A questionnaire to collect unintended effects of Transcranial Magnetic Stimulation: A consensus based approach

Height-dependent variation in corticospinal excitability modulation after active but not sham intermittent theta burst stimulation

Poor reproducibility and high inter-individual variability in responses to intermittent theta burst stimulation (iTBS) of the human motor cortex (M1) are matters of concern. Here we recruited 17 healthy young adults in a randomized, sham-controlled, crossover study. Transcranial magnetic stimulation (TMS)-elicited motor evoked potentials (MEPs) were measured pre-iTBS (T0) and post-iTBS at 4-7 (T1), 9-12 (T2), 17-20 (T3), and 27-30 minutes (T4) from the right first dorsal interosseous muscle. MEP grand average (MEPGA) was defined as the mean of the normalized-to-baseline MEPs at all timepoints post-iTBS. As secondary objectives, we measured blood pressure, heart rate, and capillary blood glucose pre-iTBS, and at 0 and 30 minutes post-iTBS. The TMSens_Q structured questionnaire was filled out at the end of each session. Two-way repeated ANOVA did not show a significant TIME×INTERVENTION interaction effect on MEP amplitude, MEP latency, blood pressure, heart rate, and blood glucose (p > 0.05). Sleepiness was the most reported TMSens_Q sensation (82.3 %) in both groups. Surprisingly, the subjects' height negatively correlated with the normalized MEP amplitudes at T3 (r = -0.65, p = 0.005), T4 (r = -0.66, p = 0.004), and MEPGA (r = -0.68, p = 0.003), with a trend correlation at T1 (r = -0.46, p = 0.062) and T2 (r = -0.46, p = 0.065) in the active but not sham group. In view of this, we urge future studies to delve deeper into the influence of height on neuroplasticity induction of the M1 representation of peripheral muscles. In the end, we highlight unique methodological considerations in our study protocol and future recommendations for M1-iTBS studies.

Quantifying TMS-Induced Sleep Changes: A Novel Neurophysiological Assessment Approach

BACKGROUND

Neuromodulation methods such as transcranial magnetic stimulation (TMS) show promise for the research and manipulation of brain activity during sleep. Nevertheless, when it comes to accurately documenting changes in neurophysiology occurring in real-time, typical sleep evaluation approaches, such as subjective reports and routine polysomnography, fall short. Accurately quantifying changes in sleep architecture and cortical excitability generated by TMS is challenging due to these constraints.

NEW METHOD

A framework for electroencephalogram spectral analysis (EEG-SA) is presented in this paper to tackle these issues. This method compares pre- and post-TMS spectral power fluctuations in the important frequency bands delta, theta, alpha, beta, and gamma. EEG-SA provides a comprehensive evaluation of neurophysiology to identify changes in spectral properties and dynamic shifts in cortical excitability caused by TMS.

RESULTS

Research shows that EEG-SA can detect changes in sleep architecture caused by TMS. In particular, improvements in slow-wave activity and cortical synchronization are analyzed, two factors crucial to better sleep quality. These findings highlight the promise of EEG-SA for improving methods of sleep regulation.

COMPARISON WITH EXISTING METHODS

A precise, real-time measurement of neurophysiological changes is provided by EEG-SA, in contrast to conventional evaluation approaches that depend on subjective sleep reports and routine polysomnography. This paradigm analyzes TMS-induced sleep changes better than previous methods by providing a more objective and thorough evaluation.

CONCLUSION

TMS-induced sleep alterations may be reliably quantified using EEG-SA, opening the door to individualized therapy for sleep disorders. Insomnia, hypersomnia, and other sleep disorders might benefit from treatment tactics that optimize TMS settings according to individual neurophysiological responses. One way to improve the efficacy of sleep modulation treatments is to include EEG-SA in clinical settings.

Deep transcranial ultrasound stimulation using personalized acoustic metamaterials improves treatment-resistant depression in humans

BACKGROUND

Neuromodulation of deep brain regions has shown promise for treatment-resistant depression (TRD). However, it currently requires neurosurgical electrode implantation, posing significant risks and limiting widespread use while TRD affects around 100 million people worldwide. Low-intensity transcranial ultrasound stimulation (TUS) could allow precise and non-invasive deep neuromodulation, provided that the challenge of the defocusing effects of the skull is tackled.

OBJECTIVE/HYPOTHESIS

Here, we present the development of a portable and neuronavigated TUS prototype based on the use of patient-specific metamaterials (metalens) that correct for skull-induced aberrations. We then present the first application of metalens-based Transcranial Ultrasound Stimulation (mTUS) in TRD. The primary objective was to assess the safety and efficacy of mTUS targeting on individual level specific white matter tracts of the subcallosal cingulate involved in TRD.

METHODS

The safety and precision of this device was addressed through a series of numerical simulations and experimental measurements on ex vivo human skulls. Five participants with TRD were included in this open-label study (ClinicalTrials.gov identifier: NCT06085950) and underwent an intensive 5-day course of mTUS with a total of 25 sessions of 5 min each.

RESULTS

No serious adverse events occurred during the study. By day 5 of treatment, depression severity was reduced by an average of 60.9 % (range: [30 %-83.9 %]), and four out of five patients qualified as responders, with two of them in remission.

CONCLUSIONS

This study provides first-in-human evidence of the potential of mTUS as a precise, safe and effective non-invasive neuromodulation technique for neuropsychiatric disorders involving deep brain regions, offering a safer and more accessible alternative to invasive approaches.

Compared motor learning effects of motor cortical and cerebellar repetitive transcranial magnetic stimulation during a serial reaction time task in older adults

Repeated transcranial magnetic stimulation (rTMS) is a technique used to enhance motor learning in older adults. Some studies have shown that applying rTMS to the primary motor cortex (M1) and the cerebellum enhances motor learning. This study investigates the effects of M1 rTMS and cerebellar rTMS on motor learning in older adults. Seventy healthy older participants were randomly divided into M1, cerebellar rTMS, and sham rTMS groups. Participants completed the Serial Reaction Time Task (SRTT), while receiving 10 min of 10 Hz rTMS, with the sham group receiving inactive stimulation. Reaction time (RT) and error rate (ER) were recorded before, immediately, and 48 h post-task. RT and ER decreased immediately after the SRTT in all groups (P < 0.001). Both intervention groups showed greater online motor learning than the sham group (P < 0.05). Additionally, both intervention groups exhibited offline motor learning and learning consolidation with more significant changes in the cerebellar-rTMS group during lasting time (P < 0.03), whereas the sham rTMS group could not maintain motor learning (P > 0.05). The findings suggest that both M1 and cerebellar rTMS enhance motor learning in healthy older adults, with cerebellar rTMS being more effective in consolidating motor learning.

Stimulation Parameters Recruit Distinct Cortico-Cortical Pathways: Insights from Microstate Analysis on TMS-Evoked Potentials

Transcranial magnetic stimulation (TMS)-evoked potentials (TEPs) represent an innovative measure for examining brain connectivity and developing biomarkers of psychiatric conditions. Minimizing TEP variability across studies and participants, which may stem from methodological choices, is therefore vital. By combining classic peak analysis and microstate investigation, we tested how TMS pulse waveform and current direction may affect cortico-cortical circuit engagement when targeting the primary motor cortex (M1). We aim to disentangle whether changing these parameters affects the degree of activation of the same neural circuitry or may lead to changes in the pathways through which the induced activation spreads. Thirty-two healthy participants underwent a TMS-EEG experiment in which the pulse waveform (monophasic, biphasic) and current direction (posterior-anterior, anterior-posterior, latero-medial) were manipulated. We assessed the latency and amplitude of M1-TEP components and employed microstate analyses to test differences in topographies. Results revealed that TMS parameters strongly influenced M1-TEP components' amplitude but had a weaker role over their latencies. Microstate analysis showed that the current direction in monophasic stimulations changed the pattern of evoked microstates at the early TEP latencies, as well as their duration and global field power. This study shows that the current direction of monophasic pulses may modulate cortical sources contributing to TEP signals, activating neural populations and cortico-cortical paths more selectively. Biphasic stimulation reduces the variability associated with current direction and may be better suited when TMS targeting is blind to anatomical information.

Effects of repetitive transcranial magnetic stimulation in children and young people with psychiatric disorders: a systematic review

Repetitive transcranial magnetic stimulation (rTMS) has demonstrated benefits in adults with psychiatric disorders, but its clinical utility in children and young people (CYP) is unclear. This PRISMA systematic review used published and ongoing studies to examine the effects of rTMS on disorder-specific symptoms, mood and neurocognition in CYP with psychiatric disorders. We searched Medline via PubMed, Embase, PsychINFO via OVID, and Clinicaltrials.gov up to July 2023. Eligible studies involved multiple-session (i.e., treatment) rTMS in CYP (≤ 25 years-old) with psychiatric disorders. Two independent raters assessed the eligibility of studies and extracted data using a custom-built form. Out of 78 eligible studies (participant N = 1389), the majority (k = 54; 69%) reported an improvement in at least one outcome measure of disorder-specific core symptoms. Some studies (k = 21) examined rTMS effects on mood or neurocognition,: findings were largely positive. Overall, rTMS was well-tolerated with minimal side-effects. Of 17 ongoing or recently completed studies, many are sham-controlled RCTs with better blinding techniques and a larger estimated participant enrolment. Findings provide encouraging evidence for rTMS-related improvements in disorder-specific symptoms in CYP with different psychiatric disorders. However, in terms of both mood (for conditions other than depression) and neurocognitive outcomes, evidence is limited. Importantly, rTMS is well-tolerated and safe. Ongoing studies appear to be of improved methodological quality; however, future studies should broaden outcome measures to more comprehensively assess the effects of rTMS and develop guidance on dosage (i.e., treatment regimens).

TMS in the Kingdom of Denmark: an overview of current clinical practice

PURPOSE

Repetitive TMS (rTMS) has been demonstrated to be an effective treatment of several neuropsychiatric disorders. Its safety and efficacy are well established, and multiple rTMS devices have been approved by both Conformitè Europëenne Mark and U.S. Food and Drug Administration. We aimed to survey TMS practice in Psychiatry in the Kingdom of Denmark and compare it with the international state of the art.

METHODS

A survey of rTMS clinical practice in 2023 was sent to all general adult psychiatry departments practicing TMS in the Danish Realm (Denmark = 10, Faroe Islands = 0, Greenland = 0).

RESULTS

Response rate was 100%. rTMS was available in 37% of psychiatric departments and 3 out of 5 Danish Regions. Admission criteria required a diagnosis of unipolar depression with a degree of treatment-resistance or unacceptable side-effects to antidepressant treatment. Common contraindications included: cochlear implants (100%), pacemaker and neurostimulators (80%), other ferromagnetic/implanted devices in head, neck, or thorax (70%), active substance misuse (60%), and electrolytic disturbances (50%). Three rTMS protocols were identified: 10 Hz rTMS delivered over the L-DLPFC, iTBS delivered over the L-DLPFC and 1 Hz rTMS delivered over the right-DLPFC. 383 patients were treated with TMS.

CONCLUSIONS

rTMS is unequally available in the public healthcare of the Kingdom of Denmark. Existing strategies for solving inequalities could address such issues. Unipolar depression was the only psychiatric disorder treated with rTMS in 2023. rTMS practice in the Danish Realm considers the use of evidence-based protocols and is consistent with recommendations from international expert guidelines.

The potential of interleaved TMS-fMRI for linking stimulation-induced changes in task-related activity with behavioral modulations

The simultaneous combination of TMS with fMRI has emerged as a promising means to investigate the direct interaction between stimulation-induced changes at the behavioral and neural activity level. This enables the investigation of whole brain neurobehavioral interactions underlying cognitive disruption or facilitation. Yet to date, the literature on interleaved TMS-fMRI in cognitive neuroscience is sparse and neuromodulatory patterns of different TMS protocols are still poorly understood. Here, we synthesize interleaved TMS-fMRI studies on the relationship between direct stimulation-induced changes on task related neural activity and behavior. The following main findings are discussed. First, approximately half of the studies report a relationship between neural activity and behavioral changes as a marker for network excitation or inhibition. Secondly, task difficulty and stimulation timing are crucial factors that impact the interaction between neural activity changes and behavior. Third, stimulation-induced changes in remote, connected areas seem to be stronger associated with facilitation effects at the behavioral level. A better understanding of the relationship between stimulation-induced changes at the neural and behavioral level will increase the current understanding of the neuromodulatory potential of TMS at different levels and may help to develop more efficient stimulation protocols for basic and applied research.

Continuous theta burst stimulation at 30 hz does not modulate cortical excitability in a sham-controlled study

Theta burst stimulation (TBS) can modulate cortical excitability but suffers from high inter-subject variability. Modified TBS frequency patterns (30 Hz) showed consistent inhibitory aftereffects, but further research into the time course of these effects is needed. This study aimed to investigate the efficacy of a 30 Hz continuous TBS (cTBS) protocol. Participants (n = 20) underwent an experimental session (real cTBS) and a control session (sham cTBS). To assess cortical excitability, Transcranial Magnetic Stimulation was applied over the primary motor cortex before cTBS, and at five timepoints after cTBS. Percentage change (PC) to baseline was analysed using a Linear Mixed Model. No difference in PC was found between real and sham cTBS (p = 0.696). Our results demonstrate a significant increase in PC over time (p = 0.006) at 30, (p = 0.01), 45 (p = 0.027), and 55 min (p = 0.024) post cTBS, irrespective of condition. Secondary analysis dividing the sample into responders and paradox-responders showed no significant predictors for cTBS responsiveness. We could not replicate previously reported suppressive effects of 30 Hz cTBS. Increases in MEP amplitudes over a 60-minute time window were independent of stimulation condition and marked by high inter-subject variability. Validations of modified TBS protocols are further needed to replicate findings and understand mechanisms underlying individuals' responsiveness.

A randomised controlled feasibility trial of intermittent theta burst stimulation with an open longer-term follow-up for young people with persistent anorexia nervosa (RaISE): Study protocol

OBJECTIVE

We present the protocol of a feasibility randomised controlled trial (RCT) of intermittent theta burst stimulation (iTBS) for young people with anorexia nervosa (AN). Effective first-line psychological therapies exist for young people with AN, but little is known about how to treat those who do not respond. Non-invasive neuromodulation, such as iTBS, could address unmet treatment needs by targeting neurocircuitry associated with the development and/or maintenance of AN.

DESIGN

Sixty-six young people (aged 13-30 years) with persistent AN will be randomly allocated to receive 20 sessions of real or sham iTBS over the left dorsolateral prefrontal cortex in addition to their usual treatment. Outcomes will be measured at baseline, post-treatment (1-month post-randomisation) and 4-months post-randomisation (when unblinding will occur). Additional open follow-ups will be conducted at 12- and 24-months post-randomisation. The primary feasibility outcome is the proportion of participants retained in the study at 4-months. Secondary outcomes include AN symptomatology, other psychopathology, quality of life, service utilisation, neurocognitive processes, and neuroimaging measures.

DISCUSSION

Findings will inform the development of a future large-scale RCT. They will also provide exploratory data on treatment efficacy, and neural and neurocognitive predictors and correlates of treatment response to iTBS in AN.

Monitoring Changes in TMS-Evoked EEG and EMG Activity During 1 Hz rTMS of the Healthy Motor Cortex

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive brain stimulation technique capable of inducing neuroplasticity as measured by changes in peripheral muscle electromyography (EMG) or electroencephalography (EEG) from pre-to-post stimulation. However, temporal courses of neuromodulation during ongoing rTMS are unclear. Monitoring cortical dynamics via TMS-evoked responses using EMG (motor-evoked potentials; MEPs) and EEG (transcranial-evoked potentials; TEPs) during rTMS might provide further essential insights into its mode of action - temporal course of potential modulations. The objective of this study was to first evaluate the validity of online rTMS-EEG and rTMS-EMG analyses, and second to scrutinize the temporal changes of TEPs and MEPs during rTMS. As rTMS is subject to high inter-individual effect variability, we aimed for single-subject analyses of EEG changes during rTMS. Ten healthy human participants were stimulated with 1,000 pulses of 1 Hz rTMS over the motor cortex, while EEG and EMG were recorded continuously. Validity of MEPs and TEPs measured during rTMS was assessed in sensor and source space. Electrophysiological changes during rTMS were evaluated with model fitting approaches on a group- and single-subject level. TEPs and MEPs appearance during rTMS was consistent with past findings of single pulse experiments. Heterogeneous temporal progressions, fluctuations or saturation effects of brain activity were observed during rTMS depending on the TEP component. Overall, global brain activity increased over the course of stimulation. Single-subject analysis revealed inter-individual temporal courses of global brain activity. The present findings are in favor of dose-response considerations and attempts in personalization of rTMS protocols.

Safety and Efficacy of Deep Transcranial Magnetic Stimulation for Management of Emotional Dysregulation in Children and Adolescents with Externalizing Behavior Disorders: Protocol of a Transdiagnostic Sham Controlled fMRI Study

Background

High-frequency deep transcranial magnetic stimulation (dTMS) on the anterior cingulate cortex (ACC) and medial prefrontal cortex (mPFC) has been known to be effective in modulating emotional experience but not studied in children and adolescents with externalizing behavior disorders (EBDs). We present a novel protocol for a study that aims to assess the safety and efficacy of adjuvant dTMS in managing emotional dysregulation in EBDs in children and adolescents.

Methods

The trial is prospectively registered in the Clinical Trial Registry of India (CTRI) at www.ctri.nic.in with registration number: CTRI/2023/03/050701. In total, 40 subjects with age less than 18 years with EBDs would be randomized into two groups (active and sham dTMS); receiving 15 sessions of high-frequency dTMS, each, over 3 weeks. The subjects and rater would remain blind to treatment allocation. Assessments would be done at baseline and immediately after completion of the treatment using the Child Behavior Checklist (CBCL), Difficulty in Emotional Regulation Scale (DERS), Modified Overt Aggression Scale (MOAS), Affective Reactivity Index (ARI), Barratt's Impulsivity Scale (BIS), Drug Abuse Screening Test (DAST), Children Global Assessment Scale (CGAS), and Clinical Global Impression (CGI). A checklist for side effects will be administered following each session in both groups.

Result

Data shall be analyzed utilizing the statistical software Statistical Package for Social Sciences for outcome variables as defined for the purpose of the study. Safety of dTMS in young subjects as assessed by TMSens_Q and reduction in scores of DERS would be primary outcome variables. Functional Magnetic Resonance Imaging (fMRI) task-based assessment of the difference in activation of mPFC and ACC at baseline and after application of dTMS and reduction in scores of BIS, ARI, MOAS, CGI, and CGAS would be measured as secondary outcome variables.

Conclusion

The study's results are going to provide insight into potential role of dTMS in addressing emotional dysregulation in EBDs in children and adolescents adding one more tool to the armamentarium.

High-frequency Repetitive Transcranial Magnetic Stimulation Targeting Left Dorsolateral Prefrontal Cortex for Depression Ameliorates Insomnia yet Triggers Excessive Daytime Sleepiness: A Catch-22 Situation

Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive brain stimulation technique that is effective and safe for the treatment of depression. We observed improvement in insomnia along with symptoms of depression following high-frequency rTMS over the left dorsolateral prefrontal cortex in a patient with treatment-resistant depression, which progressed to excessive daytime sleepiness during the treatment sessions. Causality assessment suggested a probable association of rTMS with excessive sleepiness. The implications of the effect of rTMS on sleep are discussed.

Effects of transcranial magnetic stimulation on reactive response inhibition

Reactive response inhibition cancels impending actions to enable adaptive behavior in ever-changing environments and has wide neuropsychiatric implications. A canonical paradigm to measure the covert inhibition latency is the stop-signal task (SST). To probe the cortico-subcortical network underlying motor inhibition, transcranial magnetic stimulation (TMS) has been applied over central nodes to modulate SST performance, especially to the right inferior frontal cortex and the presupplementary motor area. Since the vast parameter spaces of SST and TMS enabled diverse implementations, the insights delivered by emerging TMS-SST studies remain inconclusive. Therefore, a systematic review was conducted to account for variability and synthesize converging evidence. Results indicate certain protocol specificity through the consistent perturbations induced by online TMS, whereas offline protocols show paradoxical effects on different target regions besides numerous null effects. Ancillary neuroimaging findings have verified and dissociated the underpinning network dynamics. Sources of heterogeneity in designs and risk of bias are highlighted. Finally, we outline best-practice recommendations to bridge methodological gaps and subserve the validity as well as replicability of future work.

A meta-analysis of non-invasive brain stimulation (NIBS) effects on cerebellar-associated cognitive processes

Non-invasive brain stimulation (NIBS) techniques, including transcranial magnetic stimulation (TMS) and transcranial electrical stimulation (tES), have provided valuable insights into the role of the cerebellum in cognitive processes. However, replicating findings from studies involving cerebellar stimulation poses challenges. This meta-analysis investigates the impact of NIBS on cognitive processes associated with the cerebellum. We conducted a systematic search and analyzed 66 studies and 91 experiments involving healthy adults who underwent either TMS or transcranial direct current stimulation (tDCS) targeting the cerebellum. The results indicate that anodal tDCS applied to the medial cerebellum enhances cognitive performance. In contrast, high-frequency TMS disrupts cognitive performance when targeting the lateral cerebellar hemispheres or when employed in online protocols. Similarly, low-frequency TMS and continuous theta burst stimulation (cTBS) diminish performance in offline protocols. Moreover, high-frequency TMS impairs accuracy. By identifying consistent effects and moderators of modulation, this meta-analysis contributes to improving the replicability of studies using NIBS on the cerebellum and provides guidance for future research aimed at developing effective NIBS interventions targeting the cerebellum.

Effects of repetitive transcranial magnetic stimulation on episodic memory in patients with subjective cognitive decline: study protocol for a randomized clinical trial

Introduction

Early decline of episodic memory is detectable in subjective cognitive decline (SCD). The left dorsolateral prefrontal cortex (DLPFC) is associated with encoding episodic memories. Repetitive transcranial magnetic stimulation (rTMS) is a novel and viable tool to improve cognitive function in Alzheimer's disease (AD) and mild cognitive impairment, but the treatment effect in SCD has not been studied. We aim to investigate the efficacy of rTMS on episodic memory in individuals with SCD, and to explore the potential mechanisms of neural plasticity.

Methods

In our randomized, sham-controlled trial, patients (n = 60) with SCD will receive 20 sessions (5 consecutive days per week for 4 weeks) of real rTMS (n = 30) or sham rTMS (n = 30) over the left DLPFC. The primary outcome is the Auditory Verbal Learning Test-Huashan version (AVLT-H). Other neuropsychological examinations and the long-term potentiation (LTP)-like cortical plasticity evaluation serve as the secondary outcomes. These outcomes will be assessed before and at the end of the intervention.

Discussion

If the episodic memory of SCD improve after the intervention, the study will confirm that rTMS is a promising intervention for cognitive function improvement on the early stage of dementia. This study will also provide important clinical evidence for early intervention in AD and emphasizes the significance that impaired LTP-like cortical plasticity may be a potential biomarker of AD prognosis by demonstrating the predictive role of LTP on cognitive improvement in SCD.

Ethics and dissemination

The study was approved by the Human Research Ethics Committee of the hospital (No. 2023-002-01). The results will be published in peer-review publications.

Clinical trial registration

https://www.chictr.org.cn/, identifier ChiCTR2300075517.

Noninvasive Brain Stimulation for Neurorehabilitation in Post-Stroke Patients

Characterized by high morbidity, mortality, and disability, stroke usually causes symptoms of cerebral hypoxia due to a sudden blockage or rupture of brain vessels, and it seriously threatens human life and health. Rehabilitation is the essential treatment for post-stroke patients suffering from functional impairments, through which hemiparesis, aphasia, dysphagia, unilateral neglect, depression, and cognitive dysfunction can be restored to various degrees. Noninvasive brain stimulation (NIBS) is a popular neuromodulatory technology of rehabilitation focusing on the local cerebral cortex, which can improve clinical functions by regulating the excitability of corresponding neurons. Increasing evidence has been obtained from the clinical application of NIBS, especially repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS). However, without a standardized protocol, existing studies on NIBS show a wide variation in terms of stimulation site, frequency, intensity, dosage, and other parameters. Its application for neurorehabilitation in post-stroke patients is still limited. With advances in neuronavigation technologies, functional near-infrared spectroscopy, and functional MRI, specific brain regions can be precisely located for stimulation. On the basis of our further understanding on neural circuits, neuromodulation in post-stroke rehabilitation has also evolved from single-target stimulation to co-stimulation of two or more targets, even circuits and the network. The present study aims to review the findings of current research, discuss future directions of NIBS application, and finally promote the use of NIBS in post-stroke rehabilitation.