Transcranial Direct Current Stimulation for Patients With Pharmacoresistant Epileptic Spasms: A Pilot Study

Pathogenesis, diagnosis, and treatment of epilepsy: electromagnetic stimulation-mediated neuromodulation therapy and new technologies

Epilepsy is a severe, relapsing, and multifactorial neurological disorder. Studies regarding the accurate diagnosis, prognosis, and in-depth pathogenesis are crucial for the precise and effective treatment of epilepsy. The pathogenesis of epilepsy is complex and involves alterations in variables such as gene expression, protein expression, ion channel activity, energy metabolites, and gut microbiota composition. Satisfactory results are lacking for conventional treatments for epilepsy. Surgical resection of lesions, drug therapy, and non-drug interventions are mainly used in clinical practice to treat pain associated with epilepsy. Non-pharmacological treatments, such as a ketogenic diet, gene therapy for nerve regeneration, and neural regulation, are currently areas of research focus. This review provides a comprehensive overview of the pathogenesis, diagnostic methods, and treatments of epilepsy. It also elaborates on the theoretical basis, treatment modes, and effects of invasive nerve stimulation in neurotherapy, including percutaneous vagus nerve stimulation, deep brain electrical stimulation, repetitive nerve electrical stimulation, in addition to non-invasive transcranial magnetic stimulation and transcranial direct current stimulation. Numerous studies have shown that electromagnetic stimulation-mediated neuromodulation therapy can markedly improve neurological function and reduce the frequency of epileptic seizures. Additionally, many new technologies for the diagnosis and treatment of epilepsy are being explored. However, current research is mainly focused on analyzing patients' clinical manifestations and exploring relevant diagnostic and treatment methods to study the pathogenesis at a molecular level, which has led to a lack of consensus regarding the mechanisms related to the disease.

Tolerability and Effectiveness of Cathodal Transcranial Direct Current Stimulation in Children with Refractory Epilepsy: A Case Series

There are limited treatment options for drug-resistant epilepsy (DRE) in children. We performed a pilot study to investigate the tolerability and effectiveness of cathodal transcranial direct current stimulation (tDCS) in DRE. Twelve children with DRE of varied etiology underwent three to four daily sessions of cathodal tDCS. The seizure frequency at 2 weeks before and after tDCS was obtained from seizure diaries; clinic reviews at 3 and 6 months assessed any longer-term benefits or adverse effects. The spike wave index (SWI) was analyzed in the EEGs done immediately before and after tDCS on the first and last day of tDCS. One child remained seizure free for a year after tDCS. One child had reduced frequency of ICU admissions for status epilepticus for 2 weeks, likely due to reduced severity of seizures. In four children, an improvement in alertness and mood was reported for 2-4 weeks after tDCS. There was no benefit following tDCS in the other children. There were no unexpected or serious adverse effects in any child. Benefit was seen in two children, and the reasons for the lack of benefit in the other children need further study. It is likely that tDCS stimulus parameters will need to be tailored for different epilepsy syndromes and etiologies.

Therapeutical impacts of transcranial direct current stimulation on drug-resistant epilepsy in pediatric patients: A double-blind parallel-group randomized clinical trial

BACKGROUND

Drug-resistant epilepsy is a challenging problem in pediatrics. Transcranial direct current stimulation (TDCS) is a non-invasive neurostimulation technique suggested as a promising method for treating epilepsy. This study aims to evaluate the efficacy of TDCS in focal epilepsy in children with drug-resistant epilepsy.

METHOD

We conducted a randomized sham-controlled study with 18 subjects between 6 and 16 years of age, divided equally into two groups. TDCS was performed in 20-minute daily stimulation protocol for five days for both groups. The current intensity was one mA for the first three days, increasing to 1.5 mA on day four and 2 mA on the last day of stimulation. EEG was done before and after the intervention.

RESULTS

There was a significant reduction in seizure duration in the case group compared with the sham group.

CONCLUSION

five consecutive days of performing TDCS significantly reduced seizure duration in children with focal Drug-resistant epilepsy. However,further studies in this field are necessary to test the effectiveness and set up a coherent and comprehensive protocol.

Personalized, Multisession, Multichannel Transcranial Direct Current Stimulation in Medication-Refractory Focal Epilepsy: An Open-Label Study

PURPOSE

Animal and proof-of-principle human studies suggest that cathodal transcranial direct current stimulation may suppress seizures in drug-resistant focal epilepsy. The present study tests the safety, tolerability, and effect size of repeated daily cathodal transcranial direct current stimulation in epilepsy have not been established, limiting development of clinically meaningful interventions.

METHODS

We conducted a 2-center, open-label study on 20 participants with medically refractory, focal epilepsy, aged 9 to 56 years (11 women and 9 children younger than18 years). Each participant underwent 10 sessions of 20 minutes of cathodal transcranial direct current stimulation over 2 weeks. Multielectrode montages were designed using a realistic head model-driven approach to conduct an inhibitory electric field to the target cortical seizure foci and surrounding cortex to suppress excitability and reduce seizure rates. Patients recorded daily seizures using a seizure diary 8 weeks prior, 2 weeks during, and 8 to 12 weeks after the stimulation period.

RESULTS

The median seizure reduction was 44% relative to baseline and did not differ between adult and pediatric patients. Three patients experienced an increase in seizure frequency of >50% during the stimulation period; in one, a 36% increase in seizure frequency persisted through 12 weeks of follow-up. Otherwise, participants experienced only minor adverse events-the most common being scalp discomfort during transcranial direct current stimulation.

CONCLUSIONS

This pilot study supports the safety and efficacy of multifocal, personalized, multichannel, cathodal transcranial direct current stimulation for adult and pediatric patients with medication-refractory focal epilepsy, although identifies a possibility of seizure exacerbation in some. The data also provide insight into the effect size to inform the design of a randomized, sham-stimulation controlled trial.

Repeated long sessions of transcranial direct current stimulation reduces seizure frequency in patients with refractory focal epilepsy: An open-label extension study

OBJECTIVE

Although clinical trials have demonstrated that cathodal transcranial direct current stimulation (tDCS) is effective for seizure reduction, its long-term efficacy is unknown. This study aimed to determine the long-term effects of repeated cathodal long tDCS sessions on seizure suppression in patients with refractory epilepsy.

METHODS

Patients were recruited to participate in an extended phase of a previous randomized, double-blind, sham-controlled, three-arm, parallel, multicenter study on tDCS. The patients were divided into an active tDCS group (20 min of tDCS per day) and an intensified tDCS group (2 × 20 min of tDCS per day). Each tDCS session lasted 2 weeks and the patients underwent repeated sessions at intervals of 2 to 6 months. The cathode was placed over the epileptogenic focus with the current intensity set as 2 mA. Seizure frequency reduction from baseline was analyzed using the Wilcoxon signed-rank test for two related samples. A generalized estimating equation model was used to estimate group, time, and interaction effects.

RESULTS

Among the 19 patients who participated in the extended phase, 11 were in the active tDCS group and underwent 2-16 active tDCS sessions, and eight were in the intensified tDCS group and underwent 3-11 intensified tDCS sessions. Seizure reduction was significant from the first to the seventh follow-up, with a median seizure frequency reduction of 41.7%-83.3% (p < 0.05). Compared to the regular tDCS protocol, each intensified tDCS session substantially decreased seizure frequency by 0.3680 (p < 0.05). One patient experienced an increase of 8.5%-232.8% in the total number of seizures during three treatment sessions and follow-ups.

CONCLUSION

Repeated long cathodal tDCS sessions yielded significant and progressive long-term seizure reductions in patients with refractory focal epilepsy.

Brain augmentation and neuroscience technologies: current applications, challenges, ethics and future prospects

Ever since the dawn of antiquity, people have strived to improve their cognitive abilities. From the advent of the wheel to the development of artificial intelligence, technology has had a profound leverage on civilization. Cognitive enhancement or augmentation of brain functions has become a trending topic both in academic and public debates in improving physical and mental abilities. The last years have seen a plethora of suggestions for boosting cognitive functions and biochemical, physical, and behavioral strategies are being explored in the field of cognitive enhancement. Despite expansion of behavioral and biochemical approaches, various physical strategies are known to boost mental abilities in diseased and healthy individuals. Clinical applications of neuroscience technologies offer alternatives to pharmaceutical approaches and devices for diseases that have been fatal, so far. Importantly, the distinctive aspect of these technologies, which shapes their existing and anticipated participation in brain augmentations, is used to compare and contrast them. As a preview of the next two decades of progress in brain augmentation, this article presents a plausible estimation of the many neuroscience technologies, their virtues, demerits, and applications. The review also focuses on the ethical implications and challenges linked to modern neuroscientific technology. There are times when it looks as if ethics discussions are more concerned with the hypothetical than with the factual. We conclude by providing recommendations for potential future studies and development areas, taking into account future advancements in neuroscience innovation for brain enhancement, analyzing historical patterns, considering neuroethics and looking at other related forecasts.

Transcranial current stimulation in epilepsy: A systematic review of the fundamental and clinical aspects

Purpose

Transcranial electrical current stimulation (tES or tCS, as it is sometimes referred to) has been proposed as non-invasive therapy for pharmacoresistant epilepsy. This technique, which includes direct current (tDCS) and alternating current (tACS) stimulation involves the application of weak currents across the cortex to change cortical excitability. Although clinical trials have demonstrated the therapeutic efficacy of tES, its specific effects on epileptic brain activity are poorly understood. We sought to summarize the clinical and fundamental effects underlying the application of tES in epilepsy.

Methods

A systematic review was performed in accordance with the PRISMA guidelines. A database search was performed in PUBMED, MEDLINE, Web of Science and Cochrane CENTRAL for articles corresponding to the keywords “epilepsy AND (transcranial current stimulation OR transcranial electrical stimulation)”.

Results

A total of 56 studies were included in this review. Through these records, we show that tDCS and tACS epileptic patients are safe and clinically relevant techniques for epilepsy. Recent articles reported changes of functional connectivity in epileptic patients after tDCS. We argue that tDCS may act by affecting brain networks, rather than simply modifying local activity in the targeted area. To explain the mechanisms of tES, various cellular effects have been identified. Among them, reduced cell loss, mossy fiber sprouting, and hippocampal BDNF protein levels. Brain modeling and human studies highlight the influence of individual brain anatomy and physiology on the electric field distribution. Computational models may optimize the stimulation parameters and bring new therapeutic perspectives.

Conclusion

Both tDCS and tACS are promising techniques for epilepsy patients. Although the clinical effects of tDCS have been repeatedly assessed, only one clinical trial has involved a consistent number of epileptic patients and little knowledge is present about the clinical outcome of tACS. To fill this gap, multicenter studies on tES in epileptic patients are needed involving novel methods such as personalized stimulation protocols based on computational modeling. Furthermore, there is a need for more in vivo studies replicating the tES parameters applied in patients. Finally, there is a lack of clinical studies investigating changes in intracranial epileptiform discharges during tES application, which could clarify the nature of tES-related local and network dynamics in epilepsy.

Non-invasive transcranial electrical brain stimulation guided by functional near-infrared spectroscopy for targeted neuromodulation: A review

One of the primary goals in cognitive neuroscience is to understand the neural mechanisms on which cognition is based. Researchers are trying to find how cognitive mechanisms are related to oscillations generated due to brain activity. The research focused on this topic has been considerably aided by developing non-invasive brain stimulation techniques. The dynamics of brain networks and the resultant behavior can be affected by non-invasive brain stimulation techniques, which make their use a focus of interest in many experiments and clinical fields. One essential non-invasive brain stimulation technique is transcranial electrical stimulation (tES), subdivided into transcranial direct and alternating current stimulation. tES has recently become more well-known because of the effective results achieved in treating chronic conditions. In addition, there has been exceptional progress in the interpretation and feasibility of tES techniques. Summarizing the beneficial effects of tES, this article provides an updated depiction of what has been accomplished to date, brief history, and the open questions that need to be addressed in the future. An essential issue in the field of tES is stimulation duration. This review briefly covers the stimulation durations that have been utilized in the field while monitoring the brain using functional-near infrared spectroscopy-based brain imaging.

Safety and efficacy of cathodal transcranial direct current stimulation in patients with Lennox Gastaut Syndrome: An open-label, prospective, single-center, single-blinded, pilot study

PURPOSE

Lennox-Gastaut Syndrome (SLG) is a severe form of childhood refractory epilepsy. Only one pilot study has been conducted using cathodal transcranial direct current stimulation (c-tDCs; 2mAx30minx5days) in LGS with promising results (-99% seizure reduction at 5 days). Our aim was to explore and replicate the efficacy and safety of 10 daily sessions of c-tDCs in SLG.

METHODS

We conducted a one-blinded, single-center pilot clinical study of c-tDCs (2mAx 30 min x 10 days), applied over the highest amplitude or frequent epileptiform interictal discharges areas using scalp EEG recordings without changes in their treatments. The tDCS device used was Enobio EEG® (Neuroelectrics, Barcelona, Spain). The primary outcome was based on the seizure frequency using seizure diaries before, during 10 days of treatment, and then on a 4 and 8 weeks of follow-up. The rate of adverse events was recorded as a secondary outcome. Descriptive statistics and Wilcoxon signed-rank test were used RESULTS: Twenty-four patients were enrolled. The mean age was 10.1 ± 5.8 years old and 75% male. All the patients had severe mental retardation and abnormal neurological examinations. A significant median percentual seizure frequency reduction was found: 68.12% (p = 0.05) at 1 week, 68.12% (p = 0.002) in the second week. We found no significant reduction at 1 and 2 months; mainly tonic and atonic seizures were reduced significantly at all times. Only mild self-limited side effects were recorded mainly itching and erythema in the application zone CONCLUSION: Ten sessions of c-tDCs in combination with pharmacologic treatment in LGS is safe and appears to reduce significatively tonic and atonic seizure frequency at 2 months of follow-up.

Cathodal Transcranial Direct Current Stimulation in Refractory Epilepsy: A Noninvasive Neuromodulation Therapy

SUMMARY

Epilepsy is a chronic disease of the brain that affects individuals of all ages and has a worldwide distribution. According to a 2006 World Health Organization report, 50 million people had epilepsy. Approximately 30% of people with epilepsy have refractory disease despite recent therapeutic developments. Consequently, new treatments are necessary. Transcranial direct current stimulation (tDCS) is a noninvasive method for cortical excitability modulation by subthreshold membrane depolarization or hyperpolarization (cathodal stimulation decreases cortical excitability, whereas anodal stimulation increases it), which has been shown to be safe, economical, and easy to use. The mechanism of action of tDCS is partially understood. Cathodal tDCS in vitro and in vivo animal studies have shown that direct current and cathodal tDCS can successfully induce suppression of epileptiform activity in EEG recordings. Cathodal tDCS has been used in heterogeneous clinical trials in pediatric and adult patients with refractory epilepsy and is well tolerated. A comprehensive review of the clinical trials based on their quality and biases shows evidence that cathodal tDCS in patients with epilepsy is potentially effective. However, additional randomized clinical trials are needed with other etiologies, special populations, additional concomitants therapies, long-term follow-up, and new parameters of stimulation.

Acute effects of spaced cathodal transcranial direct current stimulation in drug resistant focal epilepsies

OBJECTIVE

To evaluate the safety and temporal dynamic of the antiepileptic effect of spaced transcranial direct current stimulation (tDCS) in different focal epilepsies.

METHODS

Cathodal tDCS with individual electrode placement was performed in 15 adults with drug resistant focal epilepsy. An amplitude of 2 mA was applied twice for 9 minutes, with an interstimulation interval of 20 minutes. Tolerability was assessed via the Comfort Rating Questionnaire and the frequency of interictal epileptiform discharges (IEDs) was sequentially compared between the 24 hours before and after tDCS.

RESULTS

TDCS led to a significant reduction in the total number of IEDs/24 h by up to 68% (mean ± SD: -30.4 ± 21.1%, p = 0.001) as well as in seizure frequency (p = 0.041). The maximum IED reduction was observed between the 3rd and 21st hour after stimulation. Favorable clinical response was associated with structural etiology and clearly circumscribed epileptogenic foci but did not differ between frontal and temporal epilepsies. Overall, the tDCS treatment was well tolerated and did not lead to severe adverse events.

CONCLUSIONS

The spaced stimulation approach proved to be safe and well-tolerated in patients with drug-resistant unifocal epilepsies, leading to sustained IED and seizure frequency reduction.

SIGNIFICANCE

Spaced tDCS induces mediate antiepileptic effects with promising therapeutic potential.

Systemic Review on Transcranial Electrical Stimulation Parameters and EEG/fNIRS Features for Brain Diseases

Background

Brain disorders are gradually becoming the leading cause of death worldwide. However, the lack of knowledge of brain disease’s underlying mechanisms and ineffective neuropharmacological therapy have led to further exploration of optimal treatments and brain monitoring techniques.

Objective

This study aims to review the current state of brain disorders, which utilize transcranial electrical stimulation (tES) and daily usable noninvasive neuroimaging techniques. Furthermore, the second goal of this study is to highlight available gaps and provide a comprehensive guideline for further investigation.

Method

A systematic search was conducted of the PubMed and Web of Science databases from January 2000 to October 2020 using relevant keywords. Electroencephalography (EEG) and functional near-infrared spectroscopy were selected as noninvasive neuroimaging modalities. Nine brain disorders were investigated in this study, including Alzheimer’s disease, depression, autism spectrum disorder, attention-deficit hyperactivity disorder, epilepsy, Parkinson’s disease, stroke, schizophrenia, and traumatic brain injury.

Results

Sixty-seven studies (1,385 participants) were included for quantitative analysis. Most of the articles (82.6%) employed transcranial direct current stimulation as an intervention method with modulation parameters of 1 mA intensity (47.2%) for 16–20 min (69.0%) duration of stimulation in a single session (36.8%). The frontal cortex (46.4%) and the cerebral cortex (47.8%) were used as a neuroimaging modality, with the power spectrum (45.7%) commonly extracted as a quantitative EEG feature.

Conclusion

An appropriate stimulation protocol applying tES as a therapy could be an effective treatment for cognitive and neurological brain disorders. However, the optimal tES criteria have not been defined; they vary across persons and disease types. Therefore, future work needs to investigate a closed-loop tES with monitoring by neuroimaging techniques to achieve personalized therapy for brain disorders.

Transcranial direct current stimulation (tDCS) in the management of epilepsy: A systematic review

PURPOSE

Current therapies for the management of epilepsy are still suboptimal for several patients due to inefficacy, major adverse events, and unavailability. Transcranial direct current stimulation (tDCS), an emergent non-invasive neuromodulation technique, has been tested in epilepsy samples over the past two decades to reduce either seizure frequency or electroencephalogram (EEG) epileptiform discharges.

METHODS

A systematic review was performed in accordance with PRISMA guidelines (PROSPERO record CRD42020160292). A thorough electronic search was completed in MEDLINE, EMBASE, CENTRAL and Scopus databases for trials that applied tDCS interventions to children and adults with epilepsy of any cause, from inception to April 30, 2020.

RESULTS

Twenty-seven studies fulfilled eligibility criteria, including nine sham-controlled and 18 uncontrolled trials or case reports/series. Samples consisted mainly of drug-resistant focal epilepsy patients that received cathodal tDCS stimulation targeted at the site with maximal EEG abnormalities. At follow-up, 84 % (21/25) of the included studies reported a reduction in seizure frequency and in 43 % (6/14) a decline in EEG epileptiform discharge rate was observed. No serious adverse events were reported.

CONCLUSIONS

Cathodal tDCS is both a safe and probably effective technique for seizure control in patients with drug-resistant focal epilepsy. However, published trials are heterogeneous regarding samples and methodology. More and larger sham-controlled randomized trials are needed, preferably with mechanistic informed stimulation protocols, to further advance tDCS therapy in the management of epilepsy.

Modeling epileptic spasms during infancy: Are we heading for the treatment yet?

Infantile spasms (IS or epileptic spasms during infancy) were first described by Dr. William James West (aka West syndrome) in his own son in 1841. While rare by definition (occurring in 1 per 3200-3400 live births), IS represent a major social and treatment burden. The etiology of IS varies - there are many (>200) different known pathologies resulting in IS and still in about one third of cases there is no obvious reason. With the advancement of genetic analysis, role of certain genes (such as ARX or CDKL5 and others) in IS appears to be important. Current treatment strategies with incomplete efficacy and serious potential adverse effects include adrenocorticotropin (ACTH), corticosteroids (prednisone, prednisolone) and vigabatrin, more recently also a combination of hormones and vigabatrin. Second line treatments include pyridoxine (vitamin B6) and ketogenic diet. Additional treatment approaches use rapamycin, cannabidiol, valproic acid and other anti-seizure medications. Efficacy of these second line medications is variable but usually inferior to hormonal treatments and vigabatrin. Thus, new and effective models of this devastating condition are required for the search of additional treatment options as well as for better understanding the mechanisms of IS. Currently, eight models of IS are reviewed along with the ideas and mechanisms behind these models, drugs tested using the models and their efficacy and usefulness. Etiological variety of IS is somewhat reflected in the variety of the models. However, it seems that for finding precise personalized approaches, this variety is necessary as there is no "one-size-fits-all" approach possible for both IS in particular and epilepsy in general.