Non-Invasive Brain Stimulation in Children With Unilateral Cerebral Palsy: A Protocol and Risk Mitigation Guide

Safety and efficacy of non-invasive brain stimulation for the upper extremities in children with cerebral palsy: A systematic review

AIM

To evaluate available evidence examining safety and efficacy of non-invasive brain stimulation (NIBS) on upper extremity outcomes in children with cerebral palsy (CP).

METHOD

We electronically searched 12 sources up to May 2023 using JBI and Cochrane guidelines. Two reviewers selected articles with predetermined eligibility criteria, conducted data extraction, and assessed risk of bias using the Cochrane Risk of Bias criteria.

RESULTS

Nineteen studies were included: eight using repetitive transcranial magnetic stimulation (rTMS) and 11 using transcranial direct current stimulation (tDCS). Moderate certainty evidence supports the safety of rTMS and tDCS for children with CP. Very low to moderate certainty evidence suggests that rTMS and tDCS result in little to no difference in upper extremity outcomes.

INTERPRETATION

Evidence indicates that NIBS is a safe and feasible intervention to target upper extremity outcomes in children with CP, although it also indicates little to no significant impact on upper extremity outcomes. These findings are discussed in relation to the heterogeneous participants' characteristics and stimulation parameters. Larger studies of high methodological quality are required to inform future research and protocols for NIBS.

Remote ischaemic conditioning combined with bimanual task training to enhance bimanual skill learning and corticospinal excitability in children with unilateral cerebral palsy: a study protocol of a single centre, phase II randomised controlled trial

INTRODUCTION

Children with unilateral cerebral palsy (UCP) have difficulty in bimanual coordination that restricts the child's independence in daily activities. Although several efficacious interventions to improve bimanual coordination exist, these interventions often require higher training doses and have modest effect sizes. Thus, there is a critical need to find an effective priming agent that, when paired with task-specific training, will facilitate neurobiological processes to enhance the magnitude of training effects and subsequently improve functional capabilities of children with UCP. The aim of this study is to determine the effects of a novel priming agent, remote ischaemic conditioning (RIC), combined with bimanual training on bimanual skill learning and corticospinal excitability in children with UCP.

METHODS AND ANALYSES

46 children, aged 8-16 years, will be randomly assigned to receive RIC or sham conditioning combined with 5 days of bimanual skill (cup stacking) training (15 trials per session). RIC or sham conditioning will be performed with a standard conditioning protocol of five cycles of alternative inflation and deflation of a pressure cuff on the affected arm with the pressure of at least 20 mm Hg above systolic blood pressure for RIC and 25 mm Hg for sham conditioning. Primary outcomes will be movement time and corticospinal excitability measures determined with a single-pulse transcranial magnetic stimulation (TMS). Secondary outcomes include Assisting Hand Assessment, spatio-temporal kinematic variables and paired pulse TMS measures. All measures will be conducted before and immediately after the intervention. A mixed model analysis of variance will test the group×time interaction for all outcomes with group (RIC and sham) as between-subject and time (preintervention, postintervention) as within-subject factors.

ETHICS AND DISSEMINATION

The study has been approved by the University Medical Centre Institutional Review Board (UMCIRB #21-001913). We will disseminate the study findings via peer-reviewed publications and presentations at professional conferences.

TRIAL REGISTRATION NUMBER

NCT05777070.

Safety and feasibility of transcranial direct current stimulation stratified by corticospinal organization in children with hemiparesis

Children with hemiparesis (CWH) due to stroke early in life face lifelong impairments in motor function. Transcranial direct current stimulation (tDCS) may be a safe and feasible adjuvant therapy to augment rehabilitation. Given the variability in outcomes following tDCS, tailored protocols of tDCS are required. We evaluated the safety, feasibility, and preliminary effects of a single session of targeted anodal tDCS based on individual corticospinal tract organization on corticospinal excitability. Fourteen CWH (age = 13.8 ± 3.63) were stratified into two corticospinal organization subgroups based on transcranial magnetic stimulation (TMS)-confirmed motor evoked potentials (MEP): ipsilesional MEP presence (MEPIL+) or absence (MEPIL-). Subgroups were randomized to real anodal or sham tDCS (1.5 mA, 20 min) applied to the ipsilesional (MEPIL + group) or contralesional (MEPIL- group) hemisphere combined with hand training. Safety was assessed with questionnaires and motor function evaluation, and corticospinal excitability was assessed at baseline and every 15 min for 1 h after tDCS. No serious adverse events occurred and anticipated minor side effects were reported and were self-limiting. Six of 14 participants had consistent ipsilesional MEPs (MEPIL + group). Paretic hand MEP amplitude increased in 5/8 participants who received real anodal tDCS to either the ipsilesional or contralesional hemisphere (+80% change). Application of tDCS based on individual corticospinal organization was safe and feasible with expected effects on excitability, indicating the potential for tailored tDCS protocols for CWH. Additional research involving expanded experimental designs is needed to confirm these effects and to determine if this approach can be translated into a clinically relevant intervention.

Digitalized transcranial electrical stimulation: A consensus statement

OBJECTIVE

Although relatively costly and non-scalable, non-invasive neuromodulation interventions are treatment alternatives for neuropsychiatric disorders. The recent developments of highly-deployable transcranial electric stimulation (tES) systems, combined with mobile-Health technologies, could be incorporated in digital trials to overcome methodological barriers and increase equity of access. The study aims are to discuss the implementation of tES digital trials by performing a systematic scoping review and strategic process mapping, evaluate methodological aspects of tES digital trial designs, and provide Delphi-based recommendations for implementing digital trials using tES.

METHODS

We convened 61 highly-productive specialists and contacted 8 tES companies to assess 71 issues related to tES digitalization readiness, and processes, barriers, advantages, and opportunities for implementing tES digital trials. Delphi-based recommendations (>60% agreement) were provided.

RESULTS

The main strengths/opportunities of tES were: (i) non-pharmacological nature (92% of agreement), safety of these techniques (80%), affordability (88%), and potential scalability (78%). As for weaknesses/threats, we listed insufficient supervision (76%) and unclear regulatory status (69%). Many issues related to methodological biases did not reach consensus. Device appraisal showed moderate digitalization readiness, with high safety and potential for trial implementation, but low connectivity.

CONCLUSIONS

Panelists recognized the potential of tES for scalability, generalizability, and leverage of digital trials processes; with no consensus about aspects regarding methodological biases.

SIGNIFICANCE

We further propose and discuss a conceptual framework for exploiting shared aspects between mobile-Health tES technologies with digital trials methodology to drive future efforts for digitizing tES trials.

The Effect of Constraint-Induced Movement Therapy Combined With Repetitive Transcranial Magnetic Stimulation on Hand Function in Preschool Children With Unilateral Cerebral Palsy: A Randomized Controlled Preliminary Study

Constraint-induced movement therapy (CIMT) combined with repetitive transcranial magnetic stimulation (rTMS) have shown great potential in improving function in schoolchildren with unilateral cerebral palsy attributed to perinatal stroke. However, the prospect of application in preschool children with unilateral cerebral palsy (UCP) attributed to various brain disorders remains unclear. In this prospective, assessor-blinded, randomized controlled study, 40 preschool children with UCP (aged 2.5–6 years) were randomized to receive 10 days of CIMT combined with active or sham rTMS. Assessments were performed at baseline, 2 weeks, and 6 months post-intervention to investigate upper limb extremity, social life ability, and perceived changes by parents and motor-evoked potentials. Overall, 35 participants completed the trial. The CIMT plus active stimulation group had greater gains in the affected hand function (range of motion, accuracy, and fluency) than the CIMT plus sham stimulation group (P < 0.05), but there was no significant difference in muscular tone, social life ability, and perceived changes by parents between the two groups (P > 0.05). In addition, there was no significant difference in hand function between children with and without motor-evoked potential (P > 0.05). No participants reported severe adverse events during the study session. In short, the treatment of CIMT combined with rTMS is safe and feasible for preschool children with UCP attributed to various brain disorders. Randomized controlled studies with large samples and long-term effects are warranted.

Study Protocol: Multimodal Longitudinal Assessment of Infant Brain Organization and Recovery in Perinatal Brain Injury

PURPOSE

Perinatal brain injury is a primary cause of cerebral palsy, a condition resulting in lifelong motor impairment. Infancy is an important period of motor system development, including development of the corticospinal tract (CST), the primary pathway for cortical movement control. The interaction between perinatal stroke recovery, CST organization, and resultant motor outcome in infants is not well understood.

METHODS

Here, we present a protocol for multimodal longitudinal assessment of brain development and motor function following perinatal brain injury using transcranial magnetic stimulation and magnetic resonance imaging to noninvasively measure CST functional and structural integrity across multiple time points in infants 3 to 24 months of age. We will further assess the association between cortical excitability, integrity, and motor function.

DISCUSSION

This protocol will identify bioindicators of motor outcome and neuroplasticity and subsequently inform early detection, diagnosis, and intervention strategies for infants with perinatal stroke, brain bleeds, and related diagnoses.

HABIT+tDCS: a study protocol of a randomised controlled trial (RCT) investigating the synergistic efficacy of hand-arm bimanual intensive therapy (HABIT) plus targeted non-invasive brain stimulation to improve upper extremity function in school-age children with unilateral cerebral palsy

INTRODUCTION

Unilateral spastic cerebral palsy (USCP) is characterised by movement deficits primarily on one body side. The best available upper extremity (UE) therapies are costly and intensive. Thus, there is an urgent need for better, more efficient and thus more accessible therapies. Transcranial direct current stimulation (tDCS) is non-invasive and may enhance physical rehabilitation approaches. The aim of this study is to determine whether tDCS targeted to the hemisphere with corticospinal tract (CST) connectivity enhances the efficacy of UE training in children with USCP. Our central hypothesis is that hand-arm bimanual intensive therapy (HABIT) combined with a tDCS montage targeting the hemisphere with CST connectivity to the impaired UE muscles will improve UE function more than HABIT plus sham stimulation. We will test this by conducting a randomised clinical trial with clinical and motor cortex physiology outcomes.

METHODS AND ANALYSES

81 children, aged 6-17 years, will be randomised to receive 2 mA anodal tDCS targeted to the affected UE motor map, 2 mA cathodal tDCS to the contralesional motor cortex or sham tDCS during the first 20 min of each HABIT session (10 hours: 2 hours/day for 5 days). Primary outcomes will be Box and Blocks Test, Assisting Hand Assessment and motor cortex excitability, determined with single-pulse transcranial magnetic stimulation. Secondary outcomes include ABILHAND-Kids, Canadian Occupational Performance Measure, Cooper Stereognosis, Dimension of Mastery Questionnaire and Participation and Environment Measure-Children and Youth. All measures will be collected before, immediately and 6 months after treatment. A group × test session Analysis of Variance will test differences among groups on all measures.

ETHICS AND DISSEMINATION

The study has been approved by the BRANY Institutional Review Board (#18-10-285-512). We will leverage our subject and family relationships to maximise dissemination and share results with the academic and patient/family advocacy groups.

TRIAL REGISTRATION NUMBER

NCT03402854.

The Effects of tDCS with NDT on the Improvement of Motor Development in Cerebral Palsy

We investigated the effects of transcranial direct current stimulation (tDCS) over the primary motor cortex (M1) with neurodevelopmental treatment (NDT) on the improvement of motor development and reduction of spasticity in children with cerebral palsy (CP). Twenty-four children with CP were allocated to two groups: the tDCS + NDT group and the only NDT group, done 3 times per week for 5 weeks. The Gross Motor Function Measurement (GMFM-88) and Box and Block Test (BBT) were used to assess changes in motor development, and the Modified Ashworth Scale (MAS) was used to evaluate changes in spasticity. All measurements were carried out at 3 time points: baseline, post-intervention, and 1 month follow-up. We found improvements in the GMFM-88 total scores and in each individual GMFM-88 dimension scores, favoring the tDCS + NDT group over the only NDT group. The BBT scores improved only in the tDCS + NDT group. In addition, the MAS scores reduced in the hemibody with significant motor impairment only in the tDCS + NDT group. The present findings suggest that tDCS combined with NDT can be considered a promising intervention for children with CP, as it can enhance motor development and reduce spasticity in this population.

Brazilian research on noninvasive brain stimulation applied to health conditions

BACKGROUND

Brazil has a top position regarding scientific production on noninvasive neuromodulation worldwide. Knowledge of scientometric phenomena involving Brazilian researchers who produce science on this theme may aid confidence in Brazilian clinical and research professionals.

OBJECTIVE

To investigate the scenario of research on the theme of noninvasive neuromodulation in Brazil.

METHODS

This was a scientometric study for mapping scientific production on this subject involving network phenomena, the professions of researchers, institutional affiliation, main research unit, total number of scientific articles on noninvasive neuromodulation published in journals, research sub-area and year of obtaining the PhD title. Public data from Lattes Platform curricula vitae and from VOSViewer© were used.

RESULTS

A total of 54 Brazilian researchers were identified, of whom 16 are research productivity fellows. Most of them are linked to institutions in southeastern Brazil, involving the professions of biology, biochemistry, physical education, physiotherapy, speech therapy, gerontology, medicine and psychology, with 1175 articles published in journals. These studies involve experimental animal and human models to account for mechanisms, observational studies, case reports, randomized clinical trials, systematic reviews, meta-analyses, product and process development, computer modeling and guidelines.

CONCLUSIONS

Brazil occupies a prominent place in the world scenario of research on noninvasive neuromodulation, which is used by different professions for treatment of brain dysfunctions, with a trend towards expansion to other fields.

Effects of the Combination of Music Therapy and Physiotherapy in the Improvement of Motor Function in Cerebral Palsy: A Challenge for Research

BACKGROUND

There are different therapeutic strategies such as physiotherapy and music therapy for the treatment of cerebral palsy. Intervention protocols using both therapies to unify the measurement of motor function have not been investigated. Aims and scope: To summarize the effects of the treatment of cerebral palsy through the use of both for the improvement of motor function, analyse the challenges encountered, and submit proposals for improving them.

METHODS

The systematic review was conducted following PRISMA guidelines and registered in the PROSPERO database (CRD42020162493). Clinical trials that described the results obtained in terms of motor function through physiotherapy and music therapy were included.

RESULTS

Eight clinical trials with 234 participants were considered with a significant improvement in motor function. Results of meta-analysis suggested improvements in gait velocity in favour of the control group for cerebral palsy (mean differences = 0.03; 95% confidence interval = 0.01, 0.04, p = 0.001; I2 = 97%). However, high heterogeneity was identified in the meta-analysis due to the small number of studies included.

CONCLUSIONS

The combination can be effective in subjects with cerebral palsy to improve motor function, although due to the diversity of studies analysed, it is complex to extrapolate results.

Cardiovascular Effects of Transcranial Direct Current Stimulation and Bimanual Training in Children With Cerebral Palsy

PURPOSE

To determine the influence of combined transcranial direct current stimulation (tDCS) to the motor cortex (M1) and bimanual training on cardiovascular function in children with cerebral palsy (CP).

METHODS

Mean arterial pressure (MAP), heart rate (HR), and HR variability (HRV) were measured immediately before and after 20 minutes of cathodal tDCS to contralesional M1 and bimanual training on days 1, 6, and 10 of a 10-day trial in 8 participants (5 females, 7-19 years).

RESULTS

Baseline MAP and HR were similar across days (93 ± 10 mm Hg and 90 ± 10 bpm, P > .05). MAP was similar from baseline to postintervention across all 3 days. Systolic pressure, diastolic pressure, nor HR significantly changed. HRV was not influenced by the 10-day intervention.

CONCLUSIONS

Combined cathodal tDCS to M1 and bimanual training does not influence autonomic and cardiovascular function in children with CP due to perinatal stroke.

Guidelines for TMS/tES clinical services and research through the COVID-19 pandemic

BACKGROUND

The COVID-19 pandemic has broadly disrupted biomedical treatment and research including non-invasive brain stimulation (NIBS). Moreover, the rapid onset of societal disruption and evolving regulatory restrictions may not have allowed for systematic planning of how clinical and research work may continue throughout the pandemic or be restarted as restrictions are abated. The urgency to provide and develop NIBS as an intervention for diverse neurological and mental health indications, and as a catalyst of fundamental brain research, is not dampened by the parallel efforts to address the most life-threatening aspects of COVID-19; rather in many cases the need for NIBS is heightened including the potential to mitigate mental health consequences related to COVID-19.

OBJECTIVE

To facilitate the re-establishment of access to NIBS clinical services and research operations during the current COVID-19 pandemic and possible future outbreaks, we develop and discuss a framework for balancing the importance of NIBS operations with safety considerations, while addressing the needs of all stakeholders. We focus on Transcranial Magnetic Stimulation (TMS) and low intensity transcranial Electrical Stimulation (tES) - including transcranial Direct Current Stimulation (tDCS) and transcranial Alternating Current Stimulation (tACS).

METHODS

The present consensus paper provides guidelines and good practices for managing and reopening NIBS clinics and laboratories through the immediate and ongoing stages of COVID-19. The document reflects the analysis of experts with domain-relevant expertise spanning NIBS technology, clinical services, and basic and clinical research - with an international perspective. We outline regulatory aspects, human resources, NIBS optimization, as well as accommodations for specific demographics.

RESULTS

A model based on three phases (early COVID-19 impact, current practices, and future preparation) with an 11-step checklist (spanning removing or streamlining in-person protocols, incorporating telemedicine, and addressing COVID-19-associated adverse events) is proposed. Recommendations on implementing social distancing and sterilization of NIBS related equipment, specific considerations of COVID-19 positive populations including mental health comorbidities, as well as considerations regarding regulatory and human resource in the era of COVID-19 are outlined. We discuss COVID-19 considerations specifically for clinical (sub-)populations including pediatric, stroke, addiction, and the elderly. Numerous case-examples across the world are described.

CONCLUSION

There is an evident, and in cases urgent, need to maintain NIBS operations through the COVID-19 pandemic, including anticipating future pandemic waves and addressing effects of COVID-19 on brain and mind. The proposed robust and structured strategy aims to address the current and anticipated future challenges while maintaining scientific rigor and managing risk.

A retrospective qualitative report of symptoms and safety from transcranial focused ultrasound for neuromodulation in humans

Low intensity transcranial focused ultrasound (LIFU) is a promising method of non-invasive neuromodulation that uses mechanical energy to affect neuronal excitability. LIFU confers high spatial resolution and adjustable focal lengths for precise neuromodulation of discrete regions in the human brain. Before the full potential of low intensity ultrasound for research and clinical application can be investigated, data on the safety of this technique is indicated. Here, we provide an evaluation of the safety of LIFU for human neuromodulation through participant report and neurological assessment with a comparison of symptomology to other forms of non-invasive brain stimulation. Participants (N = 120) that were enrolled in one of seven human ultrasound neuromodulation studies in one laboratory at the University of Minnesota (2015–2017) were queried to complete a follow-up Participant Report of Symptoms questionnaire assessing their self-reported experience and tolerance to participation in LIFU research (I_sppa 11.56–17.12 W/cm²) and the perceived relation of symptoms to LIFU. A total of 64/120 participant (53%) responded to follow-up requests to complete the Participant Report of Symptoms questionnaire. None of the participants experienced serious adverse effects. From the post-hoc assessment of safety using the questionnaire, 7/64 reported mild to moderate symptoms, that were perceived as ‘possibly’ or ‘probably’ related to participation in LIFU experiments. These reports included neck pain, problems with attention, muscle twitches and anxiety. The most common unrelated symptoms included sleepiness and neck pain. There were initial transient reports of mild neck pain, scalp tingling and headache that were extinguished upon follow-up. No new symptoms were reported upon follow up out to 1 month. The profile and incidence of symptoms looks to be similar to other forms of non-invasive brain stimulation.

Single-arm, open-label, dose escalation phase I study to evaluate the safety and feasibility of transcranial direct current stimulation with electroencephalography biomarkers in paediatric disorders of consciousness: a study protocol

INTRODUCTION

Children with disorders of consciousness (DOC) represent the highest end of the acquired brain injury (ABI) severity spectrum for survivors and experience a multitude of functional impairments. Current clinical management in DOC uses behavioural evaluation measures and interventions that fail to (1) describe the physiological consequences of ABI and (2) elicit functional gains. In paediatric DOC, there is a critical need to develop evidence-based interventions to promote recovery of basic responses to improve rehabilitation and aid decision-making for medical teams and caregivers. The purpose of this investigation is to examine the safety, tolerability and feasibility of transcranial direct current stimulation (tDCS) in children with DOC.

METHODS AND ANALYSIS

This study is an open-label dose escalation trial evaluating the safety, tolerability and feasibility of tDCS in 10 children (5-17 years) receiving inpatient rehabilitation for DOC. This study will follow a modified rule-based design, allowing for intrapatient escalation, where a cohort of patients will be assigned to an initial tDCS current of 0.5 or 1 mA based on participant's head circumference and according to the safety data available in other paediatric populations. The subsequent assignment of increased current (1 or 2 mA) according to the prespecified rules will be based on the clinical observation of adverse events in the patients. The study will include up to three, 20 min sessions of anodal tDCS (sham, 0.5 or 1 mA, 1 or 2 mA) applied over the dorsolateral prefrontal cortex. The primary outcomes are adverse events, pain associated with tDCS and intolerable disruption of inpatient care. Secondary outcomes are changes in electroencephalography (EEG) phase-locking and event-related potential components and the Coma Recovery Scale-Revised total score from prestimulation to poststimulation.

ETHICS AND DISSEMINATION

The Johns Hopkins IRB (#IRB00174966) approved this study. Trial results will be disseminated through journals and conferences.

REGISTRATION NUMBER

NCT03618849.

Safety and Feasibility of Transcranial Magnetic Stimulation as an Exploratory Assessment of Corticospinal Connectivity in Infants After Perinatal Brain Injury: An Observational Study

BACKGROUND

Perinatal brain injuries often impact the corticospinal system, leading to motor impairment and cerebral palsy. Although transcranial magnetic stimulation (TMS) has been widely used to study corticospinal connectivity in adults and older children, similar studies of young infants are limited.

OBJECTIVES

The objective was to establish the safety and feasibility of advanced TMS assessments of the corticospinal connectivity of young infants with perinatal brain injury.

DESIGN

This was a pilot, cross-sectional study of 3- to 12-month-old (corrected age) infants with perinatal stroke or intracranial hemorrhage.

METHODS

Six participants (2 term, 4 preterm) were assessed with stereotactic neuronavigation-guided TMS. Single-pulse TMS was applied to each hemisphere and responses were recorded simultaneously from both upper limbs. During data collection, vital signs and stress responses were measured to assess safety. Developmental motor outcomes were evaluated using the General Movements Assessment and Bayley Scales of Infant and Toddler Development (3rd edition). A clinical diagnosis of cerebral palsy was recorded, if available.

RESULTS

No adverse events occurred during TMS testing. All sessions were well tolerated. Contralateral motor evoked responses were detected in 4 of 6 participants. Both contralateral and ipsilateral responses were observed in 2 of 6 participants.

LIMITATIONS

TMS responses were not obtained in all participants. This could be related to the location of brain injury or developmental stage of the corticospinal system controlling the wrist flexor muscle group from which responses were recorded.

CONCLUSIONS

This study provides a summary of the framework for performing novel TMS assessments in infants with perinatal brain injury. Implementing this approach to measure corticospinal connectivity in hypothesis-driven studies in young infants appears to be justified. Such studies could inform the characterization of corticospinal development and the neural mechanisms driving recovery following early interventions.

Transcranial Direct Current Stimulation (tDCS) in Unilateral Cerebral Palsy: A Pilot Study of Motor Effect

Transcranial Direct Current Stimulation (tDCS) is an emerging tool to improve upper limb motor functions after stroke acquired in adulthood; however, there is a paucity of reports on its efficacy for upper limb motor rehabilitation in congenital or early-acquired stroke. In this pilot study we have explored, for the first time, the immediate effects, and their short-term persistence, of a single application of anodal tDCS on chronic upper limb motor disorders in children and young individuals with Unilateral Cerebral Palsy (UCP). To this aim, in a crossover sham-controlled study, eight subjects aged 10-28 years with UCP underwent two sessions of active and sham tDCS. Anodal tDCS (1.5 mA, 20 min) was delivered over the primary motor cortex (M1) of the ipsilesional hemisphere. Results showed, only following the active stimulation, an immediate improvement in unimanual gross motor dexterity of hemiplegic, but not of nonhemiplegic, hand in Box and Block test (BBT). Such improvement remained stable for at least 90 minutes. Performance of both hands in Hand Grip Strength test was not modified by anodal tDCS. Improvement in BBT was unrelated to participants' age or lesion size, as revealed by MRI data analysis. No serious adverse effects occurred after tDCS; some mild and transient side effects (e.g., headache, tingling, and itchiness) were reported in a limited number of cases. This study provides an innovative contribution to scientific literature on the efficacy and safety of anodal tDCS in UCP. This trial is registered with NCT03137940.

Influence of Combined Transcranial Direct Current Stimulation and Motor Training on Corticospinal Excitability in Children With Unilateral Cerebral Palsy

Combined non-invasive brain stimulation (NIBS) and rehabilitation interventions have the potential to improve function in children with unilateral cerebral palsy (UCP), however their effects on developing brain function are not well understood. In a proof-of-principle study, we used single-pulse transcranial magnetic stimulation (TMS) to measure changes in corticospinal excitability and relationships to motor performance following a randomized controlled trial consisting of 10 days of combined constraint-induced movement therapy (CIMT) and cathodal transcranial direct current stimulation (tDCS) applied to the contralesional motor cortex. Twenty children and young adults (mean age = 12 years, 9 months, range = 7 years, 7 months, 21 years, 7 months) with UCP participated. TMS testing was performed before, after, and 6 months after the intervention to measure motor evoked potential (MEP) amplitude and cortical silent period (CSP) duration. The association between neurophysiologic and motor outcomes and differences in excitability between hemispheres were examined. Contralesional MEP amplitude decreased as hypothesized in five of five participants receiving active tDCS immediately after and 6 months after the intervention, however no statistically significant differences between intervention groups were noted for MEP amplitude [mean difference = −323.9 μV, 95% CI = (−989, 341), p = 0.34] or CSP duration [mean difference = 3.9 ms, 95% CI = (−7.7, 15.5), p = 0.51]. Changes in corticospinal excitability were not statistically associated with improvements in hand function after the intervention. Across all participants, MEP amplitudes measured in the more-affected hand from both contralesional (mean difference = −474.5 μV) and ipsilesional hemispheres (−624.5 μV) were smaller compared to the less-affected hand. Assessing neurophysiologic changes after tDCS in children with UCP provides an understanding of long-term effects on brain excitability to help determine its potential as a therapeutic intervention. Additional investigation into the neurophysiologic effects of tDCS in larger samples of children with UCP are needed to confirm these findings.

Transcranial direct current stimulation for promoting motor function in cerebral palsy: a review

Transcranial direct current stimulation (tDCS) has the potential to improve motor function in a range of neurological conditions, including Cerebral Palsy (CP). Although there have been many studies assessing tDCS in adult stroke, the literature regarding the efficacy of tDCS in CP is more limited. This review therefore focuses on the neurophysiological and clinical findings in children and adolescents with CP. Initial studies applying anodal tDCS to promote lower limb function are promising, with improvements in gait, mobility and balance reported. However, the results of upper limb studies are mixed and more research is needed. Studies investigating neurophysiological changes or predictors of response are also lacking. Large-scale longitudinal studies are needed for the lower limb to ascertain whether the initial pilot results translate into clinically meaningful improvements. Future studies of the upper limb should focus on determining the optimal stimulation parameters and consider tailoring stimulation to the individual based on the (re)organisation of their motor system.

EMG breakthrough during cortical silent period in congenital hemiparesis: a descriptive case series

BACKGROUND

The cortical silent period is a transient suppression of electromyographic activity after a transcranial magnetic stimulation pulse, attributed to spinal and supraspinal inhibitory mechanisms. Electromyographic breakthrough activity has been observed in healthy adults as a result of a spinal reflex response within the cortical silent period.

OBJECTIVES

The objective of this case series is to report the ipsilesional and contralesional cortical silent period and the electromyographic breakthrough activity of 7 children with congenital hemiparesis.

METHODS

TMS was delivered over the ipsilesional and contralesional primary motor cortices with resting motor threshold and cortical silent period measures recorded from first dorsal interosseous muscle.

RESULTS

Seven children (13±2 years) were included. Ipsilesional and contralesional resting motor thresholds ranged from 49 to 80% and from 38 to 63% of maximum stimulator output, respectively. Ipsilesional (n=4) and contralesional (n=7) cortical silent period duration ranged from 49 to 206ms and 81 to 150ms, respectively. Electromyographic breakthrough activity was observed ipsilesionally in 3/4 (75%) and contralesionally in 3/7 (42.8%) participants. In the 3 children with ipsilesional breakthrough activity during the cortical silent period, all testing trials showed breakthrough. Contralesional breakthrough activity was observed in only one of the analyzable trials in each of those 3 participants. The mean peak amplitude of breakthrough activity ranged from 45 to 214μV (ipsilesional) and from 23 to 93μV (contralesional).

CONCLUSION

Further research is warranted to understand the mechanisms and significance of electromyographic breakthrough activity within the cortical silent period in congenital hemiparesis. Understanding these mechanisms may lead to the design of tailored neuromodulation interventions for physical rehabilitation.

TRIAL REGISTRATION

NCT02250092 (https://clinicaltrials.gov/ct2/show/NCT02250092).