Pathophysiology of muscle contractures in cerebral palsy

Expert Consensus on Classification and Performance in Paralympic Powerlifting: A Delphi Study

BACKGROUND

In Paralympic sports, classification ensures fair competition by grouping athletes based on their impairments. The International Paralympic Committee has provided scientific principles to guide evidence-based classification procedures. In Paralympic Powerlifting, athletes compete in one class, divided by sex and bodyweight categories, overlooking impairment impact on performance.

OBJECTIVE

This study aimed to establish a consensus among international Paralympic powerlifting experts regarding classification and performance issues to guide future research.

METHODS

A two-round Delphi study was conducted involving 26 experts. The study sought to identify the adequacy of the current classification and competition systems, explore the impact of various impairments, and lay the initial groundwork for a performance determinants model.

RESULTS

Experts agreed that existing classification and competition systems in Paralympic powerlifting do not align with Paralympic standards. Impairments from neurological conditions and those causing anthropometric changes were suggested to have opposing performance impacts. Initial directions for a performance determinants model were outlined, focusing on arm and bar kinematics, anthropometry, and body composition.

CONCLUSIONS

This study underscores the need for comprehensive research in Paralympic powerlifting, revealing critical discrepancies between current classification system and Paralympic standards. Insights into the multifaceted relationship between impairments and performance are provided to shape the future of Paralympic powerlifting research.

Muscle synergy-informed neuromusculoskeletal modelling to estimate knee contact forces in children with cerebral palsy

Cerebral palsy (CP) includes a group of neurological conditions caused by damage to the developing brain, resulting in maladaptive alterations of muscle coordination and movement. Estimates of joint moments and contact forces during locomotion are important to establish the trajectory of disease progression and plan appropriate surgical interventions in children with CP. Joint moments and contact forces can be estimated using electromyogram (EMG)-informed neuromusculoskeletal models, but a reduced number of EMG sensors would facilitate translation of these computational methods to clinics. This study developed and evaluated a muscle synergy-informed neuromusculoskeletal modelling approach using EMG recordings from three to four muscles to estimate joint moments and knee contact forces of children with CP and typically developing (TD) children during walking. Using only three to four experimental EMG sensors attached to a single leg and leveraging an EMG database of walking data of TD children, the synergy-informed approach estimated total knee contact forces comparable to those estimated by EMG-assisted approaches that used 13 EMG sensors (children with CP, n = 3, R2 = 0.95 ± 0.01, RMSE = 0.40 ± 0.14 BW; TD controls, n = 3, R2 = 0.93 ± 0.07, RMSE = 0.19 ± 0.05 BW). The proposed synergy-informed neuromusculoskeletal modelling approach could enable rapid evaluation of joint biomechanics in children with unimpaired and impaired motor control within a clinical environment.

Diagnosis and therapies for patients with cerebral palsy over the past 30 years: a bibliometric analysis

Background

Currently, the incidence of cerebral palsy is high in newborns. However, the current methods for diagnosing and treating patients with cerebral palsy are complex and poorly targeted. Moreover, these studies lack the support of bibliometric analysis results.

Objective

Our study focused on a bibliometric analysis of published papers on the diagnosis and treatment of patients with cerebral palsy. This study identified the primary authors, institutions, and countries involved in analyzing the status and trends of research on the diagnosis and treatment of patients with cerebral palsy. Additionally, the study also involved screening pathways related to cerebral palsy.

Methods

The PubMed database was searched for publications on the diagnosis and treatment of patients with cerebral palsy between 1990 and 2023. R v4.2.2 and VOSviewer v1.6.18 software tools were utilized to perform bibliometric analysis and visualization.

Results

There were 1,965 publications on cerebral palsy diagnosis and 5,418 articles on the qualified treatment strategies, and the annual number of publications also increased. The United States dominated in this field of research. Gregory Y.H. Lip and Patrizio Lancellotti published the most number of papers. The Cleveland Clinic published the most number of papers in the field. According to the analysis of the co-occurrence of keywords, we found that the main research directions were age, sex, disease diagnosis, and treatment. Newly emerging research has focused mainly on heart failure, which is related to valvular heart disease.

Conclusion

The findings presented in this study offer valuable insights into ongoing research and potential future directions pertaining to cerebral palsy. These insights can assist researchers in identifying suitable collaborators and enhancing their investigations aimed at identifying the underlying molecular mechanisms associated with cerebral palsy, encompassing its etiology, preventive measures, and therapeutic interventions.

Tracing vitamins on the long non-coding lane of the transcriptome: vitamin regulation of LncRNAs

A major revelation of genome-scale biological studies in the post-genomic era has been that two-thirds of human genes do not encode proteins. The majority of non-coding RNA transcripts in humans are long non-coding RNA (lncRNA) molecules, non-protein-coding regulatory transcripts with sizes greater than 500 nucleotides. LncRNAs are involved in nearly every aspect of cellular physiology, playing fundamental regulatory roles both in normal cells and in disease. As result, they are functionally linked to multiple human diseases, from cancer to autoimmune, inflammatory, and neurological disorders. Numerous human conditions and diseases stem from gene-environment interactions; in this regard, a wealth of reports demonstrate that the intake of specific and essential nutrients, including vitamins, shapes our transcriptome, with corresponding impacts on health. Vitamins command a vast array of biological activities, acting as coenzymes, antioxidants, hormones, and regulating cellular proliferation and coagulation. Emerging evidence suggests that vitamins and lncRNAs are interconnected through several regulatory axes. This type of interaction is expected, since lncRNA has been implicated in sensing the environment in eukaryotes, conceptually similar to riboswitches and other RNAs that act as molecular sensors in prokaryotes. In this review, we summarize the peer-reviewed literature to date that has reported specific functional linkages between vitamins and lncRNAs, with an emphasis on mammalian models and humans, while providing a brief overview of the source, metabolism, and function of the vitamins most frequently investigated within the context of lncRNA molecular mechanisms, and discussing the published research findings that document specific connections between vitamins and lncRNAs.

Histological analysis of the gastrocnemius muscle in preschool and school age children with cerebral palsy compared with age-matched typically developing children

Inconsistent alterations in skeletal muscle histology have been reported in adolescents with cerebral palsy (CP) and whether alterations are present in young children and differ from older children is not yet known. This study aimed to define histological alterations in the medial gastrocnemius (MG) of ambulant CP (gross-motor classification system, GMFCS I-III) stratified in two age groups (preschool children, PS: 2-5 and school age children, SA: 6-9-yr old) compared with age-matched typically developing (TD) children. We hypothesized that alterations in muscle microscopic properties are already present in PS-CP and are GMFCS level specific. Ultrasound guided percutaneous microbiopsies were collected in 46 CP (24-PS) and 45 TD (13-PS) children. Sections were stained to determine fiber cross-sectional area (fCSA) and proportion, capillary, and satellite cell amount. Average absolute and normalized fCSA were similar in CP and TD, but a greater percentage of smaller fibers was found in CP. Coefficient of variation (CV) was significantly larger in PS-CP-GMFCS I-II and for type I fiber. In SA-CP, all fiber types contributed to the higher CV. Type IIx proportion was higher and type I was lower in PS-CP-GMFCS-III and for all SA-CP. Reduced capillary-to-fiber ratio was present in PS-CP-GMFCS II-III and in all SA-CP. Capillary fiber density was lower in SA-CP. Capillary domain was enhanced in all CP, but capillary spatial distribution was maintained as was satellite cell content. We concluded that MG histological alterations are already present in very young CP but are only partly specific for GMFCS level and age.NEW & NOTEWORTHY Inconsistent histological alterations have been reported in children with cerebral palsy (CP) but whether they are present in very young and ambulant CP children and differ from those reported in old CP children is not known. This study highlighted for the first time that enhanced muscle fiber size variability and loss of capillaries are already present in very young CP children, even in the most ambulant ones, and these alterations seem to extend with age.

Selective dorsal rhizotomy and its effect on muscle force during walking: A comprehensive study

Selective dorsal rhizotomy (SDR) is commonly used to permanently reduce spasticity in children with cerebral palsy (CP). However, studies have yielded varying results regarding muscle strength and activity after SDR. Some studies indicate weakness or no changes, while a recent study using NMSK simulations demonstrates improvements in muscle forces during walking. These findings suggest that SDR may alleviate spasticity, reducing dynamic muscle constraints and enhancing muscle force without altering muscle activity during walking in children with CP. In this study, we combined NMSK simulations with physical examinations to assess children with CP who underwent SDR, comparing them to well-matched peers who did not undergo the procedure. Each group (SDR and No-SDR) included 81 children, with pre- and post-SDR assessments. Both groups were well-matched in terms of demographics, clinical characteristics, and gait parameters. The results of the physical examination indicate that SDR significantly reduces spasticity without impacting muscle strength. Furthermore, our findings show no significant differences in gait deviation index improvements and walking speed between the two groups. Additionally, there were no statistically significant changes in muscle activity during walking before and after SDR for both groups. NMSK results demonstrate a significant increase in muscle force in the semimembranosus and calf muscles during walking, compared to children with CP who received other clinical treatments. Our findings confirm that although SDR does not significantly impact muscle strength compared to other treatments, it creates a more favorable dynamic environment for suboptimal muscle force production, which is essential for walking.

RCOR1 improves neurobehaviors and neuron injury in rat cerebral palsy by Endothelin-1 targeting-induced Akt/GSK-3β pathway upregulation

BACKGROUND

RE1 Silencing Transcription factor (REST) corepressor 1 (RCOR1) has been reported to orchestrate neurogenesis, while its role in cerebral palsy (CP) remains elusive. Besides, RCOR1 can interact with Endothelin-1 (EDN1), and EDN1 expression is related to brain damage. Therefore, this study aimed to explore the effects of RCOR1/EDN1 on brain damage during the progression of CP.

METHODS

CP rats were established via hypoxia-ischemia insult, and injected with lentivirus-RCOR1, followed by examination of brain pathological conditions. The RCOR1 and EDN1 interaction was recognized using hTFtarget. Healthy rat cortical neuron cells received interference of RCOR1/EDN1 expression, and underwent oxygen-glucose deprivation/reoxygenation (OGD/R) treatment, after which phenotypic and molecular assays were conducted through the biochemical method, qRT-PCR and/or western blot.

RESULTS

RCOR1 was low-expressed but EDN1 was high-expressed in CP model rats and OGD/R-treated neurons. RCOR1 overexpression ameliorated rat neurobehaviors, alleviated brain pathological conditions, reduced TUNEL-positive cells, decreased the levels of reactive oxygen species (ROS) and malondialdehyde (MDA), increased superoxide dismutase (SOD) level and repressed EDN1 expression in the brains of CP model rats. In neurons, RCOR1 overexpression counteracted OGD/R-induced viability decrease, reduction of the levels of RCOR1, SOD, Bcl-2, caspase-3, p-Akt/Akt and p-GSK-3β/GSK-3β, and elevation of the levels of EDN1, ROS, Bax, and cleaved caspase-3, while EDN1 overexpression did contrarily on these events. Moreover, there was a negative interplay between RCOR1 overexpression and EDN1 overexpression in OGD/R-induced neurons.

CONCLUSION

RCOR1 ameliorates neurobehaviors and suppresses neuronal apoptosis and oxidative stress in CP through EDN1 targeting-mediated upregulation of Akt/GSK-3β.

Beyond pediatrics: noninvasive spinal neuromodulation improves motor function in an adult with cerebral palsy

Regaining motor function in individuals with cerebral palsy (CP) has been predominantly studied in children, resulting in an underrepresentation of adults in research efforts. We tested the efficacy of noninvasive spinal neuromodulation with neurorehabilitation (Spinal Cord Innovation in Pediatrics; SCiP™ therapy). A 60-year-old CP participant underwent 8 weeks of SCiP™ therapy, resulting in significant motor recovery measured by 14.2-points increase in gross motor function measure (GMFM-88) score, ~ three times the Minimal Clinically Important Difference (MCID) of 5-points. This represented gains in kneeling, sitting, and walking functions. The improvement in GMFM-88 score was maintained above the MCID at the follow up visit (10.3 points above the baseline), twenty weeks following the last therapy session, indicating a persistent effect of the therapy. Our preliminary findings support the therapeutic promise of SCiP™ therapy for enhancing motor function in CP adults. Broader investigations are needed to establish its wider applicability.

Time course of surface electromyography during walking of children with spastic cerebral palsy treated with botulinum toxin type A and its rehabilitation implications

BACKGROUND

The timing of the effects of botulinum toxin A on spastic muscles is not yet fully clarified. The goal of this study was to follow the temporal changes of surface electromyographic activity of lower limb muscles during walking, after a therapeutic dose of botulinum toxin A injected into the calf muscles of children with spastic cerebral palsy.

METHODS

A group of children with spastic equinus foot was administered botulinum toxin A into the gastrocnemius medialis and lateralis muscles. Surface electromyographic activity of the tibialis anterior, gastrocnemius medialis, rectus femoris and medial hamstrings, was recorded before botulinum toxin A injections and after 4, 8, and 16 weeks. Children walked on ground and on a treadmill at an incline of 0% and 12%. The area of electromyographic activity and the index of muscle co-contraction were calculated for specific segments of gait cycle.

FINDINGS

Botulinum toxin A did not modify the speed of gait on ground. ANOVA showed significant differences in electromyography during the stance phase segments with a maximum decrease between 4 and 8 weeks' post botulinum toxin A and a full recovery at 16 weeks. A significant co-contraction of rectus femoris/gastrocnemius medialis, between 0 and 20% and 35-50% of the gait cycle, was observed from the 4th to the 8th week post- botulinum toxin A for both treadmill settings.

INTERPRETATION

The temporal identification of deterioration/recovery of electromyographic activity as well as of muscle co-contractions, could be key elements in a rehabilitation program planning combined with botulinum toxin A.

Cerebral Palsy: A Narrative Review on Childhood Disorder

Cerebral palsy, one of the most common reasons for infirmity in children and young people in developed countries, refers to several neurological diseases that impact movement and coordination. Central nervous system damage received during the first stages of brain development can cause cerebral palsy, a non-progressive condition that manifests as impairments of movement and posture. Two cases per 1000 are reported, and the causes include those mentioned for high-risk infants. Mental retardation, sensory deficiencies, failure to thrive, seizures, and behavioral or emotional issues are some of the associated difficulties. To enable interdisciplinary intervention, early identification is crucial. The result varies depending on the topography, severity, and presence of concomitant abnormalities in cerebral palsy. Cerebral palsy is caused by a static injury to the cerebral motor cortex that happens before, during, or within five years after birth. Various circumstances can influence the disease, including cerebral anoxia, cerebral hemorrhage, infection, and hereditary disorders. Interventions for children are typically provided as part of multidisciplinary rehabilitation programs. Musculoskeletal complaints are common, and pain is a significant underreported symptom.

Impact of lower muscle stiffness on ankle dorsiflexion restriction in children with cerebral palsy evaluated using ultrasound elastography

BACKGROUND

Plantar flexor muscles always contribute to limiting the range of motion of ankle dorsiflexion in children with spastic cerebral palsy, but the individual contributions of these muscles are not well defined. This study aimed to identify which muscles' stiffness impacts the dorsiflexion range of motion in children with cerebral palsy.

METHODS

Twenty-five children with cerebral palsy were included. The maximum passive dorsiflexion range of motion was measured in two positions: hip and knee joints in flexion, and both joints in full extension. Strain ratios indicating muscle stiffness were measured using strain elastography of the lateral and medial gastrocnemius, soleus, flexor hallucis longus, peroneus longus, peroneus brevis, and tibialis posterior muscles. To analyze which muscles impact the limitation of the dorsiflexion range, multiple regression analyses were conducted. The values of muscle stiffness were included as independent valuables, and the values of the dorsiflexion range were included as dependent valuables. A p-value <0.05 was considered statistically significant.

FINDINGS

In the analyses, the soleus and flexor hallucis longus muscle stiffness were significant independent factors for the dorsiflexion range of motion of hip and knee flexion (adjusted R2: 0.50). The lateral gastrocnemius muscle stiffness was a significant independent factor for the dorsiflexion range of motion with both joints in full extension (adjusted R2: 0.61).

INTERPRETATION

Flexor hallucis longus muscle stiffness, in addition to triceps surae muscle stiffness, was shown to impact dorsiflexion range; attention should be paid to muscle stiffness in children with cerebral palsy.

Ex vivo adult stem cell characterization from multiple muscles in ambulatory children with cerebral palsy during early development of contractures

Cerebral palsy (CP) is one of the most common conditions leading to lifelong childhood physical disability. Literature reported previously altered muscle properties such as lower number of satellite cells (SCs), with altered fusion capacity. However, these observations highly vary among studies, possibly due to heterogeneity in patient population, lack of appropriate control data, methodology and different assessed muscle. In this study we aimed to strengthen previous observations and to understand the heterogeneity of CP muscle pathology. Myogenic differentiation of SCs from the Medial Gastrocnemius (MG) muscle of patients with CP (n = 16, 3-9 years old) showed higher fusion capacity compared to age-matched typically developing children (TD, n = 13). Furthermore, we uniquely assessed cells of two different lower limb muscles and showed a decreased myogenic potency in cells from the Semitendinosus (ST) compared to the MG (TD: n = 3, CP: n = 6). Longitudinal assessments, one year after the first botulinum toxin treatment, showed slightly reduced SC representations and lower fusion capacity (n = 4). Finally, we proved the robustness of our data, by assessing in parallel the myogenic capacity of two samples from the same TD muscle. In conclusion, these data confirmed previous findings of increased SC fusion capacity from MG muscle of young patients with CP compared to age-matched TD. Further elaboration is reported on potential factors contributing to heterogeneity, such as assessed muscle, CP progression and reliability of primary outcome parameters.

Differences in kinetic characteristics during countermovement jump of football players with cerebral palsy according to impairment profiles

Objectives: The purpose of this study was 1) to determine and compare kinetic parameters during the realization of a countermovement jump (CMJ) between footballers with cerebral palsy (CP) and non-impaired footballers, and 2) to analyze the differences in this action between different players' impairment profiles and a group of non-impaired footballers. Methods: This study involved 154 participants comprising 121 male footballers with CP from 11 national teams and 33 male non-impaired football players recruited as the control group (CG). The footballers with CP were described according to the different impairment profiles (bilateral spasticity = 10; athetosis or ataxia = 16; unilateral spasticity = 77; minimum impairment = 18). All participants performed three CMJs on a force platform to record kinetic parameters during the test. Results: The group of para-footballers presented significantly lower values than the CG in the jump height (p < 0.01, d = -1.28), peak power (p < 0.01, d = -0.84), and the net concentric impulse (p < 0.01, d = -0.86). Concerning the pairwise comparisons between CP profiles and the CG, significant differences were found for the bilateral spasticity, athetosis or ataxia, and unilateral spasticity subgroups compared to the non-impaired players for jump height (p < 0.01; d = -1.31 to -2.61), power output (p < 0.05; d = -0.77 to -1.66), and concentric impulse of the CMJ (p < 0.01; d = -0.86 to -1.97). When comparing the minimum impairment subgroup with the CG, only significant differences were found for jump height (p = 0.036; d = -0.82). Footballers with minimum impairment presented higher jumping height (p = 0.002; d = -1.32) and concentric impulse (p = 0.029; d = -1.08) compared to those with bilateral spasticity. Also, the unilateral spasticity subgroup reports a higher jump height performance than the bilateral group (p = 0.012; d = -1.12). Conclusion: These results suggest that the variables related to power production during the concentric phase of the jump are crucial for the performance differences between groups with and without impairment. This study provides a more comprehensive understanding of kinetic variables that would differentiate CP and non-impaired footballers. However, more studies are necessary to clarify which parameters better differentiate among different profiles of CP. The findings could help to prescribe effective physical training programs and support the classifier's decision-making for class allocation in this para-sport.

Morphological Medial Gastrocnemius Muscle Growth in Ambulant Children with Spastic Cerebral Palsy: A Prospective Longitudinal Study

Only cross-sectional studies have demonstrated muscle deficits in children with spastic cerebral palsy (SCP). The impact of gross motor functional limitations on altered muscle growth remains unclear. This prospective longitudinal study modelled morphological muscle growth in 87 children with SCP (age range 6 months to 11 years, Gross Motor Function Classification System [GMFCS] level I/II/III = 47/22/18). Ultrasound assessments were performed during 2-year follow-up and repeated for a minimal interval of 6 months. Three-dimensional freehand ultrasound was applied to assess medial gastrocnemius muscle volume (MV), mid-belly cross-sectional area (CSA) and muscle belly length (ML). Non-linear mixed models compared trajectories of (normalized) muscle growth between GMFCS-I and GMFCS-II&III. MV and CSA growth trajectories showed a piecewise model with two breakpoints, with the highest growth before 2 years and negative growth rates after 6-9 years. Before 2 years, children with GMFCS-II&III already showed lower growth rates compared to GMFCS-I. From 2 to 9 years, the growth rates did not differ between GMFCS levels. After 9 years, a more pronounced reduction in normalized CSA was observed in GMFCS-II&III. Different trajectories in ML growth were shown between the GMFCS level subgroups. These longitudinal trajectories highlight monitoring of SCP muscle pathology from early ages and related to motor mobility. Treatment planning and goals should stimulate muscle growth.

MRI Based Fiber Strain Mapping of the Medial Gastrocnemius Muscle at Submaximal Isometric Contractions at Different Ankle Angles

Muscle force production is influenced by muscle fiber and aponeurosis architecture. This prospective cohort study utilizes special MR imaging sequences to examine the structure-function in-vivo in the Medial Gastrocnemius (MG) at three-ankle angles (dorsiflexion, neutral, and plantar flexion) and two sub-maximal levels of maximum voluntary contraction (25% and 50% MVC). The study was performed on 6 young male subjects. Muscle fiber and aponeurosis strain, fiber strain normalized to force, fiber length and pennation angle (at rest and peak contraction) were analyzed for statistical differences between ankle positions and %MVC. A two-way repeated measures ANOVA and post hoc Bonferroni-adjusted tests were conducted for normal data. A related samples test with Friedman's 2-way ANOVA by ranks with corrections for multiple comparisons was conducted for non-normal data. The dorsiflexed ankle position generated significantly higher force with lower fiber strain than neutral and plantarflexed positions. Sarcomere length extracted from muscle fiber length at each ankle angle was used to track the location on the Force-Length curve and showed the MG operates on the curve's ascending limb. Muscle force changes predicted from the F-L curve going from dorsi- to plantarflexion was less than that experimentally observed suggesting other determinants of force changes with ankle position.

Children With Cerebral Palsy Show Higher Static-But Not Higher Dynamic-Motor Fatigability in Grip and Pinch Tasks Than Children With Typical Development Do

OBJECTIVE

The purpose of this study was to investigate differences in static and dynamic motor fatigability during grip and pinch tasks between children with unilateral spastic cerebral palsy (USCP) and children with typical development (TD) and between preferred and nonpreferred hands.

METHODS

Fifty-three children with USCP and 53 age-matched children with TD (mean = 11 years 1 month; SD = 3 years 8 months) participated in 30-second maximum exertion sustained and repeated grip and pinch tasks. For sustained tasks, the Static Fatigue Index and the ratio of mean force between the first and last thirds of the curve were calculated. For repeated tasks, the ratio of mean force and the ratio of numbers of peaks between the first and last thirds of the curve were calculated.

RESULTS

Higher Static Fatigue Index scores for grip and pinch were found with USCP in both hands and between hands in both groups. Dynamic motor fatigability showed inconsistent results, with higher levels of fatigability in children with TD than in children with USCP for grip in the ratio of mean force between the first and last thirds of the curve in nonpreferred hands and in the ratio of number of peaks between the first and last thirds of the curve in preferred hands.

CONCLUSION

Higher motor fatigability in children with USCP than in children with TD was found for static but not dynamic grip and pinch. Underlying mechanisms may play different roles in static and dynamic motor fatigability.

IMPACT

These results highlight that static motor fatigability in grip and pinch tasks should be part of a comprehensive upper limb assessment and that this could be the target of individualized interventions.

American Society of Biomechanics Clinical Biomechanics Award 2021: Redistribution of muscle-tendon work in children with cerebral palsy who walk in crouch

BACKGROUND

Previous study showed the triceps surae exhibits spring-like behavior about the ankle during walking in children with cerebral palsy. Thus, the work generated by the triceps surae is diminished relative to typically developing children. This study investigated whether the quadriceps offset the lack of triceps surae work production in children with cerebral palsy who walk in crouch.

METHODS

Seven children with cerebral palsy (8-16 yrs) and 14 typically developing controls (8-17 yrs) walked overground at their preferred speed in a motion analysis laboratory. Shear wave tensiometers were used to track patellar and Achilles tendon loading throughout the gait cycle. Tendon force measures were coupled with muscle-tendon kinematic estimates to characterize the net work generated by the quadriceps and triceps surae about the knee and ankle, respectively.

FINDINGS

Children with cerebral palsy generated significantly less triceps surae work when compared to controls (P < 0.001). The reverse was true at the knee. Children with cerebral palsy generated positive net work from the quadriceps about the knee, which exceeded the net quadriceps work generated by controls (P = 0.028).

INTERPRETATION

There was a marked difference in functional behavior of the triceps surae and quadriceps in children with cerebral palsy who walk in crouch. In particular, the triceps surae of children with cerebral palsy exhibited spring-like behavior about the ankle while the quadriceps exhibited more motor-like behavior about the knee. This redistribution in work could partly be associated with the elevated energetic cost of walking in children with cerebral palsy and is relevant to consider when planning treatments to correct crouch gait.

Total Hip Arthroplasty in Patients With Neurological Conditions: A Systematic Review

Background

As operative techniques and implant design have evolved over time, total hip arthroplasty (THA) is increasingly being carried out for patients with neurological impairment. This patient group places unique surgical challenges to the arthroplasty surgeon, which may include contractures, instability, and altered muscular tone. The purpose of this systematic review is to report the patient outcomes, complications, and implant survival following THA for patients with neurological conditions affecting the hip. Thus, we aim to support orthopaedic surgeon decision-making when considering and planning THA for these patients.

Methods

A systematic review was performed as per Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines using the PubMed/Medline OVID, Cochrane, and Embase databases. All studies reporting the outcomes of THA in the neurological population which met defined inclusion criteria were included.

Results

From an initial screen of 1820 studies, 45 studies with a total of 36,251 THAs were included in the final selection. All 45 studies reported complication rates, with controls included in 16 for comparison. High complication rates were observed following THA in the neurologically impaired population, most notably dislocation with observed rates up to 10.6%. An improvement was noted in all 36 studies (1811 THAs) which reported upon patient-reported outcomes.

Conclusions

THA may be beneficial in the selected patients with neurological conditions, to reduce pain and improve function. There is an increased risk of complications which require careful consideration when planning the operation and open discussion with prospective patients and caregivers before proceeding with surgery.

Surgical Strategies and Perioperative Considerations for Cervical Deformity With Cerebral Palsy: A Comprehensive Review of the Literature

The complex nature of the cervical spine makes surgical intervention challenging when treating cervical deformity in patients with cerebral palsy (CDCP). However, few studies have investigated the unique characteristics of cerebral palsy that create the need for surgery, the most effective surgical strategies, and the possible perioperative complications. The intended benefit and the potential risk of postoperative complications must be considered when deciding to operate for CDCP. Because the approach and correction strategy depend on the type of cervical deformity, as well as the patient's comorbidities and functional status, a customized strategy is needed. Perioperatively, botulinum toxin injections and muscle division techniques can help control excessive involuntary movements and improve the spinal fusion success rate. Surgical intervention for CDCP requires a multidisciplinary approach, and the information presented in this article is intended to help in the perioperative management and surgical treatment of CDCP.

The Effects of Prolonged Vibrotactile EMG-Based Biofeedback on Ankle Joint Range of Motion During Gait in Children with Spastic Cerebral Palsy: A Case Series

AIMS

The objective of this case series was to examine the feasibility of vibrotactile EMG-based biofeedback (BF) as a home-based intervention tool to enhance sensory information during everyday motor activities and to explore its effectiveness to induce changes in active ankle range of motion during gait in children with spastic cerebral palsy (CP).

METHODS

Ten children ages 6 to 13 years with spastic CP were recruited. Participants wore two EMG-based vibro-tactile BF devices for at least 4 hours per day for 1-month on the ankle and knee joints muscles. The device computed the amplitude of the EMG signal of the target muscle and actuated a silent vibration motor proportional to the magnitude of the EMG.

RESULTS

Our results demonstrated the feasibility of the augmented sensory information of muscle activity to induce changes of the active ankle range of motion during gait for 6 children with an increase ranging from 8.9 to 51.6% compared to a one-month period without treatment.

CONCLUSIONS

Preliminary findings of this case series demonstrate the feasibility of vibrotactile EMG-based BF and suggest potential effectiveness to increase active ankle range of motion, therefore serving as a promising therapeutic tool to improve gait in children with spastic CP.

Plant based food bioactives: A boon or bane for neurological disorders

Neurological disorders are the foremost occurring diseases across the globe resulting in progressive dysfunction, loss of neuronal structure ultimately cell death. Therefore, attention has been drawn toward the natural resources for the search of neuroprotective agents. Plant-based food bioactives have emerged as potential neuroprotective agents for the treatment of neurodegenerative disorders. This comprehensive review primarily focuses on various plant food bioactive, mechanisms, therapeutic targets, in vitro and in vivo studies in the treatment of neurological disorders to explore whether they are boon or bane for neurological disorders. In addition, the clinical perspective of plant food bioactives in neurological disorders are also highlighted. Scientific evidences point toward the enormous therapeutic efficacy of plant food bioactives in the prevention or treatment of neurological disorders. Nevertheless, identification of food bioactive components accountable for the neuroprotective effects, mechanism, clinical trials, and consolidation of information flow are warranted. Plant food bioactives primarily act by mediating through various pathways including oxidative stress, neuroinflammation, apoptosis, excitotoxicity, specific proteins, mitochondrial dysfunction, and reversing neurodegeneration and can be used for the prevention and therapy of neurodegenerative disorders. In conclusion, the plant based food bioactives are boon for neurological disorders.

Contribution of stroke-related changes in neuromuscular factors to gear ratio during isometric contraction of medial gastrocnemius muscle: A simulation study

BACKGROUND

It is not clear which neuromuscular factors are most closely associated with the loss of variable fascicle gearing after chronic stroke. The purpose of this simulation study is to determine the effects of stroke-related changes in key neuromuscular factors on the gear ratio.

METHODS

A modified Hill-type model of the medial gastrocnemius was developed to determine the gear ratio for a given muscle activation level and musculotendon length. Model parameters were then systematically adjusted to simulate known stroke-related changes in neuromuscular factors, and the gear ratio was computed for each change in the parameters. A Monte Carlo simulation was performed to understand which neuromuscular factors and fiber behavior-related parameters are most relevant to the loss of variable gearing. Dominance analyses were also conducted to quantify the relative importance of fiber behavior-related parameters on the gear ratio.

FINDINGS

The gear ratio decreases significantly with smaller pennation angle and with shorter optimal fiber length. In addition, muscle thickness and pennation angle at optimal fiber length appear to be the most important muscle architectural parameters. Dominance analyses further suggest that primary determinants of gear ratio include initial pennation angle, fiber rotation-shortening ratio, initial muscle thickness, and fiber rotation.

INTERPRETATION

Our findings provide insight that the pennation angle may play an important role for efficient muscular contraction, implying that maintaining muscle architecture and/or improving fiber/fascicle rotation could a key goal in rehabilitation interventions. Our findings will help us to better interpret altered gearing behavior in aging and pathological muscles.

The Short-Term Impact of Botulinum Neurotoxin-A on Muscle Morphology and Gait in Children with Spastic Cerebral Palsy

Children with spastic cerebral palsy (SCP) are often treated with intramuscular Botulinum Neurotoxin type-A (BoNT-A). Recent studies demonstrated BoNT-A-induced muscle atrophy and variable effects on gait pathology. This group-matched controlled study in children with SCP compared changes in muscle morphology 8-10 weeks post-BoNT-A treatment (n = 25, median age 6.4 years, GMFCS level I/II/III (14/9/2)) to morphological changes of an untreated control group (n = 20, median age 7.6 years, GMFCS level I/II/III (14/5/1)). Additionally, the effects on gait and spasticity were assessed in all treated children and a subgroup (n = 14), respectively. BoNT-A treatment was applied following an established integrated approach. Gastrocnemius and semitendinosus volume and echogenicity intensity were assessed by 3D-freehand ultrasound, spasticity was quantified through electromyography during passive muscle stretches at different velocities. Ankle and knee kinematics were evaluated by 3D-gait analysis. Medial gastrocnemius (p = 0.018, -5.2%) and semitendinosus muscle volume (p = 0.030, -16.2%) reduced post-BoNT-A, but not in the untreated control group, while echogenicity intensity did not change. Spasticity reduced and ankle gait kinematics significantly improved, combined with limited effects on knee kinematics. This study demonstrated that BoNT-A reduces spasticity and partly improves pathological gait but reduces muscle volume 8-10 weeks post-injections. Close post-BoNT-A follow-up and well-considered treatment selection is advised before BoNT-A application in SCP.

Effect of Functional Electrical Stimulation on Gait Parameters in Children with Cerebral Palsy: A Meta-Analysis

Objective

At present, there are controversies on the effectiveness of functional electrical stimulation devices in gait improvement in the clinic, and the results reported in limited literature are contradictory. This paper summarizes and analyzes the relationship between functional electrical stimulation treatment and gait parameter changes in children with cerebral palsy, thus exploring the above controversies' results.

Methods

Two researchers conducted a detailed search of the literature from the establishment of the database to June 2022. Literature retrieved from databases, including PubMed, Embase, Ovid, Cochrane Library, and Web of Science and the search process followed the principles of Cochrane. The search keywords were “cerebral palsy”, “functional electrical stimulation”, “gait”, or “walk”. Gait and balance parameters were extracted from the literature. Gait parameters, such as walking speed and step length, were included in the meta-analysis. The study used standard mean difference (STD) and 95% confidence interval (CI) to calculate the mean difference between the two groups. The statistic I² was used to evaluate the heterogeneity between the evaluation studies. Begg's test detected publication bias and the funnel chart was used for visual analysis. Furthermore, Review Manager software was used to make a risk bias map for literature publication bias analysis.

Results

9 literatures were included in the analysis, with a total of 282 children with cerebral palsy, including 142 patients in the functional electrical stimulation treatment group and 140 patients in the comfort treatment, general nursing, or other physical therapy. The randomization scheme and result report used in most studies were low risk, which was important for the credibility of this study. Most studies have limitations in the blinding method of participants and subjects, and most of them were single-blind studies, which might have a high risk. The results showed that functional electrical stimulation could increase the walking speed of children with cerebral palsy (SMD = 0.82, P < 0.0001) and increase the walking step length of children with cerebral palsy (SMD = 1.34, 95%CI = 1.07, 1.60, Z = 9.91, P < 0.0001). Funnel plot analysis showed that the literature distribution was uniform and symmetrical, and Begg's test showed no publication bias in included literature.

Conclusion

This study compared the effects of the functional nerve stimulation treatment group and control group on improving gait parameters of children with cerebral palsy. The results indicated that functional nerve stimulation treatment could increase the gait speed and step length of children with cerebral palsy, which could improve the walking of children with cerebral palsy. Furthermore, this study needs more research data to support our findings. The results of this study might better guide the clinical practice and better use of health as well as financial resources.

Increased Sensitivity to Serotonin Syndrome in Cerebral Palsy

Serotonin syndrome is characterized by symptoms of neuromuscular and autonomic excitation and altered mental status. It is most often drug induced with antidepressants being the main precipitants. However, other classes have been implicated as well including antipsychotics, antiemetic and pain medications, and lithium. The syndrome is typically induced by the combination of two or more serotonergic agents; however, there have been instances of serotonin syndrome occurring while a patient is on a single medication. The literature is limited regarding the study of risk factors associated with the production of serotonin syndrome while on only monotherapy or otherwise atypically causative agents. One such risk factor may be underlying neuromuscular pathology. This study is the first case series to our knowledge reporting two separate cases of serotonin syndrome being induced in patients with cerebral palsy as an underlying common factor.

The Myotube Analyzer: how to assess myogenic features in muscle stem cells

Background

The analysis of in vitro cultures of human adult muscle stem cells obtained from biopsies delineates the potential of skeletal muscles and may help to understand altered muscle morphology in patients. In these analyses, the fusion index is a commonly used quantitative metric to assess the myogenic potency of the muscle stem cells. Since the fusion index only partly describes myogenic potency, we developed the Myotube Analyzer tool, which combines the definition of the fusion index with extra features of myonuclei and myotubes obtained from satellite cell cultures.

Results

The software contains image adjustment and mask editing functions for preprocessing and semi-automatic segmentation, while other functions can be used to determine the features of nuclei and myotubes. The fusion index and a set of five novel parameters were tested for reliability and validity in a comparison between satellite cell cultures from children with cerebral palsy and typically developing children. These novel parameters quantified extra nucleus and myotube properties and can be used to describe nucleus clustering and myotube shape. Two analyzers who were trained in cell culture defined all parameters using the Myotube Analyzer app. Out of the six parameters, five had good reliability reflected by good intra-class correlation coefficients (> 0.75). Children with cerebral palsy were significantly different from the typically developing children (p < 0.05) for five parameters, and for three of the six parameters, these differences exceeded the minimal detectable differences.

Conclusions

The Myotube Analyzer can be used for the analysis of fixed differentiated myoblast cultures with nuclear and MyHC staining. The app can calculate the fusion index, an already existing parameter, but also provides multiple new parameters to comprehensively describe myogenic potential in its output. The raw data used to determine these parameters are also available in the output. The parameters calculated by the tool can be used to detect differences between cultures from children with cerebral palsy and typically developing children. Since the program is open source, users can customize it to fit their own analysis requirements.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13395-022-00297-6.

Causal Effects of Motor Control on Gait Kinematics After Orthopedic Surgery in Cerebral Palsy: A Machine-Learning Approach

Background

Altered motor control is common in cerebral palsy (CP). Understanding how altered motor control affects movement and treatment outcomes is important but challenging due to complex interactions with other neuromuscular impairments. While regression can be used to examine associations between impairments and movement, causal modeling provides a mathematical framework to specify assumed causal relationships, identify covariates that may introduce bias, and test model plausibility. The goal of this research was to quantify the causal effects of altered motor control and other impairments on gait, before and after single-event multi-level orthopedic surgery (SEMLS).

Methods

We evaluated the impact of SEMLS on change in Gait Deviation Index (ΔGDI) between gait analyses. We constructed our causal model with a Directed Acyclic Graph that included the assumed causal relationships between SEMLS, ΔGDI, baseline GDI (GDIpre), baseline neurologic and orthopedic impairments (Imppre), age, and surgical history. We identified the adjustment set to evaluate the causal effect of SEMLS on ΔGDI and the impact of Imppre on ΔGDI and GDIpre. We used Bayesian Additive Regression Trees (BART) and accumulated local effects to assess relative effects.

Results

We prospectively recruited a cohort of children with bilateral CP undergoing SEMLS (N = 55, 35 males, age: 10.5 ± 3.1 years) and identified a control cohort with bilateral CP who did not undergo SEMLS (N = 55, 30 males, age: 10.0 ± 3.4 years). There was a small positive causal effect of SEMLS on ΔGDI (1.70 GDI points). Altered motor control (i.e., dynamic and static motor control) and strength had strong effects on GDIpre, but minimal effects on ΔGDI. Spasticity and orthopedic impairments had minimal effects on GDIpre or ΔGDI.

Conclusion

Altered motor control did have a strong effect on GDIpre, indicating that these impairments do have a causal effect on a child's gait pattern, but minimal effect on expected changes in GDI after SEMLS. Heterogeneity in outcomes suggests there are other factors contributing to changes in gait. Identifying these factors and employing causal methods to examine the complex relationships between impairments and movement will be required to advance our understanding and care of children with CP.

Ballistic strength training in adults with cerebral palsy may increase rate of force development in plantar flexors, but transition to walking remains unclear: a case series

Background

Persons with cerebral palsy (CP) walk with reduced ankle plantar flexor power compared to typically developing. In this study, we investigated whether a ballistic strength-training programme targeting ankle plantar flexors could improve muscle strength, muscle architecture and walking function in adults with CP.

Methods

Eight adults (mildly affected CP) underwent eight weeks of ballistic strength training, with two sessions per week. Before and after the intervention preferred walking speed, ankle plantar flexion rate of force development (RFD), maximal voluntary contraction (MVC), muscle thickness, pennation angle and fascicle length were measured. Data are presented for individuals, as well as for groups. Group changes were analysed using the Wilcoxon signed-rank test.

Results

Data were analysed for eight participants (five women, mean age 37.9 years; six GMFCS I and two GMFCS II). Two participants increased their walking speed, but there were no significant group changes. In terms of muscle strength, there were significant group changes for RFD at 100 ms and MVC. In the case of muscle architecture, there were no group changes.

Conclusion

In this study, we found that eight weeks of ballistic strength training improved ankle plantar flexor muscle strength but walking function and muscle architecture were unchanged. Larger studies will be needed to obtain conclusive evidence of the efficacy of this training method.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13102-022-00487-1.

Therapeutic effect of scalp-based acupuncture and moxibustion as an adjunctive treatment on children with cerebral palsy comparing to conventional rehabilitation therapy: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Cerebral palsy (CP) in children is a predominantly congenital developmental disease with complex causes and diverse symptoms. Chinese medicine mainly uses acupuncture for the treatment of CP; as the disease site is in the brain, emphasis is placed on scalp acupuncture therapy. There were studies about the treatment but different studies had very different results. In this study, we performed a systematic review and meta-analysis of the recent reports on scalp acupuncture in the treatment of CP in children, providing evidence for clinical diagnosis and treatment.

METHODS

The databases of PubMed, Chinese Biomedical Literature (CBM), China National Knowledge Infrastructure (CNKI), and VIP were searched for randomized controlled trials (RCTs) on scalp acupuncture treatment of pediatric CP published from January 2000 to December 2021. The inclusion criteria of studies were made according to the Participants, Intervention, Control, Outcomes, Study design (PICOS) principles. The Cochrane risk of bias 2.0 was used to evaluate the bias of the included literature. Meta-analysis was performed using the effective rate, Mental Development Index (MDI), Psychological Development Index (PDI), and Gross Motor Function Measure (GMFM-88 scale) as outcome indicators for the efficacy, and the safety of scalp acupuncture was assessed.

RESULTS

Initially, 332 articles were retrieved; after screening, 11 articles were included in the selection, including a total of 731 children, with 369 and 362 children for the experimental group and control group respectively. Meta-analysis showed that scalp acupuncture significantly improved the symptoms of children with CP [odds ratio (OR) =3.73, 95% confidence interval (CI): 2.49-5.58, Z=6.41, P<0.00001], could significantly improve their mental development [mean difference (MD) =15.58, 95% CI: 11.74-19.43, Z=7.95, P<0.00001] and psychological development (MD =13.23, 95% CI: 6.17-20.28, Z=3.67, P=0.0002) of children, and significantly improved the motor ability of CP children (MD =17.45, 95% CI: 8.19-26.72, Z=3.69, P=0.0002).

DISCUSSION

The curative effect of scalp acupuncture is better than that of conventional rehabilitation. Scalp-based acupuncture therapy can effectively improve the symptoms of pediatric CP, promote the mental and psychological development of children, and improve their gross motor function, the treatment is safe.

Muscle Contractures in Adults With Cerebral Palsy Characterized by Combined Ultrasound-Derived Echo Intensity and Handheld Dynamometry Measures

We used ultrasound-derived echo intensity and hand-held dynamometry to characterize plantar flexor muscle contractures in adults with cerebral palsy (CP). Eleven adults with CP (aged 41 ± 12 y, Gross Motor Function Classification System I-II) and 11 neurologically intact adults (aged 35 ± 10 y) participated in the study. Echo intensity was measured from the medial gastrocnemius muscle using brightness mode ultrasound. Hand-held dynamometry was used to quantify plantar flexor passive muscle stiffness and ankle joint passive range of motion (pROM). Echo intensity correlated with both passive muscle stiffness (r = 0.57, p = 0.006) and pROM (r = -0.56, p = 0.006). Ultrasound echo intensity (p = 0.02, standardized mean difference [SMD] = 1.13) and passive muscle stiffness (p < 0.001, SMD = 1.99) were higher and ankle joint pROM (p < 0.001, SMD = 2.69) was lower in adults with CP than in neurologically intact adults. We conclude that combined ultrasound-derived echo intensity and hand-held dynamometry may be used to provide an objective characterization of muscle contractures.

HACE1, GLRX5, and ELP2 gene variant cause spastic paraplegies

Hereditary spastic paraplegias (HSPs) are a clinically and genetically heterogeneous group of conditions that are characterized by lower limb spasticity and weakness. Considering the clinical overlap between metabolic causes, genetic diseases, and autosomal recessive HSP, differentiation between these types can be difficult based solely on their clinical characteristics. This study aimed to investigate the genetic etiology of patients with clinically suspected HSP. The study group was composed of seven Turkish families who each had two affected children and three families who each had a single affected child (17 total patients). The 17 probands (14 males, 3 females) underwent whole exome sequencing. Five typical HSP genes (FA2H, AP4M1, AP4E1, CYP7B1, and MAG) and three genes not previously related to HSP (HACE1, GLRX5, ad ELP2) were identified in 14 probands. Eight novel variants were identified in seven families: c.653 T > C (p.Leu218Pro) in the FA2H gene, c.347G > A (p.Gly116Asp) in the GLRX5 gene, c.2581G > C (p.Ala861Pro) in the HACE1 gene, c.1580G > A (p.Arg527Gln) and c.1189-1G > A in the ELP2 gene, c.10C > T (p.Gln4*) and c.1025 + 1G > A in the AP4M1 gene, c.1291delG (p.Gly431Alafs*3) and c.3250delA (p.Ile1084*) in the AP4E1 gene, and c.475 T > G (p.Cys159Gly) in the MAG gene. The growing use of next-generation sequencing improved diagnosis but also led to the continual identification of new causal genes for neurogenetic diseases associated with lower limb spasticity. The increasing number of HSP genes identified thus far highlights the extreme genetic heterogeneity of these disorders and their clinical and functional overlap with other neurological conditions. Our findings suggest that the HACE1, GLRX5, and ELP2 genes are genetic causes of HSP.

Number of synergies impacts sensitivity of gait to weakness and contracture

Muscle activity during gait can be described by a small set of synergies, weighted groups of muscles, that are theorized to reflect underlying neural control. For people with neurologic injuries, like cerebral palsy or stroke, even fewer synergies are required to explain muscle activity during gait. This reduction in synergies is thought to reflect altered control and is associated with impairment severity and treatment outcomes. Individuals with neurologic injuries also develop secondary musculoskeletal impairments, like weakness or contracture, that can impact gait. Yet, the combined impacts of altered control and musculoskeletal impairments on gait remains unclear. In this study, we use a two-dimensional musculoskeletal model constrained to synergy control to simulate unimpaired gait. We vary the number of synergies, while simulating muscle weakness and contracture to examine how altered control impacts sensitivity to musculoskeletal impairment while tracking unimpaired gait. Results demonstrate that reducing the number of synergies increases sensitivity to weakness and contracture for specific muscle groups. For example, simulations using five-synergy control tolerated 40% and 51% more knee extensor weakness than those using four- or three-synergy control, respectively. Furthermore, when constrained to four- or three-synergy control, the model was increasingly sensitive to contracture and weakness of proximal muscles, such as the hamstring and hip flexors. Contrastingly, neither the amount of generalized nor plantarflexor weakness tolerated was affected by the number of synergies. These findings highlight the interactions between altered control and musculoskeletal impairments, emphasizing the importance of measuring and incorporating both in future simulation and experimental studies.

Reduced Cross-Sectional Muscle Growth Six Months after Botulinum Toxin Type-A Injection in Children with Spastic Cerebral Palsy

Botulinum Neurotoxin type-A (BoNT-A) injections are widely used as first-line spasticity treatment in spastic cerebral palsy (SCP). Despite improved clinical outcomes, concerns regarding harmful effects on muscle morphology have been raised. Yet, the risk of initiating BoNT-A to reduce muscle growth remains unclear. This study investigated medial gastrocnemius (MG) morphological muscle growth in children with SCP (n = 26, median age of 5.2 years (3.5)), assessed by 3D-freehand ultrasound prior to and six months post-BoNT-A injections. Post-BoNT-A MG muscle growth of BoNT-A naive children (n = 11) was compared to (a) muscle growth of children who remained BoNT-A naive after six months (n = 11) and (b) post-BoNT-A follow-up data of children with a history of BoNT-A treatment (n = 15). Six months after initiating BoNT-A injection, 17% decrease in mid-belly cross-sectional area normalized to skeletal growth and 5% increase in echo-intensity were illustrated. These muscle outcomes were only significantly altered when compared with children who remained BoNT-A naive (+4% and -3%, respectively, p < 0.01). Muscle length growth persevered over time. This study showed reduced cross-sectional growth post-BoNT-A treatment suggesting that re-injections should be postponed at least beyond six months. Future research should extend follow-up periods investigating muscle recovery in the long-term and should include microscopic analysis.

The diagnostic levels of evidence of instrumented devices for measuring viscoelastic joint properties and spasticity; a systematic review

BACKGROUND

Many diagnostic robotic devices have been developed to quantify viscoelastic properties and spasticity of patients with upper motor neuron lesions. However, in clinical practice, subjective and nonvalid clinical scales are still commonly used. To understand the limited use of diagnostic robotic devices assessing viscoelastic joint properties and spasticity in clinical practice, we evaluate the diagnostic level of evidence of studies on these devices.

METHOD

A systematic literature review was performed using multiple databases. Two of the authors independently screened all articles. Studies investigating human subjects diagnosed with stroke or cerebral palsy, measured with a mechanical device to assess viscoelastic joint properties and/or spasticity of an extremity. All articles were assigned a diagnostic level of evidence, which was established with a classification strategy based on the number of participants and the design of the study, from a Level 0 (less than 10 subjects) to a Level IV, reporting the long-term clinical consequences in daily care.

RESULTS

Fifty-nine articles were included. Most studies measured the upper limb (64%) in stroke patients (81%). The highest level of evidence found was Level IIa (53%); these studies correlated the test values of the robotic device with a clinical test or within subgroups. Level 0 (30%) and Level I (17%; determining the range of values of the robotic test) were also common. None of the studies tested their device for diagnostic accuracy (Level III), clinical added value (Level IV).

CONCLUSION

The diagnostic evidence needed for implementing robotic devices in clinical practice is lacking. Our findings indicate that more effort should be invested in studying diagnostic accuracy (Level III) or added value for clinical care (Level IV); only these studies can provide clinicians with evidence that robotic devices have added value above the currently-used clinical scales.

To What Degree Does Limb Spasticity Affect Motor Performance in Para-Footballers With Cerebral Palsy?

Spasticity is considered a contributor to hypertonia, frequently presented in people with cerebral palsy (CP), affecting muscle function and motor activities. In CP football, the classification system determines that this impairment is eligible for competitive para-sports due to the impact on activity limitation and sports performance. However, the relationship between this feature (i.e., spastic hypertonia) and performance determinants has not been explored yet. This study aimed to assess the association of clinical spasticity measurements with the performance of sport-specific tests used for classification purposes. Sixty-nine international footballers with CP voluntarily participated in this study. The Australian Spasticity Assessment Scale was used to measure spasticity in lower limbs muscle groups and activity limitation tests were conducted considering dynamic balance, coordination, vertical and horizontal jumps, acceleration, and change of direction ability. Low-to-moderate negative significant associations were found between the hip spasticity and measures of dynamic balance and dominant unipedal horizontal jump capacity. Additionally, moderate associations were reported between the knee spasticity and the non-dominant unipedal horizontal jump capacity and the change of direction actions with the ball. The ankle spasticity score reported small to moderate associations with the change of direction assessment without the ball and bipedal and dominant unipedal horizontal jump capability. Finally, the total spasticity score only presented a significant association with horizontal jump performance. This is a novel study that provides evidence of the associations between an eligible neural impairment and relevant specific measures of activity limitation tests. These results suggest that the amount of spasticity according to each evaluated joint muscle group of the lower limbs presents a low-to-moderate significant relationship with determined measures of dynamic balance, coordination, horizontal jump, acceleration, and change of direction ability with and without the ball in international-level CP footballers. Further studies are necessary to elucidate the real contribution of neural and non-neural impairments related to hypertonia on fundamental sport-specific motor skills of para-footballers with CP.

Neuromuscular electrical stimulation for motor recovery in pediatric neurological conditions: a scoping review

AIM

To explore the breadth of pediatric neurological conditions for which neuromuscular electrical stimulation (NMES) has been studied.

METHOD

Databases (PubMed, Google Scholar, Scopus, and Embase) were searched from 2000 to 2020, using the search terms 'neuromuscular electrical stimulation' OR 'functional electrical stimulation' with at least one of the words 'pediatric OR child OR children OR adolescent', and without the words 'dysphagia OR implanted OR enuresis OR constipation'. Articles focused on adults or individuals with cerebral palsy (CP) were excluded.

RESULTS

Thirty-five studies met the inclusion criteria, with a total of 353 pediatric participants (293 unique participants; mean age 7y 4mo, range 1wk-38y). NMES was applied in a range of pediatric conditions other than CP, including stroke, spinal cord injury, myelomeningocele, scoliosis, congenital clubfoot, obstetric brachial plexus injury, genetic neuromuscular diseases, and other neuromuscular conditions causing weakness.

INTERPRETATION

All 35 studies concluded that NMES was well-tolerated and most studies suggested that NMES could augment traditional therapy methods to improve strength. Outcome measurements were heterogeneous. Further research on NMES with larger, randomized studies will help clarify its potential to improve physiology and mobility in pediatric patients with neuromuscular conditions. What this paper adds Neuromuscular electrical stimulation (NMES) appears to be tolerated by pediatric patients. NMES shows potential for augmenting recovery in pediatric patients with a range of rehabilitation needs.

Transcriptional analysis of muscle tissue and isolated satellite cells in spastic cerebral palsy

AIM

To analyze transcriptomes from muscle tissue and cells to improve our understanding of differences in gene expression and molecular function in cerebral palsy (CP) muscle.

METHOD

In this case-control study, eight participants with CP (five males, three females; mean [SD] age 14y 2mo [1y 8mo]) and 11 comparison individuals (eight males, three females; mean [SD] age 14y 0mo [2y 6mo]) were enrolled after informed consent/assent and skeletal muscle was obtained during surgery. RNA was extracted from tissue and from primary satellite cells grown to form myotubes in vitro. RNA sequencing data were analyzed using validated informatics pipelines.

RESULTS

Analysis identified expression of 6308 genes in the tissue samples and 7459 in the cultured cells. Significant differential expression between CP and control was identified in 87 genes in the tissue and 90 genes in isolated satellite cell-derived myotube cultures.

INTERPRETATION

Both tissue and cell analyses identified differential expression of genes associated with muscle development and multiple pathways of interest. What this paper adds Expression differences were found in muscle tissue and in isolated muscle cells. There was low variability in expression among cells isolated from different muscles. Expression differences suggest complex functional alterations in spastic cerebral palsy.

Stretch-induced satellite cell deformation incontracturedmuscles in children with cerebral palsy

Satellite cells (SCs) are quiescent, adult skeletal muscle stem cells responsible for postnatal muscle growth and repair. Children with cerebral palsy (CP) have muscle contractures with reduced SC abundance, extracellular matrix abnormalities and reduced serial sarcomere number resulting in greatly increased in vivo sarcomere length, perhaps due to impaired sarcomere addition, compared to children with typical development (TD). Stretch is a strong activator of SCs that leads to addition of sarcomeres during bone-muscle growth. Mechanical loading and subsequent deformation of intracellular structures can lead to activation and proliferation, perhaps by cytoskeletal transmissions of extracellular mechanical signals to the nuclei. The primary aim of this study was to determine the effect of ex vivo stretch-induced sarcomere length change on SC deformation in children with CP and TD. Muscle biopsies were obtained from twelve children (7 CP, 5 TD) during surgery. Fiber bundles were labeled with fluorescent antibodies for Pax7 (SC), DRAQ5 (nuclei), and alpha-actinin (sarcomere protein). Fibers were stretched using a custom jig and imaged using confocal microscopy. SC nuclear length, height and aspect ratio underwent increased deformation with increasing sarcomere length (p < 0.05) in both groups. Slopes of association for SC nuclear length, aspect ratio and sarcomere lengths were similar between CP and TD. Our results indicate that SC in children with CP undergo similar deformation as TD across sarcomere lengths.

Serial sarcomere number is substantially decreased within the paretic biceps brachii in individuals with chronic hemiparetic stroke

A muscle's structure, or architecture, is indicative of its function and is plastic; changes in input to or use of the muscle alter its architecture. Stroke-induced neural deficits substantially alter both input to and usage of individual muscles. We combined in vivo imaging methods (second-harmonic generation microendoscopy, extended field-of-view ultrasound, and fat-suppression MRI) to quantify functionally meaningful architecture parameters in the biceps brachii of both limbs of individuals with chronic hemiparetic stroke and in age-matched, unimpaired controls. Specifically, serial sarcomere number (SSN) and physiological cross-sectional area (PCSA) were calculated from data collected at three anatomical scales: sarcomere length, fascicle length, and muscle volume. The interlimb differences in SSN and PCSA were significantly larger for stroke participants than for participants without stroke (P = 0.0126 and P = 0.0042, respectively), suggesting we observed muscle adaptations associated with stroke rather than natural interlimb variability. The paretic biceps brachii had ∼8,200 fewer serial sarcomeres and ∼2 cm² smaller PCSA on average than the contralateral limb (both P < 0.0001). This was manifested by substantially smaller muscle volumes (112 versus 163 cm³), significantly shorter fascicles (11.0 versus 14.0 cm; P < 0.0001), and comparable sarcomere lengths (3.55 versus 3.59 μm; P = 0.6151) between limbs. Most notably, this study provides direct evidence of the loss of serial sarcomeres in human muscle observed in a population with neural impairments that lead to disuse and chronically place the affected muscle at a shortened position. This adaptation is consistent with functional consequences (increased passive resistance to elbow extension) that would amplify already problematic, neurally driven motor impairments.

Contribution of extracellular matrix components to the stiffness of skeletal muscle contractures in patients with cerebral palsy

Purpose: Joint contractures in children with cerebral palsy contain muscle tissue that is mechanically stiffer with higher collagen content than typically developing children. Interestingly, the correlation between collagen content and stiffness is weak. To date, no data are available on collagen types or other extracellular matrix proteins in these muscles, nor any information regarding their function. Thus, our purpose was to measure specific extracellular protein composition in cerebral palsy and typically developing human muscles along with structural aspects of extracellular matrix architecture to determine the extent to which these explain mechanical properties. Materials and Methods: Biopsies were collected from children with cerebral palsy undergoing muscle lengthening procedures and typically developing children undergoing anterior cruciate ligament reconstruction. Tissue was prepared for the determination of collagen types I, III, IV, and VI, proteoglycan, biglycan, decorin, hyaluronic acid/uronic acid and collagen crosslinking. Results: All collagen types increased in cerebral palsy along with pyridinoline crosslinks, total proteoglycan, and uronic acid. In all cases, type I or total collagen and total proteoglycan were positive predictors, while biglycan was a negative predictor of stiffness. Together these parameters accounted for a greater degree of variance within groups than across groups, demonstrating an altered relationship between extracellular matrix and stiffness with cerebral palsy. Further, stereological analysis revealed a significant increase in collagen fibrils organized in cables and an increased volume fraction of fibroblasts in CP muscle. Conclusions: These data demonstrate a novel adaptation of muscle extracellular matrix in children with cerebral palsy that includes alterations in extracellular matrix protein composition and structure related to mechanical function.

Using Decision Trees to Support Classifiers' Decision-Making about Activity Limitation of Cerebral Palsy Footballers

This study aimed (1) to determine the appropriateness of using decision trees as a classification tool for determining the allocation of sport classes of para-footballers with "moderate vs. mild" cerebral palsy (CP) profiles of spastic diplegia/hemiplegia and ataxia/athetosis based on observational outcomes by international classifiers, and (2) to identify what key observational features were relevant to discriminating among different impairment levels. A sample of 16 experienced international classifiers from five world regions participated in this study, observing activity limitation of a final sample of 21 international CP footballers when performing 16 gross-motor and sports-specific tests for balance (n = 3), coordination (n = 5), running, accelerations and decelerations (n = 3), jumping (n = 4), and change of direction ability (n = 1). For the overall sample (336 observations), the model included eight decision nodes and 24 branches with 17 leaves, including side-step, side-stepping, and triple hop as the tests with the best sensitivity (precision = 67.0%). For those with spastic diplegia (64 observations: Two nodes, six branches with five leaves), the range of motion in the side-step test and the balance in the tandem walk tests correctly classified 89.1% of the observations. In those with athetosis and ataxia (96 observations), the model included five nodes, 15 branches, and 11 leaves (176 observations, precision = 86.5%). For those with spastic hemiplegia, a model containing two nodes, six branches, and five leaves had 90.9% accuracy, including observational features of balance in the side-step test and symmetry in the side-stepping test. The observational tool used in this study, based on the impact of specific impairment measurements of hypertonia, athetosis, and ataxia, can be used to determine which assessments are more appropriate for discriminating between functional profiles in para-footballers with CP.

The Prognosis of Arthrofibroses: Prevalence, Clinical Shortcomings, and Future Prospects

Fibrosis is the dysregulated biosynthesis of connective tissue that results from persistent infection, high serum cholesterol, surgery, trauma, or prolonged joint immobilization. As a disease that impacts connective tissue, it is prevalent across the body and disrupts normal extracellular and tissue organization. Ultimately, fibrosis impairs the tissue structural, mechanical, or biochemical function. This review describes the clinical landscape of joint fibrosis, that is, arthrofibrosis, including the risk factors and causes, as well as current clinical treatments and their shortcomings. Because treating arthrofibrosis remains an unmet clinical challenge, we present several animal models used for exploration of the physiopathology of arthrofibrosis and summarize their use for testing novel treatments. We then discuss therapeutics for the prevention or treatment of arthrofibrosis that are in preclinical development and in ongoing clinical trials. We conclude with recent findings from molecular biological studies of arthrofibroses that shed insight on future areas of research for improved treatments.

Combination of Quantitative MRI Fat Fraction and Texture Analysis to Evaluate Spastic Muscles of Children With Cerebral Palsy

Background: Cerebral palsy (CP) is the most common cause of physical disability in childhood. Muscle pathologies occur due to spasticity and contractures; therefore, diagnostic imaging to detect pathologies is often required. Imaging has been used to assess torsion or estimate muscle volume, but additional methods for characterizing muscle composition have not thoroughly been investigated. MRI fat fraction (FF) measurement can quantify muscle fat and is often a part of standard imaging in neuromuscular dystrophies. To date, FF has been used to quantify muscle fat and assess function in CP. In this study, we aimed to utilize a radiomics and FF analysis along with the combination of both methods to differentiate affected muscles from healthy ones.

Materials and Methods: A total of 9 patients (age range 8–15 years) with CP and 12 healthy controls (age range 9–16 years) were prospectively enrolled (2018–2020) after ethics committee approval. Multi-echo Dixon acquisition of the calf muscles was used for FF calculation. The images of the second echo (TE = 2.87 ms) were used for feature extraction from the soleus, gastrocnemius medialis, and gastrocnemius lateralis muscles. The least absolute shrinkage and selection operator (LASSO) regression was employed for feature selection. RM, FF model (FFM), and combined model (CM) were built for each calf muscle. The receiver operating characteristic (ROC) curve and their respective area under the curve (AUC) values were used to evaluate model performance.

Results: In total, the affected legs of 9 CP patients and the dominant legs of 12 healthy controls were analyzed. The performance of RM for soleus, gastrocnemius medialis, and gastrocnemius lateralis (AUC 0.92, 0.92, 0.82, respectively) was better than the FFM (AUC 0.88, 0.85, 0.69, respectively). The combination of both models always had a better performance than RM or FFM (AUC 0.95, 0.93, 0.83). FF was higher in the patient group (FF_S 9.1%, FF_GM 8.5%, and FF_GL 10.2%) than control group (FF_S 3.3%, FF_GM 4.1%, FF_GL 6.6%).

Conclusion: The combination of MRI quantitative fat fraction analysis and texture analysis of muscles is a promising tool to evaluate muscle pathologies due to CP in a non-invasive manner.

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.

Serum trace element and amino acid profile in children with cerebral palsy

BACKGROUND

The existing data demonstrate that both trace elements and amino acids play a significant role in neurodevelopment and brain functioning. Certain studies have demonstrated alteration of micronutrient status in children with cerebral palsy, although multiple inconsistencies exist.

THE OBJECTIVE

of the present study was to assess serum trace element and mineral, as well as amino acid levels in children with cerebral palsy.

METHODS

71 children with cerebral palsy (39 boys and 32 girls, 5.7 ± 2.3 y.o.) and 84 healthy children (51 boys and 33 girls, 5.4 ± 2.3 y.o.) were enrolled in the present study. Serum trace element and mineral levels were assessed using inductively-coupled plasma mass-spectrometry (ICP-MS). Amino acid profile was evaluated by means of high-pressure liquid chromatography (HPLC).

RESULTS

Children with cerebral palsy are characterized by significantly lower Cu and Zn levels by 6% and 8%, whereas serum I concentration exceeded the control values by 7%. A tendency to increased serum Mn and Se levels was also observed in patients with cerebral palsy. Serum citrulline, leucine, tyrosine, and valine levels were 15 %, 23 %, 15 %, and 11 % lower than those in healthy controls. Nearly twofold lower levels of serum proline were accompanied by a 44 % elevation of hydroxyproline concentrations when compared to the control values. In multiple regression model serum I, Zn, and hydroxyproline levels were found to be independently associated with the presence of cerebral palsy. Correlation analysis demonstrated a significant correlation between Cu, Mn, Se, I, and Zn levels with hydroxyproline and citrulline concentrations.

CONCLUSION

The observed alterations in trace element and amino acid metabolism may contribute to neurological deterioration in cerebral palsy. However, the cross-sectional design of the study does not allow to estimate the causal trilateral relationships between cerebral palsy, altered trace element, and amino acid metabolism.

Passive stiffness of fibrotic skeletal muscle in mdx mice relates to collagen architecture

KEY POINTS

The amount of fibrotic material in dystrophic mouse muscles relates to contractile function, but not passive function. Collagen fibres in skeletal muscle are associated with increased passive muscle stiffness in fibrotic muscles. The alignment of collagen is independently associated with passive stiffness in dystrophic skeletal muscles. These outcomes demonstrate that collagen architecture rather than collagen content should be a target of anti-fibrotic therapies to treat muscle stiffness.

ABSTRACT

Fibrosis is prominent in many skeletal muscle pathologies including dystrophies, neurological disorders, cachexia, chronic kidney disease, sarcopenia and metabolic disorders. Fibrosis in muscle is associated with decreased contractile forces and increased passive stiffness that limits joint mobility leading to contractures. However, the assumption that more fibrotic material is directly related to decreased function has not held true. Here we utilize novel measurement of extracellular matrix (ECM) and collagen architecture to relate ECM form to muscle function. We used mdx mice, a model for Duchenne muscular dystrophy that becomes fibrotic, and wildtype mice. In this model, extensor digitorum longus (EDL) muscle was significantly stiffer, but with similar total collagen, while the soleus muscle did not change stiffness, but increased collagen. The stiffness of the EDL was associated with increased collagen crosslinking as determined by collagen solubility. Measurement of ECM alignment using polarized light microscopy showed a robust relationship between stiffness and alignment for wildtype muscle that broke down in mdx muscles. Direct visualization of large collagen fibres with second harmonic generation imaging revealed their relative abundance in stiff muscles. Collagen fibre alignment was linked to stiffness across all muscles investigated and the most significant factor in a multiple linear regression-based model of muscle stiffness from ECM parameters. This work establishes novel characteristics of skeletal muscle ECM architecture and provides evidence for a mechanical function of collagen fibres in muscle. This finding suggests that anti-fibrotic strategies to enhance muscle function and excessive stiffness should target large collagen fibres and their alignment rather than total collagen.

Gene expressions in cerebral palsy subjects reveal structural and functional changes in the gastrocnemius muscle that are closely associated with passive muscle stiffness

Cerebral palsy (CP) is a non-progressive motor disorder that affects posture and gait due to contracture development. The purpose of this study is to analyze a possible relation between muscle stiffness and gene expression levels in muscle tissue of children with CP. Next-generation sequencing (NGS) of gene transcripts was carried out in muscle biopsies from gastrocnemius muscle (n = 13 children with CP and n = 13 typical developed (TD) children). Passive stiffness of the ankle plantarflexors was measured. Structural changes of the basement membranes and the sarcomere length were measured. Twelve pre-defined gene target sub-categories of muscle function, structure and metabolism showed significant differences between muscle tissue of CP and TD children. Passive stiffness was significantly correlated to gene expression levels of HSPG2 (p = 0.02; R² = 0.67), PRELP (p = 0.002; R² = 0.84), RYR3 (p = 0.04; R² = 0.66), C COL5A3 (p = 0.0007; R² = 0.88), ASPH (p = 0.002; R² = 0.82) and COL4A6 (p = 0.03; R² = 0.97). Morphological differences in the basement membrane were observed between children with CP and TD children. The sarcomere length was significantly increased in children with CP when compared with TD (p = 0.04). These findings show that gene targets in the categories: calcium handling, basement membrane and collagens, were significantly correlated to passive muscle stiffness. A Reactome pathway analysis showed that pathways involved in DNA repair, ECM proteoglycans and ion homeostasis were amongst the most upregulated pathways in CP, while pathways involved in collagen fibril crosslinking, collagen fibril assembly and collagen turnover were amongst the most downregulated pathways when compared with TD children. These results underline that contracture formation and motor impairment in CP is an interplay between multiple factors.