rTMS reduces focal brain hyperperfusion in two patients with EPC

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.

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

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

Neuromodulation in Children with Drug-Resistant Epilepsy

The introduction of neuromodulation was a revolutionary advancement in the antiseizure armamentarium for refractory epilepsy. The basic principle of neuromodulation is to deliver an electrical stimulation to the desired neuronal site to modify the neuronal functions not only at the site of delivery but also at distant sites by complex neuronal processes like disrupting the neuronal circuitry and amplifying the functions of marginally functional neurons. The modality is considered open-loop when electrical stimulation is provided at a set time interval or closed-loop when delivered in response to an incipient seizure. Neuromodulation in individuals older than 18 years with epilepsy has proven efficacious and safe. The use of neuromodulation is extended off-label to pediatric patients with epilepsy and the results are promising. Vagus nerve stimulation (VNS), responsive neurostimulation (RNS), and deep brain stimulation (DBS) are Food and Drug Administration-approved therapeutic techniques. The VNS provides retrograde signaling to the central nervous system, whereas DBS and RNS are more target specific in the central nervous system. While DBS is open-loop and approved for stimulation of the anterior nucleus of the thalamus, the RNS is closed-loop and can stimulate any cortical or subcortical structure. We will review different modalities and their clinical efficacy in individuals with epilepsy, with a focus on pediatric patients.

Repetitive transcranial magnetic stimulation (rTMS) as therapy in an infant with epilepsia partialis continua

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rTMS was safely performed in a 10-month old at 10 Hz without apparent adverse effects.

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rTMS was successfully performed in an infant for refractory epilepsia partialis continua.

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rTMS may have a treatment role in recurring, refractory epilepsia partialis continua in children.

Introduction: We present a case of a 10-month-old girl undergoing repetitive TMS (rTMS) for the treatment of drug-resistant epilepsy. Case report: A 10-month-old girl, later diagnosed with pathogenic POLG1 mutations, presented to our institution with chronic progressive EPC (epilepsia partialis continua) manifesting as a frequent, left-sided, synchronous continuous jerking of the arms and legs. The seizures were drug-resistant to multiple antiseizure medications and epilepsy surgery, responding only to continuous anesthesia. rTMS therapy was attempted to interrupt seizures. Results: rTMS therapy, using an activating protocol to introduce a temporary lesion effect, was used to interrupt persistent, ongoing seizures. Conclusion: rTMS can be safely used to abort seizures in patients as young as 10 months old.

Neuromodulation in Pediatric Epilepsy

Neuromodulation alters neuronal activity with electrical impulses delivered to the targeted neurologic sites. The various neuromodulation options available today for epilepsy management have proven efficacy primarily in adult trials. These include open-loop stimulation with invasive vagus nerve stimulation and deep brain stimulation, as well as closed-loop responsive neurostimulation. The use of neurostimulation therapy to treat intractable epilepsy in children is growing. This article reviews the literature, historical background, and current principles in pediatric patients.

Review of Transcranial Magnetic Stimulation in Epilepsy

PURPOSE

Despite the availability of numerous pharmacologic and nonpharmacologic antiseizure therapies, a fraction of patients with epilepsy remain refractory to current treatment options, underscoring the need for novel drugs and neuromodulatory therapies. Transcranial magnetic stimulation (TMS), coupled with either electromyography or electroencephalography, enables rapid measurement of the cortical excitation/inhibition ratio, which is pathologically shifted toward excess excitability in patients with epilepsy. In this review, we summarize: (1) TMS protocols that have been deployed to identify promising compounds in the antiepilepsy drug (AED)-development pipeline, and (2) the therapeutic potential of TMS in the treatment of drug-resistant seizures.

METHODS

A focused literature review of the use of TMS in epilepsy, using a PubMed search, was performed. Over 70 articles were included that pertained to: (1) the use of TMS-EMG and TMS-EEG in elucidating the mechanisms of action of AEDs and in discovering potential new AEDs; and (2) the use of repetitive TMS in the treatment of seizures.

FINDINGS

Studies from the literature have reported that AEDs alter TMS-derived metrics, typically by leading to a net increase in cortical inhibition with successful therapy. Preclinical TMS work in rodent models of epilepsy has led to the development of novel antiseizure drug compounds. Clinical translational studies of TMS have been used to determine guidelines on the dosages of other agents in the AED pipeline in preparation for clinical trials. Several studies have described the use of therapeutic repetitive TMS in both the ictal and interictal states of epilepsy, with inconsistent results.

IMPLICATIONS

TMS has diagnostic and therapeutic potential in epilepsy. TMS-derived markers can enable early-stage measures of AED target engagement, and can facilitate studies of the pharmacokinetic and pharmacodynamic properties of AEDs. TMS may also be used in the early prediction of the efficacy of different AEDs in treating patients, and in direct neuromodulation of epileptic networks. From the therapeutics perspective, despite favorable results in some trials, the optimization of treatment paradigms and the determination of ideal candidates for TMS are still needed. Finally, preclinical experiments of TMS have provided mechanistic insight into its effects on the excitation/inhibition ratio, and may facilitate rational drug-device coupling paradigms. Overall, the capacity of TMS in both the modulation and measurement of changes in cortical excitability highlights its unique role in advancing antiepilepsy therapeutics.

Transcranial Magnetic Stimulation for the Treatment of Pediatric Neurological Disorders

PURPOSE OF REVIEW

Repetitive transcranial magnetic stimulation (rTMS) is a form of noninvasive brain stimulation that is used for the treatment of migraine and major depression in adults and is now being evaluated for use in other disorders. The purpose of this review is to summarize the physiology underlying TMS, the safety and tolerability in pediatric patients, and the evidence for TMS efficacy in the treatment of pediatric neurologic disorders.

RECENT FINDINGS

Studies investigating rTMS for adolescent depression, hemiparesis due to pediatric stroke, autism, and tics/Tourette syndrome have demonstrated some therapeutic benefit. rTMS has been insufficiently studied for migraine in children despite benefits demonstrated for adult migraine. Evidence for rTMS in childhood epilepsy and ADHD remains mixed. Repetitive transcranial magnetic stimulation is emerging as a safe, tolerable, and potentially effective therapeutic strategy in a number of pediatric neurological disorders, though high-quality, randomized controlled trials are needed. Ongoing studies should focus on optimization of treatment protocols, development of biomarkers to identify children who will benefit from the technique, and identification of the most appropriate indicators of response.

Bursts of high-frequency repetitive transcranial magnetic stimulation (rTMS), together with lorazepam, suppress seizures in a rat kainate status epilepticus model

BACKGROUND

Status epilepticus (SE) is a condition of prolonged or recurrent and often drug-resistant seizures where nonsedating SE therapy remains an important unmet need. Repetitive transcranial magnetic stimulation (rTMS) is emerging as a means to suppress seizures but has not been extensively studied in models.

OBJECTIVES

We aimed to test the antiepileptic potential of high-frequency rTMS in SE. As a step toward eventual coupling of rTMS with antiepileptic pharmacotherapy, we also tested whether high-frequency rTMS in combination with a low (ineffective but less likely to cause a side effect) lorazepam dose is as effective as a full lorazepam dose in suppressing seizures in a rat SE model.

METHODS

EEG was recorded to measure epileptic spike frequency in the rat kainate SE model. Epileptic spikes were counted before, during, and after either high-frequency rTMS treatment alone or high-frequency rTMS treatment in combination with lorazepam, a firstline SE treatment.

RESULTS

We found that rTMS alone decreases epileptic spike frequency only acutely. However, combinatory treatment with half-dose lorazepam together with rTMS was as effective as a full lorazepam dose.

CONCLUSION

We report that high-frequency rTMS has modest antiepileptic potential alone but acts in complement with lorazepam to suppress seizures.

Seizure Induced by Deep Transcranial Magnetic Stimulation in an Adolescent with Depression

OBJECTIVE

Deep transcranial magnetic stimulation (TMS) with an H-1 coil was recently approved by the U.S. Food and Drug Administration (U.S. FDA) for treatment-resistant depression (TRD) in adults. Studies assessing the safety and effectiveness of deep TMS in adolescent TRD are lacking. The purpose of this brief report is to provide a case history of an adolescent enrolled in an investigational deep TMS protocol.

METHODS

A case history is described of the first participant of a sham-controlled clinical trial who had a seizure in the course of deep TMS with parameter settings extrapolated from the adult studies that led to US FDA approval (H-1 coil, 120% target stimulation intensity, 18 Hz, 55 trains of 2-second duration, total 1980 pulses).

RESULTS

The participant was a 17-year-old unmedicated female, with no significant medical history and no history of seizures or of drug or alcohol use. Brain magnetic resonance imaging showed no structural abnormalities. She initially received sham, which was well tolerated. During active treatment sessions, titration began at 85% of motor threshold (MT) and increased by 5% per day. Her weekly MT measurements were stable. On her first day of 120% MT (8th active treatment), during the 48th train, the participant had a generalized, tonic-clonic seizure that lasted 90 seconds and resolved spontaneously. She had an emergency medicine evaluation and was discharged home without anticonvulsant medications. There were no further seizures reported at a 6-month follow-up.

CONCLUSIONS

We report a deep TMS-induced generalized tonic-clonic seizure in an adolescent with TRD participating in a clinical trial. Given the demonstrated benefits of deep TMS for adult TRD, research investigating its use in adolescents with TRD is an important area. However, in light of this experience, additional precautions for adolescents should be considered. We propose that further dose-finding investigations are needed to refine adolescent-specific parameters that may be safe and effective for treating adolescents with TRD with deep TMS.

Safety of repetitive transcranial magnetic stimulation in patients with epilepsy: A systematic review

Approximately one-third of patients with epilepsy remain with pharmacologically intractable seizures. An emerging therapeutic modality for seizure suppression is repetitive transcranial magnetic stimulation (rTMS). Despite being considered a safe technique, rTMS carries the risk of inducing seizures, among other milder adverse events, and thus, its safety in the population with epilepsy should be continuously assessed. We performed an updated systematic review on the safety and tolerability of rTMS in patients with epilepsy, similar to a previous report published in 2007 (Bae EH, Schrader LM, Machii K, Alonso-Alonso M, Riviello JJ, Pascual-Leone A, Rotenberg A. Safety and tolerability of repetitive transcranial magnetic stimulation in patients with epilepsy: a review of the literature. Epilepsy Behav. 2007; 10 (4): 521-8), and estimated the risk of seizures and other adverse events during or shortly after rTMS application. We searched the literature for reports of rTMS being applied on patients with epilepsy, with no time or language restrictions, and obtained studies published from January 1990 to August 2015. A total of 46 publications were identified, of which 16 were new studies published after the previous safety review of 2007. We noted the total number of subjects with epilepsy undergoing rTMS, medication usage, incidence of adverse events, and rTMS protocol parameters: frequency, intensity, total number of stimuli, train duration, intertrain intervals, coil type, and stimulation site. Our main data analysis included separate calculations for crude per subject risk of seizure and other adverse events, as well as risk per 1000 stimuli. We also performed an exploratory, secondary analysis on the risk of seizure and other adverse events according to the type of coil used (figure-of-8 or circular), stimulation frequency (≤ 1 Hz or > 1 Hz), pulse intensity in terms of motor threshold (<100% or ≥ 100%), and number of stimuli per session (< 500 or ≥ 500). Presence or absence of adverse events was reported in 40 studies (n = 426 subjects). A total of 78 (18.3%) subjects reported adverse events, of which 85% were mild. Headache or dizziness was the most common one, occurring in 8.9%. We found a crude per subject seizure risk of 2.9% (95% CI: 1.3-4.5), given that 12 subjects reported seizures out of 410 subjects included in the analysis after data of patients with epilepsia partialis continua or status epilepticus were excluded from the estimate. Only one of the reported seizures was considered atypical in terms of the clinical characteristics of the patients' baseline seizures. The atypical seizure happened during high-frequency rTMS with maximum stimulator output for speech arrest, clinically arising from the region of stimulation. Although we estimated a larger crude per subject seizure risk compared with the previous safety review, the corresponding confidence intervals contained both risks. Furthermore, the exclusive case of atypical seizure was the same as reported in the previous report. We conclude that the risk of seizure induction in patients with epilepsy undergoing rTMS is small and that the risk of other adverse events is similar to that of rTMS applied to other conditions and to healthy subjects. Our results should be interpreted with caution, given the need for adjusted analysis controlling for potential confounders, such as baseline seizure frequency. The similarity between the safety profiles of rTMS applied to the population with epilepsy and to individuals without epilepsy supports further investigation of rTMS as a therapy for seizure suppression.

Transcranial Magnetic Stimulation for Status Epilepticus

Background. Our goal was to perform a systematic review on the use of repetitive transcranial magnetic stimulation (rTMS) in the treatment of status epilepticus (SE) and refractory status epilepticus (RSE). Methods. MEDLINE, BIOSIS, EMBASE, Global Health, Healthstar, Scopus, Cochrane Library, the International Clinical Trials Registry Platform, clinicaltrials.gov (inception to August 2015), and gray literature were searched. The strength of evidence was adjudicated using Oxford and GRADE methodology. Results. We identified 11 original articles. Twenty-one patients were described, with 13 adult and 8 pediatric. All studies were retrospective. Seizure reduction/control with rTMS occurred in 15 of the 21 patients (71.4%), with 5 (23.8%) and 10 (47.6%) displaying partial and complete responses, respectively. Seizures recurred after rTMS in 73.3% of the patients who had initially responded. All studies were an Oxford level 4, GRADE D level of evidence. Conclusions. Oxford level 4, GRADE D evidence exists to suggest a potential impact on seizure control with the use of rTMS for FSE and FRSE, though durability of the therapy is short-lived. Routine use of rTMS in this context cannot be recommended at this time. Further prospective study of this intervention is warranted.

Safety of noninvasive brain stimulation in children and adolescents

BACKGROUND

Noninvasive brain stimulation (NIBS) techniques such as transcranial magnetic stimulation (TMS) and transcranial current stimulation (tCS) have the potential to mitigate a variety of symptoms associated with neurological and psychiatric conditions, including stroke, cerebral palsy, autism, depression, and Tourette syndrome. While the safety of these modalities has been established in adults, there is a paucity of research assessing the safety of NIBS among children.

OBJECTIVE

To examine the existing literature regarding the safety of NIBS techniques in children and adolescents with neurologic and neuropsychiatric disorders.

METHODS

An electronic search was performed on online databases for studies using NIBS in individuals less than 18 years of age. Non-English publications, diagnostic studies, electroconvulsive therapy, single/dual pulse TMS studies, and reviews were excluded. Adverse events reported in the studies were carefully examined and synthesized to understand the safety and tolerability of NIBS among children and adolescents.

RESULTS

The data from 48 studies involving more than 513 children/adolescents (2.5-17.8 years of age) indicate that the side effects of NIBS were, in general, mild and transient [TMS: headache (11.5%), scalp discomfort (2.5%), twitching (1.2%), mood changes (1.2%), fatigue (0.9%), tinnitus (0.6%); tCS: tingling (11.5%), itching (5.8%), redness (4.7%), scalp discomfort (3.1%)] with relatively few serious adverse events.

CONCLUSION

Our findings indicate that both repetitive TMS and tCS are safe modalities in children and adolescents with various neurological conditions, especially when safety guidelines are followed. The incidence of adverse events appears to be similar to that observed in adults; however, further studies with longer treatment and follow-up periods are needed to better understand the benefits and tolerance of long-term use of NIBS in children.

Evidence-based guidelines on the therapeutic use of repetitive transcranial magnetic stimulation (rTMS)

A group of European experts was commissioned to establish guidelines on the therapeutic use of repetitive transcranial magnetic stimulation (rTMS) from evidence published up until March 2014, regarding pain, movement disorders, stroke, amyotrophic lateral sclerosis, multiple sclerosis, epilepsy, consciousness disorders, tinnitus, depression, anxiety disorders, obsessive-compulsive disorder, schizophrenia, craving/addiction, and conversion. Despite unavoidable inhomogeneities, there is a sufficient body of evidence to accept with level A (definite efficacy) the analgesic effect of high-frequency (HF) rTMS of the primary motor cortex (M1) contralateral to the pain and the antidepressant effect of HF-rTMS of the left dorsolateral prefrontal cortex (DLPFC). A Level B recommendation (probable efficacy) is proposed for the antidepressant effect of low-frequency (LF) rTMS of the right DLPFC, HF-rTMS of the left DLPFC for the negative symptoms of schizophrenia, and LF-rTMS of contralesional M1 in chronic motor stroke. The effects of rTMS in a number of indications reach level C (possible efficacy), including LF-rTMS of the left temporoparietal cortex in tinnitus and auditory hallucinations. It remains to determine how to optimize rTMS protocols and techniques to give them relevance in routine clinical practice. In addition, professionals carrying out rTMS protocols should undergo rigorous training to ensure the quality of the technical realization, guarantee the proper care of patients, and maximize the chances of success. Under these conditions, the therapeutic use of rTMS should be able to develop in the coming years.

Transcranial magnetic stimulation for refractory focal status epilepticus in the intensive care unit

PURPOSE

To examine the efficacy and safety profile of antiepileptic repetitive transcranial magnetic stimulation (rTMS) for refractory status epilepticus (RSE) in the intensive care unit (ICU) setting. In addition, hypothetical concerns about electrical interference of rTMS with ICU equipment have been previously raised.

METHODS

We describe two cases of RSE treated with rTMS in the ICU.

RESULTS

In one case, rTMS contributed to decreased seizure frequency; in the second case, rTMS transiently decreased seizure frequency. In both cases, rTMS was safe and did not interfere with the functioning of the ICU equipment.

CONCLUSION

rTMS is a potential therapy for RSE when conventional therapies have failed. Future studies should investigate the efficacy of various rTMS stimulation parameters, safety issues, and bioengineering considerations in the ICU setting.

Non-invasive brain stimulation for the treatment of brain diseases in childhood and adolescence: state of the art, current limits and future challenges

In the last decades interest in application of non-invasive brain stimulation for enhancing neural functions is growing continuously. However, the use of such techniques in pediatric populations remains rather limited and mainly confined to the treatment of severe neurological and psychiatric diseases. In this article we provide a complete review of non-invasive brain stimulation studies conducted in pediatric populations. We also provide a brief discussion about the current limitations and future directions in a field of research still very young and full of issues to be explored.

NON-INVASIVE BRAIN STIMULATION IN CHILDREN: APPLICATIONS AND FUTURE DIRECTIONS

Transcranial magnetic stimulation (TMS) is a neurostimulation and neuromodulation technique that has provided over two decades of data in focal, non-invasive brain stimulation based on the principles of electromagnetic induction. Its minimal risk, excellent tolerability and increasingly sophisticated ability to interrogate neurophysiology and plasticity make it an enviable technology for use in pediatric research with future extension into therapeutic trials. While adult trials show promise in using TMS as a novel, non-invasive, non-pharmacologic diagnostic and therapeutic tool in a variety of nervous system disorders, its use in children is only just emerging. TMS represents an exciting advancement to better understand and improve outcomes from disorders of the developing brain.

Therapeutic devices for epilepsy

Therapeutic devices provide new options for treating drug-resistant epilepsy. These devices act by a variety of mechanisms to modulate neuronal activity. Only vagus nerve stimulation (VNS), which continues to develop new technology, is approved for use in the United States. Deep brain stimulation of anterior thalamus for partial epilepsy recently was approved in Europe and several other countries. Responsive neurostimulation, which delivers stimuli to 1 or 2 seizure foci in response to a detected seizure, recently completed a successful multicenter trial. Several other trials of brain stimulation are in planning or underway. Transcutaneous magnetic stimulation (TMS) may provide a noninvasive method to stimulate cortex. Controlled studies of TMS are split on efficacy, which may depend on whether a seizure focus is near a possible region for stimulation. Seizure detection devices in the form of shake detectors via portable accelerometers can provide notification of an ongoing tonic-clonic seizure, or peace of mind in the absence of notification. Prediction of seizures from various aspects of electroencephalography (EEG) is in early stages. Prediction appears to be possible in a subpopulation of people with refractory seizures, and a clinical trial of an implantable prediction device is underway. Cooling of neocortex or hippocampus reversibly can attenuate epileptiform EEG activity and seizures, but engineering problems remain in its implementation. Optogenetics is a new technique that can control excitability of specific populations of neurons with light. Inhibition of epileptiform activity has been demonstrated in hippocampal slices, but use in humans will require more work. In general, devices provide useful palliation for otherwise uncontrollable seizures, but with a different risk profile than with most drugs. Optimizing the place of devices in therapy for epilepsy will require further development and clinical experience.

[French guidelines on the use of repetitive transcranial magnetic stimulation (rTMS): safety and therapeutic indications]

During the past decade, a large amount of work on transcranial magnetic stimulation (TMS) has been performed, including the development of new paradigms of stimulation, the integration of imaging data, and the coupling of TMS techniques with electroencephalography or neuroimaging. These accumulating data being difficult to synthesize, several French scientific societies commissioned a group of experts to conduct a comprehensive review of the literature on TMS. This text contains all the consensual findings of the expert group on the mechanisms of action, safety rules and indications of TMS, including repetitive TMS (rTMS). TMS sessions have been conducted in thousands of healthy subjects or patients with various neurological or psychiatric diseases, allowing a better assessment of risks associated with this technique. The number of reported side effects is extremely low, the most serious complication being the occurrence of seizures. In most reported seizures, the stimulation parameters did not follow the previously published recommendations (Wassermann, 1998) [430] and rTMS was associated to medication that could lower the seizure threshold. Recommendations on the safe use of TMS / rTMS were recently updated (Rossi et al., 2009) [348], establishing new limits for stimulation parameters and fixing the contraindications. The recommendations we propose regarding safety are largely based on this previous report with some modifications. By contrast, the issue of therapeutic indications of rTMS has never been addressed before, the present work being the first attempt of a synthesis and expert consensus on this topic. The use of TMS/rTMS is discussed in the context of chronic pain, movement disorders, stroke, epilepsy, tinnitus and psychiatric disorders. There is already a sufficient level of evidence of published data to retain a therapeutic indication of rTMS in clinical practice (grade A) in chronic neuropathic pain, major depressive episodes, and auditory hallucinations. The number of therapeutic indications of rTMS is expected to increase in coming years, in parallel with the optimisation of stimulation parameters.

rTMS for adolescents: Safety and efficacy considerations

In light of both the FDA's clearance of repetitive transcranial magnetic stimulation (rTMS) for adult major depressive disorder and concerns about safety and efficacy of existing antidepressant therapies for adolescent depression, there is increasing interest in rTMS as a novel treatment for adolescent depression. We reviewed English-language studies using rTMS in persons under the age of 18, yielding 6 published reports. Because rTMS is typically delivered at or above 1 Hz for psychiatric indications, our search was confined to these frequencies. Also included are studies involving rTMS above 1 Hz for non-psychiatric indications. Articles were retrieved from the MEDLINE database. There were 19 reported subjects under age 18 who have been administered rTMS at a frequency above 1 Hz: 10 for major depression, 5 for spastic cerebral palsy and 4 for epilepsia partialis continua. We found that most subjects responded favorably to rTMS and no adverse events have been reported. However data are insufficient for drawing firm conclusions about safety and efficacy. Further studies of rTMS as a treatment for adolescent depression are warranted.

Noninvasive brain stimulation protocols in the treatment of epilepsy: current state and perspectives

In epileptic seizures, there is an enhanced probability of neuronal networks to fire synchronously at high frequency, initiated by a paroxysmal depolarisation shift. Reducing neuronal excitability is a common target of antiepileptic therapies. Beyond or in addition to pharmacological interventions, excitability-reducing brain stimulation is pursued as an alternative therapeutic approach. Hereby, noninvasive brain stimulation tools, such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS), have gained increased interest as efficient tools to modulate cortical excitability and activity. In animal models, stimulation-induced cortical excitability diminution has been shown to be suited to reduce seizures. Clinical studies conducted to date, however, have shown mixed results. Reasons for this, as well as possible optimization strategies that might lead to more efficient future stimulation protocols, will be discussed.

Repetitive transcranial magnetic stimulation in the treatment of epilepsia partialis continua

OBJECTIVE

Repetitive transcranial magnetic stimulation (rTMS) is a technique for noninvasive focal brain stimulation by which small intracranial electrical currents are generated by a fluctuating extracranial magnetic field. In clinical epilepsy, rTMS has been applied most often interictally to reduce seizure frequency. Less often, rTMS has been used to terminate ongoing seizures, as in instances of epilepsia partialis continua (EPC). Whether ictal rTMS is effective and safe in the treatment of EPC has not been extensively studied. Here, we describe our recent experience with rTMS in the treatment of EPC, as an early step toward evaluating the safety and efficacy of rTMS in the treatment of intractable ongoing focal seizures.

METHODS

Seven patients with EPC of mixed etiologies were treated with rTMS applied over the seizure. rTMS was delivered in high-frequency (20-100 Hz) bursts or as prolonged low-frequency (1 Hz) trains. The EEG was recorded for three of the seven patients.

RESULTS

rTMS resulted in a brief (20-30 min) pause in seizures in three of seven patients and a lasting (>or=1 day) pause in two of seven. A literature search identified six additional reports of EPC treated with rTMS where seizures were suppressed in three of six. Seizures were not exacerbated by rTMS in any patient. Generally mild side effects included transient head and limb pain, and limb stiffening during high-frequency rTMS trains.

CONCLUSIONS

Our clinical observations in a small number of patients suggest that rTMS may be safe and effective in suppressing ongoing seizures associated with EPC. However, a controlled trial is needed to assess the safety and anticonvulsive efficacy of rTMS in the treatment of EPC.

Seizure suppression by EEG-guided repetitive transcranial magnetic stimulation in the rat

OBJECTIVE

To test the anticonvulsive potential of a range of repetitive transcranial magnetic stimulation (rTMS) frequencies by novel methods for simultaneous EEG and rTMS in a rat seizure model.

METHODS

Seizures were triggered by intraperitoneal kainic acid (KA; 10mg/kg). Rats (n=21) were divided into three groups in which individual seizures were treated with rTMS trains at one of three frequencies: 0.25, 0.5 or 0.75 Hz. EEG was continuously viewed by an operator who identified each seizure onset. Consecutive seizures in each animal were (1) treated with active rTMS, (2) treated with sham rTMS, or (3) were untreated. EEG was re-analyzed post hoc by visual inspection, and seizure durations were compared within and between treatment groups.

RESULTS

KA-induced seizures were abbreviated by 0.75 Hz (P=0.019) and 0.5 Hz (P=0.033) active EEG-guided rTMS. In contrast, neither active 0.25 Hz rTMS nor the control conditions affected seizure duration (P>0.2).

CONCLUSIONS

We demonstrate that EEG-guided rTMS can suppress seizures in the rat KA epilepsy model, and that the effect is frequency dependent, with 0.75 and 0.5 Hz rTMS being superior to 0.25 Hz rTMS.

SIGNIFICANCE

These data support the use of rat seizure models in translational research aimed at evaluation and development of effective rTMS anticonvulsive protocols. We also offer a proof of principle that real-time analysis of EEG can be used to guide rTMS to suppress individual seizures.

Transient suppression of seizures by repetitive transcranial magnetic stimulation in a case of Rasmussen's encephalitis

Repetitive transcranial magnetic stimulation (rTMS) has been applied with variable success to terminate the seizures of epilepsia partialis continua. The rationale for using this technique to suppress ongoing seizures is the capacity of rTMS to interrupt ongoing neuronal activity, and to produce a lasting decrease in cortical excitability with low-frequency (1 Hz) stimulation. We report a case of epilepsia partialis continua in a child with Rasmussen's encephalitis, in whom seizures were transiently suppressed by 1-Hz rTMS delivered in nine daily 30-minute sessions. In this case, total ictal time was significantly reduced during stimulation, but the daily baseline seizure rate remained unchanged. Notably, the detection and quantification of this short-lived improvement were enabled by recording EEG continuously during the rTMS session. Thus, we present this case to illustrate a potential utility of combined continuous EEG recording and rTMS in seizure treatment.

Transcranial magnetic stimulation in child neurology: current and future directions

Transcranial magnetic stimulation (TMS) is a method for focal brain stimulation based on the principle of electromagnetic induction, where small intracranial electric currents are generated by a powerful, rapidly changing extracranial magnetic field. Over the past 2 decades TMS has shown promise in the diagnosis, monitoring, and treatment of neurological and psychiatric disease in adults, but has been used on a more limited basis in children. We reviewed the literature to identify potential diagnostic and therapeutic applications of TMS in child neurology and also its safety in pediatrics. Although TMS has not been associated with any serious side effects in children and appears to be well tolerated, general safety guidelines should be established. The potential for applications of TMS in child neurology and psychiatry is significant. Given its excellent safety profile and possible therapeutic effect, this technique should develop as an important tool in pediatric neurology over the next decade.

Safety and tolerability of repetitive transcranial magnetic stimulation in patients with epilepsy: a review of the literature

Repetitive transcranial magnetic stimulation (rTMS) is emerging as a new therapeutic tool in epilepsy, where it can be used to suppress seizures or treat comorbid conditions such as mood disorder. However, as rTMS carries a risk of inducing seizures among other adverse events, its safety and tolerability in the population with epilepsy warrant distinct consideration, as this group is especially seizure-prone. Accordingly, we performed a review of the literature to estimate the risk of seizures and other adverse events associated with rTMS in patients with epilepsy. We performed an English-language literature search, and reviewed all studies published from January 1990 to February 2007 in which patients with epilepsy were treated with rTMS, and complemented the literature search with personal correspondence with authors when necessary. We identified 30 publications that described patients with epilepsy who underwent rTMS, and noted total number of relevant subjects, medication usage, incidence of adverse events, and rTMS parameters including stimulus frequency, number of stimuli, train duration, intertrain interval, coil type, and stimulation sites. The data were analyzed for adverse events related to rTMS. Crude per-subject risk, as well as per-subject mean risk weighted by sample size and risk per 1000 stimuli weighted by number of stimuli in each study, were computed for seizures and for other adverse events. Adverse events or lack thereof was reported in 26 studies (n=280 subjects). Adverse events attributed to rTMS were generally mild and occurred in 17.1% of subjects. Headache was most common, occurring in 9.6%. The most serious adverse event was seizure during treatment, which occurred in four patients (1.4% crude per-subject risk). All but one case were the patients' typical seizures with respect to duration and semiology, and were associated with low-frequency rTMS. A single case of an atypical seizure appearing to arise from the region of stimulation during high-frequency rTMS is reported. No rTMS-related episodes of status epilepticus were reported. We cautiously conclude that the risk of seizure in patients with epilepsy undergoing rTMS is small, and the risk of other mild adverse events is comparable to that seen when rTMS is used to treat other diseases. Status epilepticus or life-threatening seizures have not been reported in patients undergoing rTMS treatment. rTMS thus appears to be nearly as safe in patients with epilepsy as in nonepileptic individuals, and warrants further investigation as a therapy in this population.

Effects of repetitive transcranial magnetic stimulation on spike-and-wave discharges

Aim of this study was to evaluate the effect of 5Hz-suprathreshold repetitive transcranial magnetic stimulation (rTMS) on the duration of the spike-and-wave discharges (SWDs) in a patient presenting idiopathic absence seizures. At the moment of the study the patient presented a mild blunting of consciousness due to the high frequency of absences and EEG recordings showed sub-continuous, generalized, symmetrical and synchronous 3c/s SWDs, petit mal status. Trains of 10 stimuli (120% resting motor threshold) were delivered at 5Hz frequency at the beginning of the SWDs. 5Hz-rTMS trains significantly changed the EEG activity by reducing the duration of SWDs without changing the intervals between two consecutive discharges. rTMS had not significant after-effects on the epileptic activity and patient's clinical status. Despite the limitations of a single case report, our neurophysiological findings suggest that 5Hz-suprathreshold rTMS delivered in short trains induces a transitory interference of the ongoing epileptic activity.

Hemispheric cerebellar rTMS to treat drug-resistant epilepsy: Case reports

Electrical stimulation of the cerebellar cortex by implanted electrodes has been shown to ameliorate refractory epilepsy. We investigated the potential therapeutic role of high-frequency cerebellar rTMS in patients affected by refractory epilepsy due to single or multiple foci. Six patients, three with single and three with multiple epileptic foci, underwent 20 rTMS sessions. Each session was given daily, excluding weekends, and consisted of two trains of 50 stimuli (5 Hz frequency and 90% motor threshold intensity), separated by 50s interval. rTMS was delivered through a focal coil (2 cm below and lateral to the inion) bilaterally in patients with multiple foci (two trains for hemisphere: 100 stimuli each side) and contralaterally to the epileptic focus in the others. Seizure frequency was monitored four weeks before stimulation (pre-rTMS), during the four-week treatment (rTMS) and four weeks after the treatment (post-rTMS). The rTMS over the cerebellar cortex was associated with a significant decrease of rTMS versus pre-rTMS seizure frequency both in patients with single and multiple epileptic foci. However, during the post-rTMS period seizure frequency was back to the pre-rTMS frequency. Although the results are still preliminary, they encourage further studies on larger series of patients. In particular, this rTMS approach, as compared with others, might be more useful in patients with multiple epileptic foci.

Transcranial magnetic stimulation in persons younger than the age of 18

OBJECTIVES

To review the use of transcranial magnetic stimulation (single-pulse TMS, paired TMS, and repetitive TMS [rTMS]) in persons younger than the age of 18 years. I discuss the technical differences, as well as the diagnostic, therapeutic, and psychiatric uses of TMS/rTMS in this age group.

METHODS

I evaluated English-language studies from 1993 to August 2004 on nonconvulsive single-pulse, paired, and rTMS that supported a possible role for the use of TMS in persons younger than 18. Articles reviewed were retrieved from the MEDLINE database and Clinical Scientific index.

RESULTS

The 48 studies reviewed involved a total of 1034 children ages 2 weeks to 18 years; 35 of the studies used single-pulse TMS (980 children), 3 studies used paired TMS (20 children), and 7 studies used rTMS (34 children). Three studies used both single and rTMS. However, the number of subjects involved was not reported.

CONCLUSIONS

Single-pulse TMS, paired TMS, and rTMS in persons younger than 18 has been used to examine the maturation/activity of the neurons of various central nervous system tracts, plasticity of neurons in epilepsy, other aspects of epilepsy, multiple sclerosis, myoclonus, transcallosal inhibition, and motor cortex functioning with no reported seizure risk. rTMS has been applied to psychiatric disorders such as ADHD, ADHD with Tourette's, and depression. Adult studies support an antidepressant effect from repetitive TMS, but there is only one study that has been reported on 7 patients that used rTMS to the left dorsal prefrontal cortex on children/adolescents with depression (5 of the 7 subjects treated responded). Although there are limited studies using rTMS (in 34 children), these studies did not report significant adverse effects or seizures. Repetitive TMS safety, ethical, and neurotoxicity concerns also are discussed.