A Review of Neurostimulation for Epilepsy in Pediatrics

A pediatrician's guide to epilepsy surgery

Surgical intervention for epilepsy emerged in the second half of the 20th century as an important option for pediatric patients with medically refractory epilepsy. Both the number of patients undergoing epilepsy surgery and the available surgical procedures for epilepsy have expanded in the last 3 decades, and now range from surgical resection to neuromodulatory device placement1,2 Studies showing that many patients who would be excellent candidates for surgery are still not being offered appropriate interventions have prompted an interest in ensuring that all providers who see patients with epilepsy are aware of the options for epilepsy surgery to facilitate earlier referrals when medications have not been effective3 In this article, we will introduce the pediatrician to the process involved in determining epilepsy surgery candidacy and to surgical outcomes, with the goal of empowering pediatric providers to refer their medically refractory epilepsy patients to a pediatric epilepsy center.

Efficacy and safety of transcranial pulse stimulation in young adolescents with attention-deficit/hyperactivity disorder: a pilot, randomized, double-blind, sham-controlled trial

Background

This is the first study to evaluate the efficacy and safety of transcranial pulse stimulation (TPS) for the treatment of attention-deficit/hyperactivity disorder (ADHD) among young adolescents in Hong Kong.

Methods

This double-blind, randomized, sham-controlled trial included a TPS group and a sham TPS group, encompassing a total of 30 subjects aged 12-17 years who were diagnosed with ADHD. Baseline measurements SNAP-IV, ADHD RS-IV, CGI and executive functions (Stroop tests, Digit Span) and post-TPS evaluation were collected. Both groups were assessed at baseline, immediately after intervention, and at 1-month and 3-month follow-ups. Repeated-measures ANOVAs were used to analyze data.

Results

The TPS group exhibited a 30% reduction in the mean SNAP-IV score at postintervention that was maintained at 1- and 3-month follow-ups.

Conclusion

TPS is an effective and safe adjunct treatment for the clinical management of ADHD.

Clinical trial registration

ClinicalTrials.Gov, identifier NCT05422274.

The role of psychology and neuropsychology in pediatric epilepsy surgery evaluation

Epilepsy is one of the most common neurological problems affecting 470,000 children in the United States. While most youth will achieve seizure freedom using medication, up to a third will continue to have seizures and are therefore considered to have drug-resistant epilepsy (DRE). Children and adolescents with epilepsy are at higher risk of behavioral, cognitive, and emotional disorders. Youth with DRE are at even greater risk of behavioral and emotional problems impacting quality of life and may need to pursue surgical interventions, including resective surgery or device implantation. Due to advances in the evaluation of candidates and surgical options, epilepsy surgery is more effective and has become second-line treatment for youth with DRE. This paper highlights the importance of exploring, assessing, and treating psychological and neuropsychological factors throughout the three phases of the epilepsy surgery process and ways pediatricians can support youth and families.

Predictors of therapeutic response following thalamic neuromodulation for drug-resistant pediatric epilepsy: A systematic review and individual patient data meta-analysis

We sought to perform a systematic review and individual participant data meta-analysis to identify predictors of treatment response following thalamic neuromodulation in pediatric patients with medically refractory epilepsy. Electronic databases (MEDLINE, Ovid, Embase, and Cochrane) were searched, with no language or data restriction, to identify studies reporting seizure outcomes in pediatric populations following deep brain stimulation (DBS) or responsive neurostimulation (RNS) implantation in thalamic nuclei. Studies featuring individual participant data of patients with primary or secondary generalized drug-resistant epilepsy were included. Response to therapy was defined as >50% reduction in seizure frequency from baseline. Of 417 citations, 21 articles reporting on 88 participants were eligible. Mean age at implantation was 13.07 ± 3.49 years. Fifty (57%) patients underwent DBS, and 38 (43%) RNS. Sixty (68%) patients were implanted in centromedian nucleus and 23 (26%) in anterior thalamic nucleus, and five (6%) had both targets implanted. Seventy-four (84%) patients were implanted bilaterally. The median time to last follow-up was 12 months (interquartile range = 6.75-26.25). Sixty-nine percent of patients achieved response to treatment. Age, target, modality, and laterality had no significant association with response in univariate logistic regression. Until thalamic neuromodulation gains widespread approval for use in pediatric patients, data on efficacy will continue to be limited to small retrospective cohorts and case series. The inherent bias of these studies can be overcome by using individual participant data. Thalamic neuromodulation appears to be a safe and effective treatment for epilepsy. Larger, prolonged prospective, multicenter studies are warranted to further evaluate the efficacy of DBS over RNS in this patient population where resection for curative intent is not a safe option.

Safety & feasibility of responsive neurostimulation in children with refractory epilepsy: A single-center experience

OBJECTIVES

Responsive neurostimulation (RNS) is a relatively recent addition to the epilepsy surgery armory, gaining FDA approval in 2013 for use in adults with intractable focal epilepsy. Data for the use of RNS system in patients less than 18 years of age is limited. We aim to determine the safety and feasibility of RNS in children with refractory epilepsy.

METHODS

A retrospective chart review was conducted for all patients who underwent RNS implantation at an urban tertiary children's hospital. Demographics of the patients were obtained, including age at the time of implant, MRI findings, seizure onset zone identification, and RNS targets.

RESULTS

Out of a fourteen patient cohort, one patient had a post-operative complication of infection at surgical site requiring explantation. Thirteen out of 14 patients had immediate post-operative head imaging that was negative for hemorrhage, infarction, or skull fracture; one patient did not undergo head imaging. No patients reported a worsening clinical seizure frequency at a 6-month follow up visit. In the subset of patients who were implanted with RNS and did not undergo concurrent resections, there was a statistically significant reduction in the average number of long episodes at the most recent visit when compared to the 1-month post-operative visit (p = 0.0268).

CONCLUSIONS

RNS is a feasible and safe option for children as young as six years with refractory epilepsy when appropriate seizure focus identification has been performed with stereo CT and stereo EEG evaluations, and can be used in conjunction with other surgical epilepsy treatment modalities. Two canister RNS placement is achievable for patients with a broad epileptogenic network or multifocal seizure onset zones.

The Utility of Responsive Neurostimulation for the Treatment of Pediatric Drug-Resistant Epilepsy

Drug-resistant epilepsy (DRE) has a strongly negative impact on quality of life, as well as the development of pediatric patients. Surgical treatments have evolved over time, including more invasive craniotomies for resection or disconnection. More recently, neuromodulation techniques have been employed as a less invasive option for patients. Responsive neurostimulation (RNS) is the first closed-loop technology that allows for both treatment and device data collection, which allows for an internal assessment of the efficacy of treatment. This novel technology has been approved in adults and has been used off label in pediatrics. This review seeks to describe this technology, its history, and future directions.

Neurosurgical management of non-spastic movement disorders

BACKGROUND

Non-spastic movement disorders in children are common, although true epidemiologic data is difficult to ascertain. Children are more likely than adults to have hyperkinetic movement disorders defined as tics, dystonia, chorea/athetosis, or tremor. These conditions manifest from acquired or heredodegenerative etiologies and often severely limit function despite medical and surgical management paradigms. Neurosurgical management for these conditions is highlighted.

METHODS

We performed a focused review of the literature by searching PubMed on 16 May 2023 using key terms related to our review. No temporal filter was applied, but only English articles were considered. We searched for the terms (("Pallidotomy"[Mesh]) OR "Rhizotomy"[Mesh]) OR "Deep Brain Stimulation"[Mesh], dystonia, children, adolescent, pediatric, globus pallidus, in combination. All articles were reviewed for inclusion in the final reference list.

RESULTS

Our search terms returned 37 articles from 2004 to 2023. Articles covering deep brain stimulation were the most common (n = 34) followed by pallidotomy (n = 3); there were no articles on rhizotomy.

DISCUSSION

Non-spastic movement disorders are common in children and difficult to treat. Most of these patients are referred to neurosurgery for the management of dystonia, with modern neurosurgical management including pallidotomy, rhizotomy, and deep brain stimulation. Historically, pallidotomy has been effective and may still be preferred in subpopulations presenting either in status dystonicus or with high risk for hardware complications. Superiority of DBS over pallidotomy for secondary dystonia has not been determined. Rhizotomy is an underutilized surgical tool and more study characterizing efficacy and risk profile is indicated.

The increase in c-fos expression in epileptic seizures is inhibited by magnetic field application, but not KCa1.1 channel expression

The aim of this study was to understand the expression of big potassium (BK, KCa1.1) channels in epileptic seizures under magnetic field application. Forty Wistar albino adult male rats were divided into five groups (n = 8). First group rats were control group. Pentylenetetrazole (PTZ) administrated to second group rats to induce the seizures with 35 mg/kg intraperitoneally injection every two days. Levetiracetam (LEV) i.p. at a dose of 108 mg/kg was given to third group rats as positive control group (PC) before 20 minutes PTZ administration. Pulsed magnetic field with 1.5 mT was exposed to the fourth group rats for 3 hours a day for 1 month as magnetic field (MF) group. 1.5 mT pulsed magnetic field was exposed to the fifth group rats for 3 hours a day for 1 month in addition to PTZ administration (PTZ+MF). KCa1.1 not changed in hippocampus of PTZ rats while increased in frontal cortex and pons for PTZ group but not changed with magnetic field exposure. KCa1.1 increased in heart of PTZ animals and turned back to mean control values with magnetic field exposure. Suppressing the expected increase of c-fos protein expression in seizures with magnetic field application but not being able to change the KCa1.1 expression shows that new studies can be done by increasing the frequency of 1.5 mT magnetic field.

Emerging approaches in neurostimulation for epilepsy

PURPOSE OF REVIEW

Neurostimulation is a quickly growing treatment approach for epilepsy patients. We summarize recent approaches to provide a perspective on the future of neurostimulation.

RECENT FINDINGS

Invasive stimulation for treatment of focal epilepsy includes vagus nerve stimulation, responsive neurostimulation of the cortex and deep brain stimulation of the anterior nucleus of the thalamus. A wide range of other targets have been considered, including centromedian, central lateral and pulvinar thalamic nuclei; medial septum, nucleus accumbens, subthalamic nucleus, cerebellum, fornicodorsocommissure and piriform cortex. Stimulation for generalized onset seizures and mixed epilepsies as well as increased efforts focusing on paediatric populations have emerged. Hardware with more permanently implanted lead options and sensing capabilities is emerging. A wider variety of programming approaches than typically used may improve patient outcomes. Finally, noninvasive brain stimulation with its favourable risk profile offers the potential to treat increasingly diverse epilepsy patients.

SUMMARY

Neurostimulation for the treatment of epilepsy is surprisingly varied. Flexibility and reversibility of neurostimulation allows for rapid innovation. There remains a continued need for excitability biomarkers to guide treatment and innovation. Neurostimulation, a part of bioelectronic medicine, offers distinctive benefits as well as unique challenges.

Evaluating the efficacy and safety of transcranial pulse stimulation on adolescents with attention deficit hyperactivity disorder: Study protocol of a pilot randomized, double-blind, sham-controlled trial

Background

Traditional treatment alone might not effectively control the severity of attention deficit hyperactivity disorder (ADHD) symptoms. Transcranial pulse stimulation (TPS) is a non-invasive brain stimulation (NIBS) technology used on older adults with mild neurocognitive disorders and adults with major depressive disorder. However, there has been no study conducted on young adolescents with ADHD. This will be the first nationwide study evaluating the efficacy and safety of TPS in the treatment of ADHD among young adolescents in Hong Kong.

Methods

This study proposes a double-blinded, randomized, sham-controlled trial including TPS as an intervention group and a sham TPS group. Both groups will be measured at baseline (T1), immediately after the intervention (T2), and at the 1-month (T3) and 3-month follow-ups (T4).

Recruitment

A total of 30 subjects aged between 12 and 17 years, diagnosed with attention deficit hyperactivity disorder (ADHD), will be recruited in this study. All subjects will be computer randomized into either the intervention group or the sham TPS group on a 1:1 ratio.

Intervention

All subjects in each group will have to undertake functional MRI (fMRI) before and after six 30-min TPS sessions, which will be completed in 2 weeks' time.

Outcomes

Baseline measurements and post-TPS evaluation of the ADHD symptoms and executive functions will also be conducted on all participants. The 1- and 3-month follow-up periods will be used to assess the long-term sustainability of the TPS intervention. For statistical analysis, ANOVA with repeated measures will be used to analyze data. Missing data were managed by multiple imputations. The level of significance will be set to p < 0.05.

Significance of the study

Results emerging from this study will generate new knowledge to ascertain whether TPS can be used as a top-on treatment for ADHD.

Clinical trial registration

clinicaltrails.gov, identifier: NCT05422274.

Retrospective Clinical Analysis of Epilepsy Treatment for Children with Drug-Resistant Epilepsy (A Single-Center Experience)

Objectives: This retrospective cohort study investigated the clinical characteristics and seizure outcomes of patients aged 1−14 years with drug-resistant epilepsy (DRE) who were treated by different typologies of therapy. Methods: Four hundred and eighteen children with DRE were recruited from Sanbo Brain Hospital of Capital Medical University from April 2008 to February 2015. The patients were divided into three groups: medication (n = 134, 32.06%), resection surgery (n = 185, 44.26%), and palliative surgery (n = 99, 23.68%) groups. Demographic characteristics were attained from medical records. All patients were followed up for at least 5 years, with seizure outcomes classified according to International League Against Epilepsy criteria. The psychological outcome was evaluated with the development quotient and Wechsler Intelligence Quotient Scale for children (Chinese version). Results: The most frequent seizure type was generalized tonic seizure in 53.83% of patients. Age at seizure onset in 54.55% of patients was <3 years. The most frequent etiologies were focal cortical dysplasia (FCD). West syndrome was the most common epilepsy syndrome. Favorable seizure outcomes at the 5-year follow-up in the medication, resection surgery, and palliative surgery groups were 5.22%, 77.30%, and 14.14%, respectively. The patients showed varying degrees of improvement in terms of developmental and intellectual outcomes post-treatment. Conclusions: Pediatric patients with DRE were characterized by frequent seizures, a variety of seizure types, and complex etiology. Recurrent seizures severely affected the cognitive function and development of children. Early surgical intervention would be beneficial for seizure control and prevention of mental retardation. Palliative surgery was also a reasonable option for patients who were not suitable candidates for resection surgery.

Repeat surgery for pediatric epilepsy: a systematic review and meta-analysis of resection and disconnection approaches

OBJECTIVE

Resection and disconnection surgeries for epilepsy in the pediatric demographic (patients ≤ 18 years of age) are two separate, definitive intervention options in medically refractory cases. Questions remain regarding the role of surgery when seizures persist after an initial incomplete surgery. The aim of this study was to review the contemporary literature and summarize the metadata on the outcomes of repeat surgery in this specific demographic.

METHODS

Searches of seven electronic databases from inception to July 2022 were conducted using PRISMA guidelines. Articles were screened using prespecified criteria. Metadata from the articles were abstracted and pooled by random-effects meta-analysis of proportions.

RESULTS

Eleven studies describing 12 cohorts satisfied all criteria, reporting outcomes of 170 pediatric patients with epilepsy who underwent repeat resection or disconnection surgery. Of these patients, 55% were male, and across all studies, median ages at initial and repeat surgeries were 7.2 and 9.4 years, respectively. The median follow-up duration after repeat surgery was 47.7 months. The most commonly reported etiology for epilepsy was cortical dysplasia. Overall, the estimated incidence of complete seizure freedom (Engel class I) following repeat surgery was 48% (95% CI 40%-56%, p value for heterogeneity = 0.93), and the estimated incidence of postoperative complications following repeat surgery was 25% (95% CI 12%-39%, p = 0.04). There were six cohorts each that described outcomes for repeat resection and repeat disconnection surgeries. There was no statistical difference between these two subgroups with respect to estimated incidence of complete seizure freedom (p value for interaction = 0.92), but postoperative complications were statistically more common following repeat resection (p ≤ 0.01).

CONCLUSIONS

For both resection and disconnection surgeries, repeat epilepsy surgery in children is likely to confer complete seizure freedom in approximately half of the patients who experience unsuccessful initial incomplete epilepsy surgery. More data are needed to elucidate the impact on efficacy based on surgical approach selection. Judicious discussion and planning between the patient, family, and a multidisciplinary team of epilepsy specialists is recommended to optimize expectations and outcomes in this setting.

Decision-making in stereotactic epilepsy surgery

Surgery can cure or significantly improve both the frequency and the intensity of seizures in patients with medication-refractory epilepsy. The set of diagnostic and therapeutic interventions involved in the path from initial consultation to definitive surgery is complex and includes a multidisciplinary team of neurologists, neurosurgeons, neuroradiologists, and neuropsychologists, supported by a very large epilepsy-dedicated clinical architecture. In recent years, new practices and technologies have emerged that dramatically expand the scope of interventions performed. Stereoelectroencephalography has become widely adopted for seizure localization; stereotactic laser ablation has enabled more focal, less invasive, and less destructive interventions; and new brain stimulation devices have unlocked treatment of eloquent foci and multifocal onset etiologies. This article articulates and illustrates the full framework for how epilepsy patients are considered for surgical intervention, with particular attention given to stereotactic approaches.

Safety and Management of Implanted Epilepsy Devices for Imaging and Surgery

Permanently implanted devices that deliver electrical stimulation are increasingly used to treat patients with drug-resistant epilepsy. Primary care physicians, neurologists, and epilepsy clinicians may encounter patients with a variety of implanted neuromodulation devices in the course of clinical care. Due to the rapidly changing landscape of available epilepsy-related neurostimulators, there may be uncertainty related to how these devices should be handled during imaging procedures and perioperative care. We review the safety and management of epilepsy-related implanted neurostimulators that may be encountered during imaging and surgery. We provide a summary of approved device labeling and recommendations for the practical management of these devices to help guide clinicians as they care for patients treated with bioelectronic medicine.

Responsive neurostimulation device therapy in pediatric patients with complex medically refractory epilepsy

OBJECTIVE

Pediatric epilepsy is characterized as drug resistant in 20%-30% of patients and defined as persistent seizures despite adequate treatment with two first-line antiepileptic medications. The American Academy of Neurology advocates surgical options earlier in the treatment of epilepsy to provide long-term seizure reduction. The new development of minimally invasive approaches has recently allowed for surgical options to patients not previously deemed surgical candidates. These may include patients with bilateral, deep, eloquent, or poorly localizing epileptogenic foci. To this end, responsive neurostimulation (RNS) is an FDA-approved closed-loop neuromodulation device for adjuvant treatment of adults with medically intractable epilepsy arising from one or multiple foci.

METHODS

In this study, the authors describe their initial institutional experience with the use of RNS in pediatric patients with drug-resistant epilepsy. An IRB-approved retrospective review was conducted of 8 pediatric patients who underwent RNS implantation at Cincinnati Children's Hospital Medical Center between 2019 and 2021.

RESULTS

Eight patients met the inclusion criteria for the study. The average age at the time of surgery was 14.7 years (range 8-18 years) with a mean follow-up of 16.5 months. All patients underwent invasive monitoring with stereo-EEG, subdural grid placement, or a combination of both. All patients had either bilateral or eloquent cortex targets. Trajectories were based on noninvasive (phase 1) and invasive (phase 2) seizure onset zone localization data. Four (50%) of the 8 patients underwent surgical intervention for epilepsy prior to RNS placement. RNS electrodes were placed with robot-assisted guidance in a hybrid operating room with intraoperative CT and electrocorticography. The authors demonstrated individualized RNS electrode trajectory and placement with targets in the amygdala/hippocampus, bilateral insula, bilateral parietal and occipital targets, and frontoparietal regions for a total of 14 implanted electrodes. One adverse event occurred, a wound infection requiring return to the operating room for removal of the RNS implant. All patients demonstrated a reduction in seizure frequency. All patients achieved > 50% reduction in seizure frequency at last follow-up.

CONCLUSIONS

RNS implantation in carefully selected pediatric patients appears safe and efficacious in reducing seizure burden with a low rate of operative complications.

Towards network-guided neuromodulation for epilepsy

Epilepsy is well-recognized as a disorder of brain networks. There is a growing body of research to identify critical nodes within dynamic epileptic networks with the aim to target therapies that halt the onset and propagation of seizures. In parallel, intracranial neuromodulation, including deep brain stimulation and responsive neurostimulation, are well-established and expanding as therapies to reduce seizures in adults with focal-onset epilepsy; and there is emerging evidence for their efficacy in children and generalized-onset seizure disorders. The convergence of these advancing fields is driving an era of 'network-guided neuromodulation' for epilepsy. In this review, we distil the current literature on network mechanisms underlying neurostimulation for epilepsy. We discuss the modulation of key 'propagation points' in the epileptogenic network, focusing primarily on thalamic nuclei targeted in current clinical practice. These include (i) the anterior nucleus of thalamus, now a clinically approved and targeted site for open loop stimulation, and increasingly targeted for responsive neurostimulation; and (ii) the centromedian nucleus of the thalamus, a target for both deep brain stimulation and responsive neurostimulation in generalized-onset epilepsies. We discuss briefly the networks associated with other emerging neuromodulation targets, such as the pulvinar of the thalamus, piriform cortex, septal area, subthalamic nucleus, cerebellum and others. We report synergistic findings garnered from multiple modalities of investigation that have revealed structural and functional networks associated with these propagation points - including scalp and invasive EEG, and diffusion and functional MRI. We also report on intracranial recordings from implanted devices which provide us data on the dynamic networks we are aiming to modulate. Finally, we review the continuing evolution of network-guided neuromodulation for epilepsy to accelerate progress towards two translational goals: (i) to use pre-surgical network analyses to determine patient candidacy for neurostimulation for epilepsy by providing network biomarkers that predict efficacy; and (ii) to deliver precise, personalized and effective antiepileptic stimulation to prevent and arrest seizure propagation through mapping and modulation of each patients' individual epileptogenic networks.

Practical considerations in epilepsy neurostimulation

Neuromodulation is a key therapeutic tool for clinicians managing patients with drug-resistant epilepsy. Multiple devices are available with long-term follow-up and real-world experience. The aim of this review is to give a practical summary of available neuromodulation techniques to guide the selection of modalities, focusing on patient selection for devices, common approaches and techniques for initiation of programming, and outpatient management issues. Vagus nerve stimulation (VNS), deep brain stimulation of the anterior nucleus of the thalamus (DBS-ANT), and responsive neurostimulation (RNS) are all supported by randomized controlled trials that show safety and a significant impact on seizure reduction, as well as a suggestion of reduction in the risk of sudden unexplained death in epilepsy (SUDEP). Significant seizure reductions are observed after 3 months for DBS, RNS, and VNS in randomized controlled trials, and efficacy appears to improve with time out to 7 to 10 years of follow-up for all modalities, albeit in uncontrolled follow-up or retrospective studies. A significant number of patients experience seizure-free intervals of 6 months or more with all three modalities. Number and location of epileptogenic foci are important factors affecting efficacy, and together with comorbidities such as severe mood or sleep disorders, may influence the choice of modality. Programming has evolved-DBS is typically initiated at lower current/voltage than used in the pivotal trial, whereas target charge density is lower with RNS, however generalizable optimal parameters are yet to be defined. Noninvasive brain stimulation is an emerging stimulation modality, although it is currently not used widely. In summary, clinical practice has evolved from those established in pivotal trials. Guidance is now available for clinicians who wish to expand their approach, and choice of neuromodulation technique may be tailored to individual patients based on their epilepsy characteristics, risk tolerance, and preferences.

Functional Source Separation-Identified Epileptic Network: Analysis Pipeline

This proof-of-concept (PoC) study presents a pipeline made by two blocks: 1. the identification of the network that generates interictal epileptic activity; and 2. the study of the time course of the electrical activity that it generates, called neurodynamics, and the study of its functional connectivity to the other parts of the brain. Network identification is achieved with the Functional Source Separation (FSS) algorithm applied to electroencephalographic (EEG) recordings, the neurodynamics quantified through signal complexity with the Higuchi Fractal Dimension (HFD), and functional connectivity with the Directed Transfer Function (DTF). This PoC is enhanced by the data collected before and after neuromodulation via transcranial Direct Current Stimulation (tDCS, both Real and Sham) in a single drug-resistant epileptic person. We observed that the signal complexity of the epileptogenic network, reduced in the pre-Real, pre-Sham, and post-Sham, reached the level of the rest of the brain post-Real tDCS. DTF changes post-Real tDCS were maintained after one month. The proposed approach can represent a valuable tool to enhance understanding of the relationship between brain neurodynamics characteristics, the effects of non-invasive brain stimulation, and epileptic symptoms.

Seizure freedom after laser amygdalohippocampotomy guided by bilateral responsive neurostimulation in pediatric epilepsy: illustrative case

BACKGROUND

For patients with difficult-to-lateralize temporal lobe epilepsy, the use of chronic recordings as a diagnostic tool to inform subsequent surgical therapy is an emerging paradigm that has been reported in adults but not in children.

OBSERVATIONS

The authors reported the case of a 15-year-old girl with pharmacoresistant temporal lobe epilepsy who was found to have bitemporal epilepsy during a stereoelectroencephalography (sEEG) admission. She underwent placement of a responsive neurostimulator system with bilateral hippocampal depth electrodes. However, over many months, her responsive neurostimulation (RNS) recordings revealed that her typical, chronic seizures were right-sided only. This finding led to a subsequent right-sided laser amygdalohippocampotomy, resulting in seizure freedom.

LESSONS

In this case, RNS chronic recording provided real-world data that enabled more precise seizure localization than inpatient sEEG data, informing surgical decision-making that led to seizure freedom. The use of RNS chronic recordings as a diagnostic adjunct to seizure localization procedures and laser ablation therapies in children is an area with potential for future study.

Innovative treatments for epilepsy: Venom peptides, cannabinoids, and neurostimulation

Antiepileptic drugs have been successfully treating epilepsy and providing individuals sustained seizure freedom. However, about 30% of the patients with epilepsy present drug resistance, which means they are not responsive to the pharmacological treatment. Considering this, it becomes extremely relevant to pursue alternative therapeutic approaches, in order to provide appropriate treatment for those patients and also improve their quality of life. In the light of that, this review aims to discuss some innovative options for the treatment of epilepsy, which are currently under investigation, addressing strategies that go from therapeutic compounds to clinical procedures. For instance, peptides derived from animal venoms, such as wasps, spiders, and scorpions, demonstrate to be promising antiepileptic molecules, acting on a variety of targets. Other options are cannabinoids and compounds that modulate the endocannabinoid system, since it is now known that this network is involved in the pathophysiology of epilepsy. Furthermore, neurostimulation is another strategy, being an alternative clinical procedure for drug-resistant patients who are not eligible for palliative surgeries.

Effect of Vagus Nerve Stimulation on Blood Inflammatory Markers in Children with Drug-Resistant Epilepsy: A Pilot Study

Background: Since one of the suggested mechanisms of action of VNS on epilepsy is the reduction of central inflammation, we carried out a comprehensive analysis of blood inflammatory markers in children considered for VNS surgery. Materials and methods: Five pediatric patients were studied. An extensive analysis of blood inflammatory markers was performed before surgery (T0) and six weeks after VNS implantation (T1). An epileptological outcome was obtained according to the McHugh score. Results: The variations of IgA, IgE, IgG, CD19, and PTX3 displayed a tendency toward a positive statistical correlation between T0 and T1. According to McHugh score, the patients were divided into Group 1 (i.e., Class I) and Group 2 (i.e., Classes II and III). IL-1β and PTX-3 tended to decrease more in Group 1, while TNF-α decreased in Group 2 (−56.65%) and slightly increased (+3.61%) in Group 1 at T1 without statistical correlation. Conclusions: The variation of IL-1β and PTX-3 seem to be related to a better outcome; thus, they do not reach statistical significance. A larger series of patients is needed to determine whether biochemical changes could relay with the clinical improvement of epilepsy.

A prediction model integrating synchronization biomarkers and clinical features to identify responders to vagus nerve stimulation among pediatric patients with drug-resistant epilepsy

Aims

Vagus nerve stimulation (VNS) is a neuromodulation therapy for children with drug‐resistant epilepsy (DRE). The efficacy of VNS is heterogeneous. A prediction model is needed to predict the efficacy before implantation.

Methods

We collected data from children with DRE who underwent VNS implantation and received regular programming for at least 1 year. Preoperative clinical information and scalp video electroencephalography (EEG) were available in 88 children. Synchronization features, including phase lag index (PLI), weighted phase lag index (wPLI), and phase‐locking value (PLV), were compared between responders and non‐responders. We further adapted a support vector machine (SVM) classifier selected from 25 clinical and 18 synchronization features to build a prediction model for efficacy in a discovery cohort (n = 70) and was tested in an independent validation cohort (n = 18).

Results

In the discovery cohort, the average interictal awake PLI in the high beta band was significantly higher in responders than non‐responders (p < 0.05). The SVM classifier generated from integrating both clinical and synchronization features had the best prediction efficacy, demonstrating an accuracy of 75.7%, precision of 80.8% and area under the receiver operating characteristic (AUC) of 0.766 on 10‐fold cross‐validation. In the validation cohort, the prediction model demonstrated an accuracy of 61.1%.

Conclusion

This study established the first prediction model integrating clinical and baseline synchronization features for preoperative VNS responder screening among children with DRE. With further optimization of the model, we hope to provide an effective and convenient method for identifying responders before VNS implantation.

An affordable implantable vagus nerve stimulator system for use in animal research

In this research, a vagus nerve stimulator has been developed and miniaturized for use in epilepsy research. The board contains all the components necessary for its operation during the standard duration of the experiments, being possible to control it once implanted and even being able to reuse it. The VNS system has been designed for rodents since the VNS devices available for human are not only too large for laboratory animals, but also too expensive. With this solution the expenditure on materials made by laboratories is greatly reduced and bioethical considerations were kept in mind. The system was validated in hamsters. This article is part of the theme issue 'Advanced neurotechnologies: translating innovation for health and well-being'.

Surgical Treatment of Drug-Resistant Generalized Epilepsy

PURPOSE OF REVIEW

To summarize current evidence and recent developments in the surgical treatment of drug-resistant generalized epilepsy.

RECENT FINDINGS

Current surgical treatments of drug-resistant generalized epilepsy include vagus nerve stimulation (VNS), deep brain stimulation (DBS) and corpus callosotomy (CC). Neurostimulation with VNS and/or DBS has been shown to be effective in reducing seizure frequency in patients with generalized epilepsy. DBS for generalized epilepsy is primarily consisted of open-loop stimulation directed at the centromedian (CM) nucleus in the thalamus, though closed-loop stimulation and additional targets are being explored. CC can be effective in treating some seizure types and can be performed using traditional surgical techniques or with the less invasive methods of laser ablation and radiosurgery. This current literature supports the use of VNS, DBS and CC, alone or in combination, as palliative treatments of drug-resistant generalized epilepsy.

Personalized tDCS for Focal Epilepsy—A Narrative Review: A Data-Driven Workflow Based on Imaging and EEG Data

Conventional transcranial electric stimulation(tES) using standard anatomical positions for the electrodes and standard stimulation currents is frequently not sufficiently selective in targeting and reaching specific brain locations, leading to suboptimal application of electric fields. Recent advancements in in vivo electric field characterization may enable clinical researchers to derive better relationships between the electric field strength and the clinical results. Subject-specific electric field simulations could lead to improved electrode placement and more efficient treatments. Through this narrative review, we present a processing workflow to personalize tES for focal epilepsy, for which there is a clear cortical target to stimulate. The workflow utilizes clinical imaging and electroencephalography data and enables us to relate the simulated fields to clinical outcomes. We review and analyze the relevant literature for the processing steps in the workflow, which are the following: tissue segmentation, source localization, and stimulation optimization. In addition, we identify shortcomings and ongoing trends with regard to, for example, segmentation quality and tissue conductivity measurements. The presented processing steps result in personalized tES based on metrics like focality and field strength, which allow for correlation with clinical outcomes.

Contributions of Magnetoencephalography to Understanding Mechanisms of Generalized Epilepsies: Blurring the Boundary Between Focal and Generalized Epilepsies?

According to the latest operational 2017 ILAE classification of epileptic seizures, the generalized epileptic seizure is still conceptualized as "originating at some point within and rapidly engaging, bilaterally distributed networks." In contrast, the focal epileptic seizure is defined as "originating within networks limited to one hemisphere." Hence, one of the main concepts of "generalized" and "focal" epilepsy comes from EEG descriptions before the era of source localization, and a presumed simultaneous bilateral onset and bi-synchrony of epileptiform discharges remains a hallmark for generalized seizures. Current literature on the pathophysiology of generalized epilepsy supports the concept of a cortical epileptogenic focus triggering rapidly generalized epileptic discharges involving intact corticothalamic and corticocortical networks, known as the cortical focus theory. Likewise, focal epilepsy with rich connectivity can give rise to generalized spike and wave discharges resulting from widespread bilateral synchronization. Therefore, making this key distinction between generalized and focal epilepsy may be challenging in some cases, and for the first time, a combined generalized and focal epilepsy is categorized in the 2017 ILAE classification. Nevertheless, treatment options, such as the choice of antiseizure medications or surgical treatment, are the reason behind the importance of accurate epilepsy classification. Over the past several decades, plentiful scientific research on the pathophysiology of generalized epilepsy has been conducted using non-invasive neuroimaging and postprocessing of the electromagnetic neural signal by measuring the spatiotemporal and interhemispheric latency of bi-synchronous or generalized epileptiform discharges as well as network analysis to identify diagnostic and prognostic biomarkers for accurate diagnosis of the two major types of epilepsy. Among all the advanced techniques, magnetoencephalography (MEG) and multiple other methods provide excellent temporal and spatial resolution, inherently suited to analyzing and visualizing the propagation of generalized EEG activities. This article aims to provide a comprehensive literature review of recent innovations in MEG methodology using source localization and network analysis techniques that contributed to the literature of idiopathic generalized epilepsy in terms of pathophysiology and clinical prognosis, thus further blurring the boundary between focal and generalized epilepsy.

Closed-Loop Tracking and Regulation of Emotional Valence State From Facial Electromyogram Measurements

Affective studies provide essential insights to address emotion recognition and tracking. In traditional open-loop structures, a lack of knowledge about the internal emotional state makes the system incapable of adjusting stimuli parameters and automatically responding to changes in the brain. To address this issue, we propose to use facial electromyogram measurements as biomarkers to infer the internal hidden brain state as feedback to close the loop. In this research, we develop a systematic way to track and control emotional valence, which codes emotions as being pleasant or obstructive. Hence, we conduct a simulation study by modeling and tracking the subject's emotional valence dynamics using state-space approaches. We employ Bayesian filtering to estimate the person-specific model parameters along with the hidden valence state, using continuous and binary features extracted from experimental electromyogram measurements. Moreover, we utilize a mixed-filter estimator to infer the secluded brain state in a real-time simulation environment. We close the loop with a fuzzy logic controller in two categories of regulation: inhibition and excitation. By designing a control action, we aim to automatically reflect any required adjustments within the simulation and reach the desired emotional state levels. Final results demonstrate that, by making use of physiological data, the proposed controller could effectively regulate the estimated valence state. Ultimately, we envision future outcomes of this research to support alternative forms of self-therapy by using wearable machine interface architectures capable of mitigating periods of pervasive emotions and maintaining daily well-being and welfare.

Non-pharmacological treatments for pediatric refractory epilepsies

INTRODUCTION

Antiseizure medications (ASMs) are the primary treatment option for epilepsies of wide etiologies, however, about 10-20% of children do not gain sustained seizure control and in this case, it is worth investigating "alternative" therapeutic approaches aside from ASMs. Nowadays, non-pharmacological strategies for epilepsy treatment encompass dietary interventions, neurostimulation-based techniques, and biobehavioral approaches.

AREAS COVERED

A search on PubMed database was conducted. Experimental and clinical studies, as well as meta-analysis and structured reviews on the latest non-pharmacological treatments for drug-resistant epilepsy (DRE) in children, were included. Special attention is given to the efficacy and tolerability outcomes, trying to infer the role novel approaches may have in the future.

EXPERT OPINION

The large heterogeneity of primary clinical outcomes and the unavoidable subjective response of each patient to treatments prevents Researchers from the identification of a single, reliable, approach to treat DRE. The understanding of fine pathophysiologic processes is giving the way to the use of alternative therapies, such as the well-known ketogenic diet, in a "personalized" view of treatment. The goal is to apply the non-pharmacological treatment most suitable for the patient's sake.

Case Report: Prolonged Effects of Short-Term Transcranial Magnetic Stimulation on EEG Biomarkers, Spectral Power, and Seizure Frequency

Transcranial magnetic stimulation (TMS) is a non-invasive modality of focal brain stimulation in which a fluctuating magnetic field induces electrical currents within the cortex. It remains unclear to what extent TMS alters EEG biomarkers and how EEG biomarkers may guide treatment of focal epilepsy. We present a case of a 48-year-old man with focal epilepsy, refractory to multiple medication trials, who experienced a dramatic reduction in seizures after targeting the area of seizure onset within the left parietal-occipital region with low-frequency repetitive TMS (rTMS). Prior to treatment, he experienced focal seizures that impacted cognition including apraxia at least 50-60 times daily. MRI of the brain showed a large focal cortical dysplasia with contrast enhancement involving the left occipital-parietal junction. Stimulation for 5 consecutive days was well-tolerated and associated with a day-by-day reduction in seizure frequency. In addition, he was monitored with continuous video EEG, which showed continued and progressive changes in spectral power (decreased broadband power and increased infraslow delta activity) and a gradual reduction in seizure frequency and duration. One month after initial treatment, 2-day ambulatory EEG demonstrated seizure-freedom and MRI showed resolution of focal contrast enhancement. He continues to receive 2-3 days of rTMS every 2-4 months. He was seizure-free for 6 months, and at last follow-up of 17 months was experiencing auras approximately every 2 weeks without progression to disabling seizures. This case demonstrates that rTMS can be a well-tolerated and effective means of controlling medication-refractory seizures, and that EEG biomarkers change gradually in a fashion in association with seizure frequency. TMS influences cortical excitability, is a promising non-invasive means of treating focal epilepsy, and has measurable electrophysiologic effects.

Effects of Stable Vagus Nerve Stimulation Efficacy on Autistic Behaviors in Ten Pediatric Patients With Drug Resistant Epilepsy: An Observational Study

Vagus nerve stimulation (VNS) is a safe and effective therapy for pediatric patients with drug-resistant epilepsy (DRE). However, in children with DRE, the effects of VNS on autistic behaviors remain controversial. We retrospectively collected data from 10 children with DRE who underwent VNS implantation and regular parameter regulation in three pediatric epilepsy centers, and completed the behavioral assessments, including the autistic behavior checklist and the child behavior checklist, at follow-ups 1 (mean 2.16 years) and 2 (mean 2.98 years). The 10 children maintained stable seizure control between the two follow-ups. Their autistic behaviors, especially in language, social and self-help, were reduced at follow-up 2 compared to follow-up 1 (p = 0.01, p = 0.01, respectively). Moreover, these improvements were not associated with their seizure control, whether it was positive or negative. These results suggested that the VNS had a positive effect on autistic behaviors, which provided a preliminary clinical basis that VNS may benefit to younger children with DRE comorbidity autism spectrum disorder (ASD).

Teaching about children with medical complexity: A blueprint for curriculum design

Children with medical complexity make up a small portion of the pediatric population but utilize a large percentage of health care time and spending. The medical needs of children with medical complexity are highly variable and the education of healthcare providers in the care of these children has taken on more significance. Designing curricula and educational innovations related to the care of children with medical complexity can be challenging. Familiarity with the sociocultural theory, the zone of proximal development, Kolb's experiential learning model, and the educational resources that already exist allow for more ease in developing a curriculum that fits the needs of learners who may have a wide range of exposure to children with medical complexity. Flipped classroom models, simulations, asynchronous modules, and home and community experiences are all useful learning modalities to provide a varied and important curriculum. Taking advantage of the knowledge and skills of the many different members of the multi-disciplinary team caring for children with medical complexity is an important educational strategy that provides benefits to the learners and can enhance interprofessional education.

Transcranial Direct Current Stimulation Reduces Anxiety, Depression and Plasmatic Corticosterone in a Rat Model of Atypical Generalized Epilepsy

Affective disorders (i.e. anxiety and depression) are commonly observed in patients with epilepsy and induce seizure aggravation. Animal models of epilepsy that exhibit affective disorder features are essential in developing new neuromodulatory treatments. GEAS-W rats (Generalized Epilepsy with Absence Seizures, Wistar background) are an inbred model of generalized epilepsy showing spontaneous spike-wave discharges concomitant with immobility. Transcranial Direct Current Stimulation (tDCS) is a safe non-invasive neuromodulatory therapy used to modulate dysfunctional circuitries frequently and successfully applied in affective disorders for symptom alleviation. Here we investigated anxiolytic and antidepressant effects of tDCS in GEAS-W rats and the role of corticosterone as a possible mechanism of action. GEAS-W and Wistar rats were randomly divided into control, sham-tDCS and active-tDCS groups. Both tDCS groups received 15 sessions of sham or active-tDCS (1 mA, cathode). Behavioural tests included the Open Field and Forced Swimming tests followed by corticosterone analysis. We observed a main effect of treatment and a significant treatment by strain interaction on anxiety-like and depressive-like behaviours, with active-tDCS GEAS-W rats entering the center of the open field more often and showing less immobility in the forced swimming test. Furthermore, there was a main effect of treatment on corticosterone with active-tDCS animals showing marked reduction in plasmatic levels. This study described preclinical evidence to support tDCS treatment of affective disorders in epilepsy and highlights corticosterone as a possible mechanism of action.

Ketogenic diet (KD) therapy in the acute phase of febrile infection-related epilepsy syndrome (FIRES): a case report

Management of frequent epileptic seizures in febrile infection-related epilepsy (FIRES) is often challenging. FIRES is an uncommon disease condition. Children with FIRES develop refractory epilepsy with severe cognitive deficits that affect the function of the temporal and frontal lobes. However, better seizure control during the acute stage of FIRES could protect against injury to the nervous system. Ketogenic diet (KD) can effectively resolve super-refractory status epilepticus (SRSE) in the acute phase and improve the prognosis of FIRES. We present the case of a previously healthy 3-year-old male with new-onset status epilepticus (SE) admitted to the paediatric intensive care unit for 55 days. Despite treatment with multiple anti-epileptic agents in addition to IV anaesthetics, the patient remained in SRSE and continued to have generalised epileptic activity on electroencephalography (EEG). KD therapy was initiated on the 14th day of the onset, and the patient achieved complete neurological recovery following the KD. Throughout the remainder of admission, the patient was successfully weaned off the ventilator, tolerated oral meals, and worked with occupational and physical therapists to return to his baseline functional status. The convulsions were well controlled after discharge. We discuss the treatment strategies for FIRES and highlight the role of KD therapy in the acute phase to control disease progression and improve the prognosis, and early diagnosis of FIRES and early initiation of KD therapy combined with anti-epileptic drugs (AEDs) could improve the prognosis.

Advances in Epilepsy Surgery

BACKGROUND

A large number of patients have epilepsy that is intractable and adversely affects a child's lifelong experience with addition societal burden that is disabling and expensive. The last two decades have seen a major explosion of new antiseizure medication options. Despite these advances, children with epilepsy continue to have intractable seizures. An option that has been long available but little used is epilepsy surgery to control intractable epilepsy.

METHODS

This article is a review of the literature as well as published opinions.

RESULTS

Epilepsy surgery in pediatrics is an underused modality to effectively treat children with epilepsy. Adverse effects of medication should be weighed against risks of surgery as well as risks of nonefficacy.

CONCLUSIONS

We discuss an approach to selecting the appropriate pediatric patient for consideration, a detailed evaluation including necessary evaluation, and the creation of an algorithm to approach patients with both generalized and focal epilepsy. We then discuss surgical options available including outcome data. New modalities are also addressed including high-frequency ultrasound and co-registration techniques including magnetic resonance imaging-guided laser therapy.

Invasive Electrophysiology for Circuit Discovery and Study of Comorbid Psychiatric Disorders in Patients With Epilepsy: Challenges, Opportunities, and Novel Technologies

Intracranial electroencephalographic (iEEG) recordings from patients with epilepsy provide distinct opportunities and novel data for the study of co-occurring psychiatric disorders. Comorbid psychiatric disorders are very common in drug-resistant epilepsy and their added complexity warrants careful consideration. In this review, we first discuss psychiatric comorbidities and symptoms in patients with epilepsy. We describe how epilepsy can potentially impact patient presentation and how these factors can be addressed in the experimental designs of studies focused on the electrophysiologic correlates of mood. Second, we review emerging technologies to integrate long-term iEEG recording with dense behavioral tracking in naturalistic environments. Third, we explore questions on how best to address the intersection between epilepsy and psychiatric comorbidities. Advances in ambulatory iEEG and long-term behavioral monitoring technologies will be instrumental in studying the intersection of seizures, epilepsy, psychiatric comorbidities, and their underlying circuitry.

Evaluation and management of drug resistant epilepsy in children

Epilepsy is one of the most common neurological conditions in children. Most children with epilepsy respond to anti- epileptic drugs (AEDs) but approximately 30% of children develop drug resistant epilepsy (DRE) defined as 'the failure of adequate trials of two tolerated, appropriately chosen and used anti-epileptic drugs (AEDs)'. DRE is associated with serious consequences including higher mortality and worse cognitive outcomes. DRE impacts several aspects of the child's and the caregiver's life.

Neuromodulation in Drug Resistant Epilepsy

Epilepsy affects approximately 70 million people worldwide, and it is a significant contributor to the global burden of neurological disorders. Despite the advent of new AEDs, drug resistant-epilepsy continues to affect 30-40% of PWE. Once identified as having drug-resistant epilepsy, these patients should be referred to a comprehensive epilepsy center for evaluation to establish if they are candidates for potential curative surgeries. Unfortunately, a large proportion of patients with drug-resistant epilepsy are poor surgical candidates due to a seizure focus located in eloquent cortex, multifocal epilepsy or inability to identify the zone of ictal onset. An alternative treatment modality for these patients is neuromodulation. Here we present the evidence, indications and safety considerations for the neuromodulation therapies in vagal nerve stimulation (VNS), responsive neurostimulation (RNS), or deep brain stimulation (DBS).

The Pharmacoresistant Epilepsy: An Overview on Existent and New Emerging Therapies

Epilepsy is one of the most common neurological chronic disorders, with an estimated prevalence of 0. 5 - 1%. Currently, treatment options for epilepsy are predominantly based on the administration of symptomatic therapy. Most patients are able to achieve seizure freedom by the first two appropriate drug trials. Thus, patients who cannot reach a satisfactory response after that are defined as pharmacoresistant. However, despite the availability of more than 20 antiseizure medications (ASMs), about one-third of epilepsies remain drug-resistant. The heterogeneity of seizures and epilepsies, the coexistence of comorbidities, and the broad spectrum of efficacy, safety, and tolerability related to the ASMs, make the management of these patients actually challenging. In this review, we analyze the most relevant clinical and pathogenetic issues related to drug-resistant epilepsy, and then we discuss the current evidence about the use of available ASMs and the alternative non-pharmacological approaches.

Comparison of efficiency between VNS and ANT-DBS therapy in drug-resistant epilepsy: A one year follow up study

Vagus nerve stimulation (VNS) and anterior thalamic deep brain stimulation (ANT-DBS) have both been used for treatments of drug-resistant epilepsy (DRE). However, there is no comparative study on the effectiveness of two methods from one single center. 17 patients with DRE who underwent VNS therapy and 18 patients who underwent DBS were enrolled. A retrospective study was performed starting from baseline before operation extending to 12 months after operation. The seizure types, duration of epilepsy, age at implantation, failed numbers of antiepileptic drugs (AEDs) before operation, history of craniotomy, stimulation parameters and response rate were described. The analysis of liner regression on the age of onset, duration of epilepsy, numbers of AEDs, and the seizure reduction at 12 months after operation was applied. The mean seizure reduction in patients with DBS at 3, 6, 9 and 12 months after the operation was 57.22%, 61.61%, 63.94% and 65.28%, and that in cases with VNS was 36.06%, 39.94%, 45.24% and 48.35%, respectively. At 1 year after the operation, the patients with older operation age, focal seizures and older age of onset responded better to VNS; and those older operation age, focal generalized seizures, history of craniotomy and longer duration of disease responded better to DBS. The efficiency of ANT-DBS was higher than that of VNS at each follow up time point. Patients can choose the appropriate treatment according to the individual clinical characteristics.

Is vagal-nerve stimulation safe during pregnancy? A mini review

BACKGROUND

Vagus-nerve stimulation (VNS) is the most common neuromodulation technique and has been approved by the FDA for treating refractory epilepsy and refractory depression. Although VNS has been used for nearly 32 years, the impact of VNS on the safety of pregnant women and neonate remains to be evaluated.

METHODS

We first analyze the relationship between the vagus nerve and the reproductive system (ovary and uterus) and then determine whether harm is inflicted to the reproductive system, thereby affecting the pregnancy. A comprehensive literature search is performed on PubMed/MEDLINE database, Web of Science, and Scopus. Ten articles are included in the study, and 44 pregnancies of 38 patients are analyzed.

RESULTS

The vagus nerve is connected with the reproductive system, but VNS may have little effect on pregnancy. We analyze 10 articles (38 patients with 44 pregnancies) about VNS complications during pregnancy. Two of the 44 pregnancies (2/44, 4.5 %) are miscarriages, and two pregnancies have fetuses with congenital malformations (2/42, 4.8 %), which could also be attributed to polytherapy with antiepileptic drugs. The rest of the pregnant women have no postpartum complications, and their fetuses are healthy.

CONCLUSIONS

VNS may be relatively safe and effective for the fetus and mother during pregnancy, and turning off VNS during pregnancy is unnecessary. However, owing to the small sample size and short follow-up time in the present study, further research is needed.

Responsive neurostimulation for the treatment of medically refractory epilepsy in pediatric patients: strategies, outcomes, and technical considerations

OBJECTIVE

Children with medically refractory partial-onset epilepsy arising from eloquent cortex present a therapeutic challenge, as many are not suitable for resective surgery. For these patients, responsive neurostimulation may prove to be a potential tool. Although responsive neurostimulation has demonstrated utility in adults, little has been discussed regarding its utility in the pediatric population. In this study, the authors present their institution's experience with responsive neurostimulation via the RNS System through a case series of 5 pediatric patients.

METHODS

A single-center retrospective study of patients who underwent RNS System implantation at Children's National Hospital was performed.

RESULTS

Five patients underwent RNS System implantation. The mean patient age at treatment was 16.8 years, and the average follow-up was 11.2 months. All patients were considered responders, with a seizure frequency reduction of 64.2% without adverse events.

CONCLUSIONS

All 5 patients experienced medium-term improvements in seizure control after RNS System implantation with decreases in seizure frequency > 50% from baseline preoperative seizure frequency. The authors demonstrated two primary configurations of electrode placement: hippocampal or amygdala placement via an occipitotemporal trajectory, as well as infratemporal surface electrodes and surface electrodes on the primary motor cortex. No adverse events were experienced in this case series.

Altered amplitude of low-frequency fluctuations and regional homogeneity in drug-resistant epilepsy patients with vagal nerve stimulators under different current intensity

BACKGROUND

The mechanisms of vagal nerve stimulation (VNS) for the treatment of drug-resistant epilepsy (DRE) remain unclear. This study aimed to measure spontaneous brain activity changes caused by VNS in DRE patients using resting-state functional MRI (rs-fMRI).

METHODS

The rs-fMRI scans were performed in 16 DRE patients who underwent VNS surgery. Amplitude of low-frequency fluctuations (ALFF) and regional homogeneity (ReHo) was generated and examined using paired sample t-test to compare activity changes at different current intensity stage. The preoperative and postoperative ALFF/ReHo were also compared in eight responders (≥50% reduction of seizure frequency three months after surgery) and eight nonresponders using paired sample t-test.

RESULTS

The significant ALFF and ReHo changes were shown in various cortical/subcortical structures in patients under different current intensity. After three months of stimulation, responders exhibited increased ALFF in the right middle cingulate gyrus, left parahippocampal gyrus, and left cerebellum, and increased ReHo in the right postcentral gyrus, left precuneus, left postcentral gyrus, right superior parietal gyrus, right precentral gyrus, and right superior frontal gyrus. Nonresponders exhibited decreased ALFF in the left temporal lobe and right cerebellum, increased ALFF in bilateral brainstem, decreased ReHo in bilateral lingual gyri, and increased ReHo in the right middle frontal gyrus and right anterior cingulate gyrus.

CONCLUSIONS

The spontaneous neural activity changes in DRE patients caused by VNS were in an ongoing process. Increased ALFF/ReHo in frontal cortex, cingulate gyri, precentral/postcentral gyri, parahippocampal gyri, precuneus, parietal cortex, and cerebellum may implicate in VNS-induced improvement in seizure frequency.

Youth Weigh In: Views on Advanced Neurotechnology for Drug-Resistant Epilepsy

BACKGROUND

Epilepsy affects over 500,000 children in North America of whom 30% have drug-resistant epilepsy. Advancements with neurotechnologies show promising benefits, but the perceptions of these procedures by youth is unknown.

METHODS

We conducted semistructured interviews with 10 youth in British Columbia, Canada who underwent procedures for drug-resistant epilepsy involving different forms of neurotechnology (subdural grids, vagus nerve stimulation, responsive neurostimulation). Interviews were analyzed using the constant comparative qualitative method.

RESULTS

Four major thematic categories emerged from the interviews. Treatment values, impact of the disorder, personal context, and impact of neurotechnology.

CONCLUSIONS

Besides the predictable goal of seizure reduction, a desire for autonomy and the importance of trust in the medical team emerged as dominant values within the 4 thematic categories that were explicit to the use of new neurotechnologies for the management of drug-resistant epilepsy.

Safety of responsive neurostimulation in pediatric patients with medically refractory epilepsy

OBJECTIVE

Approximately 75% of pediatric patients who suffer from epilepsy are successfully treated with antiepileptic drugs, while the disease is drug resistant in the remaining patients, who continue to have seizures. Patients with drug-resistant epilepsy (DRE) may have options to undergo invasive treatment such as resection, laser ablation of the epileptogenic focus, or vagus nerve stimulation. To date, treatment with responsive neurostimulation (RNS) has not been sufficiently studied in the pediatric population because the FDA has not approved the RNS device for patients younger than 18 years of age. Here, the authors sought to investigate the safety of RNS in pediatric patients.

METHODS

The authors performed a retrospective single-center study of consecutive patients with DRE who had undergone RNS system implantation from September 2015 to December 2019. Patients were followed up postoperatively to evaluate seizure freedom and complications.

RESULTS

Of the 27 patients studied, 3 developed infections and were treated with antibiotics. Of these 3 patients, one required partial removal and salvaging of a functioning system, and one required complete removal of the RNS device. No other complications, such as intracranial hemorrhage, stroke, or device malfunction, were seen. The average follow-up period was 22 months. All patients showed improvement in seizure frequency.

CONCLUSIONS

The authors demonstrated the safety and efficacy of RNS in pediatric patients, with infections being the main complication.

ABBREVIATIONS

DBS = deep brain stimulation; DRE = drug-resistant epilepsy; MDC = multidisciplinary conference; MER = microelectrode recording; MSHS = Mount Sinai Health System; RNS = responsive neurostimulation; SEEG = stereo-EEG; VNS = vagus nerve stimulation.

Cortical stimulation in pharmacoresistant focal epilepsies

Pharmacoresistance and adverse drug events designate a considerable group of patients with focal epilepsies that require alternative treatments such as neurosurgical intervention and neurostimulation. Electrical or magnetic stimulations of cortical brain areas for the treatment of pharmacoresistant focal epilepsies emerged from preclinical studies and experience through intraoperative neurophysiological monitoring in patients. Direct neurostimulation of seizure onset zones in neocortical brain areas may specifically affect neuronal networks involved in epileptiform activity without remarkable adverse influence on physiological cortical processing in immediate vicinity. Noninvasive low-frequency transcranial magnetic stimulation and cathodal transcranial direct current stimulation are suggested to be anticonvulsant; however, potential effects are ephemeral and require effect maintenance by ongoing stimulation. Invasive responsive neurostimulation, chronic subthreshold cortical stimulation, and epicranial cortical stimulation cover a broad range of different emerging technologies with intracranial and epicranial approaches that still have limited market access partly due to ongoing clinical development. Despite significant differences, the present bioelectronic technologies share common mode of actions with acute seizure termination by high-frequency stimulation and long-term depression induced by low-frequency magnetic or electrical stimulation or transcranial direct current stimulation.

Neurophysiological and Genetic Findings in Patients With Juvenile Myoclonic Epilepsy

Objective

Transcranial magnetic stimulation (TMS), a non-invasive procedure, stimulates the cortex evaluating the central motor pathways. The response is called motor evoked potential (MEP). Polyphasia results when the response crosses the baseline more than twice (zero crossing). Recent research shows MEP polyphasia in patients with generalized genetic epilepsy (GGE) and their first-degree relatives compared with controls. Juvenile Myoclonic Epilepsy (JME), a GGE type, is not well studied regarding polyphasia. In our study, we assessed polyphasia appearance probability with TMS in JME patients, their healthy first-degree relatives and controls. Two genetic approaches were applied to uncover genetic association with polyphasia.

Methods

20 JME patients, 23 first-degree relatives and 30 controls underwent TMS, obtaining 10–15 MEPs per participant. We evaluated MEP mean number of phases, proportion of MEP trials displaying polyphasia for each subject and variability between groups. Participants underwent whole exome sequencing (WES) via trio-based analysis and two-case scenario. Extensive bioinformatics analysis was applied.

Results

We identified increased polyphasia in patients (85%) and relatives (70%) compared to controls (47%) and significantly higher mean number of zero crossings (i.e., occurrence of phases) (patients 1.49, relatives 1.46, controls 1.22; p < 0.05). Trio-based analysis revealed a candidate polymorphism, p.Glu270del,in SYT14 (Synaptotagmin 14), in JME patients and their relatives presenting polyphasia. Sanger sequencing analysis in remaining participants showed no significant association. In two-case scenario, a machine learning approach was applied in variants identified from odds ratio analysis and risk prediction scores were obtained for polyphasia. The results revealed 61 variants of which none was associated with polyphasia. Risk prediction scores indeed showed lower probability for non-polyphasic subjects on having polyphasia and higher probability for polyphasic subjects on having polyphasia.

Conclusion

Polyphasia was present in JME patients and relatives in contrast to controls. Although no known clinical symptoms are linked to polyphasia this neurophysiological phenomenon is likely due to common cerebral electrophysiological abnormality. We did not discover direct association between genetic variants obtained and polyphasia. It is likely these genetic traits alone cannot provoke polyphasia, however, this predisposition combined with disturbed brain-electrical activity and tendency to generate seizures may increase the risk of developing polyphasia, mainly in patients and relatives.

Open-tES: An open-source stimulator for transcranial electrical stimulation designed for rodent research

Non-invasive neuromodulatory techniques, including transcranial direct current stimulation (tDCS), have been shown to modulate neuronal function and are used both in cognitive neuroscience and to treat neuropsychiatric conditions. In this context, animal models provide a powerful tool to identify the neurobiological mechanisms of action of tDCS. However, finding a current generator that is easily usable and which allows a wide range of stimulation parameters can be difficult and/or expensive. Here, we introduce the Open-tES device, a project under a Creative Commons License (CC BY, SA 4.0) shared on the collaborative platform Git-Hub. This current generator allows tDCS (and other kinds of stimulations) to be realized, is suitable for rodents, is easy to use, and is low-cost. Characterization has been performed to measure the precision and accuracy of the current delivered. We also aimed to compare its effects with a commercial stimulator used in clinical trials (DC-Stimulator Plus, NeuroConn, Germany). To achieve this, a behavioral study was conducted to evaluate its efficacy for decreasing depression related-behavior in mice. The stimulator precision and accuracy were better than 250 nA and 25 nA, respectively. The behavioral evaluation performed in mice in the present study did not reveal any significant differences between the commercial stimulator used in clinical trials and the Open-tES device. Accuracy and precision of the stimulator ensure high repeatability of the stimulations. This current generator constitutes a reliable and inexpensive tool that is useful for preclinical studies in the field of non-invasive electrical brain stimulation.

History of the Network Approach in Epilepsy Surgery

We provide a history and overview of the network approach to epilepsy surgery. Models of the epileptogenic zone (EZ) have evolved considerably over the years with more recent models accounting for the connectivity and network properties of epileptic foci. Next, we describe several examples of network phenotypes of focal epilepsy and how these have the potential to influence surgical decision-making and patient outcome. Future research will provide new insight into how network models of the EZ can determine optimal surgical interventions that improve seizure outcomes and optimize cognitive outcomes.

Variability Between Direct and Indirect Targeting of the Anterior Nucleus of the Thalamus

BACKGROUND

Preoperative thalamic targeting methods have historically relied on indirect targeting techniques that do not fully account for variances in anatomy or for thalamic atrophy in epilepsy. We aimed to address variability noted between traditional indirect targeting and direct targeting methods for the anterior nucleus of the thalamus (ANT).

METHODS

Fifteen consecutive patients undergoing ANT deep brain stimulator placement were evaluated (30 thalamic nuclei). Direct ANT targeting was performed using a fast gray matter acquisition T1 inversion recovery sequence and compared with standard stereotactic coordinates. Thalamic volumes were calculated for each patient, and degree of thalamic volume loss was assessed compared with matched control subjects. Vertex analysis was performed to assess shape changes in the thalamus compared with age- and sex-matched subjects.

RESULTS

There was significant variation between direct and indirect targets in the y-axis and z-axis on both sides. On the left, the direct target was located at y = 2 ± 1.3 mm and z = 9.3 ± 1.8 mm (both P = 0.02). On the right, the direct target was located at y = 2.9 ± 1.8 mm and z = 9.2 ± 2 mm (both P ≤ 0.0003). There was no significant difference in the x-coordinate on either side (P > 0.5). Additionally, there was a correlation between thalamic volume and difference between direct and indirect targets in the y-axis and the z-axis.

CONCLUSIONS

We showed a significant difference in direct and indirect targeting in the y-axis and z-axis when targeting the ANT for deep brain stimulation for epilepsy. This difference is correlated to thalamic volume, with a larger difference noted in patients with thalamic atrophy.