Randomized controlled trial of trigeminal nerve stimulation for drug-resistant epilepsy

A Review of Neurostimulation for Epilepsy in Pediatrics

Neurostimulation for epilepsy refers to the application of electricity to affect the central nervous system, with the goal of reducing seizure frequency and severity. We review the available evidence for the use of neurostimulation to treat pediatric epilepsy, including vagus nerve stimulation (VNS), responsive neurostimulation (RNS), deep brain stimulation (DBS), chronic subthreshold cortical stimulation (CSCS), transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS). We consider possible mechanisms of action and safety concerns, and we propose a methodology for selecting between available options. In general, we find neurostimulation is safe and effective, although any high quality evidence applying neurostimulation to pediatrics is lacking. Further research is needed to understand neuromodulatory systems, and to identify biomarkers of response in order to establish optimal stimulation paradigms.

Novel therapies for epilepsy in the pipeline

Despite the availability of many antiepileptic drugs (AEDs) (old and newly developed) and, as recently suggested, their optimization in the treatment of patients with uncontrolled seizures, more than 30% of patients with epilepsy continue to experience seizures and have drug-resistant epilepsy; the management of these patients represents a real challenge for epileptologists and researchers. Resective surgery with the best rates of seizure control is not an option for all of them; therefore, research and discovery of new methods of treating resistant epilepsy are of extreme importance. In this article, we will discuss some innovative approaches, such as P-glycoprotein (P-gp) inhibitors, gene therapy, stem cell therapy, traditional and novel antiepileptic devices, precision medicine, as well as therapeutic advances in epileptic encephalopathy in children; these treatment modalities open up new horizons for the treatment of patients with drug-resistant epilepsy.

Neurostimulation Therapies

Depression is one of the most disabling conditions in the world. In many cases patients continue to suffer with depressive disorders despite a series of adequate trials of medication and psychotherapy. Neuromodulation treatments offer a qualitatively different modality of treatment that can frequently prove efficacious in these treatment-refractory patients. The field of neuromodulation focuses on the use of electrical/electromagnetic energy, both invasively and noninvasively, to interface with and ultimately alter activity within the human brain for therapeutic purposes. These treatments provide another set of options to offer patients when clinically indicated, and knowledge of their safety, risks and benefits, and appropriate clinical application is essential for modern psychiatrists and other mental health professionals. Although neuromodulation techniques hold tremendous promise, only three such treatments are currently approved by the United States Food and Drug Administration (FDA) for the treatment of major depressive disorder: electroconvulsive therapy (ECT), vagus nerve stimulation (VNS), and repetitive transcranial magnetic stimulation (rTMS). Additionally, numerous other neurostimulation modalities (deep brain stimulation [DBS], magnetic seizure therapy [MST], transcranial electric stimulation [tES], and trigeminal nerve stimulation [TNS]), though currently experimental, show considerable therapeutic promise. Researchers are actively looking for ways to optimize outcomes and clinical benefits by making neuromodulation treatments safer, more efficacious, and more durable.

Electroacupuncture Reduces Seizure Activity and Enhances GAD 67 and Glutamate Transporter Expression in Kainic Acid Induced Status Epilepticus in Infant Rats

Status epilepticus (SE) is one of the most significant complications in pediatric neurology. Clinical studies have shown positive effects of electroacupuncture (EA) as a therapeutic alternative in the control of partial seizures and secondary generalized clonic seizures. EA promotes the release of neurotransmitters such as GABA and some opioids. The present study aimed to evaluate the anticonvulsive and neuromodulatory effects of Shui Gou DM26 (SG_DM26) acupuncture point electrostimulation on the expression of the glutamate decarboxylase 67 (GAD67) enzyme and the glutamate transporter EAAC1 in an early SE model. At ten postnatal days (10-PD), male rats weighing 22-26 g were divided into 16 groups, including control and treatment groups: Simple stimulation, electrostimulation, anticonvulsant drug treatment, and combined treatment-electrostimulation and pentobarbital (PB). SE was induced with kainic acid (KA), and the following parameters were measured: Motor behavior, and expression of GAD67 and EAAC1. The results suggest an antiepileptic effect derived from SG DM26 point EA. The possible mechanism is most likely the increased production of the inhibitory neurotransmitter GABA, which is observed as an increase in the expression of both GAD67 and EAAC1, as well as the potential synergy between the neuromodulator effects of EA and PB.

Effect of short-term transcutaneous trigeminal nerve stimulation on EEG activity in drug-resistant epilepsy

BACKGROUND

Transcutaneous trigeminal nerve stimulation (TNS) has antiepileptic effects in patients with drug-resistant epilepsy (DRE). However, whether and how TNS is able to modulate the electroencephalogram (EEG) background activity in patients with DRE is still unknown.

OBJECTIVES

To investigate the effect of short-term TNS on EEG background activity in DRE by qualitative and quantitative analyses.

METHODS

Twenty-nine DRE patients participated in the study. Twenty-two were randomly divided into a "sham-TNS" or "real-TNS" group; seven patients underwent stimulation of the median nerve (MNS) at the wrist. Real-TNS was delivered bilaterally to the infraorbital nerve (trains of 1-20 mA, 120 Hz, cyclic modality for 20 min). The sham-TNS protocol mimicked the real-TNS one but at a zero intensity. For MNS, the same parameters as real-TNS were used. EEG was continuously acquired for 40 min: 10' pre, 20' during and 10' post stimulation. EEG was visually inspected for interictal epileptiform discharge (IEDs) changes and processed by spectral analysis for changes in mean frequency and absolute power of each frequency band.

RESULTS

A significant increase of EEG absolute alpha power was observed during real-TNS compared with the sham-TNS (F_34,680 = 1.748; p = 0.006). Conversely, no significant effects were noticed either for quantitative analysis of other frequency bands or for IEDs detection. MNS proved unable to modulate EEG activity.

CONCLUSIONS

Short-term TNS induces an acute and specific effect on background EEG of DRE by increasing the absolute alpha band power. EEG alpha rhythm enhancement may index a cortical functional inhibition and act as a seizure-preventing mechanism.

Double-Blind, Sham-Controlled, Pilot Study of Trigeminal Nerve Stimulation for Attention-Deficit/Hyperactivity Disorder

OBJECTIVE

Trigeminal nerve stimulation (TNS), a minimal-risk noninvasive neuromodulation method, showed potential benefits for attention-deficit/hyperactivity disorder (ADHD) in an unblinded open study. The present blinded sham-controlled trial was conducted to assess the efficacy and safety of TNS for ADHD and potential changes in brain spectral power using resting-state quantitative electroencephalography.

METHOD

Sixty-two children 8 to 12 years old, with full-scale IQ of at least 85 and Schedule for Affective Disorders and Schizophrenia-diagnosed ADHD, were randomized to 4 weeks of nightly treatment with active or sham TNS, followed by 1 week without intervention. Assessments included weekly clinician-administered ADHD Rating Scales (ADHD-RS) and Clinical Global Impression (CGI) scales and quantitative electroencephalography at baseline and week 4.

RESULTS

ADHD-RS total scores showed significant group-by-time interactions (F1,228 = 8.12, p = .005; week 4 Cohen d = 0.5). CGI-Improvement scores also favored active treatment (χ21,168 = 8.75, p = .003; number needed to treat = 3). Resting-state quantitative electroencephalography showed increased spectral power in the right frontal and frontal midline frequency bands with active TNS. Neither group had clinically meaningful adverse events.

CONCLUSION

This study demonstrates TNS efficacy for ADHD in a blinded sham-controlled trial, with estimated treatment effect size similar to non-stimulants. TNS is well tolerated and has minimal risk. Additional research should examine treatment response durability and potential impact on brain development with sustained use.

CLINICAL TRIAL REGISTRATION INFORMATION

Trigeminal Nerve Stimulation for ADHD; http://clinicaltrials.gov/; NCT02155608.

Comparison and Selection of Current Implantable Anti-Epileptic Devices

Implantable neural stimulators represent an advanced treatment adjunct to medication for pharmacoresistant epilepsy and alternative for patients that are not good candidates for resective surgery. Three treatment modalities are currently FDA-approved: vagus nerve stimulation, responsive neurostimulation, and deep brain stimulation. These devices were originally trialed in very similar patient populations with focal epilepsy, but head-to-head comparison trials have not been performed. As such, device selection may be challenging due to large overlaps in clinical indications and efficacy. Here we will review the data reported in the original pivotal clinical trials as well as long-term experience with these technologies. We will highlight differences in their features and mechanisms of action which may help optimize device selection on a case-by-case basis.

Changes in self-perception in patients treated with neurostimulating devices

BACKGROUND

In recent years, qualitative changes in self-perception have been reported in individual patients undergoing brain stimulation to treat their neurological disease. We here report a first systematic study addressing these unwanted treatment effects in a semiquantitative way.

HYPOTHESES

Hypothesis 1 (H1): Changes in self-perception can be detected and documented in patients following interventions with various neurostimulating devices using standardized assessment tools. Hypothesis 2 (H2): Central nervous-implanted neurostimulating devices (deep brain stimulation [DBS]) will have a greater impact on the patient's self-perception than "peripheral" implanted devices (implanted vagus nerve stimulation [iVNS]) and external devices (transcutaneous vagus nerve stimulation [tVNS] or transcutaneous electrical trigeminal nerve stimulation [eTNS]).

METHODS

Application of a newly developed semiquantitative questionnaire (FST-questionnaire [Fragebogen zur Veränderung der Selbstwahrnehmung unter tiefer Hirnstimulation]: Questionnaire regarding changes in self-perception while treated with DBS) to systematically assess changes in self-perception in a single-center, cross-sectional pilot-study at the University Hospital Freiburg, Germany on 50 patients (44% male; age 50 years [range: 27-73 years]), undergoing neurostimulation (DBS, iVNS, tVNS, or eTNS) to treat Parkinson's disease or epilepsy.

RESULTS

Standardized assessment detected alterations in self-perception in all treatment groups (H1 approved). This included rare self-alienating changes in self-perception. Unexpectedly, peripheral neurostimulation had similar effects as central stimulation techniques.

CONCLUSIONS

Properly designed questionnaires - like the FST-questionnaire as standardized assessment tool - can detect changes in self-perception in patients during neurostimulatory treatment in a wide spectrum of brain stimulation techniques. This may provide a strategy to systematically identify the subgroup of patients liable to experience such problems during treatment already prior to treatment decisions.

Effects of acute trigeminal nerve stimulation on rest EEG activity in healthy adults

Trigeminal nerve stimulation (TNS) is a non-invasive neuromodulation method which is increasingly used for its beneficial effects on symptoms of several neuropsychiatric disorders such as drug-resistant epilepsy. Sites and mechanisms of its action are still unknown. The present study was aimed at investigating the physiological effects of acute TNS on rest electroencephalographic (EEG) activity. EEG was recorded with a 19-channel EEG system from 18 healthy adults who underwent 20 min of sham- and real-TNS (cycles of 30 s ON and 30 s OFF) in two separate sessions. EEG was continuously acquired in the 10-min preceding TNS, during TNS in the "OFF" period and throughout 10 min after TNS. Mean frequency, total power over the 0.5-48 Hz frequency range and absolute power for delta, theta, alpha, beta and gamma bands were analyzed by a discrete Fast Fourier Transform algorithm. Interhemispheric and intrahemispheric coherences were also analyzed for each band at different time points. Intra- and interhemispheric coherences were significantly reduced for the beta frequencies only during real-TNS (p = 0.002 and p = 0.006, respectively). No TNS effect on the power spectra of any band was detected. A trend of increase in the mean EEG frequency total power during real-TNS (p = 0.03) and of decrease in interhemispheric gamma coherence after real-TNS (p = 0.01) was observed. Acute TNS may induce a spatially diffuse desynchronization of fast EEG rhythms in healthy adults, this desynchronization may underpin the antiepileptic effect of TNS described by clinical studies.

Evaluation of long-term antiepileptic drug use in patients with temporal lobe epilepsy: Assessment of risk factors for drug resistance and polypharmacy

PURPOSE

To evaluate risk factors for drug resistance and polypharmacy in patients with temporal lobe epilepsy.

METHODS

Patients with temporal lobe epilepsy, treated for more than 5 years, completed questionnaires on antiepileptic drug use and effect. Logistic regression models were used for analysis of risk factors.

RESULTS

Of 135 patients included in the study, 65% were classified as drug resistant and 41% identified as using polypharmacy. Poor effects associated with first-choice antiepileptic drug were reported by 59% of the patients, and 70% reported poor effects of second-line treatment. The most frequently used first-generation antiepileptic drugs had a similar mean effect to those of second-generation. Univariate regression analyses showed a significant association between drug resistance and mesial temporal sclerosis, seizure onset below 18 years, and lack of family history of epilepsy. However, multivariate regression analysis showed no association with any demographic or clinical features. Unsuccessful treatment with the first antiepileptic drug increased the risk of drug resistance by 18 times, and the risk of poor effect from the second antiepileptic drug by 9 times. Disease duration was associated with annual risk for drug resistance of 7% and for polypharmacy of 5%.

CONCLUSIONS

A poor effect from initial pharmacotherapy is the only early risk factor for drug resistance found in this study. Long disease duration increases the risk of drug resistance and polypharmacy. Second-generation antiepileptic drugs provide no additional effect for poor responders to first-generation drugs.

Efficacy and mode of action of external trigeminal neurostimulation in migraine

INTRODUCTION

Available preventive drug treatments for migraine lack complete efficacy and often have unpleasant adverse effects. Hence, their clinical utility and therapeutic adherence are limited. Noninvasive neurostimulation methods applied over various peripheral sites (forehead, mastoid, upper arm, cervical vagus nerve) have raised great interest because of their excellent efficacy/tolerance profile. Among them external trigeminal nerve stimulation (eTNS) was first to obtain FDA approval for migraine therapy. Areas covered: All clinical trials of eTNS as preventive or acute migraine treatment published in extenso or presented at congresses are reviewed. The paper analyzes neuroimaging and neurophysiological studies on mechanisms of action of eTNS. As many of these studies point toward the anterior cingulate cortex (ACC) as a likely eTNS target, the paper scrutinizes the available literature on the ACC implication in migraine pathophysiology. Expert commentary: eTNS is a viable alternative to standard pharmacological antimigraine strategies both for prevention and abortive therapy. eTNS could chiefly exert its action by modulating the perigenual ACC, which might also be of interest for treating other disorders like fibromyalgia or depression. It remains to be determined if this might be a common mechanism to other peripheral noninvasive neurostimulation methods.

Epilepsy and Neuromodulation-Randomized Controlled Trials

Neuromodulation is a treatment strategy that is increasingly being utilized in those suffering from drug-resistant epilepsy who are not appropriate for resective surgery. The number of double-blinded RCTs demonstrating the efficacy of neurostimulation in persons with epilepsy is increasing. Although reductions in seizure frequency is common in these trials, obtaining seizure freedom is rare. Invasive neuromodulation procedures (DBS, VNS, and RNS) have been approved as therapeutic measures. However, further investigations are necessary to delineate effective targeting, minimize side effects that are related to chronic implantation and to improve the cost effectiveness of these devices. The RCTs of non-invasive modes of neuromodulation whilst showing much promise (tDCS, eTNS, rTMS), require larger powered studies as well as studies that focus at better targeting techniques. We provide a review of double-blinded randomized clinical trials that have been conducted for neuromodulation in epilepsy.

Effect of neurostimulation on cognition and mood in refractory epilepsy

Epilepsy is a common, debilitating neurological disorder characterized by recurrent seizures. Mood disorders and cognitive deficits are common comorbidities in epilepsy that, like seizures, profoundly influence quality of life and can be difficult to treat. For patients with refractory epilepsy who are not candidates for resection, neurostimulation, the electrical modulation of epileptogenic brain tissue, is an emerging treatment alternative. Several forms of neurostimulation are currently available, and therapy selection hinges on relative efficacy for seizure control and amelioration of neuropsychiatric comorbidities. Here, we review the current evidence for how invasive and noninvasive neurostimulation therapies affect mood and cognition in persons with epilepsy. Invasive therapies include vagus nerve stimulation (VNS), deep brain stimulation (DBS), and responsive neurostimulation (RNS). Noninvasive therapies include trigeminal nerve stimulation (TNS), repetitive transcranial magnetic stimulation (rTMS), and transcranial direct current stimulation (tDCS). Overall, current evidence supports stable cognition and mood with all neurostimulation therapies, although there is some evidence that cognition and mood may improve with invasive forms of neurostimulation. More research is required to optimize the effects of neurostimulation for improvements in cognition and mood.

Intense olfactory stimulation blocks seizures in an experimental model of epilepsy

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

Auricular Neuromodulation: The Emerging Concept beyond the Stimulation of Vagus and Trigeminal Nerves

Neuromodulation, thanks to intrinsic and extrinsic brain feedback loops, seems to be the best way to exploit brain plasticity for therapeutic purposes. In the past years, there has been tremendous advances in the field of non-pharmacological modulation of brain activity. This review of different neurostimulation techniques will focus on sites and mechanisms of both transcutaneous vagus and trigeminal nerve stimulation. These methods are scientifically validated non-invasive bottom-up brain modulation techniques, easily implemented from the outer ear. In the light of this, auricles could transpire to be the most affordable target for non-invasive manipulation of central nervous system functions.

Limited output transcranial electrical stimulation (LOTES-2017): Engineering principles, regulatory statutes, and industry standards for wellness, over-the-counter, or prescription devices with low risk

We present device standards for low-power non-invasive electrical brain stimulation devices classified as limited output transcranial electrical stimulation (tES). Emerging applications of limited output tES to modulate brain function span techniques to stimulate brain or nerve structures, including transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS), and transcranial pulsed current stimulation (tPCS), have engendered discussion on how access to technology should be regulated. In regards to legal regulations and manufacturing standards for comparable technologies, a comprehensive framework already exists, including quality systems (QS), risk management, and (inter)national electrotechnical standards (IEC). In Part 1, relevant statutes are described for medical and wellness application. While agencies overseeing medical devices have broad jurisdiction, enforcement typically focuses on those devices with medical claims or posing significant risk. Consumer protections regarding responsible marketing and manufacture apply regardless. In Part 2 of this paper, we classify the electrical output performance of devices cleared by the United States Food and Drug Administration (FDA) including over-the-counter (OTC) and prescription electrostimulation devices, devices available for therapeutic or cosmetic purposes, and devices indicated for stimulation of the body or head. Examples include iontophoresis devices, powered muscle stimulators (PMS), cranial electrotherapy stimulation (CES), and transcutaneous electrical nerve stimulation (TENS) devices. Spanning over 13 FDA product codes, more than 1200 electrical stimulators have been cleared for marketing since 1977. The output characteristics of conventional tDCS, tACS, and tPCS techniques are well below those of most FDA cleared devices, including devices that are available OTC and those intended for stimulation on the head. This engineering analysis demonstrates that with regard to output performance and standing regulation, the availability of tDCS, tACS, or tPCS to the public would not introduce risk, provided such devices are responsibly manufactured and legally marketed. In Part 3, we develop voluntary manufacturer guidance for limited output tES that is aligned with current regulatory standards. Based on established medical engineering and scientific principles, we outline a robust and transparent technical framework for ensuring limited output tES devices are designed to minimize risks, while also supporting access and innovation. Alongside applicable medical and government activities, this voluntary industry standard (LOTES-2017) further serves an important role in supporting informed decisions by the public.

Neurostimulation as a promising epilepsy therapy

The revolution in theory, swift technological developments, and invention of new devices have driven tremendous progress in neurostimulation as a third‐line treatment for epilepsy. Over the past decades, neurostimulation took its place in the field of epilepsy as an advanced treatment technique and opened up a new world. Numerous animal studies have proven the physical efficacy of stimulation of the brain and peripheral nerves. Based on this optimistic fundamental research, new advanced techniques are being explored in clinical practice. Over the past century, drawing on the benefits brought about by vagus nerve stimulation for the treatment of epilepsy, various new neurostimulation modalities have been developed to control seizures. Clinical studies including case reports, case series, and clinical trials have been booming in the past several years. This article gives a comprehensive review of most of these clinical studies. In addition to highlighting the advantages of neurostimulation for the treatment of epilepsy, concerns with this modality and future development directions are also discussed. The biggest advantage of neurostimulation over pharmacological treatments for epilepsy is the modulation of the epilepsy network by delivering stimuli at a specific target or the “hub.” Conversely, however, a lack of knowledge of epilepsy networks and the mechanisms of neurostimulation may hinder further development. Therefore, theoretical research on the mechanism of epileptogenesis and epilepsy networks is needed in the future. Within the multiple modalities of neuromodulation, the final choice should be made after full discussion with a multidisciplinary team at a presurgical conference. Furthermore, the establishment of a neurostimulation system with standardized parameters and rigorous guidelines is another important issue. To achieve this goal, a worldwide collaboration of epilepsy centers is also suggested in the future.

Neuroprotective Effects of Trigeminal Nerve Stimulation in Severe Traumatic Brain Injury

Following traumatic brain injury (TBI), ischemia and hypoxia play a major role in further worsening of the damage, a process referred to as 'secondary injury'. Protecting neurons from causative factors of secondary injury has been the guiding principle of modern TBI management. Stimulation of trigeminal nerve induces pressor response and improves cerebral blood flow (CBF) by activating the rostral ventrolateral medulla. Moreover, it causes cerebrovasodilation through the trigemino-cerebrovascular system and trigemino-parasympathetic reflex. These effects are capable of increasing cerebral perfusion, making trigeminal nerve stimulation (TNS) a promising strategy for TBI management. Here, we investigated the use of electrical TNS for improving CBF and brain oxygen tension (PbrO2), with the goal of decreasing secondary injury. Severe TBI was produced using controlled cortical impact (CCI) in a rat model, and TNS treatment was delivered for the first hour after CCI. In comparison to TBI group, TBI animals with TNS treatment demonstrated significantly increased systemic blood pressure, CBF and PbrO2 at the hyperacute phase of TBI. Furthermore, rats in TNS-treatment group showed significantly reduced brain edema, blood-brain barrier disruption, lesion volume, and brain cortical levels of TNF-α and IL-6. These data provide strong early evidence that TNS could be an effective neuroprotective strategy.

Management of Adult Onset Seizures

Epilepsy is a common yet heterogeneous disease. As a result, management often requires complex decision making. The ultimate goal of seizure management is for the patient to have no seizures and no considerable adverse effects from the treatment. Antiepileptic drugs are the mainstay of therapy, with more than 20 medications currently approved in the United States. Antiepileptic drug selection requires an understanding of the patient's epilepsy, along with consideration of comorbidities and potential for adverse events. After a patient has failed at least 2 appropriate antiepileptic drugs, they are determined to be medically refractory. At this time, additional therapy, including dietary, device, or surgical treatments, need to be considered, typically at a certified epilepsy center. All these treatments require consideration of the potential for seizure freedom, balanced against potential adverse effects, and can have a positive effect on seizure control and quality of life. This review article discussed the treatment options available for adults with epilepsy, including medical, surgical, dietary, and device therapies.

What can we do for people with drug-resistant epilepsy? The 2016 Wartenberg Lecture

Treatment goals for epilepsy are no seizures, no side effects, as soon as possible, but these goals are too often unmet. Approximately 1 million people in the United States continue to have seizures despite adequate treatment with antiseizure drugs, representing 40% of those with epilepsy, and 80% of the cost of epilepsy. Drug-resistant epilepsy (DRE) can be associated with developmental delay in infants and young children, and severe disability and morbidity in older children and adults, as well as a mortality rate 5-10 times that of the general population. While diagnosis and treatment at a full-service (levels 3 and 4) epilepsy center are demonstrated to improve seizure control, fewer than 1% of people with DRE are referred, and those who are, are referred an average of over 20 years after onset of habitual seizures. A possible reason for this is the misconception that all these epilepsy centers offer is surgery. Specialized multidisciplinary teams, consisting of neurologists, clinical neurophysiologists, neurosurgeons, neuroradiologists, psychologists, psychiatrists, social workers, and counselors, which constitute full-service epilepsy centers, can recognize and address pseudopharmacoresistance due to nonadherence, seizures that are not epilepsy, treatable underlying conditions, misdiagnosis of epilepsy syndromes, treatment with the wrong drug or wrong dosage, and lifestyle issues that are remediable. A variety of alternative treatment approaches are offered in addition to surgery, and for patients who continue to have seizures, full-service epilepsy centers have psychologists, psychiatrists, social workers, and counselors specialized in recognizing, and addressing, the psychological and social challenges experienced by people with epilepsy. Surgery for epilepsy remains, arguably, the most underutilized of all acceptable medical interventions, and the reasons for this are unclear. Often, excellent surgical candidates are not recognized as such by general neurologists, but if more patients with DRE were referred to full-service epilepsy centers, more surgical candidates would be identified by epilepsy specialists. All patients with medication-resistant epilepsy, defined as failure of 2 appropriate trials of antiseizure drugs due to inefficacy and not intolerance, who continue to be compromised by seizures deserve a timely consultation at a full-service epilepsy center. Early referral provides the best opportunity to avoid irreversible psychological and social problems, a lifetime of disability, and premature death.

A Closed Loop Brain-machine Interface for Epilepsy Control Using Dorsal Column Electrical Stimulation

Although electrical neurostimulation has been proposed as an alternative treatment for drug-resistant cases of epilepsy, current procedures such as deep brain stimulation, vagus, and trigeminal nerve stimulation are effective only in a fraction of the patients. Here we demonstrate a closed loop brain-machine interface that delivers electrical stimulation to the dorsal column (DCS) of the spinal cord to suppress epileptic seizures. Rats were implanted with cortical recording microelectrodes and spinal cord stimulating electrodes, and then injected with pentylenetetrazole to induce seizures. Seizures were detected in real time from cortical local field potentials, after which DCS was applied. This method decreased seizure episode frequency by 44% and seizure duration by 38%. We argue that the therapeutic effect of DCS is related to modulation of cortical theta waves, and propose that this closed-loop interface has the potential to become an effective and semi-invasive treatment for refractory epilepsy and other neurological disorders.

Not all that glitters is gold: A guide to surgical trials in epilepsy

Epilepsy surgery is often the only effective treatment in appropriately selected patients with drug‐resistant epilepsy, a disease affecting about 30% of those with epilepsy. We review the evidence supporting the use of epilepsy surgery, with a focus on randomized controlled trials (RCTs). Second, we identify gaps in knowledge about the benefits of epilepsy surgery for certain populations, the challenges of individualizing the choice of surgery, and our lack of understanding of the mechanisms of surgical outcomes. We conducted a search (MEDLINE, Embase, Cochrane, Clinicaltrials.gov) on March 2, 2016, to identify epilepsy surgery RCTs, systematic reviews, or health technology assessments (HTAs). Abstracts were screened to identify resective, palliative (e.g., corpus callosotomy, multiple subpial transection [MST]), ablative (e.g., Laser interstitial thermal therapy [LITT], gamma knife radiosurgery [RS]), and neuromodulation (e.g., cerebellar stimulation [CS], hippocampal stimulation [HS], repetitive transcranial magnetic stimulation [rTMS], responsive neurostimulation [RNS], thalamic stimulation [TS], trigeminal nerve stimulation [TNS], and vagal nerve stimulation [VNS]) RCTs. Study characteristics and outcomes were extracted. Knowledge gaps were identified. Of 1,205 abstracts, 20 RCTs were identified (resective surgery including corpus callosotomy [n = 7], MST [n = 0], RS [n = 1, 3 papers], LITT [n = 0], CS [n = 1], HS [n = 2], RNS [n = 1], rTMS [n = 1], TNS [n = 1], TS [n = 1], and VNS [n = 5]). Most studies targeted patients with temporal lobe epilepsy (TLE) and none examined the effectiveness of resective surgical therapies in patients with extra‐TLE (ETLE) or with specific lesions aside from mesial temporal lobe sclerosis. No pediatric surgical RCTs were identified except for VNS. Few RCTs address the effectiveness of surgery in epilepsy and most are of limited generalizability. Future studies are needed to compare the effectiveness of different surgical strategies, better understand the mechanisms of surgical outcomes, and define the ideal surgical approaches, particularly for patients with high or very low cognitive function, normal imaging, or ETLE.

Technical aspects of neurostimulation: Focus on equipment, electric field modeling, and stimulation protocols

Neuromodulation is a field of science, medicine, and bioengineering that encompasses implantable and non-implantable technologies for the purpose of improving quality of life and functioning of humans. Brain neuromodulation involves different neurostimulation techniques: transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), vagus nerve stimulation (VNS), and deep brain stimulation (DBS), which are being used both to study their effects on cognitive brain functions and to treat neuropsychiatric disorders. The mechanisms of action of neurostimulation remain incompletely understood. Insight into the technical basis of neurostimulation might be a first step towards a more profound understanding of these mechanisms, which might lead to improved clinical outcome and therapeutic potential. This review provides an overview of the technical basis of neurostimulation focusing on the equipment, the present understanding of induced electric fields, and the stimulation protocols. The review is written from a technical perspective aimed at supporting the use of neurostimulation in clinical practice.

Chronic Trigeminal Nerve Stimulation Protects Against Seizures, Cognitive Impairments, Hippocampal Apoptosis, and Inflammatory Responses in Epileptic Rats

Trigeminal nerve stimulation (TNS) has recently been demonstrated effective in the treatment of epilepsy and mood disorders. Here, we aim to determine the effects of TNS on epileptogenesis, cognitive function, and the associated hippocampal apoptosis and inflammatory responses. Rats were injected with pilocarpine to produce status epilepticus (SE) and the following chronic epilepsy. After SE induction, TNS treatment was conducted for 4 consecutive weeks. A pilocarpine re-injection was then used to induce a seizure in the epileptic rats. The hippocampal neuronal apoptosis induced by seizure was assessed by TUNEL staining and inflammatory responses by immunohistochemistry and enzyme-linked immunosorbent assay (ELISA). The spontaneous recurrent seizure (SRS) number was counted through video monitoring, and the cognitive function assessed through Morris Water Maze (MWM) test. TNS treatment attenuated the SRS attacks and improved the cognitive impairment in epileptic rats. A pilocarpine re-injection resulted in less hippocampal neuronal apoptosis and reduced level of interleukin-1 beta (IL-1β), tumor necrosis factor-α (TNF-α), and microglial activation in epileptic rats with TNS treatment in comparison to the epileptic rats without TNS treatment. It is concluded that TNS treatment shortly after SE not only protected against the chronic spontaneous seizures but also improved cognitive impairments. These antiepileptic properties of TNS may be related to its attenuating effects on hippocampal apoptosis and pro-inflammatory responses.

Oral Implant-Prostheses: New Teeth for a Brighter Brain

Several studies have demonstrated that chewing can be regarded as a preventive measure for cognitive impairment, whereas masticatory deficiency, associated with soft-diet feeding, is a risk factor for the development of dementia. At present the link between orofacial sensorimotor activity and cognitive functions is unknown. In subjects with unilateral molar loss we have shown asymmetries in both pupil size and masticatory muscles electromyographic (EMG) activity during clenching: the molar less side was characterized by a lower EMG activity and a smaller pupil. Since implant-prostheses, greatly reduced both the asymmetry in EMG activity and in pupil's size, trigeminal unbalance, leading to unbalance in the activity of the Locus Coeruleus (LC), may be responsible for the pupil's asymmetry. According to the findings obtained in animal models, we propose that the different activity of the right and left LC may induce an asymmetry in brain activity, thus leading to cognitive impairment. According to this hypothesis, prostheses improved the performance in a complex sensorimotor task and increased the mydriasis associated with haptic tasks. In conclusion, the present study indicates that the implant-prosthesis therapy, which reduces the unbalance of trigeminal proprioceptive afferents and the asymmetry in pupil's size, may improve arousal, boosting performance in a complex sensorimotor task.

White matter stimulation for the treatment of epilepsy

Electrical stimulation in the treatment of epilepsy has been tried in numerous forms and with a variety of targets. Some of these, such as anterior thalamic stimulation, responsive cortical stimulation, and vagal nerve stimulation, have shown promise. A relatively novel concept, that of white matter stimulation, offers a different mechanism in that a small population of stimulated axons can transmit current to a large population of epileptogenic neurons. In theory, this allows for the modulation of seizure circuits and neural networks using lower stimulation volumes. Although clinical data is currently sparse, we review the relevant studies pertaining to white matter stimulation in epilepsy thus far, and offer explanations as to its effects, potential advantages, and utility.

Response to placebo in clinical epilepsy trials--Old ideas and new insights

Randomized placebo-controlled trials are a mainstay of modern clinical epilepsy research; the success or failure of innovative therapies depends on proving superiority to a placebo. Consequently, understanding what drives response to placebo (including the "placebo effect") may facilitate evaluation of new therapies. In this review, part one will explore observations about placebos specific to epilepsy, including the relatively higher placebo response in children, apparent increase in placebo response over the past several decades, geographic variation in placebo effect, relationship to baseline epilepsy characteristics, influence of nocebo on clinical trials, the possible increase in (SUDEP) in placebo arms of trials, and patterns that placebo responses appear to follow in individual patients. Part two will discuss the principal causes of placebo responses, including regression to the mean, anticipation, classical conditioning, the Hawthorne effect, expectations from symbols, and the natural history of disease. Included in part two will be a brief overview of recent advances using simulations from large datasets that have afforded new insights into causes of epilepsy-related placebo responses. In part three, new developments in study design will be explored, including sequential parallel comparison, two-way enriched design, time to pre-randomization, delayed start, and cohort reduction techniques.

Trigeminal Nerve Stimulation for Comorbid Posttraumatic Stress Disorder and Major Depressive Disorder

OBJECTIVES

External stimulation of the trigeminal nerve (eTNS) is an emerging neuromodulation therapy for epilepsy and depression. Preliminary studies suggest it has an excellent safety profile and is associated with significant improvements in seizures and mood. Neuroanatomical projections of the trigeminal system suggest eTNS may alter activity in structures regulating mood, anxiety, and sleep. In this proof-of-concept trial, the effects of eTNS were evaluated in adults with posttraumatic stress disorder (PTSD) and comorbid unipolar major depressive disorder (MDD) as an adjunct to pharmacotherapy for these commonly co-occurring conditions.

MATERIALS AND METHODS

Twelve adults with PTSD and MDD were studied in an eight-week open outpatient trial (age 52.8 [13.7 sd], 8F:4M). Stimulation was applied to the supraorbital and supratrochlear nerves for eight hours each night as an adjunct to pharmacotherapy. Changes in symptoms were monitored using the PTSD Patient Checklist (PCL), Hamilton Depression Rating Scale (HDRS-17), Quick Inventory of Depressive Symptomatology (QIDS-C), and the Quality of Life Enjoyment and Satisfaction Questionnaire (Q-LES-Q).

RESULTS

Over the eight weeks, eTNS treatment was associated with significant decreases in PCL (p = 0.003; median decrease of 15 points; effect size d 1.5), HDRS-17 (p < 0.001; 42% response rate, 25% remission; d 2.1), and QIDS-C scores (p < 0.001; d 1.8), as well as an improvement in quality of life (Q-LES-Q, p < 0.01). eTNS was well tolerated with few treatment emergent adverse events.

CONCLUSIONS

Significant improvements in PTSD and depression severity were achieved in the eight weeks of acute eTNS treatment. This novel approach to wearable brain stimulation may have use as an adjunct to pharmacotherapy in these disorders if efficacy and tolerability are confirmed with additional studies.

Anterior Nucleus Deep Brain Stimulation for Refractory Epilepsy

BACKGROUND:

Anterior nucleus (AN) deep brain stimulation (DBS) is a palliative treatment for medically refractory epilepsy. The long-term efficacy and the optimal target localization for AN DBS are not well understood.

OBJECTIVE:

To analyze the long-term efficacy of AN DBS and its predictors.

METHODS:

We performed a retrospective review of 16 patients who underwent AN DBS. We selected only patients with reliable seizure frequency data and at least a 1-year follow-up. We studied the duration of the seizure reduction after DBS insertion and before stimulation (the insertional effect) and its association with long-term outcome. We modeled the volume of activation using the active contacts, stimulation parameters, and postoperative imaging. The overlap of this volume was plotted in Montreal Neurological Institute 152 space in 7 patients with significant clinical efficacy.

RESULTS:

Nine patients reported a decrease in seizure frequency immediately after electrode insertion (insertional or microthalamotomy effect). The duration of insertional effect varied from 2 to 4 months. However, 1 patient had a long-term insertional effect of 36 months. Altogether, 11 patients reported &gt;50% decrease in seizure frequency with long-term stimulation. The most common pattern of seizure control was immediate and sustained stimulation benefit (n = 8). In patients with long-term stimulation benefit, the efficacious target was localized in the anteroventral AN in close proximity to the mammillothalamic tract.

CONCLUSION:

AN DBS is efficacious in the control of seizure frequency in selected patients. An insertional effect is commonly observed (56%). The most efficacious site of stimulation appears to be the anteroventral AN.

Transcutaneous trigeminal nerve stimulation induces a long-term depression-like plasticity of the human blink reflex

The beneficial effects of trigeminal nerve stimulation (TNS) on several neurological disorders are increasingly acknowledged. Hypothesized mechanisms include the modulation of excitability in networks involved by the disease, and its main site of action has been recently reported at brain stem level. Aim of this work was to test whether acute TNS modulates brain stem plasticity using the blink reflex (BR) as a model. The BR was recorded from 20 healthy volunteers before and after 20 min of cyclic transcutaneous TNS delivered bilaterally to the infraorbital nerve. Eleven subjects underwent sham-TNS administration and were compared to the real-TNS group. In 12 subjects, effects of unilateral TNS were tested. The areas of the R1 and R2 components of the BR were recorded before and after 0 (T0), 15 (T15), 30 (T30), and 45 (T45) min from TNS. In three subjects, T60 and T90 time points were also evaluated. Ipsi- and contralateral R2 areas were significantly suppressed after bilateral real-TNS at T15 (p = 0.013), T30 (p = 0.002), and T45 (p = 0.001), while R1 response appeared unaffected. The TNS-induced inhibitory effect on R2 responses lasted up to 60 min. Real- and sham-TNS protocols produced significantly different effects (p = 0.005), with sham-TNS being ineffective at any time point tested. Bilateral TNS was more effective (p = 0.009) than unilateral TNS. Acute TNS induced a bilateral long-lasting inhibition of the R2 component of the BR, which resembles a long-term depression-like effect, providing evidence of brain stem plasticity produced by transcutaneous TNS. These findings add new insight into mechanisms of TNS neuromodulation and into physiopathology of those neurological disorders where clinical benefits of TNS are recognized.

Neuromodulation for Epilepsy

Several palliative neuromodulation treatment modalities are currently available for adjunctive use in the treatment of medically intractable epilepsy. Over the past decades, a variety of different central and peripheral nervous system sites have been identified, clinically and experimentally, as potential targets for chronic, nonresponsive therapeutic neurostimulation. Currently, the main modalities in clinical use, from most invasive to least invasive, are anterior thalamus deep brain stimulation, vagus nerve stimulation, and trigeminal nerve stimulation. Significant reductions in seizure frequency have been demonstrated in clinical trials using each of these neuromodulation therapies.

Transdermal neuromodulation of noradrenergic activity suppresses psychophysiological and biochemical stress responses in humans

We engineered a transdermal neuromodulation approach that targets peripheral (cranial and spinal) nerves and utilizes their afferent pathways as signaling conduits to influence brain function. We investigated the effects of this transdermal electrical neurosignaling (TEN) method on sympathetic physiology under different experimental conditions. The TEN method involved delivering high-frequency pulsed electrical currents to ophthalmic and maxillary divisions of the right trigeminal nerve and cervical spinal nerve afferents. Under resting conditions, TEN significantly suppressed basal sympathetic tone compared to sham as indicated by functional infrared thermography of facial temperatures. In a different experiment, subjects treated with TEN reported significantly lower levels of tension and anxiety on the Profile of Mood States scale compared to sham. In a third experiment when subjects were experimentally stressed TEN produced a significant suppression of heart rate variability, galvanic skin conductance, and salivary α-amylase levels compared to sham. Collectively these observations demonstrate TEN can dampen basal sympathetic tone and attenuate sympathetic activity in response to acute stress induction. Our physiological and biochemical observations are consistent with the hypothesis that TEN modulates noradrenergic signaling to suppress sympathetic activity. We conclude that dampening sympathetic activity in such a manner represents a promising approach to managing daily stress.

Epilepsy: A Spectrum Disorder

Epilepsy, a disorder of unprovoked seizures is a multifaceted disease affecting individuals of all ages with a particular predilection for the very young and old. In addition to seizures, many patients often report cognitive and psychiatric problems associated with both the seizures themselves and its therapy. Epilepsy has numerous etiologies both idiopathic and acquired with a wide range of therapeutic responses. Despite numerous treatments available to control repetitive seizures including medications, diets, immunotherapy, surgery, and neuromodulatory devices, a large percentage of patients continue to suffer the consequences of uncontrolled seizures, which include psychosocial stigma and death.

Early Seizure Detection Using Neuronal Potential Similarity: A Generalized Low-Complexity and Robust Measure

A novel approach using neuronal potential similarity (NPS) of two intracranial electroencephalogram (iEEG) electrodes placed over the foci is proposed for automated early seizure detection in patients with refractory partial epilepsy. The NPS measure is obtained from the spectral analysis of space-differential iEEG signals. Ratio between the NPS values obtained from two specific frequency bands is then investigated as a robust generalized measure, and reveals invaluable information about seizure initiation trends. A threshold-based classifier is subsequently applied on the proposed measure to generate alarms. The performance of the method was evaluated using cross-validation on a large clinical dataset, involving 183 seizure onsets in 1785 h of long-term continuous iEEG recordings of 11 patients. On average, the results show a high sensitivity of 86.9% (159 out of 183), a very low false detection rate of 1.4 per day, and a mean detection latency of 13.1 s from electrographic seizure onsets, while in average preceding clinical onsets by 6.3 s. These high performance results, specifically the short detection latency, coupled with the very low computational cost of the proposed method make it adequate for using in implantable closed-loop seizure suppression systems.