Practical Drug Treatment Recommendations on the Drug Refractory Epilepsy Patients: 2021 Clinical Guideline Subcommittee for Epilepsy in the Korean Neurological Association

One third of the overall epilepsy population are estimated to be a drug refractory epilepsy (DRE), defined as the patients who failed to control seizure reduction, even tried two or more appropriate antiepileptic drugs (AEDs) trials. Those people need additional AEDs trials or other treatment options (resective surgery, neuromoulation, etc.). Here, we, clinical guideline committee of the Korean Neurological Association (KNA) introduce the recommendations of AEDs treatments including not only old and new AEDs currently available in Korea but also AEDs planned to be launched in the new future for DRE patients with literature review to help efficient decision of the clinician. The authors reviewed literatures and assessed efficacy and tolerability on 12 currently available and four newly introduced/or planned AEDs applied to DRE patients, published from November 2015 to July 2021. Brivaracetam, eslicarbazepine, canabidiol and cenobamate are the four AEDs that are newly introduced or planned to be launched soon. The reviewed articles are publications after November 2015, 2018 American Association of Neurology guideline, new AEDs which were introduced or planned to be launched as of 2021. All AEDs are classified based on the therapeutic rating scheme, generating recommendations. Overall 173 papers have been reviewed and analyzed for recommendation rationales. KNA introduce additional add-on treatment or conversional monotherapy guidelines on the drug refractory focal and generalized epilepsy. We hope these guidelines or recommendations to help clinical decision for the treatment of drug refractory epilepsy patients

P.023 Neurostimulation in Drug-Resistant Epilepsy: Systematic Review and Meta-Analysis from the ILAE Evidence-Based Epilepsy Surgery Task Force

Background: Drug-resistant epilepsy (DRE) can affect up to one third of individuals with epilepsy. We conducted a systematic review and meta-analysis of vagus nerve stimulation (VNS), responsive neurostimulation (RNS), and deep brain stimulation (DBS) in patients with DRE to summarize the current evidence on efficacy and tolerability for these neuromodulation modalities. Methods: We searched three online databases with a pre-specified search strategy. We included published randomized controlled trials (RCT) and their open-label extension studies, as well as prospective case series, with samples greater than 20 participants, reporting efficacy and tolerability. Results: We identified 31 studies, six of which are RCTs and 25 prospective observational studies. At long term follow-up, five observational studies for VNS reported a pooled mean decrease in seizure frequency at last follow-up of 35%. In the extension studies for RNS, the median seizure reduction was 53%, 66% and 75.0% at two, five and nine years respectively. For DBS, the median reduction was then 56%, 69% and 75% at two, five and seven years respectively. Conclusions: Neurostimulation modalities are effective for the treatment of DRE, with improving outcomes over time and few major complications. Higher quality long-term data on DBS and RNS suggest larger seizure reduction rates than VNS.

Effects of Vagus Nerve Stimulation Following Corpus Callosotomy for Patients with Drug-Resistant Epilepsy

Objective: The effectiveness of vagus nerve stimulation (VNS) for residual seizures after corpus callosotomy (CC) has not yet been fully investigated. We hypothesized that seizure control would be improved by VNS after CC. The purpose of this study was to compare seizure frequency between patients with implantation of a VNS generator (post-VNS group) or without VNS (non-post-VNS group) following CC. Methods: We retrospectively reviewed patients who underwent CC between January 2009 and May 2019 in our institution. We evaluated proportions of ≥50% reduction in seizure frequency (responders) and seizure reduction rate 1 and 2 years after VNS. To investigate factors related to responders, uni- and multivariate logistic regression analyses were performed regarding age, number of anti-seizure medications (ASMs), addition of novel ASMs (levetiracetam, lacosamide or perampanel), and post-VNS or non-post-VNS status. Results: Thirteen post-VNS patients and 24 non-post-VNS patients were analyzed in this study. Responder rate at 1 year after VNS differed significantly between the post-VNS group (53.9%) and non-post-VNS group (12.5%, p = 0.017). Number of ASMs at the time of CC and post-VNS were significantly associated with responders in univariate analyses (odds ratio [OR] 0.34, 95% confidence interval [CI] 0.13–0.88, p = 0.025 and OR 8.2, 95%CI 1.6–41.6, p = 0.011, respectively), whereas age, sex, seizure frequency, and addition of novel ASMs were not. In multivariate analysis, the presence of VNS procedures after CC was the only factor favorably associated with responder status (OR 82.2, 95%CI 1.55–4355.7, p = 0.03). Conclusions: VNS therapy after CC may increase the proportion of responders independent of the addition of novel ASMs.

Intracranial neuromodulation with deep brain stimulation and responsive neurostimulation in children with drug-resistant epilepsy: a systematic review

OBJECTIVE In children with drug-resistant epilepsy (DRE), resective, ablative, and disconnective surgery may not be feasible or may fail. Neuromodulation in the form of deep brain stimulation (DBS) and responsive neurostimulation (RNS) may be viable treatment options, however evidence for their efficacies in children is currently limited. This systematic review aimed to summarize the literature on DBS and RNS for the treatment of DRE in the pediatric population. Specifically, the authors focused on currently available data for reported indications, neuromodulation targets, clinical efficacy, and safety outcomes. METHODS PRISMA guidelines were followed throughout this systematic review (PROSPERO no. CRD42020180669). Electronic databases, including PubMed, Embase, Cochrane Library, OpenGrey, and CINAHL Plus, were searched from their inception to February 19, 2021. Inclusion criteria were 1) studies with at least 1 pediatric patient (age < 19 years) who underwent DBS and/or RNS for DRE; and 2) retrospective, prospective, randomized, or nonrandomized controlled studies, case series, and case reports. Exclusion criteria were 1) letters, commentaries, conference abstracts, and reviews; and 2) studies without full text available. Risk of bias of the included studies was assessed using the Cochrane ROBINS-I (Risk of Bias in Non-randomised Studies - of Interventions) tool. RESULTS A total of 35 studies were selected that identified 72 and 46 patients who underwent DBS and RNS, respectively (age range 4–18 years). Various epilepsy etiologies and seizure types were described in both cohorts. Overall, 75% of patients had seizure reduction > 50% after DBS (among whom 6 were seizure free) at a median (range) follow-up of 14 (1–100) months. In an exploratory univariate analysis of factors associated with favorable response, the follow-up duration was shorter in those patients with a favorable response (18 vs 33 months, p < 0.05). In the RNS cohort, 73.2% of patients had seizure reduction > 50% after RNS at a median (range) follow-up of 22 (5–39) months. On closer inspection, 83.3% of patients who had > 50% reduction in seizures actually had > 75% reduction, with 4 patients being seizure free. CONCLUSIONS Overall, both DBS and RNS showed favorable response rates, indicating that both techniques should be considered for pediatric patients with DRE. However, serious risks of overall bias were found in all included studies. Many research needs in this area would be addressed by conducting high-quality clinical trials and establishing an international registry of patients who have undergone pediatric neuromodulation, thereby ensuring robust prospective collection of predictive variables and outcomes.

Real-World Preliminary Experience With Responsive Neurostimulation in Pediatric Epilepsy: A Multicenter Retrospective Observational Study

BACKGROUND Despite the well-documented utility of responsive neurostimulation (RNS, NeuroPace) in adult epilepsy patients, literature on the use of RNS in children is limited. OBJECTIVE To determine the real-world efficacy and safety of RNS in pediatric epilepsy patients. METHODS Patients with childhood-onset drug-resistant epilepsy treated with RNS were retrospectively identified at 5 pediatric centers. Reduction of disabling seizures and complications were evaluated for children (&lt;18 yr) and young adults (&gt;18 yr) and compared with prior literature pertaining to adult patients. RESULTS Of 35 patients identified, 17 were &lt;18 yr at the time of RNS implantation, including a 3-yr-old patient. Four patients (11%) had concurrent resection. Three complications, requiring additional surgical interventions, were noted in young adults (2 infections [6%] and 1 lead fracture [3%]). No complications were noted in children. Among the 32 patients with continued therapy, 2 (6%) achieved seizure freedom, 4 (13%) achieved ≥90% seizure reduction, 13 (41%) had ≥50% reduction, 8 (25%) had &lt;50% reduction, and 5 (16%) experienced no improvement. The average follow-up duration was 1.7 yr (median 1.8 yr, range 0.3-4.8 yr). There was no statistically significant difference for seizure reduction and complications between children and young adults in our cohort or between our cohort and the adult literature. CONCLUSION These preliminary data suggest that RNS is well tolerated and an effective off-label surgical treatment of drug-resistant epilepsy in carefully selected pediatric patients as young as 3 yr of age. Data regarding long-term efficacy and safety in children will be critical to optimize patient selection.

Genetic variations of adenosine kinase as predictable biomarkers of efficacy of vagus nerve stimulation in patients with pharmacoresistant epilepsy

OBJECTIVE Vagus nerve stimulation (VNS) is an alternative treatment option for individuals with refractory epilepsy, with nearly 40% of patients showing no benefit after VNS and only 6%–8% achieving seizure freedom. It is presently unclear why some patients respond to treatment and others do not. Therefore, identification of biomarkers to predict efficacy of VNS is of utmost importance. The objective of this study was to explore whether genetic variations in genes involved in adenosine kinase (ADK), ecto-5′-nucleotidase (NT5E), and adenosine A1 receptor (A1R) are linked to outcome of VNS in patients with refractory epilepsy. METHODS Thirty single-nucleotide polymorphisms (SNPs), including 9 in genes encoding ADK, 3 in genes encoding NT5E, and 18 in genes encoding A1R, were genotyped in 194 refractory epilepsy patients who underwent VNS. The chi-square test and binary logistic regression were used to determine associations between genetic differences and VNS efficacy. RESULTS A significant association between ADK SNPs rs11001109, rs7899674, and rs946185 and seizure reduction with VNS was found. Regardless of sex, age, seizure frequency and type, antiseizure drug use, etiology, and prior surgical history, all patients (10/10 patients [100%]) with minor allele homozygosity at rs11001109 (genotype AA) or rs946185 (AA) achieved > 50% seizure reduction and 4 patients (4/10 [40%]) achieved seizure freedom. VNS therapy demonstrated higher efficacy among carriers of minor allele rs7899674 (CG + GG) (68.3% vs 48.8% for patients with major allele homozygosity). CONCLUSIONS Homozygous ADK SNPs rs11001109 (AA) and rs946185 (AA), as well as minor allele rs7899674 (CG + GG), may serve as useful biomarkers for prediction of VNS therapy outcome.

Long-term brain network reorganization predicts responsive neurostimulation outcomes for focal epilepsy

Responsive neurostimulation (RNS) devices, able to detect imminent seizures and to rapidly deliver electrical stimulation to the brain, are effective in reducing seizures in some patients with focal epilepsy. However, therapeutic response to RNS is often slow, is highly variable, and defies prognostication based on clinical factors. A prevailing view holds that RNS efficacy is primarily mediated by acute seizure termination; yet, stimulations greatly outnumber seizures and occur mostly in the interictal state, suggesting chronic modulation of brain networks that generate seizures. Here, using years-long intracranial neural recordings collected during RNS therapy, we found that patients with the greatest therapeutic benefit undergo progressive, frequency-dependent reorganization of interictal functional connectivity. The extent of this reorganization scales directly with seizure reduction and emerges within the first year of RNS treatment, enabling potential early prediction of therapeutic response. Our findings reveal a mechanism for RNS that involves network plasticity and may inform development of next-generation devices for epilepsy.

Vagus Nerve Stimulation Therapy for the Treatment of Seizures in Refractory Postencephalitic Epilepsy: A Retrospective Study

BackgroundVagus nerve stimulation (VNS) has been demonstrated to be safe and effective for patients with refractory epilepsy, but there are few reports on the use of VNS for postencephalitic epilepsy (PEE). This retrospective study aimed to evaluate the efficacy of VNS for refractory PEE.MethodsWe retrospectively studied 20 patients with refractory PEE who underwent VNS between August 2017 and October 2019 in Chinese PLA General Hospital and Beijing Children’s Hospital. VNS efficacy was evaluated based on seizure reduction, effective rate (percentage of cases with seizure reduction ≥ 50%), McHugh classification, modified Early Childhood Epilepsy Severity Scale (E-Chess) score, and Grand Total EEG (GTE) score. The follow-up time points were 3, 6, and 12 months after VNS. Pre- and postoperative data were compared and analyzed.ResultsThe median [interquartile range (IQR)] seizure reduction rates at 3, 6, and 12 months after VNS were 23.72% (0, 55%), 46.61% (0, 79.04%), and 67.99% (0, 93.78%), respectively. The effective rates were 30% at 3 months, 45% at 6 months, and 70% at 12 months. E-chess scores before the operation and at 3, 6, and 12 months after the operation were 10 (10, 10.75), 9 (9, 10), 9 (9, 9.75), and 9 (8.25, 9) (P &lt; 0.05), respectively. GTE scores before surgery and at 12 months after the operation were 11 (9, 13) and 9 (7, 11) (P &lt; 0.05), respectively. The mean intensity of VNS current was 1.76 ± 0.39 (range: 1.0–2.5) mA. No intraoperative complications or severe post-operative adverse effects were reported.ConclusionsOur study shows that VNS can reduce the frequency and severity of seizure in patients with refractory PEE. VNS has a good application prospect in patients with refractory PEE.

Making the Invisible Visible: Advanced Neuroimaging Techniques in Focal Epilepsy

It has been a clinically important, long-standing challenge to accurately localize epileptogenic focus in drug-resistant focal epilepsy because more intensive intervention to the detected focus, including resection neurosurgery, can provide significant seizure reduction. In addition to neurophysiological examinations, neuroimaging plays a crucial role in the detection of focus by providing morphological and neuroanatomical information. On the other hand, epileptogenic lesions in the brain may sometimes show only subtle or even invisible abnormalities on conventional MRI sequences, and thus, efforts have been made for better visualization and improved detection of the focus lesions. Recent advance in neuroimaging has been attracting attention because of the potentials to better visualize the epileptogenic lesions as well as provide novel information about the pathophysiology of epilepsy. While the progress of newer neuroimaging techniques, including the non-Gaussian diffusion model and arterial spin labeling, could non-invasively detect decreased neurite parameters or hypoperfusion within the focus lesions, advances in analytic technology may also provide usefulness for both focus detection and understanding of epilepsy. There has been an increasing number of clinical and experimental applications of machine learning and network analysis in the field of epilepsy. This review article will shed light on recent advances in neuroimaging for focal epilepsy, including both technical progress of images and newer analytical methodologies and discuss about the potential usefulness in clinical practice.

Ketogenic Diet Therapy for Epilepsy Associated With Aicardi Syndrome

Introduction: Aicardi syndrome is a rare neurodevelopmental disorder associated with epilepsy in females. Ketogenic diet therapy represents a possible nonpharmacologic treatment in Aicardi syndrome patients. Methods: All patients with Aicardi syndrome seen at Johns Hopkins Hospital (Baltimore, MD) and Johns Hopkins All Children’s Hospital (St Petersburg, FL) treated with ketogenic diet therapy since 1994 were evaluated retrospectively. Results: Fifteen patients, ages 4 months to 34 years, were identified. Ten (67%) patients experienced a ≥50% seizure reduction after 3 months, with 3 (20%) having a ≥90% reduction. Only 1 patient was seizure-free for a short period of time. The number of drugs tried prior to ketogenic diet therapy initiation was correlated with ≥50% seizure reduction at 3 months, 5.8 vs 2.6 in responders versus nonresponders ( P = .01). In addition, the mean number of drugs actively received also correlated, 3.0 vs 1.2, P = .005. Ketogenic diet therapy was slightly more successful in those without infantile spasms, 78% vs 50%, P = .33. Conclusion: Ketogenic diet therapy was helpful in Aicardi syndrome, although seizure freedom was rare. It was especially helpful for those who were more drug-resistant and did not have infantile spasms at ketogenic diet therapy onset.