Muscle plasticity and ankle control after repetitive use of a functional electrical stimulation device for foot drop in cerebral palsy

Simple within-stride changes in treadmill speed can drive selective changes in human gait symmetry

Millions of people walk with asymmetric gait patterns, highlighting a need for customizable rehabilitation approaches that can flexibly target different aspects of gait asymmetry. Here, we studied how simple within-stride changes in treadmill speed could drive selective changes in gait symmetry. In Experiment 1, healthy adults (n = 10) walked on an instrumented treadmill with and without a closed-loop controller engaged. This controller changed the treadmill speed to 1.50 or 0.75 m/s depending on whether the right or left leg generated propulsive ground reaction forces, respectively. Participants walked asymmetrically when the controller was engaged: the leg that accelerated during propulsion (right) showed smaller leading limb angles, larger trailing limb angles, and smaller propulsive forces than the leg that decelerated (left). In Experiment 2, healthy adults (n = 10) walked on the treadmill with and without an open-loop controller engaged. This controller changed the treadmill speed to 1.50 or 0.75 m/s at a prescribed time interval while a metronome guided participants to step at different time points relative to the speed change. Different patterns of gait asymmetry emerged depending on the timing of the speed change: step times, leading limb angles, and peak propulsion were asymmetric when the speed changed early in stance while step lengths, step times, and propulsion impulses were asymmetric when the speed changed later in stance. In sum, we show that simple manipulations of treadmill speed can drive selective changes in gait symmetry. Future work will explore the potential for this technique to restore gait symmetry in clinical populations.

tDCS does not add effect to foot drop stimulator and gait training in improving clinical parameters and neuroplasticity biomarkers in chronic post-stroke: randomized controlled trial

BACKGROUND

Transcranial direct current stimulation (tDCS) and foot drop stimulators (FDS) are widely used for stroke rehabilitation. However, no study has investigated if tDCS could boost the effects of FDS and gait training in improving clinical parameters and neuroplasticity biomarkers of chronic post-stroke subjects.

OBJECTIVE

To investigate the effects of combining tDCS and FDS on motor impairment, functional mobility, and brain-derived neurotrophic factor (BDNF) serum levels. Also, to evaluate the effects of this protocol on the insulin-like growth factor-1 (IGF-1), insulin growth factor-binding proteins-3 (IGFBP-3), interleukin (IL) 6 and 10, and tumor necrosis factor-α (TNF-α) levels.

METHODS

Thirty-two chronic post-stroke individuals were randomized to tDCS plus FDS or sham tDCS plus FDS groups. Both groups underwent ten gait training sessions for two weeks using a FDS device and real or sham tDCS. Blood samples and clinical data were acquired before and after the intervention. Motor impairment was assessed by the Fugl-Meyer Assessment and functional mobility using the Timed up and Go test.

RESULTS

Both groups improved the motor impairment and functional mobility and increased the BDNF levels. Both groups also increased the IL-10 and decreased the cortisol, IL-6, and TNF-α levels. No difference was observed between groups.

CONCLUSION

tDCS did not add effect to FDS and gait training in improving clinical parameters and neuroplasticity biomarkers in chronic post-stroke individuals. Only FDS and gait training might be enough for people with chronic stroke to modify some clinical parameters and neuroplasticity biomarkers.

The Determination of Assistance-as-Needed Support by an Ankle-Foot Orthosis for Patients with Foot Drop

Patients who suffer from foot drop have impaired gait pattern functions and a higher risk of stumbling and falling. Therefore, they are usually treated with an assistive device, a so-called ankle-foot orthosis. The support of the orthosis should be in accordance with the motor requirements of the patient and should only be provided when needed, which is referred to as assistance-as-needed. Thus, in this publication, an approach is presented to determine the assistance-as-needed support using musculoskeletal human models. Based on motion capture recordings of multiple subjects performing gaits at different speeds, a parameter study varying the optimal force of a reserve actuator representing the ankle-foot orthosis added in the musculoskeletal simulation is conducted. The results show the dependency of the simulation results on the selected optimal force of the reserve actuator but with a possible identification of the assistance-as-needed support required from the ankle-foot orthosis. The required increase in support due to the increasing severity of foot drop is especially demonstrated with the approach. With this approach, information for the required support of individual subjects can be gathered, which can further be used to derive the design of an ankle-foot orthosis that optimally assists the subjects.

Precision medicine in neurosurgery: The evolving role of theranostics

Theranostics in neurosurgery is a rapidly advancing field of precision medicine that combines diagnostic and therapeutic modalities to optimize patient outcomes. This approach has the potential to provide real-time feedback during therapy and diagnose a condition while simultaneously providing treatment. One such form of theranostics is focused ultrasound, which has been found to be effective in inducing neuroablation and neuromodulation and improving the efficacy of chemotherapy drugs by disrupting the blood-brain barrier. Targeted radionuclide therapy, which pairs positron emission tomography tracers with therapeutic effects and imaging modalities, is another promising form of theranostics for neurosurgery. Automated pathology analysis is yet another form of theranostics that can provide real-time feedback during the surgical resection of tumors. Electrical stimulation has also shown promise in optimizing therapies for patients with cerebral palsy. Overall, theranostics is a cost-effective way to optimize medical care for patients in neurosurgery. It is a relatively new field, but the advancements made so far show great promise for improving patient outcomes.

Functional Benefit and Orthotic Effect of Dorsiflexion-FES in Children with Hemiplegic Cerebral Palsy

Functional electrical stimulation of the ankle dorsiflexor (DF-FES) may have advantages over ankle foot orthoses (AFOs) in managing pediatric cerebral palsy (CP). This study assessed the functional benefit and orthotic effect of DF-FES in children with hemiplegic CP. We conducted an open-label prospective study on children with hemiplegic CP ≥ 6 years who used DF-FES for five months. The functional benefit was assessed by repeated motor function tests and the measurement of ankle biomechanical parameters. Kinematic and spatiotemporal parameters were assessed by gait analysis after one and five months. The orthotic effect was defined by dorsiflexion ≥ 0° with DF-FES at either the mid or terminal swing. Among 26 eligible patients, 15 (median age 8.2 years, range 6-15.6) completed the study. After five months of DF-FES use, the results on the Community Balance and Mobility Scale improved, and the distance in the Six-Minute Walk Test decreased (six-point median difference, 95% CI (1.89, 8.1), -30 m, 95% CI (-83.67, -2.6), respectively, p < 0.05) compared to baseline. No significant changes were seen in biomechanical and kinematic parameters. Twelve patients (80%) who showed an orthotic effect at the final gait analysis experienced more supported walking over time, with a trend toward slower walking. We conclude that the continuous use of DF-FES increases postural control and may cause slower but more controlled gait.

Case report: The gait deviation index may predict neurotherapeutic effects of FES-assisted gait training in children with cerebral palsy

Background

Children with cerebral palsy (CP) show progressive loss of ambulatory function characterized by kinematic deviations at the hip, knee, and ankle. Functional electrical stimulation (FES) can lead to more typical lower limb kinematics during walking by eliciting appropriately timed muscle contractions. FES-assisted walking interventions have shown mixed to positive results in improving lower limb kinematics through immediate correction of gait during the application of FES, or long-term, persisting effects of non-FES-assisted gait improvements following multi-week FES-assisted gait training, at the absence of stimulation, i.e., neurotherapeutic effects. It is unknown, however, if children with CP will demonstrate a neurotherapeutic response following FES-assisted gait training because of the CP population's heterogeneity in gait deviations and responses to FES. Identifying the neurotherapeutic responders is, therefore, important to optimize the training interventions to those that have higher probability of benefiting from the intervention.

Objective

The purpose of this case study was to investigate the relationship between immediate and neurotherapeutic effects of FES-assisted walking to identify responders to a FES-assisted gait training protocol.

Methods

The primary outcome was Gait Deviation Index (GDI) and secondary outcome was root mean squared error (RMSE) of the lower extremity joint angles in the sagittal plane between participants with CP and a typically developing (TD) dataset. Potential indicators were defined as immediate improvements from baseline during FES-assisted walking followed by neurotherapeutic improvements at the end of training.

Case description

Gait analysis of two adolescent female participants with spastic diplegia (Gross Motor Function Classification System level II and III) was conducted at the start and end of a 12-week FES-assisted treadmill training protocol. Participant 1 had scissoring crouch gait, while participant 2 had jump gait.

Outcomes

The GDI showed both immediate (presence of FES) and neurotherapeutic (absence of FES after training period) improvements from baseline in our two participants. Joint angle RMSE showed mixed trends between immediate and neurotherapeutic changes from baseline. The GDI warrants investigation in a larger sample to determine if it can be used to identify responders to FES-assisted gait training.

Comprehensive dynamic and kinematic analysis of the rodent hindlimb during over ground walking

The rat hindlimb is a frequently utilized pre-clinical model system to evaluate injuries and pathologies impacting the hindlimbs. These studies have demonstrated the translational potential of this model but have typically focused on the force generating capacity of target muscles as the primary evaluative outcome. Historically, human studies investigating extremity injuries and pathologies have utilized biomechanical analysis to better understand the impact of injury and extent of recovery. In this study, we expand that full biomechanical workup to a rat model in order to characterize the spatiotemporal parameters, ground reaction forces, 3-D joint kinematics, 3-D joint kinetics, and energetics of gait in healthy rats. We report data on each of these metrics that meets or exceeds the standards set by the current literature and are the first to report on all these metrics in a single set of animals. The methodology and findings presented in this study have significant implications for the development and clinical application of the improved regenerative therapeutics and rehabilitative therapies required for durable and complete functional recovery from extremity traumas, as well as other musculoskeletal pathologies.

A deep learning method to predict ankle joint moment during walking at different speeds with ultrasound imaging: A framework for assistive devices control

Robotic assistive or rehabilitative devices are promising aids for people with neurological disorders as they help regain normative functions for both upper and lower limbs. However, it remains challenging to accurately estimate human intent or residual efforts non-invasively when using these robotic devices. In this article, we propose a deep learning approach that uses a brightness mode, that is, B-mode, of ultrasound (US) imaging from skeletal muscles to predict the ankle joint net plantarflexion moment while walking. The designed structure of customized deep convolutional neural networks (CNNs) guarantees the convergence and robustness of the deep learning approach. We investigated the influence of the US imaging's region of interest (ROI) on the net plantarflexion moment prediction performance. We also compared the CNN-based moment prediction performance utilizing B-mode US and sEMG spectrum imaging with the same ROI size. Experimental results from eight young participants walking on a treadmill at multiple speeds verified an improved accuracy by using the proposed US imaging + deep learning approach for net joint moment prediction. With the same CNN structure, compared to the prediction performance by using sEMG spectrum imaging, US imaging significantly reduced the normalized prediction root mean square error by 37.55% ( < .001) and increased the prediction coefficient of determination by 20.13% ( < .001). The findings show that the US imaging + deep learning approach personalizes the assessment of human joint voluntary effort, which can be incorporated with assistive or rehabilitative devices to improve clinical performance based on the assist-as-needed control strategy.

Neuromuscular electrical stimulation to augment lower limb exercise and mobility in individuals with spastic cerebral palsy: A scoping review

Background: Neuromuscular Electrical Stimulation (NMES) is an emerging assistive technology applied through surface or implanted electrodes to augment skeletal muscle contraction. NMES has the potential to improve function while reducing the neuromuscular impairments of spastic cerebral palsy (CP). This scoping review examines the application of NMES to augment lower extremity exercises for individuals with spastic CP and reports the effects of NMES on neuromuscular impairments and function in spastic CP, to provide a foundation of knowledge to guide research and development of more effective treatment. Methods: A literature review of Scopus, Medline, Embase, and CINAHL databases were searched from 2001 to 2 November 2021 with identified inclusion and exclusion criteria. Results: Out of 168 publications identified, 33 articles were included. Articles on three NMES applications were identified, including NMES-assisted strengthening, NMES-assisted gait, and NMES for spasticity reduction. NMES-assisted strengthening included the use of therapeutic exercises and cycling. NMES-assisted gait included the use of NMES to improve gait patterns. NMES-spasticity reduction included the use of transcutaneous electrical stimulation or NMES to decrease tone. Thirteen studies investigated NMES-assisted strengthening, eleven investigated therapeutic exercise and demonstrated significant improvements in muscle structure, strength, gross motor skills, walking speed, and functional mobility; three studies investigated NMES-assisted cycling and demonstrated improved gross motor skills and walking distance or speed. Eleven studies investigated NMES-assisted gait and demonstrated improved muscle structure, strength, selective motor control, gross motor skills, and gait mechanics. Seven studies investigated NMES for spasticity reduction, and five of the seven studies demonstrated reduced spasticity. Conclusion: A growing body of evidence supports the use of NMES-assisted strengthening, NMES-assisted gait, and NMES for spasticity reduction to improve functional mobility for individuals with spastic CP. Evidence for NMES to augment exercise in individuals with spastic CP remains limited. NMES protocols and parameters require further clarity to translate knowledge to clinicians. Future research should be completed to provide richer evidence to transition to more robust clinical practice.

Fused ultrasound and electromyography-driven neuromuscular model to improve plantarflexion moment prediction across walking speeds

Background

Improving the prediction ability of a human-machine interface (HMI) is critical to accomplish a bio-inspired or model-based control strategy for rehabilitation interventions, which are of increased interest to assist limb function post neurological injuries. A fundamental role of the HMI is to accurately predict human intent by mapping signals from a mechanical sensor or surface electromyography (sEMG) sensor. These sensors are limited to measuring the resulting limb force or movement or the neural signal evoking the force. As the intermediate mapping in the HMI also depends on muscle contractility, a motivation exists to include architectural features of the muscle as surrogates of dynamic muscle movement, thus further improving the HMI’s prediction accuracy.

Objective

The purpose of this study is to investigate a non-invasive sEMG and ultrasound (US) imaging-driven Hill-type neuromuscular model (HNM) for net ankle joint plantarflexion moment prediction. We hypothesize that the fusion of signals from sEMG and US imaging results in a more accurate net plantarflexion moment prediction than sole sEMG or US imaging.

Methods

Ten young non-disabled participants walked on a treadmill at speeds of 0.50, 0.75, 1.00, 1.25, and 1.50 m/s. The proposed HNM consists of two muscle-tendon units. The muscle activation for each unit was calculated as a weighted summation of the normalized sEMG signal and normalized muscle thickness signal from US imaging. The HNM calibration was performed under both single-speed mode and inter-speed mode, and then the calibrated HNM was validated across all walking speeds.

Results

On average, the normalized moment prediction root mean square error was reduced by 14.58 % (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$p=0.012$$\end{document}p=0.012) and 36.79 % (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$p<0.001$$\end{document}p<0.001) with the proposed HNM when compared to sEMG-driven and US imaging-driven HNMs, respectively. Also, the calibrated models with data from the inter-speed mode were more robust than those from single-speed modes for the moment prediction.

Conclusions

The proposed sEMG-US imaging-driven HNM can significantly improve the net plantarflexion moment prediction accuracy across multiple walking speeds. The findings imply that the proposed HNM can be potentially used in bio-inspired control strategies for rehabilitative devices due to its superior prediction.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12984-022-01061-z.

Muscle architecture, growth, and biological Remodelling in cerebral palsy: a narrative review

Cerebral palsy (CP) is caused by a static lesion to the brain occurring in utero or up to the first 2 years of life; it often manifests as musculoskeletal impairments and movement disorders including spasticity and contractures. Variable manifestation of the pathology across individuals, coupled with differing mechanics and treatments, leads to a heterogeneous collection of clinical phenotypes that affect muscles and individuals differently. Growth of muscles in CP deviates from typical development, evident as early as 15 months of age. Muscles in CP may be reduced in volume by as much as 40%, may be shorter in length, present longer tendons, and may have fewer sarcomeres in series that are overstretched compared to typical. Macroscale and functional deficits are likely mediated by dysfunction at the cellular level, which manifests as impaired growth. Within muscle fibres, satellite cells are decreased by as much as 40-70% and the regenerative capacity of remaining satellite cells appears compromised. Impaired muscle regeneration in CP is coupled with extracellular matrix expansion and increased pro-inflammatory gene expression; resultant muscles are smaller, stiffer, and weaker than typical muscle. These differences may contribute to individuals with CP participating in less physical activity, thus decreasing opportunities for mechanical loading, commencing a vicious cycle of muscle disuse and secondary sarcopenia. This narrative review describes the effects of CP on skeletal muscles encompassing substantive changes from whole muscle function to cell-level effects and the effects of common treatments. We discuss growth and mechanics of skeletal muscles in CP and propose areas where future work is needed to understand these interactions, particularly the link between neural insult and cell-level manifestation of CP.

Effect of functional electrical stimulation versus TheraTogs on gait and balance in children with hemiplegic cerebral palsy: a randomized controlled trial

Background

Children with cerebral palsy exhibit postural restrictions and gait problems as a result of both primary and secondary brain damage impairments. One of the main goals of cerebral palsy rehabilitation is to improve gait and balance. As a result, the purpose of this study was to compare the effects of FES and TheraTogs on gait and balance in children with hemiplegic CP. A randomized controlled study was conducted on 30 children with hemiplegic CP (18 boys and 12 girls) between the ages of 8 and 12 years. The children were divided into two equal groups. In addition to the traditional physical treatment program, the FES group received functional electrical stimulation (pulse width 300 μs, frequency 33 Hz, 2 h/day, 3 days/week, 3 months). The TheraTogs group, on the other hand, received the TheraTogs strapping system as well as the same traditional program for the same time period. The 3-D motion analysis and the Biodex balance system were used to analyze gait parameters and postural stability at baseline and 3 months after the intervention.

Results

When comparing the mean values of the gait parameters and postural stability indices of children in both groups before and after treatment, a significant improvement was reported. Furthermore, the FES group showed a greater improvement in all of the measured outcomes (P < 0.001).

Conclusion

Functional electrical stimulation improves gait pattern and postural stability in children with hemiplegic cerebral palsy significantly more than TheraTogs strapping systems.

Clinical trial registration

This study was registered in the ClinicalTrial.gov PRS (NCT05020834).

Effect of functional electrical stimulation on postural control in children with hemiplegic cerebral palsy: a randomized controlled trial

Background

Children with cerebral palsy have impairments of postural control during static and dynamic activities. Improving postural control is one of the primary objectives of rehabilitation for children with cerebral palsy. Therefore, the objective of this study was to study the effect of functional electric stimulation on postural control in children with hemiplegic cerebral palsy. A randomized controlled study was conducted on 30 children with hemiplegic cerebral palsy (18 boys and 12 girls) between the ages of 8 and 12 years. The children were distributed in two equal groups. The experimental group received functional electrical stimulation (pulse width 300 μs, frequency 33 Hz, 2 h/day, 3 days/week, / 3 consecutive months) in addition to the traditional physical therapy program. While the control group received the traditional physiotherapy program only for the same duration. The outcomes included postural stability indices that were measured at baseline and following 3 months of intervention using the Biodex balance system.

Results

A significant improvement was found in the postural stability indices of children in both groups, comparing their mean values before and after treatment. Furthermore, the results revealed a greater improvement in the postural stability of the experimental group (P < 0.001).

Conclusion

Functional electrical stimulation may be a useful tool to enhance the postural stability of children with hemiplegic cerebral palsy.

Clinical trial registration

This study was registered in the ClinicalTrial.gov PRS (NCT04269798). https://register.clinicaltrials.gov/prs/app/action/SelectProtocol?sid=S0009LHP&selectaction=Edit&uid=U0003GAI&ts=4&cx=74k74l

Plantarflexion Moment Prediction during the Walking Stance Phase with an sEMG-Ultrasound Imaging-Driven Model

Many rehabilitative exoskeletons use non-invasive surface electromyography (sEMG) to measure human volitional intent. However, signals from adjacent muscle groups interfere with sEMG measurements. Further, the inability to measure sEMG signals from deeply located muscles may not accurately measure the volitional intent. In this work, we combined sEMG and ultrasound (US) imaging-derived signals to improve the prediction accuracy of voluntary ankle effort. We used a multivariate linear model (MLM) that combines sEMG and US signals for ankle joint net plantarflexion (PF) moment prediction during the walking stance phase. We hypothesized that the proposed sEMG-US imaging-driven MLM would result in more accurate net PF moment prediction than sEMG-driven and US imaging-driven MLMs. Synchronous measurements including reflective makers coordinates, ground reaction forces, sEMG signals of lateral/medial gastrocnemius (LGS/MGS), and soleus (SOL) muscles, and US imaging of LGS and SOL muscles were collected from five able-bodied participants walking on a treadmill at multiple speeds. The ankle joint net PF moment benchmark was calculated based on inverse dynamics, while the net PF moment prediction was determined by the sEMG-US imaging-driven, sEMG-driven, and US imaging-driven MLMs. The findings show that the sEMG-US imaging-driven MLM can significantly improve the prediction of net PF moment during the walking stance phase at multiple speeds. Potentially, the proposed sEMG-US imaging-driven MLM can be used as a superior joint motion intent model in advanced and intelligent control strategies for rehabilitative exoskeletons.

Evaluation of Individualized Functional Electrical Stimulation-Induced Acute Changes during Walking: A Case Series in Children with Cerebral Palsy

Functional electrical stimulation (FES) walking interventions have demonstrated improvements to gait parameters; however, studies were often confined to stimulation of one or two muscle groups. Increased options such as number of muscle groups targeted, timing of stimulation delivery, and level of stimulation are needed to address subject-specific gait deviations. We aimed to demonstrate the feasibility of using a FES system with increased stimulation options during walking in children with cerebral palsy (CP). Three physical therapists designed individualized stimulation programs for six children with CP to target participant-specific gait deviations. Stimulation settings (pulse duration and current) were tuned to each participant. Participants donned our custom FES system that utilized gait phase detection to control stimulation to lower extremity muscle groups and walked on a treadmill at a self-selected speed. Motion capture data were collected during walking with and without the individualized stimulation program. Eight gait metrics and associated timing were compared between walking conditions. The prescribed participant-specific stimulation programs induced significant change towards typical gait in at least one metric for each participant with one iteration of FES-walking. FES systems with increased stimulation options have the potential to allow the physical therapist to better target the individual's gait deviations than a one size fits all device.

Effects of elastic neutral ankle-foot orthoses on 3 dimensional parameters during gait training in patients with stroke: A pilot study

BACKGROUND

General ankle-foot orthosis (AFO) cannot be flexibly adjusted to volumetric change in the lower leg because the molding is custom-fit. Thus, we developed a flexible assistive device called elastic neutral AFO (EN-AFO) to help stroke patients hold a neutral ankle position. The purpose of this study was to investigate the effects of EN-AFO and improve gait patterns in stroke patients with rearfoot varus deformity.

METHODS

Fifteen stroke patients with a varus deformity of the foot performed a walking test with and without the use of EN-AFO. Kinematic data were measured with a 3D motion analysis system with inertial measurement unit (IMU) sensors.

RESULTS

In the stance phase, maximal pelvic tilt and maximal ankle dorsiflexion in the affected side changed, and maximal and minimal pelvic tilts and maximal hip abduction in the less-affected limb effectively changed, as well. During the swing phase, minimal pelvic tilt and minimal ankle abduction in the affective limb greatly changed; particularly, the reduction of maximal ankle inversion was significantly cleared.

CONCLUSIONS

The EN-AFO was effective in controlling the tendency of foot inversion in patients with varus deformities. This is suitable for gait training, as it can adjust the orthosis stiffness according to the foot condition.

Measuring skeletal muscle morphology and architecture with imaging modalities in children with cerebral palsy: a scoping review

AIM

To investigate the use of ultrasound and magnetic resonance imaging (MRI) methodologies to assess muscle morphology and architecture in children with cerebral palsy (CP).

METHOD

A scoping review was conducted with systematic searches of Medline, Embase, Scopus, Web of Science, PubMed, and PsycInfo for all original articles published up to January 2019 utilizing ultrasound and/or MRI to determine morphological and architectural properties of lower limb skeletal muscle in children with CP.

RESULTS

Eighty papers used ultrasound (n=44), three-dimensional ultrasound (n=16), or MRI (n=20) to measure at least one muscle parameter in children and adolescents with CP. Most research investigated single muscles, predominantly the medial gastrocnemius muscle, included children classified in Gross Motor Function Classification System levels I (n=62) and II (n=65), and assessed fascicle length (n=35) and/or muscle volume (n=35). Only 21 papers reported reliability of imaging techniques. Forty-six papers assessed measures of Impairment (n=39), Activity (n=24), and Participation (n=3).

INTERPRETATION

Current research study design, variation in methodology, and preferences towards investigation of isolated muscles may oversimplify the complexities of CP muscle but provide a foundation for the understanding of the changes in muscle parameters in children with CP.

WHAT THIS PAPER ADDS

Current evidence is biased towards the medial gastrocnemius muscle and more functionally able children with cerebral palsy (CP). Variations in imaging techniques and joint positioning limit comparisons between studies. Clinimetric testing of parameters of CP muscle is not always considered. Assessment of parameter(s) of muscle with measures of participation is sparse.

Interventions and lower-limb macroscopic muscle morphology in children with spastic cerebral palsy: a scoping review

AIM

To identify and map studies that have assessed the effect of interventions on lower-limb macroscopic muscle-tendon morphology in children with spastic cerebral palsy (CP).

METHOD

We conducted a literature search of studies that included pre- and post-treatment measurements of lower-limb macroscopic muscle-tendon morphology in children with spastic CP. Study quality was evaluated and significant intervention effects and effect sizes were extracted.

RESULTS

Twenty-eight articles were identified. They covered seven different interventions including stretching, botulinum neurotoxin A (BoNT-A), strengthening, electrical stimulation, whole-body vibration, balance training, and orthopaedic surgery. Study quality ranged from poor (14 out of 28 studies) to good (2 out of 28). Study samples were small (n=4-32) and studies were variable regarding which muscles and macroscopic morphological parameters were assessed. Inconsistent effects after intervention (thickness and cross-sectional area for strengthening, volume for BoNT-A), no effect (belly length for stretching), and small effect sizes were reported.

INTERPRETATION

Intervention studies reporting macroscopic muscle-tendon remodelling after interventions are limited and heterogeneous, making it difficult to generalize results. Studies that include control groups and standardized assessment protocols are needed to improve study quality and data synthesis. Lack or inconclusive effects at the macroscopic level could indicate that the effects of interventions should also be evaluated at the microscopic level.

WHAT THIS PAPER ADDS

Muscle-targeted interventions to remodel muscle morphology are not well understood. Studies reporting macroscopic muscle remodelling following interventions are limited and heterogeneous. Passive stretching may preserve but does not increase muscle length. The effects of isolated botulinum neurotoxin A injections on muscle volume are inconsistent. Isolated strengthening shows no consistent increase in muscle volume or thickness.

Functional Electrical Stimulation for Foot Drop in Post-Stroke People: Quantitative Effects on Step-to-Step Symmetry of Gait Using a Wearable Inertial Sensor

The main purpose of the present study was to assess the effects of foot drop stimulators (FDS) in individuals with stroke by means of spatio-temporal and step-to-step symmetry, harmonic ratio (HR), parameters obtained from trunk accelerations acquired using a wearable inertial sensor. Thirty-two patients (age: 56.84 ± 9.10 years; 68.8% male) underwent an instrumental gait analysis, performed using a wearable inertial sensor before and a day after the 10-session treatment (PRE and POST sessions). The treatment consisted of 10 sessions of 20 min of walking on a treadmill while using the FDS device. The spatio-temporal parameters and the HR in the anteroposterior (AP), vertical (V), and mediolateral (ML) directions were computed from trunk acceleration data. The results showed that time had a significant effect on the spatio-temporal parameters; in particular, a significant increase in gait speed was detected. Regarding the HRs, the HR in the ML direction was found to have significantly increased (+20%), while those in the AP and V directions decreased (approximately 13%). Even if further studies are necessary, from these results, the HR seems to provide additional information on gait patterns with respect to the traditional spatio-temporal parameters, advancing the assessment of the effects of FDS devices in stroke patients.

Toward a hybrid exoskeleton for crouch gait in children with cerebral palsy: neuromuscular electrical stimulation for improved knee extension

BACKGROUND

Neuromuscular Electrical Stimulation (NMES) has been utilized for many years in cerebral palsy (CP) with limited success despite its inherent potential for improving muscle size and/or strength, inhibiting or reducing spasticity, and enhancing motor performance during functional activities such as gait. While surface NMES has been shown to successfully improve foot drop in CP and stroke, correction of more complex gait abnormalities in CP such as flexed knee (crouch) gait remains challenging due to the level of stimulation needed for the quadriceps muscles that must be balanced with patient tolerability and the ability to deliver NMES assistance at precise times within a gait cycle.

METHODS

This paper outlines the design and evaluation of a custom, noninvasive NMES system that can trigger and adjust electrical stimulation in real-time. Further, this study demonstrates feasibility of one possible application for this digitally-controlled NMES system as a component of a pediatric robotic exoskeleton to provide on-demand stimulation to leg muscles within specific phases of the gait cycle for those with CP and other neurological disorders who still have lower limb sensation and volitional control. A graphical user interface was developed to digitally set stimulation parameters (amplitude, pulse width, and frequency), timing, and intensity during walking. Benchtop testing characterized system delay and power output. System performance was investigated during a single session that consisted of four overground walking conditions in a 15-year-old male with bilateral spastic CP, GMFCS Level III: (1) his current Ankle-Foot Orthosis (AFO); (2) unassisted Exoskeleton; (3) NMES of the vastus lateralis; and (4) NMES of the vastus lateralis and rectus femoris. We hypothesized in this participant with crouch gait that NMES triggered with low latency to knee extensor muscles during stance would have a modest but positive effect on knee extension during stance.

RESULTS

The system delivers four channels of NMES with average delays of 16.5 ± 13.5 ms. Walking results show NMES to the vastus lateralis and rectus femoris during stance immediately improved mean peak knee extension during mid-stance (p = 0.003*) and total knee excursion (p = 0.009*) in the more affected leg. The electrical design, microcontroller software and graphical user interface developed here are included as open source material to facilitate additional research into digitally-controlled surface stimulation ( github.com/NIHFAB/NMES ).

CONCLUSIONS

The custom, digitally-controlled NMES system can reliably trigger electrical stimulation with low latency. Precisely timed delivery of electrical stimulation to the quadriceps is a promising treatment for crouch. Our ultimate goal is to synchronize NMES with robotic knee extension assistance to create a hybrid NMES-exoskeleton device for gait rehabilitation in children with flexed knee gait from CP as well as from other pediatric disorders.

TRIAL REGISTRATION

clinicaltrials.gov, ID: NCT01961557 . Registered 11 October 2013; Last Updated 27 January 2020.

A Scoping Review of Neuromuscular Electrical Stimulation to Improve Gait in Cerebral Palsy: The Arc of Progress and Future Strategies

Background: Neuromuscular deficits of children with spastic cerebral palsy (CP) limits mobility, due to muscle weakness, short muscle-tendon unit, spasticity, and impaired selective motor control. Surgical and pharmaceutical strategies have been partially effective but often cause further weakness. Neuromuscular electrical stimulation (NMES) is an evolving technology that can improve neuromuscular physiology, strength, and mobility. This review aims to identify gaps in knowledge to motivate future NMES research.

Methods: Research publications from 1990- July 20th 2019 that investigated gait-specific NMES in CP were reviewed using the PubMed and Google Scholar databases. Results were filtered by the National Institute of Neurological Disorder and Stroke common data elements guidelines for CP. The Oxford Centre for Evidence Based Medicine guidelines were used to determine levels of evidence for each outcome. Gait-specific NMES research protocols and trends are described, with implications for future research.

Results: Eighteen studies met inclusion criteria, reporting on 212 participants, 162 of whom received NMES while walking, average age of 9.8 years, GMFCS levels I–III. Studies included 4 randomized control trials, 9 cohort studies and 5 case studies. A historical trend emerged that began with experimental multi-channel NMES device development, followed by the commercial development of single-channel devices with inertial sensor-based gait event detection to facilitate ankle dorsiflexion in swing phase. This research reported strong evidence demonstrating improved ankle dorsiflexion kinematics in swing and at initial contact. Improved walking speed, step length, and muscle volume were also reported. However, improvements in global walking scores were not consistently found, motivating a recent return to investigating multi-channel gait-specific NMES applications.

Conclusions: Research on single-channel gait-specific NMES found that it improved ankle motion in swing but was insufficient to address more complex gait abnormalities common in CP, such as flexed-knee and stiff-knee gait. Early evidence indicates that multi-channel gait-specific NMES may improve gait patterns in CP, however significantly more research is needed. The conclusions of this review are highly limited by the low level of evidence of the studies available. This review provides a historical record of past work and a technical context, with implications for future research on gait-specific NMES to improve walking patterns and mobility in CP.

Kinematic and Functional Gait Changes After the Utilization of a Foot Drop Stimulator in Pediatrics

Foot drop is one of the most common secondary conditions associated with hemiplegia post stroke and cerebral palsy (CP) in children, and is characterized by the inability to lift the foot (dorsiflexion) about the ankle. This investigation focuses on children and adolescents diagnosed with brain injury and aims to evaluate the orthotic and therapeutic effects due to continuous use of a foot drop stimulator (FDS). Seven children (10 ± 3.89 years) with foot drop and hemiplegia secondary to brain injury (stroke or CP) were evaluated at baseline and after 3 months of FDS usage during community ambulation. Primary outcome measures included using mechanistic (joint kinematics, toe displacement, temporal-spatial asymmetry), and functional gait parameters (speed, step length, time) to evaluate the orthotic and therapeutic effects. There was a significant correlation between spatial asymmetry and speed without FDS at 3 months (r = 0.76, p < 0.05, df = 5) and no correlation between temporal asymmetry and speed for all conditions. The results show orthotic effects including significant increase in toe displacement (p < 0.025 N = 7) during the swing phase of gait while using the FDS. A positive correlation exists between toe displacement and speed (with FDS at 3 months: r = 0.62, p > 0.05, without FDS at 3 months: r = 0.44, p > 0.05). The results indicate an orthotic effect of increased dorsiflexion and toe displacement during swing with the use of the FDS in children with hemiplegia. Further, the study suggests that there could be a potential long-term effect of increased dorsiflexion during swing with continuous use of FDS.

Analysis and Modeling of Rat Gait Biomechanical Deficits in Response to Volumetric Muscle Loss Injury

There is currently a substantial volume of research underway to develop more effective approaches for the regeneration of functional muscle tissue as treatment for volumetric muscle loss (VML) injury, but few studies have evaluated the relationship between injury and the biomechanics required for normal function. To address this knowledge gap, the goal of this study was to develop a novel method to quantify the changes in gait of rats with tibialis anterior (TA) VML injuries. This method should be sensitive enough to identify biomechanical and kinematic changes in response to injury as well as during recovery. Control rats and rats with surgically-created VML injuries were affixed with motion capture markers on the bony landmarks of the back and hindlimb and were recorded walking on a treadmill both prior to and post-surgery. Data collected from the motion capture system was exported for post-hoc analysis in OpenSim and Matlab. In vivo force testing indicated that the VML injury was associated with a significant deficit in force generation ability. Analysis of joint kinematics showed significant differences at all three post-surgical timepoints and gait cycle phase shifting, indicating augmented gait biomechanics in response to VML injury. In conclusion, this method identifies and quantifies key differences in the gait biomechanics and joint kinematics of rats with VML injuries and allows for analysis of the response to injury and recovery. The comprehensive nature of this method opens the door for future studies into dynamics and musculoskeletal control of injured gait that can inform the development of regenerative technologies focused on the functional metrics that are most relevant to recovery from VML injury.

Use of a Novel Functional Electrical Stimulation Gait Training System in 2 Adolescents With Cerebral Palsy: A Case Series Exploring Neurotherapeutic Changes

BACKGROUND AND PURPOSE

Cerebral palsy (CP) is characterized by decreased passive joint range-of-motion and impaired walking, resulting in progressive loss of function. Typical gait training interventions for children with CP appear insufficient to mitigate these effects. The purpose of this case report is to describe the use of a new treadmill-based gait training intervention using active correction with functional electrical stimulation (FES) in 2 adolescents with CP.

CASE DESCRIPTION

Two participants with CP (13-year-old girls, Gross Motor Function Classification System [GMFCS] level II and III) trained by walking on a treadmill, with FES assistance, for 30 minutes, 3 times per week, for 12 weeks. The intervention used a feedback control system to detect all 7 phases of gait in real time and triggered FES to the appropriate muscle groups (up to 5 bilaterally) based on the detected gait phase. Joint kinematics, step width, stride length, walking endurance, peak oxygen uptake ($\dot{v}^{o}_{2}$), and oxygen (O2) cost of walking were evaluated preintervention and postintervention.

OUTCOMES

Both participants showed improved knee and ankle angles and step width relative to children who are typically developing, and both exhibited increased stride length. One participant (GMFCS III) improved peak $\dot{v}^{o}_{2}$and walking endurance but not O2 cost of walking at her original self-selected walking speed. The other participant (GMFCS II) improved O2 cost of walking but not peak $\dot{v}^{o}_{2}$ or walking endurance. These differences are partly explained by differences in gait type, functional abilities, and initial fitness levels. Most improvements persisted at follow-up, indicating short-term neurotherapeutic effects.

DISCUSSION

Most improvements persisted at follow-up, suggesting short-term neurotherapeutic effects. This case series demonstrates the promising utility of FES-assisted gait-training interventions, tailored to target individual gait deviations, in improving walking performance.

Evaluation of Gait Phase Detection Delay Compensation Strategies to Control a Gyroscope-Controlled Functional Electrical Stimulation System During Walking

Functional electrical stimulation systems are used as neuroprosthetic devices in rehabilitative interventions such as gait training. Stimulator triggers, implemented to control stimulation delivery, range from open- to closed-loop controllers. Finite-state controllers trigger stimulators when specific conditions are met and utilize preset sequences of stimulation. Wearable sensors provide the necessary input to differentiate gait phases during walking and trigger stimulation. However, gait phase detection is associated with inherent system delays. In this study, five stimulator triggers designed to compensate for gait phase detection delays were tested to determine which trigger most accurately delivered stimulation at the desired times of the gait cycle. Motion capture data were collected on seven typically-developing children while walking on an instrumented treadmill. Participants wore one inertial measurement unit on each ankle and gyroscope data were streamed into the gait phase detection algorithm. Five triggers, based on gait phase detection, were used to simulate stimulation to five muscle groups, bilaterally. For each condition, stimulation signals were collected in the motion capture software via analog channels and compared to the desired timing determined by kinematic and kinetic data. Results illustrate that gait phase detection is a viable finite-state control, and appropriate system delay compensations, on average, reduce stimulation delivery delays by 6.7% of the gait cycle.

Functional Task Training Combined With Electrical Stimulation Improves Motor Capacity in Children With Unilateral Cerebral Palsy: A Single-Subject Design

PURPOSE

Reduced propulsive capability can impact negatively on mobility activities of many children with spastic unilateral cerebral palsy (SUCP). This study investigated the effect of a task-oriented training program combined with functional electrical stimulation (FES) on the motor capacity of children with SUCP.

METHODS

Single-case A-B design with follow-up. Gross motor function and biomechanical walking data of 4 children with SUCP were measured repeatedly across the baseline, intervention, and follow-up phases. Intervention was a task-oriented training program combined with FES applied on the gastrocnemius. Outcome variables included gait speed, impulsive torque, and ankle/hip power generation ratio. The 2-SD band and celeration line methods compared outcomes among the baseline, intervention, and follow-up periods.

RESULTS

One child improved walking speed. All children improved impulsive torque and ankle/hip power ratio of the affected leg. All children improved gross motor function.

CONCLUSION

The intervention improved children's propulsive capability and positively influenced their mobility.

Technical development of transcutaneous electrical nerve inhibition using medium-frequency alternating current

Background

Innovative technical approaches to controlling undesired sensory and motor activity, such as hyperalgesia or spasticity, may contribute to rehabilitation techniques for improving neural plasticity in patients with neurologic disorders. To date, transcutaneous electrical stimulation has used low frequency pulsed currents for sensory inhibition and muscle activation. Yet, few studies have attempted to achieve motor nerve inhibition using transcutaneous electrical stimulation. This study aimed to develop a technique for transcutaneous electrical nerve inhibition (TENI) using medium-frequency alternating current (MFAC) to suppress both sensory and motor nerve activity in humans.

Methods

Surface electrodes were affixed to the skin of eight young adults to stimulate the median nerve. Stimulation intensity was increased up to 50% and 100% of the pain threshold. To identify changes in sensory perception by transcutaneous MFAC (tMFAC) stimulation, we examined tactile and pressure pain thresholds in the index and middle fingers before and after stimulation at 10 kHz. To demonstrate the effect of tMFAC stimulation on motor inhibition, stimulation was applied while participants produced flexion forces with the index and middle fingers at target forces (50% and 90% of MVC, maximum voluntary contraction).

Results

tMFAC stimulation intensity significantly increased tactile and pressure pain thresholds, indicating decreased sensory perception. During the force production task, tMFAC stimulation with the maximum intensity immediately reduced finger forces by ~ 40%. Finger forces recovered immediately after stimulation cessation. The effect on motor inhibition was greater with the higher target force (90% MVC) than with the lower target (50% MVC). Also, higher tMFAC stimulation intensity provided a greater inhibition effect on both sensory and motor nerve activity.

Conclusion

We found that tMFAC stimulation immediately inhibits sensory and motor activity. This pre-clinical study demonstrates a novel technique for TENI using MFAC stimulation and showed that it can effectively inhibit both sensory perception and motor activity. The proposed technique can be combined with existing rehabilitation devices (e.g., a robotic exoskeleton) to inhibit undesired sensorimotor activities and to accelerate recovery after neurologic injury.

The effect of additional activation of the plantar intrinsic foot muscles on foot dynamics during gait

BACKGROUND

The plantar intrinsic foot muscles (PIFMs) contribute to support the medial longitudinal arch. But the functional role of the PIFMs during dynamic activities is not clear. The purpose of this study was to examine the change in the foot dynamics during gait accompanied with the change in the PIFMs activity to determine the functional role of the PIFMs during gait.

METHODS

Twenty healthy male subjects were randomly assigned to the electrical stimulation group (ESG) or control group (CG). In the ESG, the electrical stimulation to the PIFMs was provided from mid-stance to pre-swing using surface electrodes to simulate reinforcement of the PIFMs. The foot dynamics during the stance phase of gait was measured using a 3D motion analysis, and the amount of change from baseline (electrical stimulation was not provided) was compared between groups using an independent sample t-test.

RESULTS

In the ESG, the timing for the navicular height to reach the minimum value was significantly later, and the vertical ground reaction force (2nd peak) significantly decreased more. There were no group differences in the amount of change from baseline on gait velocity, stance phase duration, minimum navicular height and ground reaction force in other directions.

CONCLUSION

Results from this study showed that the functions of the PIFMs most likely include shock absorption and facilitation of efficient foot ground force transmission during the stance phase of gait.

The Feasibility of Functional Electrical Stimulation to Improve Upper Extremity Function in a Two-year-old Child with Perinatal Stroke: A Case Report

AIMS

To evaluate the effectiveness and feasibility (i.e. tolerability, adherence) of functional electrical stimulation (FES) for the upper extremity (UE) in a two-year-old child with perinatal stroke.

METHODS

Forty hours of FES over eight weeks was prescribed. FES to the hemiplegic triceps, extensor carpi radialis longus and brevis, extensor carpi ulnaris and extensor digitorum was timed with reaching during play. Assessments were performed before, during, and two months post-intervention. UE function (Melbourne Assessment 2 (MA2), Assisting Hand Assessment (AHA)) and spasticity (Modified Tardieu with electrogoniometry and electromyography) were measured. The mother completed a semi-structured interview post-intervention. Descriptive statistics were used for adherence and UE measures. A repeated-measures ANOVA compared Modified Tardieu parameters (e.g. catch angle) over time. Conventional content analysis was used for the interview data.

RESULTS

The child completed 39.2/40 hours. Immediately post-intervention, improvements were observed on MA2's Range of Motion subscale and catch angle (Modified Tardieu, p < 0.001). Two months post-intervention, improvements were observed on MA2's Accuracy and Fluency subscales. No change in AHA score occurred. Three themes emerged from the interview: (1) Ingredients for program success; (2) Information about the FES device; and (3) The child's response.

CONCLUSIONS

UE FES was feasible in a two-year-old child with hemiplegia.

Is functional electrical stimulation an alternative for orthotics in patients with cerebral palsy? A literature review

BACKGROUND

Functional electrical stimulation (FES) is a well-known intervention used during walking to improve walking abilities and correct gait deviations by facilitating the proper muscle group at the appropriate timing in the gait cycle. Our aim was to study the types of surface FES currently used in a cerebral palsy (CP) population and examine the evidence of its ability to improve gait deviations, functional ability and therapeutic effects.

METHODS

A computerized database search was conducted from inception until 6/2016. Included were all clinical trials performing gait analysis of children with CP applying surface FES to any lower leg muscles evaluating the efficiency of the stimulation and any carry-over effect.

RESULTS

Fifteen studies met the inclusion criteria. The most common FES stimulated the dorsi flexors muscles with a positive orthotic effect, improved dorsi flexion during the swing phase and enhanced the foot contact pattern. A smaller positive effect was found for knee extensors stimulation facilitating knee extension during the stance phase and for hip abductors stimulation improving frontal plane knee alignment. No evidence was found to support the use of plantar flexors stimulation in correcting gait deviations. There is scarce evidence of any retention effect.

CONCLUSION

We encourage the clinician to evaluate the use of FES on a case to case basis. Controlled investigations with larger numbers of participants are warranted to determine the orthotic and therapeutic efficacy of FES.

Functional electrical stimulation of the ankle dorsiflexors during walking in spastic cerebral palsy: a systematic review

AIM

To assess the effect of functional electrical stimulation (FES) of ankle dorsiflexors in children and adolescents with spastic cerebral palsy (CP) during walking.

METHOD

A systematic review was performed using the American Academy of Cerebral Palsy and Developmental Medicine methodology and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Six databases were searched for studies applying interventions to patients aged younger than 20 years. Outcomes were classified according to the International Classification of Functioning, Disability and Health (ICF).

RESULTS

Seven hundred and eighty abstracts were found, 35 articles were fully screened, and 14 articles were used for analysis. Only five articles (three studies) were of level I to III evidence. At ICF participation and activity level, there is limited evidence for a decrease in self-reported frequency of toe-drag and falls. At ICF body structure and function level, there is clear evidence (I-III) that FES increased (active) ankle dorsiflexion angle, strength, and improved selective motor control, balance, and gait kinematics, but decreased walking speed. Adverse events include skin irritation, toleration, and acceptation issues.

INTERPRETATION

There are insufficient data supporting functional gain by FES on activity and participation level. However, evidence points towards a role for FES as an alternative to orthoses in children with spastic CP.

WHAT THIS PAPER ADDS

Effects of functional electrical stimulation (FES) point towards a potential role as an alternative to orthoses for patients with spastic cerebral palsy (CP). Some evidence for a decrease in self-reported frequency of toe-drag and falls with the use of FES in spastic CP. Limited evidence for improvements in activity and participation in patients with spastic CP using FES.

Participation and community-based walking activity after neuroprosthesis use in children with hemiplegic cerebral palsy: A pilot study1

PURPOSE

To explore the effects of neuroprosthesis use on participation, level of community-based walking activity, safety and satisfaction in children with hemiplegic CP.

METHODS

Eleven children (mean 9 years 11 months) with hemiplegic CP Gross Motor Function Classification System (GMFCS) Level I and II participated in a 16-week intervention using the Ness L300 neuroprosthesis. Outcome measures included satisfaction and performance with self-selected participation goals (Canadian Occupational Performance Measure (COPM)), level of community-based walking activity (Step Watch Activity Monitor (SAM)), trip and fall frequency (caregiver report) and a satisfaction questionnaire.

RESULTS

Significant (p< 0.001) improvements in performance and satisfaction with self-selected participation goals (COPM) were demonstrated. No significant changes were noted in SAM values. A significant (p= 0.01) decrease in trips was demonstrated from baseline to post. Satisfaction with the device was high.

CONCLUSION

Results indicate that daily neuroprosthesis use may improve performance and satisfaction with participation goals and reduce trips. No changes in community-based walking activity were noted. Further study is needed to examine response based on GMFCS levels, across geographical regions and between FES neuroprosthesis and a control group.

Neurologic Correlates of Gait Abnormalities in Cerebral Palsy: Implications for Treatment

Cerebral palsy (CP) is the most common movement disorder in children. A diagnosis of CP is often made based on abnormal muscle tone or posture, a delay in reaching motor milestones, or the presence of gait abnormalities in young children. Neuroimaging of high-risk neonates and of children diagnosed with CP have identified patterns of neurologic injury associated with CP, however, the neural underpinnings of common gait abnormalities remain largely uncharacterized. Here, we review the nature of the brain injury in CP, as well as the neuromuscular deficits and subsequent gait abnormalities common among children with CP. We first discuss brain injury in terms of mechanism, pattern, and time of injury during the prenatal, perinatal, or postnatal period in preterm and term-born children. Second, we outline neuromuscular deficits of CP with a focus on spastic CP, characterized by muscle weakness, shortened muscle-tendon unit, spasticity, and impaired selective motor control, on both a microscopic and functional level. Third, we examine the influence of neuromuscular deficits on gait abnormalities in CP, while considering emerging information on neural correlates of gait abnormalities and the implications for strategic treatment. This review of the neural basis of gait abnormalities in CP discusses what is known about links between the location and extent of brain injury and the type and severity of CP, in relation to the associated neuromuscular deficits, and subsequent gait abnormalities. Targeted treatment opportunities are identified that may improve functional outcomes for children with CP. By providing this context on the neural basis of gait abnormalities in CP, we hope to highlight areas of further research that can reduce the long-term, debilitating effects of CP.

An exploratory study of gait and functional outcomes after neuroprosthesis use in children with hemiplegic cerebral palsy

PURPOSE

To evaluate the immediate orthotic, total and therapeutic effects of functional electrical stimulation (FES) neuroprosthesis use on clinic based measures of gait and function in children with hemiplegic cerebral palsy.

METHODS

Eleven children (mean 9 years 11 months) participated in an FES neuroprosthesis (Ness L300) intervention (4 week accommodation period followed by 12 weeks of daily use) and were assessed at baseline and post in stimulation off and stimulation on conditions. Measures included clinic based outcomes of gait and function.

RESULTS

No significant immediate orthotic effects were observed. Significant (p < 0.01) total effects were noted for dorsiflexion at initial contact, Six-Minute Walk Test (6MWT), and walking speed. A significant therapeutic effect was found for steps off path on the Standardized Walking Obstacle Course (SWOC).

CONCLUSIONS

Results support previous findings of neuroprosthesis total effects on gait and provide some evidence for effects on function. Therapeutic effects remain unclear. Implications for Rehabilitation In this study, children with hemiplegic CP did not demonstrate immediate improvements in gait or function at their first clinic visit using the FES neuroprosthesis device suggesting one visit using the device is not sufficient to determine potential benefits. Over time with daily use of the FES neuroprosthesis, ankle dorsiflexion in swing and at initial contact, walking speed and endurance increased with the device worn. Overtime, no carryover effects in ankle dorsiflexion in swing and at initial contact were noted at the end of the intervention period with the device off. Clinicians should consider purchasing units to loan or rent to individuals to trial a device at home before determining long-term potential for benefit.

Wireless, accelerometry-triggered functional electrical stimulation of the peroneal nerve in spastic paresis: A randomized, controlled pilot study

In hemiparesis, Wireless, Accelerometry-Triggered Functional Electrical Stimulation (WAFES) of the common peroneal nerve may hold intrinsic rehabilitative properties. The present pilot study analyzes WAFES against conventional therapy. Twenty adults with chronic hemiparesis (time since lesion 7(6) years; median (interquartile range)) were randomized into 2 10-week rehabilitation programs: a 45-minute (min) daily walk using WAFES (n = 10) and conventional physical therapy (CPT), 3 × 45 min per week (n = 10). The outcomes were 3D sagittal speed measurements, step length, cadence, maximal amplitude and velocity of hip, knee, and ankle during gait at free and fast speed without WAFES and clinical assessments of plantar flexor angles of shortening, spasticity, and weakness, before (D1) and after the program (W10). Kinematic and spasticity improvements occurred in the WAFES group only: (i) ankle dorsiflexion velocity (D1 versus W10, free speed, WAFES, +4(5)°/sec, p = 0.002; CPT, -3(8)°/sec, p = 0.007; fast, WAFES, +8(6)°/sec, p = 0.03; CPT, -1(4)°/sec, NS); (ii) maximal passive ankle dorsiflexion (WAFES,+26(85)%; CPT,+0(27)%; group-visit, p = 0.007) and knee flexion (WAFES, +13(17)%; CPT, -1(11)%; group-visit, p = 0.006) at fast speed only; (iii) 15% plantar flexor spasticity grade reduction with WAFES. Over 10 weeks, gait training using WAFES improved ankle and knee kinematics and reduced plantar flexor spasticity compared with CPT. Studies with longer WAFES use should explore functional effects.

Neuromuscular electrical stimulation-assisted gait increases muscle strength and volume in children with unilateral spastic cerebral palsy

AIM

To determine if neuromuscular electrical stimulation (NMES) applied to the ankle dorsiflexors during gait improves muscle volume and strength in children with unilateral spastic cerebral palsy (CP).

METHOD

Thirty-two children (15 females, 17 males; mean age 10y 8mo, age range 5y 5mo-18y 1mo) with unilateral spastic CP and a Gross Motor Function Classification System of level I or level II were randomly assigned to either the 8-week daily NMES treatment group or control group (usual or conventional treatments). Outcomes at week 8 (post-NMES) and week 14 (carryover) included magnetic resonance imaging for muscle volumes (tibialis anterior, anterior compartment, and gastrocnemius), strength (hand-held dynamometry for isometric dorsiflexion strength and heel raises for functional strength), and clinical measures for lower limb selective motor control.

RESULTS

At week 8, the treatment group demonstrated significantly (p<0.05) increased muscle volumes for tibialis anterior, anterior compartment, medial and lateral gastrocnemius, and dorsiflexion strength not only when compared to their baseline values but also when compared to the control group at week 8. At week 14, both tibialis anterior and lateral gastrocnemius volumes in the treatment group remained significantly increased when compared to their baseline values. However, only lateral gastrocnemius volumes had significantly greater values when compared to the control group at week 14. There were no between group differences in the clinical measures for lower limb selective motor control at week 8 and 14.

INTERPRETATION

Eight weeks of daily NMES-assisted gait increases muscle volume and strength of the stimulated ankle dorsiflexors in children with unilateral spastic CP. These changes are use-dependent and do not carry over after the 8-week treatment period. Gastrocnemius volume also increased post-treatment with carryover at week 14.

Home-Based Versus Laboratory-Based Robotic Ankle Training for Children With Cerebral Palsy: A Pilot Randomized Comparative Trial

OBJECTIVE

To examine the outcomes of home-based robot-guided therapy and compare it to laboratory-based robot-guided therapy for the treatment of impaired ankles in children with cerebral palsy.

DESIGN

A randomized comparative trial design comparing a home-based training group and a laboratory-based training group.

SETTING

Home versus laboratory within a research hospital.

PARTICIPANTS

Children (N=41) with cerebral palsy who were at Gross Motor Function Classification System level I, II, or III were randomly assigned to 2 groups. Children in home-based and laboratory-based groups were 8.7±2.8 (n=23) and 10.7±6.0 (n=18) years old, respectively.

INTERVENTIONS

Six-week combined passive stretching and active movement intervention of impaired ankle in a laboratory or home environment using a portable rehabilitation robot.

MAIN OUTCOME MEASURES

Active dorsiflexion range of motion (as the primary outcome), mobility (6-minute walk test and timed Up and Go test), balance (Pediatric Balance Scale), Selective Motor Control Assessment of the Lower Extremity, Modified Ashworth Scale (MAS) for spasticity, passive range of motion (PROM), strength, and joint stiffness.

RESULTS

Significant improvements were found for the home-based group in all biomechanical outcome measures except for PROM and all clinical outcome measures except the MAS. The laboratory-based group also showed significant improvements in all the biomechanical outcome measures and all clinical outcome measures except the MAS. There were no significant differences in the outcome measures between the 2 groups.

CONCLUSIONS

These findings suggest that the translation of repetitive, goal-directed, biofeedback training through motivating games from the laboratory to the home environment is feasible. The benefits of home-based robot-guided therapy were similar to those of laboratory-based robot-guided therapy.

Daily functional electrical stimulation during everyday walking activities improves performance and satisfaction in children with unilateral spastic cerebral palsy: a randomized controlled trial

BACKGROUND

The aim of this paper is to determine whether daily functional electrical stimulation (FES) is effective in improving self-perceptions of individually identified mobility performance problems in children with unilateral spastic cerebral palsy (USCP). We hypothesized that children receiving 8 weeks of FES treatment would have higher scores for self-perceived performance and satisfaction on the Canadian Occupational Performance Measure (COPM) for individually identified priorities than children not receiving FES.

METHODS

Thirty-two children (mean age 10 y 8 mo SD 3y 3mo) with USCP and a Gross Motor Function Classification System I or II were randomly assigned to the FES treatment group (8 weeks of daily FES) and control group (usual treatments). Participants were assessed at baseline (week 0), post treatment (week 8) and 6 weeks follow-up (week 14). The primary outcome measures were self-perceived scores for performance and satisfaction of child- and parent-identified priorities assessed using the COPM post treatment and at follow-up. The secondary outcome measures were the categorization of the performance problems from the COPM and self-report responses according to the International Classification of Functioning Child and Youth version (ICF-CY). This was clinically important because an understanding of mobility performance problems for children with USCP is needed for family-centred service planning.

RESULTS

Performance scores (mean difference 1.6, 95 % CI 0.1 to 3.2, p = 0.034) and satisfaction scores post treatment (mean difference 2.4, 95 % CI 0.5 to 4.2, p = 0.004) were significantly higher in the treatment group than in the control group. There were no significant differences between the groups for performance scores at follow up, however there was a significant difference between the groups for satisfaction (mean difference 1.9, 95 % CI 0.1 to 3.8, p = 0.03) in favour of the treatment group. Priorities were identified across all levels of the ICF-CY but were most commonly identified in the activity and participation domains of the ICF-CY (79.5 %).

CONCLUSIONS

Daily FES applied during everyday walking is effective in addressing self-perceptions of individually identified priorities by improving the performance and satisfaction of functional skills after treatment.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Register ACTRN12614000949684. Registered 4 September 2014.

A basic study on quantitative evaluation of 3-dimensional foot contact with an inertial sensor for FES foot drop correction

In these days, FES is used to control ankle dorsiflexion of hemiplegic gait. Since not only dorsiflexion but also 3-dimensional foot contact isimportant for gait stability in hemiplegic gait, evaluation and control system of 3-dimensional foot contact with FES is needed to correct foot movement. In this study, the timing of initial contact and the timing when foot movement became stationary in the sagittal plane were detected, and the inclination angles in the sagittal and the frontal planes at these timings were used for evaluation. Using the inclination angles, 10 m walking of a hemiplegic subject under the 4 different gait conditions were quantitatively evaluated. The gait conditions were without FES, stimulation to the tibialis anterior, stimulation to the common peroneal nerve, and stimulation to both the tibialis anterior and the common peroneal nerve. Result of evaluation with the inclination angles showed that stimulation to the tibialis anterior could control foot contact appropriately in the sagittal plane, and stimulation to the common peroneal nerve was better to control foot inclination angle in the frontal plane. Inclination angle at the beginning of the stance phase indicated that FES system which used in clinical site commonly is not appropriate to control 3-dimensional foot contact. It was shown that inclination angle at the beginning of the stance phase was useful to evaluate 3-dimensional foot movements for FES foot drop correction.

Electrical Stimulation Following Botulinum Toxin A in Children With Spastic Diplegia: A Within-Participant Randomized Pilot Study

AIMS

To determine whether electrical stimulation (ES) following botulinum toxin A (BoNT/A) injection increases passive extensibility of the hamstring muscles in children with spastic diplegia.

METHODS

Six children undergoing bilateral BoNT/A injections to the hamstrings participated in this within-participant single blind randomized controlled trial. One leg of each child was randomised to the experimental condition and the other to the control condition. The experimental leg received daily stretch and ES to the hamstrings for 12 weeks, while the control leg received only daily stretch. The primary outcome was passive hamstring extensibility reflected by popliteal angle measured with a standardised torque. Secondary outcomes were two goniometric measures of popliteal angle using the Modified Tardieu Scale (R1 and R2), and parents' perceptions of treatment effectiveness. Outcomes were measured at baseline, 4 weeks, 12 weeks and 6 months.

RESULTS

The mean between-group difference (95% CI) at 4 weeks was 2° (-2 to 5) for popliteal angle measured with a standardised torque, favouring the experimental leg. Tardieu results for R1 and R2 were 0° (-4 to 3) and 7° (0 to 14), respectively.

CONCLUSION

ES does not improve passive extensibility of the hamstring muscles at 4 weeks over any possible effects of BoNT/A alone.

Health-related physical fitness for children with cerebral palsy

Low levels of physical activity are a global health concern for all children. Children with cerebral palsy have even lower physical activity levels than their typically developing peers. Low levels of physical activity, and thus an increased risk for related chronic diseases, are associated with deficits in health-related physical fitness. Recent research has provided therapists with the resources to effectively perform physical fitness testing and physical activity training in clinical settings with children who have cerebral palsy, although most testing and training data to date pertains to those who walk. Nevertheless, on the basis of the present evidence, all children with cerebral palsy should engage, to the extent they are able, in aerobic, anaerobic, and muscle-strengthening activities. Future research is required to determine the best ways to evaluate health-related physical fitness in nonambulatory children with cerebral palsy and foster long-term changes in physical activity behavior in all children with this condition.