepsy centers

INTRODUCTION

Genetic testing in people with epilepsy may support presurgical decision-making. It is currently unclear to what extent epilepsy centres use genetic testing in presurgical evaluation.

METHODS

We performed an exploratory survey among members of the German Society for Epileptology to study the current practice of genetic testing in presurgical evaluation at the respective sites. Survey participants contributed educational case reports.

RESULTS

The majority of participants consider genetic testing to be useful in individuals with familial syndromes or phenotypic features suggesting a genetic etiology. We report 25 cases of individuals with a confirmed genetic diagnosis that have previously undergone epilepsy surgery. Our cases demonstrate that a genetic diagnosis has an impact on both the decision-making process during presurgical evaluation, as well as the postoperative outcome.

CONCLUSION

Genetic testing as part of the presurgical work-up is becoming increasingly established in epilepsy centres across Germany. mTORopathies and genetic hypothalamic hamartomas seem to be associated with a generally favourable surgical outcome. Synaptopathies and channelopathies may be associated with a worse outcome and should be considered on a case-by-case level. Prospective studies are needed to examine the impact of an established genetic diagnosis on postsurgical outcome.

Early Intervention via Stimulation of the Medial Septal Nucleus Improves Cognition and Alters Markers of Epileptogenesis in Pilocarpine-Induced Epilepsy

Over one-third of patients with temporal lobe epilepsy are refractory to medication. In addition, anti-epileptic drugs often exacerbate cognitive comorbidities. Neuromodulation is an FDA treatment for refractory epilepsy, but patients often wait >20 years for a surgical referral for resection or neuromodulation. Using a rodent model, we test the hypothesis that 2 weeks of theta stimulation of the medial septum acutely following exposure to pilocarpine will alter the course of epileptogenesis resulting in persistent behavioral improvements. Electrodes were implanted in the medial septum, dorsal and ventral hippocampus, and the pre-frontal cortex of pilocarpine-treated rats. Rats received 30 min/day of 7.7 Hz or theta burst frequency on days 4-16 post-pilocarpine, prior to the development of spontaneous seizures. Seizure threshold, spikes, and oscillatory activity, as well as spatial and object-based learning, were assessed in the weeks following stimulation. Non-stimulated pilocarpine animals exhibited significantly decreased seizure threshold, increased spikes, and cognitive impairments as compared to vehicle controls. Furthermore, decreased ventral hippocampal power (6-10 Hz) correlated with both the development of spikes and impaired cognition. Measures of spikes, seizure threshold, and cognitive performance in both acute 7.7 Hz and theta burst stimulated animals were statistically similar to vehicle controls when tested during the chronic phase of epilepsy, weeks after stimulation was terminated. These data indicate that modulation of the septohippocampal circuit early after pilocarpine treatment alters the progression of epileptic activity, resulting in elevated seizure thresholds, fewer spikes, and improved cognitive outcome. Results from this study support that septal theta stimulation has the potential to serve in combination or as an alternative to high frequency thalamic stimulation in refractory cases and that further research into early intervention is critical.

Medial septal GABAergic neurons reduce seizure duration upon optogenetic closed-loop stimulation

Seizures can emerge from multiple or large foci in temporal lobe epilepsy, complicating focally targeted strategies such as surgical resection or the modulation of the activity of specific hippocampal neuronal populations through genetic or optogenetic techniques. Here, we evaluate a strategy in which optogenetic activation of medial septal GABAergic neurons, which provide extensive projections throughout the hippocampus, is used to control seizures. We utilized the chronic intrahippocampal kainate mouse model of temporal lobe epilepsy, which results in spontaneous seizures and as is often the case in human patients, presents with hippocampal sclerosis. Medial septal GABAergic neuron populations were immunohistochemically labelled and were not reduced in epileptic conditions. Genetic labelling with mRuby of medial septal GABAergic neuron synaptic puncta and imaging across the rostral to caudal extent of the hippocampus, also indicated an unchanged number of putative synapses in epilepsy. Furthermore, optogenetic stimulation of medial septal GABAergic neurons consistently modulated oscillations across multiple hippocampal locations in control and epileptic conditions. Finally, wireless optogenetic stimulation of medial septal GABAergic neurons, upon electrographic detection of spontaneous hippocampal seizures, resulted in reduced seizure durations. We propose medial septal GABAergic neurons as a novel target for optogenetic control of seizures in temporal lobe epilepsy.

Brain MRI post-processing with MAP07 in the preoperative evaluation of patients with pharmacoresistant epilepsy - Croatian single centre experience

OBJECTIVE

This study aimed to determine the role of brain MRI post-processing method MAP07 (Morphometric Analysis Program) in detecting epileptogenic brain lesions in patients with pharmacoresistant epilepsy (PE). MAP07 is a sophisticated diagnostic program that offers several morphometric maps and facilitates the detection and localization of hippocampal sclerosis (HS), focal cortical dysplasias (FCD), and other types of cortical malformations, which could be undetected by conventional visual MRI analysis (CVA).

METHODS

120 patients aged > 16 years with PE have been recruited. 3 T MRI was performed according to epilepsy imaging protocol followed by image postprocessing with a fully automated MATLAB script, MAP07, by applying SPM5 algorithms. Statistical analysis was performed in IBM SPSS Statistics, version 25.0.

RESULTS

Analysis in our patients showed a high sensitivity of MAP07 with low specificity and with a high proportion of false-positive patients. After MRI analysis, out of 120 patients, 32 were found to have no structural abnormalities by conventional visual analysis in whom after MAP07 in 5 patients structural lesions were found (in one HS, in one FCD, in two perinatal vascular lesions, and in one hippocampal hyperintensity). There was a quite high overall coincidence of the findings of MAP07 and MRI for the detection of FCD, HS, perinatal ischemia/chronic vascular lesions, heterotopias, and polymicrogyria (kappa coefficient above 0.700).

CONCLUSIONS

MAP07 analysis is a useful, additional, and automated method that may guide re-evaluation of MRI by highlighting suspicious cortical regions, as a complementary method to CVA, by enhancing the visualization of cortical malformations and lesions.

Delta-gamma phase-amplitude coupling as a biomarker of postictal generalized EEG suppression

Postictal generalized EEG suppression is the state of suppression of electrical activity at the end of a seizure. Prolongation of this state has been associated with increased risk of sudden unexpected death in epilepsy, making characterization of underlying electrical rhythmic activity during postictal suppression an important step in improving epilepsy treatment. Phase-amplitude coupling in EEG reflects cognitive coding within brain networks and some of those codes highlight epileptic activity; therefore, we hypothesized that there are distinct phase-amplitude coupling features in the postictal suppression state that can provide an improved estimate of this state in the context of patient risk for sudden unexpected death in epilepsy. We used both intracranial and scalp EEG data from eleven patients (six male, five female; age range 21–41 years) containing 25 seizures, to identify frequency dynamics, both in the ictal and postictal EEG suppression states. Cross-frequency coupling analysis identified that during seizures there was a gradual decrease of phase frequency in the coupling between delta (0.5–4 Hz) and gamma (30+ Hz), which was followed by an increased coupling between the phase of 0.5–1.5 Hz signal and amplitude of 30–50 Hz signal in the postictal state as compared to the pre-seizure baseline. This marker was consistent across patients. Then, using these postictal-specific features, an unsupervised state classifier—a hidden Markov model—was able to reliably classify four distinct states of seizure episodes, including a postictal suppression state. Furthermore, a connectome analysis of the postictal suppression states showed increased information flow within the network during postictal suppression states as compared to the pre-seizure baseline, suggesting enhanced network communication. When the same tools were applied to the EEG of an epilepsy patient who died unexpectedly, ictal coupling dynamics disappeared and postictal phase-amplitude coupling remained constant throughout. Overall, our findings suggest that there are active postictal networks, as defined through coupling dynamics that can be used to objectively classify the postictal suppression state; furthermore, in a case study of sudden unexpected death in epilepsy, the network does not show ictal-like phase-amplitude coupling features despite the presence of convulsive seizures, and instead demonstrates activity similar to postictal. The postictal suppression state is a period of elevated network activity as compared to the baseline activity which can provide key insights into the epileptic pathology.

Correlations between interictal extratemporal spikes and clinical features, imaging characteristics, and surgical outcomes in patients with mesial temporal lobe epilepsy

PURPOSE

The significance of interictal epileptiform discharges (IEDs) observed in the extratemporal lobe has not been fully evaluated in patients with mesial temporal lobe epilepsy (MTLE). This study aimed to evaluate the surgical outcomes, clinical features, and functional neuroimaging characteristics of patients in relation to the presence or absence of extratemporal IED in MTLE with hippocampal sclerosis (HS).

METHODS

A total of 165 patients with HS-induced MTLE who had undergone anterior temporal lobectomy were enrolled and stratified into the extratemporal interictal epileptiform discharges (ETD) and the temporal lobe discharges (TD) groups. We analyzed the differentiating features of pre- and postsurgical evaluation data between the two groups. For outcome assessment, only patients with a follow-up of at least 2 years were enrolled, and the outcomes were classified based on Engel classification.

RESULTS

The ETD group showed extensive glucose hypometabolism involving the temporal lobe and extratemporal regions (p < 0.001), and IEDs were observed bilaterally or contralateral to the ictal focus (p = 0.02). However, there was no difference in the surgical outcomes between the two groups. On multivariate analysis, statistically significant variables related to ETD occurrence including seizure onset age were not identified nevertheless.

CONCLUSION

Our results indicate that ETD had a surgical outcome comparable to that of TD. Therefore, a surgical intervention need not be delayed even if extratemporal IED may be found in presurgical long-term scalp EEG monitoring.

P38 Regulates Kainic Acid-Induced Seizure and Neuronal Firing via Kv4.2 Phosphorylation

The subthreshold, transient A-type K⁺ current is a vital regulator of the excitability of neurons throughout the brain. In mammalian hippocampal pyramidal neurons, this current is carried primarily by ion channels comprising Kv4.2 α-subunits. These channels occupy the somatodendritic domains of these principle excitatory neurons and thus regulate membrane voltage relevant to the input-output efficacy of these cells. Owing to their robust control of membrane excitability and ubiquitous expression in the hippocampus, their dysfunction can alter network stability in a manner that manifests in recurrent seizures. Indeed, growing evidence implicates these channels in intractable epilepsies of the temporal lobe, which underscores the importance of determining the molecular mechanisms underlying their regulation and contribution to pathologies. Here, we describe the role of p38 kinase phosphorylation of a C-terminal motif in Kv4.2 in modulating hippocampal neuronal excitability and behavioral seizure strength. Using a combination of biochemical, single-cell electrophysiology, and in vivo seizure techniques, we show that kainic acid-induced seizure induces p38-mediated phosphorylation of Thr607 in Kv4.2 in a time-dependent manner. The pharmacological and genetic disruption of this process reduces neuronal excitability and dampens seizure intensity, illuminating a cellular cascade that may be targeted for therapeutic intervention to mitigate seizure intensity and progression.

Reassessing the impact of intraoperative electrocorticography on postoperative outcome of patients undergoing standard temporal lobectomy for MRI-negative temporal lobe epilepsy

OBJECTIVE

Almost 30% of the patients with suspected temporal lobe epilepsy (TLE) have normal results on MRI. Success rates for resection of MRI-negative TLE are less favorable, ranging from 36% to 76%. Herein the authors describe the impact of intraoperative electrocorticography (ECoG) augmented by opioid activation and its effect on postoperative seizure outcome.

METHODS

Adult and pediatric patients with medically resistant MRI-negative TLE who underwent standardized ECoG at the time of their elective anterior temporal lobectomy (ATL) with amygdalohippocampectomy between 1990 and 2016 were included in this study. Seizure recurrence comprised the primary outcome of interest and was assessed using Kaplan-Meier and multivariable Cox regression analysis plots based on distribution of interictal epileptiform discharges (IEDs) recorded on scalp electroencephalography, baseline and opioid-induced IEDs on ECoG, and extent of resection.

RESULTS

Of the 1144 ATLs performed at the authors' institution between 1990 and 2016, 127 (11.1%) patients (81 females) with MRI-negative TLE were eligible for this study. Patients with complete resection of tissue generating IED recorded on intraoperative ECoG were less likely to have seizure recurrence compared to those with incomplete resection on univariate analysis (p < 0.05). No difference was found in seizure recurrence between patients with bilateral independent IEDs and unilateral IEDs (p = 0.15), presence or absence of opioid-induced epileptiform activation (p = 0.61), or completeness of resection of tissue with opioid-induced IEDs on intraoperative ECoG (p = 0.41).

CONCLUSIONS

The authors found that incomplete resection of IED-generating tissue on intraoperative ECoG was associated with an increased chance of seizure recurrence. However, they found that induction of epileptiform activity with intraoperative opioid activation did not provide useful intraoperative data predictive of improving operative results for temporal lobectomy in MRI-negative epilepsy.

Hospital service utilization trajectories of individuals living with epilepsy in New South Wales, Australia, 2012-2016: A population-based study

OBJECTIVES

This study aimed to examine five-year trajectories of hospital service utilization among individuals living with epilepsy in New South Wales (NSW), Australia, and to identify factors predictive of trajectory group membership.

METHODS

This study used group-based trajectory modeling of hospital admissions over a five-year period for individuals living with epilepsy who had an epilepsy-related hospitalization during 1 January 2012 and 31 December 2012 in NSW, Australia (n = 5762).

RESULTS

The analysis revealed the following five distinct hospital service utilization trajectory groups: "one-off users" (Group 1; 22.9%), "low-chronic users" (Group 2; 47.1%), "moderate-declining users" (Group 3; 10.3%), "moderate-chronic users" (Group 4; 18.3%), and "high-chronic users" (Group 5; 1.5%). There were key features that defined trajectory group membership, in particular the relative proportions of group members with chronic health conditions, other comorbid conditions, refractory epilepsy, and status epilepticus. For instance, "high-chronic users" (Group 5) had higher proportions of individuals with chronic health conditions (34.8%) and refractory epilepsy (19.1%); "moderate-declining users" (Group 3) had higher proportions of individuals with chronic health conditions (35.1%) and status epilepticus (9.8%); and "low-chronic users" (Group 2) had the lowest proportion of individuals with chronic health conditions.

CONCLUSION

It is important to gain a better understanding of hospital service utilization among individuals living with epilepsy. This research has identified trajectory groups of hospital service utilization profiles of individuals living with epilepsy. Identification of predictors of trajectory group membership allows targeting of strategies to reduce hospital admissions, inform healthcare service delivery, and improve the health and wellbeing of individuals living with epilepsy.

Prospective validation of a machine learning model that uses provider notes to identify candidates for resective epilepsy surgery

OBJECTIVE

Delay to resective epilepsy surgery results in avoidable disease burden and increased risk of mortality. The objective was to prospectively validate a natural language processing (NLP) application that uses provider notes to assign epilepsy surgery candidacy scores.

METHODS

The application was trained on notes from (1) patients with a diagnosis of epilepsy and a history of resective epilepsy surgery and (2) patients who were seizure-free without surgery. The testing set included all patients with unknown surgical candidacy status and an upcoming neurology visit. Training and testing sets were updated weekly for 1 year. One- to three-word phrases contained in patients' notes were used as features. Patients prospectively identified by the application as candidates for surgery were manually reviewed by two epileptologists. Performance metrics were defined by comparing NLP-derived surgical candidacy scores with surgical candidacy status from expert chart review.

RESULTS

The training set was updated weekly and included notes from a mean of 519 ± 67 patients. The area under the receiver operating characteristic curve (AUC) from 10-fold cross-validation was 0.90 ± 0.04 (range = 0.83-0.96) and improved by 0.002 per week (P < .001) as new patients were added to the training set. Of the 6395 patients who visited the neurology clinic, 4211 (67%) were evaluated by the model. The prospective AUC on this test set was 0.79 (95% confidence interval [CI] = 0.62-0.96). Using the optimal surgical candidacy score threshold, sensitivity was 0.80 (95% CI = 0.29-0.99), specificity was 0.77 (95% CI = 0.64-0.88), positive predictive value was 0.25 (95% CI = 0.07-0.52), and negative predictive value was 0.98 (95% CI = 0.87-1.00). The number needed to screen was 5.6.

SIGNIFICANCE

An electronic health record-integrated NLP application can accurately assign surgical candidacy scores to patients in a clinical setting.

Intraoperative ultrasonography (ioUS) characteristics of focal cortical dysplasia (FCD) type II b

PURPOSE

Focal cortical dysplasia (FCD) is one of the major causes of drug-resistant epilepsy. Surgery has proved to be the treatment of choice, however up to a third of patients experience only partial resection. Ill-defined borders and lesions embedded in eloquent areas are two of the main drawbacks of FCD surgery. Preliminary experiences with intraoperative ultrasound (ioUS) have proved its feasibility and potential. We analyzed FCD' ioUS findings in our patients with FCD and compared them with magnetic resonance (MRI) ones.

METHODS

We retrospectively reviewed all records of patients with focal medically refractory epilepsy who underwent ioUS guided surgery between November 2014 and October 2017. Lesions other than FCD or FCD associated with other pathological entities were not considered. Patients' preoperative MRI and ioUS features were analyzed according to up-to-date literature and than compared.

RESULTS

A homogeneous population of five patients with type IIb FCD was evaluated. Focal cortical thickening and cortical ribbon hyper-intensity, blurring of the grey-white matter junction and hyper-intensity of the subcortical white matter on T2-weighted/FLAIR images were present in all patients. Cortical features had a complete concordance between ioUS and MRI. In particular ioUS thickening and hyper-echogenicity of cortical ribbon were identified in all cases (100%). Contrary, hyper-echoic subcortical white matter was detected in 60% of the patients. IoUS images resulted in clearer lesion borders than MRI images.

CONCLUSION

Our study confirms the potentials of ioUS as a valuable diagnostic tool to guide FCD surgeries.

Promoting faster pathways to surgery: a clinical audit of patients with refractory epilepsy

Background

Individuals with epilepsy who cannot be adequately controlled with anti-epileptic drugs, refractory epilepsy, may be suitable for surgical treatment following detailed assessment. This is a complex process and there are concerns over delays in referring refractory epilepsy patients for surgery and subsequent treatment. The aim of this study was to explore the different patient pathways, referral and surgical timeframes, and surgical and medical treatment options for refractory epilepsy patients referred to two Tertiary Epilepsy Clinics in New South Wales, Australia.

Methods

Clinical records were reviewed for 50 patients attending the two clinics, in two large teaching hospitals (25 in Clinic 1; 25 in Clinic 2. A purpose-designed audit tool collected detailed aspects of outpatient consultations and treatment. Patients with refractory epilepsy with their first appointment in 2014 were reviewed for up to six visits until the end of 2016. Data collection included: patient demographics, type of epilepsy, drug management, and assessment for surgery. Outcomes included: decisions regarding surgical and/or medical management, and seizure status following surgery. Patient-reported outcome measures to assess anxiety and depression were collected in Clinic 1 only.

Results

Patient mean age was 38.3 years (SD 13.4), the mean years since diagnosis was 17.3 years (SD 9.8), and 88.0% of patients had a main diagnosis of focal epilepsy. Patients were taking an average of 2.3 (SD 0.9) anti-epileptic drugs at the first clinic visit. A total of 17 (34.0%) patients were referred to the surgical team and 11 (22.0%) underwent a neuro-surgical procedure. The average waiting time between visit 1 to surgical referral was 38.8 weeks (SD 25.1), and between visit 1 and the first post-operative visit was 55.8 weeks (SD 25.0).

Conclusion

The findings confirm international data showing significant waiting times between diagnosis of epilepsy and referral to specialist clinics for surgical assessment and highlight different approaches in each clinic in terms of visit numbers and recorded activities. A standardised pathway and data collection, including patient-reported outcome measures, would provide better evidence for whether promoting earlier referral and assessment for surgery improves the lives of this disease group.

Electronic supplementary material

The online version of this article (10.1186/s12883-019-1255-0) contains supplementary material, which is available to authorized users.

De novo temporal intermittent rhythmic delta activity after laser interstitial thermal therapy for mesial temporal lobe epilepsy predicts poor seizure outcome

OBJECTIVE

To evaluate EEG abnormalities, particularly development of temporal intermittent rhythmic delta activity (TIRDA) after laser interstitial thermal therapy (LITT) and assess the role of further surgery after LITT.

METHODS

We retrospectively identified consecutive cases of LITT for the prevalence of post-operative TIRDA. We assessed baseline demographics, clinical variables including age of seizure onset, age at surgery, pre-operative and post-operative EEG changes.

RESULTS

40 patients underwent LITT for drug-resistant temporal lobe epilepsy (TLE), 29 met inclusion criteria. Median duration of follow-up was 15 months. Ten patients had post-LITT ipsilateral TIRDA, another two demonstrated post-operative TIRDA but they occurred contralateral to the side of ablation. None of the patients with TIRDA on their post-LITT EEG became seizure-free. Six out of 29 patients (21%) eventually required anterior temporal lobectomy (ATL), and of those 6 patients 4 (66%) had evidence of TIRDA on their post-LITT follow up EEG. The sensitivity and specificity of post-LITT TIRDA in predicting surgical failure was 57.14% and 100% respectively.

CONCLUSIONS

Post-LITT TIRDA may serve as a biomarker to predict unsuccessful seizure outcome following LITT and be an early indicator for ATL.

SIGNIFICANCE

The presence of TIRDA following LITT should prompt early consideration for reoperation.

Clinically indicated electrical stimulation strategies to treat patients with medically refractory epilepsy

Focal epilepsies represent approximately half of all diagnoses, and more than one-third of these patients are refractory to pharmacologic treatment. Although resection can result in seizure freedom, many patients do not meet surgical criteria, as seizures may be multifocal in origin or have a focus in an eloquent region of the brain. For these individuals, several U.S. Food and Drug Administration (FDA)-approved electrical stimulation paradigms serve as alternative options, including vagus nerve stimulation, responsive neurostimulation, and stimulation of the anterior nucleus of the thalamus. All of these are safe, flexible, and lead to progressive seizure control over time when used as an adjunctive therapy to antiepileptic drugs. Focal epilepsies frequently involve significant comorbidities such as cognitive decline. Similar to antiepilepsy medications and surgical resection, current stimulation targets and parameters have yet to address cognitive impairments directly, with patients reporting persistent comorbidities associated with focal epilepsy despite a significant reduction in the number of their seizures. Although low-frequency theta oscillations of the septohippocampal network are critical for modulating cellular activity and, in turn, cognitive processing, the coordination of neural excitability is also imperative for preventing seizures. In this review, we summarize current FDA-approved electrical stimulation paradigms and propose that theta oscillations of the medial septal nucleus represent a novel neuromodulation target for concurrent seizure reduction and cognitive improvement in epilepsy. Ultimately, further advancements in clinical neurostimulation strategies will allow for the efficient treatment of both seizures and comorbidities, thereby improving overall quality of life for patients with epilepsy.

Imaging fast electrical activity in the brain during ictal epileptiform discharges with electrical impedance tomography

Electrical Impedance Tomography (EIT) is an emerging medical imaging technique which can produce tomographic images of internal impedance changes within an object using non-penetrating surface electrodes. It has previously been used to image impedance changes due to neuronal depolarisation during evoked potentials in the rat somatosensory cortex with a resolution of 2 ms and <200 μm, using an epicortical electrode array. The purpose of this work was to use this technique to elucidate the intracortical spatiotemporal trajectory of ictal spike-and-wave discharges (SWDs), induced by electrical stimulation in an acute rat model of epilepsy, throughout the cerebral cortex. Seizures lasting 16.5 ± 5.3 s with repetitive 2-5 Hz SWDs were induced in five rats anaesthetised with fentanyl-isoflurane. Transfer impedance measurements were obtained during each seizure with a 57-electrode epicortical array by applying 50 μA current at 1.7 kHz to two electrodes and recording voltages from all remaining electrodes. Images were reconstructed from averaged SWD-related impedance traces obtained from EIT measurements in successive seizures. We report the occurrence of reproducible impedance changes during the initial spike phase, which had an early onset in the whisker barrel cortex and spread posteriorly, laterally and ventrally over 20 ms (p < 0.03125, N = 5). These findings, which confirm and extend knowledge of SWD initiation and expression, suggest that EIT is a valuable neuroimaging tool for improving understanding of neural circuits implicated in epileptic phenomena.

Leading up to saying "yes": A qualitative study on the experience of patients with refractory epilepsy regarding presurgical investigation for resective surgery

OBJECTIVES

Adult patients with refractory epilepsy who are potential candidates for resective surgery undergo a period of presurgical investigation in tertiary epilepsy centers (TECs), where they engage extensively with healthcare professionals and receive a range of treatment-related information. This qualitative study aimed to examine the experiences of adult patients with refractory epilepsy leading up to and during presurgical investigation and how their perceptions of resective surgery are shaped.

METHODS

In-depth interviews with 12 patients and six epilepsy specialist clinicians and 12 observations of routine patient-clinician consultations took place at two TECs in Sydney, Australia. Data were thematically analyzed via group work.

RESULTS

Patients reflected on prior experiences of poor seizure control and inadequate antiepileptic drug management and a lack of clarity about their condition before referral to tertiary care. Poor continuity of care and disrupted care transitions affected patients from regional locations. Tertiary referral increased engagement with personalized information about refractory epilepsy, which intensified during presurgical assessments with additional hospital visits and consultations. Experiential information, such as testimonials of other patients, influenced perceptions of surgery and fostered more trust and confidence towards healthcare professionals.

CONCLUSION

Qualitative inquiry detailed multifaceted effects of information on patients' overall treatment trajectory and experience of healthcare. Earlier patient identification for surgical assessments should be accompanied by access to good quality information at primary and community care levels and strengthened referral processes.

Examining health service utilization, hospital treatment cost, and mortality of individuals with epilepsy and status epilepticus in New South Wales, Australia 2012-2016

This study examined the health service utilization and hospital treatment cost of individuals with epilepsy by age group, mortality within 30days, and surgical outcomes for individuals with refractory epilepsy in New South Wales (NSW), Australia. A retrospective examination of linked hospitalization and mortality data for individuals hospitalized with a diagnosis of epilepsy during 2012-2016. Hospitalized incidence rates per 1000 population were calculated, and negative binomial regression was used to examine temporal trends. Mortality within 30days of hospitalization was identified, along with cause of death. There were 44,722 hospitalizations during the five-year period, with a hospitalization rate of 85.6 per 1000 population (95% confidence interval (CI): 84.7-86.4). Total hospital treatment costs were AUD$402.9 million. Children aged ≤17years accounted for 32.0% of hospitalizations. Just over half to two-thirds of hospitalizations for each age group were for a principal diagnosis of epilepsy, with 2976 hospitalizations of individuals for status epilepticus. The overall mean hospital length of stay (LOS) for epilepsy hospitalizations was 5.1days (standard deviation (SD)=9.0). Thirty-day mortality was highest for individuals aged ≥65years (6.7%), and epilepsy was identified as the underlying cause of death for 18.2% of deaths. This research has provided insight into the healthcare utilization profiles of individuals with epilepsy at different ages. Epilepsy hospitalizations constitute a substantial cost to the healthcare system, and better overall management of seizures and comorbid conditions is likely to lead to a reduction in the need for hospitalization.

Intense olfactory stimulation blocks seizures in an experimental model of epilepsy

There are reports of patients whose epileptic seizures are prevented by means of olfactory stimulation. Similar findings were described in animal models of epilepsy, such as the electrical kindling of amygdala, where olfactory stimulation with toluene (TOL) suppressed seizures in most rats, even when the stimuli were 20% above the threshold to evoke seizures in already kindled animals. The Wistar Audiogenic Rat (WAR) strain is a model of tonic-clonic seizures induced by acute acoustic stimulation, although it also expresses limbic seizures when repeated acoustic stimulation occurs - a process known as audiogenic kindling (AK). The aim of this study was to evaluate whether or not the olfactory stimulation with TOL would interfere on the behavioral expression of brainstem (acute) and limbic (chronic) seizures in the WAR strain. For this, animals were exposed to TOL or saline (SAL) and subsequently exposed to acoustic stimulation in two conditions that generated: I) acute audiogenic seizures (only one acoustic stimulus, without previous seizure experience before of the odor test) and II) after AK (20 acoustic stimuli [2 daily] before of the protocol test). We observed a decrease in the seizure severity index of animals exposed only to TOL in both conditions, with TOL presented 20s before the acoustic stimulation in both protocols. These findings were confirmed by behavioral sequential analysis (neuroethology), which clearly indicated an exacerbation of clusters of specific behaviors such as exploration and grooming (self-cleaning), as well as significant decrease in the expression of brainstem and limbic seizures in response to TOL. Thus, these data demonstrate that TOL, a strong olfactory stimulus, has anticonvulsant properties, detected by the decrease of acute and AK seizures in WARs.

Intracranial video-EEG monitoring in presurgical evaluation of patients with refractory epilepsy

OBJECTIVE

Reviewing our experience in intracranial video-EEG monitoring in the presurgical evaluation of patients with refractory epilepsy.

METHODS

We report on 62 out of 202 (31%) patients with refractory epilepsy, who underwent a long term video-EEG monitoring (LTM). The epileptogenic zone (EZ) was localised either based on the results of LTM or after intracranial EEG recordings from depth, subdural or foramen ovale electrodes. The decision on the location of the electrodes was based upon semiology of the seizures, EEG findings and the lesions visualised in MRI brain scan. Intraoperative corticography was carried out before and right after the resection of the seizure onset zone.

RESULTS

The video-EEG monitoring could localise EZ in 43 (69%) cases based. The remaining patients underwent invasive diagnostics: 10 (53%) had intracerebral depth electrodes, 6 (31%) depth and subdural and 3 (16%) foramen ovale electrodes. Intracranial video EEG recordings showed seizure focus in all the patients. Ten of them had EZ in mesial temporal structures, 4 in accessory motor area, 3 at the base of the frontal lobe and 2 in parietal lobe. There was one case of an asymptomatic intracerebral haematoma at the electrode. All patients were subsequently operated on. In 15 (79%) cases the seizures subsided (follow-up from 2 to 5 years), in 4 (21%) they decreased.

CONCLUSIONS

The intracranial EEG is required in all patients with normal MRI (so-called nonlesional cases) in whom EZ is suspected to be located in the hippocampus, insula or in the basal parts of the frontal lobe.

Cost-utility analysis of magnetoencephalography used to inform intracranial electrode placement in patients with drug resistant epilepsy: a model based analysis

OBJECTIVES

We estimated the cost-effectiveness of adding magnetoencephalography to a standard assessment for epilepsy surgery consisting of neuropsychology, magnetic resonance imagining, scalp electroencephalography, video electroencephalography and intracranial electroencephalography, in the capacity of informing intracranial electroencephalography electrode placement.

METHODS

We used Microsoft Excel (2007) to construct a decision model. Discounted costs and quality adjusted life years are aggregated to calculate incremental cost-effectiveness ratios. Sensitivity analyses are conducted to assess robustness of findings.

RESULTS

Our base case analysis yielded a result of $14 300 per quality adjusted life year gained. A total of 82.7% of probabilistic sensitivity analysis iterations resulted in incremental cost-effectiveness ratios below $100 000 in 2014 Canadian dollars.

CONCLUSIONS

Our findings demonstrate that the inclusion of Magnetoencephalography in the assessment for epilepsy surgery in the capacity of informing intracranial electroencephalography electrode placement is likely not cost saving but does represent a reasonable allocation of resources from a value for money perspective.

Optogenetic Approaches for Controlling Seizure Activity

Optogenetics, a technique that utilizes light-sensitive ion channels or pumps to activate or inhibit neurons, has allowed scientists unprecedented precision and control for manipulating neuronal activity. With the clinical need to develop more precise and effective therapies for patients with drug-resistant epilepsy, these tools have recently been explored as a novel treatment for halting seizure activity in various animal models. In this review, we provide a detailed and current summary of these optogenetic approaches and provide a perspective on their future clinical application as a potential neuromodulatory therapy.

Surgical Management of Pediatric Epilepsy: Decision-Making and Outcomes

First-line treatment for epilepsy is antiepileptic drug and requires an interdisciplinary approach and enduring commitment and adherence from the patient and family for successful outcome. Despite adherence to antiepileptic drugs, refractory epilepsy occurs in approximately 30% of children with epilepsy, and surgical treatment is an important intervention to consider. Surgical management of pediatric epilepsy is highly effective in selected patients with refractory epilepsy; however, an evidence-based protocol, including best methods of presurgical imaging assessments, and neurodevelopmental and/or behavioral health assessments, is not currently available for clinicians. Surgical treatment of epilepsy can be critical to avoid negative outcomes in functional, cognitive, and behavioral health status. Furthermore, it is often the only method to achieve seizure freedom in refractory epilepsy. Although a large literature base can be found for adults with refractory epilepsy undergoing surgical treatment, less is known about how surgical management affects outcomes in children with epilepsy. The purpose of the review was fourfold: (1) to evaluate the available literature regarding presurgical assessment and postsurgical outcomes in children with medically refractory epilepsy, (2) to identify gaps in our knowledge of surgical treatment and its outcomes in children with epilepsy, (3) to pose questions for further research, and (4) to advocate for a more unified presurgical evaluation protocol including earlier referral for surgical candidacy of pediatric patients with refractory epilepsy. Despite its effectiveness, epilepsy surgery remains an underutilized but evidence-based approach that could lead to positive short- and long-term outcomes for children with refractory epilepsy.

Single and paired-pulse electrical stimulation during invasive EEG recordings

Invasive EEG recordings are frequently required during the presurgical exploration of patients with drug-resistant focal epilepsy in order to clarify the epileptic zone location. Intracranial direct electrical stimulations (DES) induce EEG and/or clinical responses that participate in this evaluation. Clinical DES protocols (1Hz and/or 50Hz) trigger massive cortical activation that can elicit seizures, after-discharges or complex clinical signs. In contrast, low-energy (<1Hz) protocols activate more localized cortical regions using single-pulse electrical stimulations (SPES). SPES can elicit two main types of responses. Cortico-cortical evoked potentials (CCEPs) correspond to highly consistent early responses, appearing before 100ms after stimulation, with fixed latency; they are considered physiological and assess the effective connectivity between the recorded regions. Late responses appear after 100ms; they are rare, inconsistent with variable latency and are suggestive of an underlying epileptogenic cortex. Paired-pulse stimulation paradigm associates a conditioning and a test stimulation to induce intracortical inhibition or facilitation by modifying the response amplitude. Largely used in transcranial magnetic stimulation, it has rarely been applied to CCEP although the mechanisms put in place seem highly similar. Low frequency intracerebral stimulations allow analysing brain connectivity and cortical excitability with a high temporal and spatial resolution. The development of new stimulation protocols and the combination with imaging or statistical techniques recently offered promising results.

Is psychiatric assessment essential for better epilepsy surgery outcomes?

Epilepsy surgery is one of the most accepted and beneficial treatment for resistant epilepsies. However there is some variability in the comprehensive epilepsy care programs offered globally. Many centers do not do a psychiatric assessment unless required. It is now evident from a large body of research that epilepsy is associated with psychiatric morbidity which is also seen in patients considered for epilepsy surgery. There is also evidence to state that the risk for worsening or de novo psychiatric disorders is often seen post surgery. This calls for a comprehensive psychiatric assessment of all patients enrolled for the epilepsy surgery program to be evaluated pre and post surgically to minimize the risk of post surgical psychological disturbances and/or poor quality of life. Efficacious treatment of psychiatric disorders in those having psychiatric morbidity contributes to improved patient wellbeing, seizure freedom and better quality of life. Hence there is a need for most centers globally to include regular psychiatric assessment of epilepsy surgery patients as a protocol.

Application of a multidisciplinary model to a case example of presurgical epilepsy planning

This article presents a case example which illustrates the multidisciplinary model for presurgical assessment for epilepsy patients. Nearly three million people in the United States are diagnosed with epilepsy and more than one third of this population is refractory to pharmacological treatment. Poor seizure control is associated with additional impairment in quality of life and cognitive and social functioning, and even with premature death. In accordance with these concerns, surgical intervention is increasingly recognized as a viable treatment option, which should be considered soon after drug resistance becomes apparent. Despite the widespread evidence of effectiveness surgery is often delayed, in part because of the necessity, and difficulties, of correctly applying a multidisciplinary approach to presurgical assessment. And yet, a multidisciplinary team is crucial in the evaluation of risks and benefits of possible surgical intervention and in guiding the surgical procedure to maximize seizure control and minimize risk to eloquent cortex. In the model and complex case presented, the neuropsychologist has a critical role in the presurgical evaluation, as well as in the postsurgical evaluation of outcome.

[Epilepsy surgery--assessment and patient selection]

BACKGROUND

Considerable progress in diagnostic imaging and video EEG monitoring has improved the possibilities of localising the epileptogenic zone of the brain in patients with epilepsy. Despite the fact that epilepsy surgery can therefore be offered to more patients today than previously, relatively few patients are referred for an assessment for surgery. The aim of this review is to provide a brief account of the patient selection procedures and the investigations prior to epilepsy surgery.

METHOD

The review is based on a literature search in PubMed and the personal experiences of the authors in this field.

RESULTS

If the epilepsy does not respond to any kind of pharmacological treatment, and idiopathic generalised epilepsy and pseudoresistance have been ruled out, the patient should be evaluated for surgery. The evaluation is multidisciplinary, and the aim is to localise the epileptogenic zone, which can be identified by both structural and functional abnormalities. It must be determined before the operation whether the zone can be removed without leaving severe neurological or cognitive impairment. The best results after epilepsy surgery are seen in patients with a morphological substrate, particularly temporal lobe epilepsy associated with hippocampal sclerosis.

INTERPRETATION

Epilepsy surgery plays an ever more important role in the treatment of patients with drug resistant seizures. Doctors who treat epileptic patients should refer candidates for surgery at an early stage of the disease.

Choosing the tumoral epilepsy surgery candidate

The management of epilepsy is an essential clinical issue in many patients with brain tumors. Tumoral epilepsy is often drug resistant and is associated with poor quality of life. Surgery represents a key therapeutic option in the management of patients with refractory tumoral epilepsy, with high rates of postoperative seizure freedom, especially when gross total resection can be performed. The selection of surgical candidates first requires extrapolation of the presumed underlying pathology and its potential for malignant transformation from clinical and imaging data, especially MRI characteristics. These data determine the decision for surgery, as well as its timing and technical aspects in relation to the risk of postoperative deficit. In glioneuronal tumors, where seizures are often drug-resistant and risk of malignant transformation is very low, epilepsy surgery is usually recommended to alleviate disabling seizures and side effects of antiepileptic drugs. However, the risk of postoperative deficit may outweigh potential benefits of surgery in tumors located within eloquent cortex. This issue is particularly relevant for glioneuronal tumors located within the dominant mesial temporal structures in patients in whom seizure control might require additional hippocampectomy, associated with a high risk of memory decline. In contrast, in patients with low-grade gliomas or aggressive brain neoplasms, both the decision to perform surgery and selection of the best surgical approach primarily rely on the oncologic imperative rather than epileptologic considerations. In these patients, the extent of tumor resection correlates with improved survival, progression-free survival, as well as with the chances of postoperative seizure control.

Non-pharmacological treatment options for refractory epilepsy: an overview of human treatment modalities and their potential utility in dogs

Refractory epilepsy is a common disorder both in humans and dogs and treatment protocols are difficult to optimise. In humans, different non-pharmacological treatment modalities currently available include surgery, the ketogenic diet and neurostimulation. Surgery leads to freedom from seizures in 50-75% of patients, but requires strict patient selection. The ketogenic diet is indicated in severe childhood epilepsies, but efficacy is limited and long-term compliance can be problematic. In the past decade, various types of neurostimulation have emerged as promising treatment modalities for humans with refractory epilepsy. Currently, none of these treatment options are used in routine daily clinical practice to treat dogs with the condition. Since many dogs with poorly controlled seizures do not survive, the search for alternative treatment options for canine refractory epilepsy should be prioritised. This review provides an overview of non-pharmacological treatment options for human refractory epilepsy. The current knowledge and limitations of these treatments in canine refractory epilepsy is also discussed.

Safety of Staged Epilepsy Surgery in Children

BACKGROUND:

Surgical resection of epileptic foci relies on accurate localization of the epileptogenic zone, often achieved by subdural and depth electrodes. Our epilepsy center has treated selected children with poorly localized medically refractory epilepsy with a staged surgical protocol, with at least 1 phase of invasive monitoring for localization and resection of epileptic foci.

OBJECTIVE:

To evaluate the safety of staged surgical treatments for refractory epilepsy among children.

METHODS:

Data were retrospectively collected, including surgical details and complications of all patients who underwent invasive monitoring.

RESULTS:

A total of 161 children underwent 200 admissions including staged procedures (&gt;1 surgery during 1 hospital admission), and 496 total surgeries. Average age at surgery was 7 years (range, 8 months to 16.5 years). A total of 250 surgeries included resections (and invasive monitoring), and 189 involved electrode placement only. The cumulative total number of surgeries per patient ranged from 2 to 10 (average, 3). The average duration of monitoring was 10 days (range, 1–30). There were no deaths. Follow-up ranged from 1 month to 10 years. Major complications included unexpected new permanent mild neurological deficits (2%/admission), central nervous system or bone flap infections (1.5%/admission), intracranial hemorrhage, cerebrospinal fluid leak, and a retained strip (each 0.5%/admission). Minor complications included bone absorption (5%/admission), positive surveillance sub-/epidural cultures in asymptomatic patients (5.5%/admission), noninfectious fever (5%/admission), and wound complications (3%/admission). Thirty complications necessitated additional surgical treatment.

CONCLUSION:

Staged epilepsy surgery with invasive electrode monitoring is safe in children with poorly localized medically refractory epilepsy. The rate of major complications is low and appears comparable to that associated with other elective neurosurgical procedures.

The Lateralizer: a tool for students to explore the divided brain

Despite a profusion of popular misinformation about the left brain and right brain, there are functional differences between the left and right cerebral hemispheres in humans. Evidence from split-brain patients, individuals with unilateral brain damage, and neuroimaging studies suggest that each hemisphere may be specialized for certain cognitive processes. One way to easily explore these hemispheric asymmetries is with the divided visual field technique, where visual stimuli are presented on either the left or right side of the visual field and task performance is compared between these two conditions; any behavioral differences between the left and right visual fields may be interpreted as evidence for functional asymmetries between the left and right cerebral hemispheres. We developed a simple software package that implements the divided visual field technique, called the Lateralizer, and introduced this experimental approach as a problem-based learning module in a lower-division research methods course. Second-year undergraduate students used the Lateralizer to experimentally challenge and explore theories of the differences between the left and right cerebral hemispheres. Measured learning outcomes after active exploration with the Lateralizer, including new knowledge of brain anatomy and connectivity, were on par with those observed in an upper-division lecture course. Moreover, the project added to the students' research skill sets and seemed to foster an appreciation of the link between brain anatomy and function.