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

Neurostimulation, neuromodulation, and the treatment of epilepsies

Introduction.Neurostimulation and neuromodulation are techniques that may be able to affect the course of epilepsy. In the last 20 years, since the approval of VNS, we have observed a surge of studies assessing the potential of other devices and techniques for the treatment of pharmacoresistant epilepsies including deep brain stimulation (DBS), responsive neurostimulation (RNS), trigeminal nerve stimulation (TNS), transcranial direct current stimulation (tDCS), and repetitive transcranial magnetic stimulation (rTMS). Are these devices and techniques simply another treatment option that can be offered to patients with epilepsy or do they offer specific advantages when compared to the standard antiepileptic drugs (AEDs)?

Aim.The aim of this review is to present the neurostimulation and neuromodulation devices and techniques that are now in use, or at least available for testing and to discuss the science behind them, their applications, efficacy, potential risks vs. benefits and, above all, how to navigate the choices so clinicians are able to provide their patients with the best possible option for the treatment of epilepsy.

Material and methods.We analyzed PubMed and MEDLINE databases to select the most salient and recent (up to November 2014) publications on each treatment device. In addition to these searches bibliographies of selected articles were hand-searched for possible sources.

Discussion and conclusions.Great progress in neurostimulation and neuromodulation has been made over the last two decades with 2 devices (VNS, RNS) approved for the treatment of epilepsy in the US and three (DBS in addition to VNS and RNS) in Europe. The future of neuromodulation/neurostimulation is exciting – various studies and efforts are underway and will provide us with more data in the future. There appears to be one clear advantage of these treatments/devices over the AEDs that is consistently noted – routinely observed is continuous improvement in seizure control over time. This is something that the AEDs have thus far failed to deliver.

The Epilepsy Foundation's 4th Biennial Epilepsy Pipeline Update Conference

On June 5 and 6, 2014, the Epilepsy Foundation held its 4th Biennial Epilepsy Pipeline Update Conference, an initiative of the Epilepsy Therapy Project, which showcased the most promising epilepsy innovations from health-care companies and academic laboratories dedicated to pioneering and advancing drugs, biologics, technologies, devices, and diagnostics for epilepsy. Speakers and attendees included emerging biotech and medical technology companies, major pharmaceutical and device companies, as well as investigators and innovators at the cutting-edge of epilepsy. The program included panel discussions on collaboration between small and large companies, how to get products in need of funding to the marketplace, who is currently funding epilepsy and CNS innovation, and how the NIH facilitates early-stage drug development. Finally, the conference featured the third annual "Shark Tank" competition. The presentations are summarized in this paper, which is followed by a compilation of the meeting poster abstracts.

Vagus nerve stimulation therapy: indications, programing, and outcomes

Vagus nerve stimulation (VNS) provides palliation of seizure reduction for patients with medically refractory epilepsy. VNS is indicated for symptomatic localization-related epilepsy with multiple and bilateral independent foci, symptomatic generalized epilepsy with diffuse epileptogenic abnormalities, refractory idiopathic generalized epilepsy, failed intracranial epilepsy surgery, and other several reasons of contraindications to epilepsy surgery. Programing of the parameters is a principal part in VNS. Output current and duty cycle should be adjusted to higher settings particularly when a patient does not respond to the initial setting, since the pivotal randomized trials performed in the United States demonstrated high stimulation made better responses in seizure frequency. These trials revealed that a ≥ 50% seizure reduction occurred in 36.8% of patients at 1 year, in 43.2% at 2 years, and in 42.7% at 3 years in 440 patients. Safety of VNS was also confirmed because side effects including hoarseness, throat discomfort, cough, paresthesia, and headache improved progressively during the period of 3 years. The largest retrospective study with 436 patients demonstrated the mean seizure reduction of 55.8% in nearly 5 years, and also found 75.5% at 10 years in 65 consecutive patients. The intermediate analysis report of the Japan VNS Registry showed that 60% of 164 cases got a ≥ 50% seizure reduction in 12 months. In addition to seizure reduction, VNS has positive effects in mood and improves energy level, memory difficulties, social aspects, and fear of seizures. VNS is an effective and safe option for patients who are not suitable candidates for intracranial epilepsy surgery.

Electrical control of epilepsy

Epilepsy afflicts approximately 1-2% of the world's population. The mainstay therapy for treating the chronic recurrent seizures that are emblematic of epilepsy are drugs that manipulate levels of neuronal excitability in the brain. However, approximately one-third of all epilepsy patients get little to no clinical relief from this therapeutic regimen. The use of electrical stimulation in many forms to treat drug-refractory epilepsy has grown markedly over the past few decades, with some devices and protocols being increasingly used as standard clinical treatment. This article seeks to review the fundamental modes of applying electrical stimulation-from the noninvasive to the nominally invasive to deep brain stimulation-for the control of seizures in epileptic patients. Therapeutic practices from the commonly deployed clinically to the experimental are discussed to provide an overview of the innovative neural engineering approaches being explored to treat this difficult disease.

Investigating a new neuromodulation treatment for brain disorders using synchronized activation of multimodal pathways

Neuromodulation is an increasingly accepted treatment for neurological and psychiatric disorders but is limited by its invasiveness or its inability to target deep brain structures using noninvasive techniques. We propose a new concept called Multimodal Synchronization Therapy (mSync) for achieving targeted activation of the brain via noninvasive and precisely timed activation of auditory, visual, somatosensory, motor, cognitive, and limbic pathways. In this initial study in guinea pigs, we investigated mSync using combined activation of just the auditory and somatosensory pathways, which induced differential and timing dependent plasticity in neural firing within deep brain and cortical regions of the auditory system. Furthermore, by varying the location of somatosensory stimulation across the body, we increased or decreased spiking activity across different neurons. These encouraging results demonstrate the feasibility of systematically modulating the brain using mSync. Considering that hearing disorders such as tinnitus and hyperacusis have been linked to abnormal and hyperactive firing patterns within the auditory system, these results open up the possibility for using mSync to decrease this pathological activity by varying stimulation parameters. Incorporating multiple types of pathways beyond just auditory and somatosensory inputs and using other activation patterns may enable treatment of various brain disorders.

Epilepsy: new advances

Epilepsy affects 65 million people worldwide and entails a major burden in seizure-related disability, mortality, comorbidities, stigma, and costs. In the past decade, important advances have been made in the understanding of the pathophysiological mechanisms of the disease and factors affecting its prognosis. These advances have translated into new conceptual and operational definitions of epilepsy in addition to revised criteria and terminology for its diagnosis and classification. Although the number of available antiepileptic drugs has increased substantially during the past 20 years, about a third of patients remain resistant to medical treatment. Despite improved effectiveness of surgical procedures, with more than half of operated patients achieving long-term freedom from seizures, epilepsy surgery is still done in a small subset of drug-resistant patients. The lives of most people with epilepsy continue to be adversely affected by gaps in knowledge, diagnosis, treatment, advocacy, education, legislation, and research. Concerted actions to address these challenges are urgently needed.

A prospective long-term study of external trigeminal nerve stimulation for drug-resistant epilepsy

BACKGROUND

External trigeminal nerve stimulation (eTNS) is an emerging noninvasive therapy for drug-resistant epilepsy (DRE). We report the long-term safety and efficacy of eTNS after completion of a phase II randomized controlled clinical trial for drug-resistant epilepsy.

METHODS

This was a prospective open-label long-term study. Subjects who completed the phase II randomized controlled trial of eTNS for DRE were offered long-term follow-up for 1year. Subjects who were originally randomized to control settings were crossed over to effective device parameters (30s on, 30s off, pulse duration of 250s, frequency of 120Hz). Efficacy was assessed using last observation carried forward or parametric imputation methods for missing data points. Outcomes included change in median seizure frequency, RRATIO, and 50% responder rate.

RESULTS

Thirty-five of 50 subjects from the acute double-blind randomized controlled study continued in the long-term study. External trigeminal nerve stimulation was well tolerated. No serious device-related adverse events occurred through 12months of long-term treatment. At six and twelve months, the median seizure frequency for the original treatment group decreased by -2.39 seizures per month at 6 months (-27.4%) and -3.03 seizures per month at 12 months (-34.8%), respectively, from the initial baseline (p<0.05, signed-rank test). The 50% responder rates at three, six, and twelve months were 36.8% for the treatment group and 30.6% for all subjects.

CONCLUSION

The results provide long-term evidence that external trigeminal nerve stimulation is a safe and promising long-term treatment for drug-resistant epilepsy.

Acupuncture for refractory epilepsy: role of thalamus

Neurostimulation procedures like vagus nerve stimulation (VNS) and deep brain stimulation have been used to treat refractory epilepsy and other neurological disorders. While holding promise, they are invasive interventions with serious complications and adverse effects. Moreover, their efficacies are modest with less seizure free. Acupuncture is a simple, safe, and effective traditional healing modality for a wide range of diseases including pain and epilepsy. Thalamus takes critical role in sensory transmission and is highly involved in epilepsy genesis particularly the absence epilepsy. Considering thalamus serves as a convergent structure for both acupuncture and VNS and the thalamic neuronal activities can be modulated by acupuncture, we propose that acupuncture could be a promising therapy or at least a screening tool to select suitable candidates for those invasive modalities in the management of refractory epilepsy.

Advances in epilepsy surgery

This review summarises exciting recent and forthcoming advances that will impact on the surgical management of epilepsy in the near future. This does not cover the current accepted diagnostic methodologies or surgical treatments that are routinely practiced today. The content of this review was derived from a PubMed literature search, using the key words 'Epilepsy Surgery', 'Neuromodulation', 'Neuroablation', 'Advances', between 2010 and November 2013.

Future of epilepsy treatment: integration of devices

ABSTRACT 

The use of devices in the treatment of epilepsy is an emerging therapy for those patients whose seizures are not controlled by medications. This article will discuss current treatment options with devices for vagus nerve stimulation, deep brain stimulation and responsive neurostimulation. Emerging therapies in noninvasive neurostimulation such as with trigeminal nerve stimulation, transcranial magnetic stimulation and transcranial direct current stimulation may prove to be promising solutions. Finally, new and enhanced techniques of drug delivery are discussed as well as other devices with potential use in the study and treatment of epilepsy.

Trigeminal nerve stimulation (TNS) protocol for treating major depression: an open-label proof-of-concept trial

BACKGROUND

Major depressive disorder (MDD) is an incapacitating mental disorder associated with significant personal, social, and economic impairment. Patients with MDD present lower quality of life and higher prevalence of medical conditions, including epilepsy. Noninvasive brain stimulation (NIBS) is a technique that might aid in overcoming some of the current challenges related to pharmacotherapy. Trigeminal nerve stimulation is an incipient, simple, low-cost interventional strategy based on the application of an electric current over a branch of the trigeminal nerve with further propagation of the stimuli toward brain areas related to mood symptoms.

METHODS

We performed an open-label proof-of-concept trial using TNS for MDD. To the best of our knowledge, we present a TNS interventional protocol that has not been evaluated for MDD hitherto.

RESULTS

A total of 11 patients were studied, with a mean age of 50.36 years (sd: 11.8 from 30 to 60). Only one patient was male. Regarding the main outcome, there was a reduction of depressive symptoms with a mean score of 5.72 (sd: 2.24) (p<0.001) on the HDRS-17. Considering a categorical analysis, all patients presented clinical response defined as a reduction of scores of at least 50%. Only one patient did not reach a remission score (defined as an HDRS score lower than 8).

DISCUSSION

In the current neuromodulation scenario, clinical results have been working as truly hypothesis-driven forces, i.e., empirical observation and data analysis from different studies have been highlighting possible mechanisms related to the neurobiological functioning of neuromodulation strategies. The present results, however significant, need to be taken as hypothesis-driven given the study design. Data generalization is jeopardized due to the present study lacking a control group. Our results, therefore, may be overestimated due to intrinsic characteristics such as the placebo effect and Hawthorne effect.

CONCLUSION

We present a proof-of-concept trial evaluating a new TNS protocol for depression. Data analysis underscores a significant participation of TNS in ameliorating depressive symptoms of patients with moderate or severe depressive episode. Further controlled studies will contribute to establish the clinical relevance of this new strategy for MDD.

Neuromodulation for depression: invasive and noninvasive (deep brain stimulation, transcranial magnetic stimulation, trigeminal nerve stimulation)

Major depressive disorder is among the most disabling illnesses and, despite best practices with medication and psychotherapy, many patients remain ill even after several treatment trials. For many of these patients with treatment-resistant or pharmacoresistant depression, treatment with neuromodulation offers an alternative. Options range from systems that are implanted to others that are entirely noninvasive. This review surveys recent literature to update readers on 3 particular interventions: deep brain stimulation, transcranial magnetic stimulation, and trigeminal nerve stimulation. Additional comparative research is needed to delineate the relative advantages of these treatments, and how best to match individual patients to neuromodulation intervention.

Drug-resistant epilepsy: definition and treatment alternatives

INTRODUCTION

Drug-resistant epilepsy affects 25% of all epileptic patients, and quality of life decreases in these patients due to their seizures. Early detection is crucial in order to establish potential treatment alternatives and determine if the patient is a surgical candidate.

DEVELOPMENT

PubMed search for articles, recommendations published by major medical societies, and clinical practice guidelines for drug-resistant epilepsy and its medical and surgical treatment options. Evidence and recommendations are classified according to the criteria of the Oxford Centre for Evidence-Based Medicine (2001) and the European Federation of Neurological Societies (2004) for therapeutic actions.

CONCLUSIONS

Identifying patients with drug-resistant epilepsy is important for optimising drug therapy. Experts recommend rational polytherapy with antiepileptic drugs to find more effective combinations with fewer adverse effects. When adequate seizure control is not achieved, a presurgical evaluation in an epilepsy referral centre is recommended. These evaluations explore how to resect the epileptogenic zone without causing functional deficits in cases in which this is feasible. If resective surgery is not achievable, palliative surgery or neurostimulation systems (including vagus nerve, trigeminal nerve, or deep brain stimulation) may be an option. Other treatment alternatives such as ketogenic diet may also be considered in selected patients.

Approaches to refractory epilepsy

Epilepsy is one of the most common serious neurological conditions, and 30 to 40% of people with epilepsy have seizures that are not controlled by medication. Patients are considered to have refractory epilepsy if disabling seizures continue despite appropriate trials of two antiseizure drugs, either alone or in combination. At this point, patients should be referred to multidisciplinary epilepsy centers that perform specialized diagnostic testing to first determine whether they are, in fact, pharmacoresistant, and then, if so, offer alternative treatments. Apparent pharmacoresistance can result from a variety of situations, including noncompliance, seizures that are not epileptic, misdiagnosis of the seizure type or epilepsy syndrome, inappropriate use of medication, and lifestyle issues. For patients who are pharmacoresistant, surgical treatment offers the best opportunity for complete freedom from seizures. Surgically remediable epilepsy syndromes have been identified, but patients with more complicated epilepsy can also benefit from surgical treatment and require more specialized evaluation, including intracranial EEG monitoring. For patients who are not surgical candidates, or who are unwilling to consider surgery, a variety of other alternative treatments can be considered, including peripheral or central neurostimulation, ketogenic diet, and complementary and alternative approaches. When such alternative treatments are not appropriate or effective, quality of life can still be greatly improved by the psychological and social support services offered by multidisciplinary epilepsy centers. A major obstacle remains the fact that only a small proportion of patients with refractory epilepsy are referred for expert evaluation and treatment.

Electrical brain stimulation for epilepsy

Neurostimulation enables adjustable and reversible modulation of disease symptoms, including those of epilepsy. Two types of brain neuromodulation, comprising anterior thalamic deep brain stimulation and responsive neurostimulation at seizure foci, are supported by Class I evidence of effectiveness, and many other sites in the brain have been targeted in small trials of neurostimulation therapy for seizures. Animal studies have mainly assisted in the identification of potential neurostimulation sites and parameters, but much of the clinical work is only loosely based on fundamental principles derived from the laboratory, and the mechanisms by which brain neurostimulation reduces seizures remain poorly understood. The benefits of stimulation tend to increase over time, with maximal effect seen typically 1-2 years after implantation. Typical reductions of seizure frequency are approximately 40% acutely, and 50-69% after several years. Seizure intensity might also be reduced. Complications from brain neurostimulation are mainly associated with the implantation procedure and hardware, including stimulation-related paraesthesias, stimulation-site infections, electrode mistargeting and, in some patients, triggered seizures or even status epilepticus. Further preclinical and clinical experience with brain stimulation surgery should lead to improved outcomes by increasing our understanding of the optimal surgical candidates, sites and parameters.

Neurostimulation for drug-resistant epilepsy

PURPOSE OF REVIEW

The purpose of this review is to provide an evidence-based update on the neurostimulation options available for patients with drug-resistant epilepsy in the United States and in European countries.

RECENT FINDINGS

The field of neurostimulation for epilepsy has grown dramatically since 1997, when vagus nerve stimulation became the first device to be approved for epilepsy by the US Food and Drug Administration (FDA). New data from recently completed randomized controlled trials are available for deep brain stimulation of the anterior thalamus, responsive neurostimulation, and trigeminal nerve stimulation. Although vagus nerve stimulation is the only device currently approved in the United States, deep brain stimulation and responsive neurostimulation devices are awaiting FDA approval. Deep brain stimulation, trigeminal nerve stimulation, and transcutaneous vagus nerve stimulation are now approved for epilepsy in the European Union. In this article, the mechanisms of action, safety, and efficacy of new neurostimulation devices are reviewed, and the key advantages and disadvantages of each are discussed.

SUMMARY

The exponential growth of the field of neuromodulation for epilepsy is an exciting development; these new devices provide physicians with new options for patients with drug-resistant epilepsy.

Refractory status epilepticus treated with trigeminal nerve stimulation

Refractory status epilepticus (RSE) is a neurologic emergency associated with significant morbidity and mortality. Alternative therapies are needed for patients who do not respond to more traditional therapies for RSE. We report on a patient with RSE treated with external trigeminal nerve stimulation (eTNS). On admission, the patient was experiencing consecutive focal dyscognitive seizures with secondary generalization without recovery in between. His seizures remained refractory to multiple therapies, including IV lorazepam, valproic acid, levetiracetam, phenobarbital, and midazolam. Although a burst suppression pattern was achieved with a continuous pentobarbital infusion, seizures returned following attempts to taper it. Given his beneficial response to eTNS during a previous clinical trial, eTNS was initiated. Four days after starting eTNS, the pentobarbital infusion was finally weaned, and his EEG revealed no further seizures. The patient's mental status improved and he was ultimately discharged with only moderately severe disability. Our case demonstrates that eTNS may have antiseizure effects in RSE. Given our patient's quick response, such benefit may have arisen from EEG-desynchronization. If confirmed in larger studies, eTNS could one day be considered along with other adjuvant treatments for RSE.

Supraorbital stimulation does not induce an antidepressant-like response in rats

BACKGROUND

Neuromodulation therapies are currently being investigated as potential treatments for depression. One of these treatments involves the stimulation of supraorbital branches of the trigeminal nerve.

OBJECTIVE

To show that supraorbital stimulation is effective in preclinical models.

METHODS

Rats were given supraorbital stimulation at different settings in the forced swim test (FST) and open field.

RESULTS

Supraorbital stimulation did not induce an antidepressant-like response in rats undergoing the FST. This is in contrast to other neuromodulation treatments, such as deep brain stimulation, vagus nerve stimulation and electroconvulsive therapy, which are all effective in this paradigm.

CONCLUSIONS

Supraorbital stimulation was ineffective in rats undergoing the FST. Such findings do not invalidate results of recent clinical trials.

Trigeminal nerve stimulation in major depressive disorder: acute outcomes in an open pilot study

Most patients with major depressive disorder (MDD) do not recover with initial pharmacotherapy, and many pursue combination treatments. Combining a medication with neuromodulation offers an alternative to purely pharmacologic strategies. In prior open and double-blind controlled trials for drug-resistant epilepsy, adjunctive external trigeminal nerve stimulation (eTNS) was found to be safe and well tolerated, to significantly reduce seizures, and to be associated with an improvement in depressive symptoms. Here, we present a comprehensive description of the first open pilot investigation in MDD. In this 8-week trial, eleven adults with unipolar MDD received nightly stimulation (V(1) branch). All entered with moderate to severe symptom levels despite at least two antidepressant medication trials in this episode. All the eleven adults completed the acute trial, without serious adverse events. Symptoms of depression improved significantly, whether assessed with clinician- or self-rated scales (all p < 0.01; effect sizes d 1.0-1.8), as did quality of life (p < 0.02). Four of the 11 achieved remission. These improvements from nightly adjunctive eTNS in treatment-resistant depression merit replication under double-blind conditions.

Emerging devices for epilepsy

About 30% of people with epilepsy continue to have seizures despite a growing array of antiseizure drugs. For some of these people, surgical resection of brain tissue is an effective therapeutic option. For others, the likelihood of seizure freedom is low, and has not improved much despite the introduction of several new antiseizure drugs. The vagus nerve stimulator is the only device approved by the Food and Drug Administration (FDA), but it rarely results in freedom from seizures. Recently, 2 approaches to electrical stimulation of the brain have been reported. One device has been approved for use in Canada and in Europe, and it seems likely that one or more such devices will be approved for use in the United States. We examine some of the data from these studies in the context of the current FDA-approved drugs and devices.

Auricular acupuncture with laser

Auricular acupuncture is a method which has been successfully used in various fields of medicine especially in the treatment of pain relief. The introduction of lasers especially low-level lasers into medicine brought besides the already existing stimulation with needles and electricity an additional technique to auricular acupuncture. This literature research looks at the historical background, the development and the anatomical and neurological aspects of auricular acupuncture in general and auricular laser acupuncture in detail. Preliminary scientific findings on auricular acupuncture with laser have been described in detail and discussed critically in this review article. The results of the studies have shown evidence of the effect of auricular laser acupuncture. However, a comparison of these studies was impossible due to their different study designs. The most important technical as well as study parameters were described in detail in order to give more sufficient evidence and to improve the quality of future studies.