Etiology of impaired selective motor control: emerging evidence and its implications for research and treatment in cerebral palsy

Selective voluntary motor control influences knee joint torque, work and power in children with spastic cerebral palsy

BACKGROUND

Children with spastic cerebral palsy (CP) have damage to the corticospinal tracts that are responsible for selective motor control (SMC). Force, velocity and timing of joint movement are related biomechanical features controlled by the corticospinal tracts (CSTs) that are important for skilled movement.

RESEARCH QUESTION

Does SMC influence knee joint biomechanics in spastic CP?

METHODS

In this prospective study, relationships between SMC and knee biomechanics (peak torque, total work, average power) across a range of velocities (0-300 deg/s) were assessed using an isokinetic dynamometer in 23 children with spastic CP. SMC was assessed using Selective Control Assessment of the Lower Extremity (SCALE). Logistic and linear regression models were used to evaluate relationships between SCALE and biomechanical measures.

RESULTS

The ability to produce knee torque diminished with increasing velocity for both Low (0-4 points) and High (5-10 points) SCALE limb score groups (p < 0.01). More knees in the High group produced extension torque at 300 deg/s (p < 0.05) and flexion torque at 30, 90,180, 240 and 300 deg/s (p < 0.05). The ability to produce torque markedly decreased above 180 deg/s for Low group flexion. For knees that produced torque, significant positive correlations between SCALE limb scores and joint torque (0 and 120 deg/s), work (120 deg/s) and power (120 deg/s) were found (p < 0.05). Greater knee torque, work and power for the High group was found for the extensors at most velocities and the flexors for up to 120 deg/s (p < 0.05). Few Low group participants generated knee flexor torque above 120 deg/s limiting comparisons.

SIGNIFICANCE

Biomechanical impairments found for children with low SMC are concerning as skilled movements during gait, play and sport activities occur at high velocities. Differences in SMC should be considered when designing individualized assessments and interventions.

A new methodological approach to characterize selective motor control in children with cerebral palsy

Introduction

Despite being a primary impairment in individuals with cerebral palsy (CP), selective motor control (SMC) is not routinely measured. Personalized treatment approaches in CP will be unattainable without the ability to precisely characterize the types and degrees of impairments in motor control. The objective of this study is to report the development and feasibility of a new methodological approach measuring muscle activation patterns during single-joint tasks to characterize obligatory muscle co-activation patterns that may underly impaired SMC.

Methods

Muscle activation patterns were recorded during sub-maximal voluntary isometric contraction (sub-MVIC) tasks at the hip, knee, and ankle with an interactive feedback game to standardize effort across participants. We calculated indices of co-activation, synergistic movement, mirror movement, and overflow (indices range 0-2, greater scores equal to greater impairment in SMC) for each isolated joint task in 15 children - 8 with typical development (TD) (mean age 4.7 ± 1.0 SD years) and 7 with CP (mean age 5.8 ± 0.7 SD years). Indices were compared with Mann-Whitney tests. The relationships between the indices and gross motor function (GMFM-66) were examined with Pearson's r.

Results

Mean indices were higher in the CP vs. the TD group for each of the six tasks, with mean differences ranging from 0.05 (abduction and plantarflexion) to 0.44 (dorsiflexion). There was great inter-subject variability in the CP group such that significant group differences were detected for knee flexion mirroring (p = 0.029), dorsiflexion coactivation (p = 0.021), and dorsiflexion overflow (p = 0.014). Significant negative linear relations to gross motor function were found in all four indices for knee extension (r = -0.56 to -0.75), three of the indices for ankle dorsiflexion (r = -0.68 to -0.78) and in two of the indices for knee flexion (r = -0.66 to -0.67), and ankle plantarflexion (r = -0.53 to -0.60).

Discussion

Indices of coactivation, mirror movement, synergy, and overflow during single-joint lower limb tasks may quantify the type and degree of impairment in SMC. Preliminary concurrent validity between several of the indices of SMC and gross motor function was observed. Our findings established the feasibility of a new methodological approach that quantifies muscle activation patterns using electromyography paired with biofeedback during single-joint movement.

Effects of structured training on spinal posture and selective motor control in children with unilateral spastic cerebral palsy

BACKGROUND

Children with Unilateral Spastic Cerebral Palsy (USCP) have an asymmetrical postural pattern. Although functional limitations are less, deteriorations in spinal posture are observed.

RESEARCH QUESTION

What is the effect of structured training on spinal posture and selective motor control of upper extremity?

METHODS

Forty five children with USCP were included in the study. Participants were children ages 3-18 with GMFCS levels 1 and 2. Spinal posture and mobility was assessed by Spinal Mouse (SM) and the Spinal Alignment and Range of Motion Measure (SAROMM), and selective motor control of upper extremity was evaluated by the Selective Control of the Upper Extremity Scale (SCUES). Children were divided into two groups: structured training group (STG) (n = 22) and conventional physiotherapy group (CPG) (n = 23). Groups received treatment sessions lasting 45 min, 2 days a week for 8 weeks. Evaluations were made baseline and after treatment.

RESULTS

In sagittal plane, there was a significant decrease in the degree of thoracic kyphosis after treatment in the STG (p = 0.004). A significant difference was found in total spine angulation (p = 0.015) and mobility from flexion to extension in the STG group. There was a difference in total spine angulation (p = 0.014) in the CPG group, but no difference in spinal mobility. Post-training differences were found in thoracic angulation (p = 0.006) and lateral flexion mobility to the affected side in the STG in thoracic (p = 0.020), lumbar (p = 0.035) and total spine (p = 0.008) in the frontal plane. When SCUES-shoulder, elbow, wrist, total scores changes was significant in CPG (p < 0.001), SCUES-forearm (p = 0.002) and fingers (p = 0.007) changes was significant in STG.

SIGNIFICANCE

This study showed that although children with USCP are more mildly affected, there are adverse effects on their selective motor control and spinal posture. This study reveals the contribution of structured training in terms of selective movement, spinal smoothness and mobility in children.

Children with bilateral cerebral palsy use their hip joint to complete a step-up task

Performance in stair-climbing is largely associated with disruptions to mobility and community participation in children with cerebral palsy (CP). It is important to understand the nature of motor impairments responsible for making stairs a challenge in children with bilateral CP to clarify underlying causes of impaired mobility. In pediatric clinical populations, sensitive measurements of movement quality can be captured during the initial step of stair ascent. Thus, the purpose of this study was to quantify the lower limb joint moments of children with bilateral CP during the stance phases of a step-up task. Participants performed multiple stepping trials in a university gait laboratory. Outcome measures included extensor support moments (the sum of hip, knee, and ankle sagittal plane moments), hip abduction moments, and their timing. We recruited seven participants per group. We found that peak support and hip abduction moments were similar in the bilateral CP group compared to the typical development (TD) group. We also found that children with bilateral CP timed their peak moments closer together and increasingly depended on the hip joint to complete the task, especially in their more affected (MA) lower limb. Our investigation highlights some underlying causes that may make stair climbing a challenge for the CP population, including a loss of selective voluntary motor control (SVMC), and provides a possible treatment approach to strengthen lower limb muscles.

Validity and reliability of selective control of upper extremity scale (SCUES) in patients with chronic stroke

PURPOSE

The aim of this study is to investigate the validity and reliability of the Selective Control of Upper Extremity Scale (SCUES) in patients with stroke.

MATERIALS AND METHODS

Forty-two patients with stroke aged 18-75 years, were included in the study. Patients were video-recorded while SCUES was administered. The videos were scored to determine the intrarater and inter-rater reliability. Fugl Meyer Assessment of Upper Extremity (FMA-UE), Box and Block test (BBT) and Brunnstrom Stages of Motor Recovery were measured to evaluate validity of SCUES. Spearman correlation analysis was used to assess the validity of SCUES. Intraclass correlation coefficient (ICC), Kappa (κ) and weighted Kappa (κw) were calculated to determine intrarater and inter-rater reliability.

RESULTS

There were significant positive high correlations between SCUES and FMA-UE and BBT and Brunnstrom upper extremity proximal and distal values (rho = 0.944, p = 0.01; rho = 0,875, p = 0.01; rho = 0.84, p = 0.01, rho = 0.82, p = 0.01; respectively) showing validity of SCUES. The ICC value of inter-rater reliability of SCUES was 0,99 (%95 CI: 0,989-0,997, p = 0,001) showing excellent reliability. κ and κ w values for inter-rater and intrarater reliability of individual SCUES items were above 0.7 indicating excellent reliability. ICC of SCUES and FMA-UE indicated excellent intrarater reliability (ICC = 0,99; %95 CI: 0,989-0,997, p = 0,001; ICC = 0.943; %95 CI: 0.9-0.97, p = 0,0001, consecutively).

CONCLUSIONS

SCUES showed similar validity and reliability with FMA-UE and SCUES can be used in the evaluation of upper extremity selective motor control in patients with stroke.

Stroke in the Developing Brain: Neurophysiologic Implications of Stroke Timing, Location, and Comorbid Factors

BACKGROUND

Pediatric stroke, which is unique in that it represents a static insult to a developing brain, often leads to long-term neurological disability. Neuroplasticity in infants and children influences neurophysiologic recovery patterns after stroke; therefore outcomes depend on several factors including the timing and location of stroke and the presence of comorbid conditions.

METHODS

In this review, we discuss the unique implications of stroke occurring in the fetal, perinatal, and childhood/adolescent time periods. First, we highlight the impact of the developmental stage of the brain at the time of insult on the motor, sensory, cognitive, speech, and behavioral domains. Next, we consider the influence of location of stroke on the presence and severity of motor and nonmotor outcomes. Finally, we discuss the impact of associated conditions on long-term outcomes and risk for stroke recurrence.

RESULTS

Hemiparesis is common after stroke at any age, although the severity of impairment differs by age group. Risk of epilepsy is elevated in all age groups compared with those without stroke. Outcomes in other domains vary by age, although several studies suggest worse cognitive outcomes when stroke occurs in early childhood compared with fetal and later childhood epochs. Conditions such as congenital heart disease, sickle cell disease, and moyamoya increase the risk of stroke and leave patients differentially vulnerable to neurodevelopmental delay, stroke recurrence, silent infarcts, and cognitive impairment.

CONCLUSIONS

A comprehensive understanding of the interplay of various factors is essential in guiding the clinical care of patients with pediatric stroke.

Biological and environmental factors may affect children's executive function through motor and sensorimotor development: Preterm birth and cerebral palsy

Disruptive biological and environmental factors may undermine the development of children's motor and sensorimotor skills. Since the development of cognitive skills, including executive function, is grounded in early motor and sensorimotor experiences, early delays or impairments in motor and sensorimotor processing often trigger dynamic developmental cascades that lead to suboptimal executive function outcomes. The purpose of this perspective paper is to link early differences in motor/sensorimotor processing to the development of executive function in children born preterm or with cerebral palsy. Uncovering such links in clinical populations would improve our understanding of developmental pathways and key motor and sensorimotor skills that are antecedent and foundational for the development of executive function. This knowledge will allow the refinement of early interventions targeting motor and sensorimotor skills with the goal of proactively improving executive function outcomes in at-risk populations.

Reliability and validity of assessing lower-limb muscle architecture of patients with cerebral palsy (CP) using ultrasound: A systematic review

AIMS

To investigate the reliability, validity, and level of evidence of applying ultrasound in assessing the lower-limb muscles of patients with cerebral palsy (CP).

METHOD

Publications in Medline, PubMed, Web of Science, and Embase were searched on May 10, 2023, to identify and examine relevant studies investigating the reliability/validity of ultrasound in evaluating the architecture of CP lower-limb muscles systematically, following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis 2020 guidelines.

RESULTS

Out of 897 records, 9 publications with 111 CP participants aged 3.8-17.0 years were included (8 focused on intra-rater and inter-rater reliability, 2 focused on validity, and 4 were with high quality). The ultrasound-based measurements of muscle thickness (intra-rater only), muscle length, cross-sectional area, muscle volume, fascicle length, and pennation angle showed high reliability, with the majority of intraclass correlation coefficient (ICC) values being larger than 0.9. Moderate-to-good correlations between ultrasound and magnetic resonance imaging measurements existed in muscle thickness and cross-sectional area (0.62 ≤ ICC ≤ 0.82).

INTERPRETATION

Generally, ultrasound has high reliability and validity in evaluating the CP muscle architecture, but this is mainly supported by moderate and limited levels of evidence. More high-quality future studies are needed.

Effectiveness of different extrinsic feedback forms on motor learning in children with cerebral palsy: a systematic review

PURPOSE

Motor learning interventions for children with cerebral palsy (CP) that elicit relatively permanent and transferable improvements in motor skill capability are essential. Knowledge is needed about the augmented feedback forms that most effectively promote this. This review aims to collect and analyze the current evidence for the effectiveness of different forms of feedback for motor learning in children with CP to improve motor task performance.

METHODS

PubMed, PsycInfo, and Cochrane Library were searched to identify relevant studies. Studies were included if (1) they were conducted in children with CP or compared children with CP to TD children and (2) a form of augmented feedback related to a motor task was administered.

RESULTS

Initially, 401 records were identified for screening. Ultimately, 12 articles were included in the review. The evidence thus far supports the expectancy that children with CP generally benefit from feedback provided during or after performing a movement task.

CONCLUSION

Due to the heterogeneity of existing studies, it is difficult to draw firm conclusions regarding relative effectiveness of feedback forms. This review showed that more high-quality research is warranted on the effectiveness of specific feedback forms on motor learning in children with CP.Implications for RehabilitationChildren with CP benefit from several forms of knowledge of performance or knowledge of results feedback provided during or after performing a movement task.Feedback should not be provided with every performed trial.Feedback frequency can best be reduced by letting children determine after which trials they want feedback.Learning curves under similar feedback conditions varied largely between children, warranting tailor-made forms of feedback to be applied during motor learning and rehabilitation.

Analysis of cerebral palsy gait based on movement primitives

BACKGROUND

Cerebral palsy is the most prevalent motor disorder among children. Despite extensive studies on motor modularity of gait of children with cerebral palsy, kinematic modularity of their gait has not been addressed which is the main goal of this study.

METHODS

The kinematics of the gait of 13 typical development children and 188 children with cerebral palsy was captured and analyzed, where the cerebral palsy children were grouped into True, Jump, Apparent, and Crouch. Non-negative matrix factorization method was used to extract the kinematic modulus of each group, which were then clustered to find their characteristic movement primitives. The movement primitives of groups were then matched based on the similarity of their activation profiles.

FINDINGS

The number of movement primitives was three for the Crouch group, four for the other cerebral palsy groups, and five for the typical development group. Compared to the typical development children, the kinematic modules and activations of the cerebral palsy groups involved higher variability and co-activation, respectively (P < 0.05). Three temporally matched movement primitives were shared by all groups, but with altered structures.

INTERPRETATION

The gait of children with cerebral palsy involved lower complexity and higher variability due to the reduced and inconsistent kinematic modularity. Three basic movement primitives were sufficient to prodcue the overall gait kinematics, as observed in the Crouch group. Other movement primitives, were responsible for providing smooth transitions between basic movement primitives, as seen in more complex gait patterns.

Research progress of neonatal hypoxic-ischemic encephalopathy in nonhuman primate models

Neonatal hypoxic-ischemic encephalopathy (HIE) is one of the important complications of neonatal asphyxia, which not only leads to neurological disability but also seriously threatens the life of neonates. Over the years, animal models of HIE have been a research hotspot to find ways to cope with HIE and thereby reduce the risk of neonatal death or disability in moderate-to-severe HIE. By reviewing the literature related to HIE over the years, it was found that nonhuman primates share a high degree of homology with human gross neural anatomy. The basic data on nonhuman primates are not yet complete, so it is urgent to mine and develop new nonhuman primate model data. In recent years, the research on nonhuman primate HIE models has been gradually enriched and the content is more novel. Therefore, the purpose of this review is to further summarize the methods for establishing the nonhuman primate HIE model and to better elucidate the relevance of the nonhuman primate model to humans by observing the behavioral manifestations, neuropathology, and a series of biomarkers of HIE in primates HIE. Finally, the most popular and desirable treatments studied in nonhuman primate models in the past 5 years are summarized.

Correlation between Selective Motor Control of the Lower Extremities and Balance in Spastic Hemiplegic Cerebral Palsy: a randomized controlled trial

BACKGROUND

Children with cerebral palsy (CP) have motor deficits caused by spasticity, weakness, contractures, diminished selective motor control (SMC), and poor balance. The purpose of the current study was to evaluate the influence of mirror feedback on lower extremity selective motor control and balance in children with hemiplegic cerebral palsy. Understanding the relationship between SMC and balance will help children with hemiplegic CP receive more appropriate therapies.

METHODS

Forty-seven children of both sexes diagnosed with hemiplegic CP participated in the study. Group1 (Gr1 - control group) received conventional physical therapy training while group 2 (Gr2 - intervention group) received conventional physical therapy training in addition to bilateral lower extremity mirror therapy (MT). The primary outcome measure used was Selective Control Assessment of Lower Extremity scale (SCALE), while the secondary outcome measure was the Pediatric Balance Scale (PBS).

RESULTS

There were significant differences in Selective Control Assessment of Lower Extremity Scale (SCALE) and Pediatric Balance Scale (PBS) between both groups in favor of Gr2. After treatment, both groups improved significantly, yet Gr2 outperformed Gr1 by a large margin.

CONCLUSION

Mirror therapy may be a useful addition to home-based motor interventions for children with hemiplegic CP due to its relative simplicity, low cost, and high patient adherence. Additionally, it may help children improve their selective motor skills and balance.

TRIAL REGISTRATION

Current Controlled Trials using African Clinical Trials Registry website with ID number PACTR202105604636415 retrospectively registered on 21/01/202.

Selective motor control correlates with gross motor ability, functional balance and gait performance in ambulant children with bilateral spastic cerebral palsy

BACKGROUND

Selective motor control (SMC) is a fundamental component of typical human motion. As a result of brain damage, impaired SMC often leads to difficulties with coordination, balance, gait efficiency and symmetry.

RESEARCH QUESTION

What is the association between impaired SMC and lower limb motor ability, functional balance and gait performance in children with bilateral spastic cerebral palsy (CP)?

METHODS

Thirty-six children (aged 5-16 years) with spastic bilateral CP in Gross Motor Function Classification System (GMFCS) level I to II were included in this study. SMC was assessed using Selective Control Assessment of the Lower Extremity (SCALE). Gross motor function was assessed using Gross Motor Function Measure-88 items D and E dimension (GMFM-88 D&E). Functional balance was assessed using Pediatric Balance Scale (PBS) and Timed Up and Go Test (TUG). Gait quality was assessed using Edinburg Visual Gait Score (EVGS) and 10-Meter Walk Test (10MWT). Spearman's rank correlation analyses were used to determine the association between SMC and other factors.

RESULTS

Correlation analyses showed that SCALE was strongly positively correlated with GMFM-88 (D&E) (rs=0.756, p < 0.001), PBS (rs=0.769, p < 0.001), and height-normalized fast walking speed (rs=0.632, p < 0.001), and strongly negatively correlated with TUG (rs=-0.766, p < 0.001) and EVGS (rs=-0.893, p < 0.001).

SIGNIFICANCE

Lower extremity SMC deficits are associated with poor gross motor function and balance control, more severe overall gait deviations and decreased fast walking speed in children with bilateral spastic CP. Physical therapy should include interventions that promote selective motor control in order to improve overall functional ability.

Reliability and validity of the Turkish version of the Selective Control Assessment of the Lower Extremity (SCALE) in children with spastic cerebral palsy

PURPOSE

This study aims to translate the Selective Control Assessment of the Lower Extremity (SCALE) into Turkish language, assess its reliability and validity in children with spastic cerebral palsy.

MATERIALS AND METHODS

Fifty-two children with CP (mean age 9 years 8 months, range 4-18 years) included in this cross-sectional study. Intra- and interrater reliability was assessed by intraclass correlation coefficient (ICC). The SCALE was correlated with the Gross Motor Function Classification System (GMFCS), the Physician's Rating Scale (PRS), and Gross Motor Function Measurement (GMFM) to assess validity.

RESULTS

Intra- and interrater reliability of the SCALE were excellent (ICC > 0.75). SCALE and GMFCS (r = -0.786, p < 0.001), SCALE and PRS (r = 0.761, p < 0.001), SCALE and GMFM (r = 0.863, p < 0.001) were highly correlated. SCALE scores differed significantly between GMFCS levels and between types of spastic CP.

CONCLUSIONS

The Turkish version of the SCALE appears to be a valid and reliable tool to assess selective voluntary motor control of the lower limbs in children with spastic CP.IMPLICATIONS FOR REHABILITATIONThe Turkish version of the Selective Control Assessment of the Lower Extremity is a valid and reliable assessment for children with spastic CP.The SCALE scores differed significantly between Gross Motor Function Classification System levels I versus II and levels II versus III as well as between types of spastic CP.The current study suggests that the SCALE is a quick and easy outcome measure to assess selective motor control in patients with spastic CP.

Playfully Assessing Lower Extremity Selective Voluntary Motor Control in Children With Cerebral Palsy: Psychometric Study

BACKGROUND

Objective measures specifically assessing selective voluntary motor control are scarce. Therefore, we have developed an interval-scaled assessment based on accelerometers.

OBJECTIVE

This study provided a preliminary evaluation of the validity and reliability of this novel gamelike assessment measuring lower limb selective voluntary motor control in children with cerebral palsy (CP).

METHODS

Children with CP and their neurologically intact peers were recruited for this psychometric evaluation of the assessgame. The participants played the assessgame and steered an avatar by selective hip, knee, or ankle joint movements captured with accelerometers. The assessgame's scores provide information about the accuracy of the selective movement of the target joint and the amplitude and frequency of involuntary movements occurring in uninvolved joints. We established discriminative validity by comparing the assessgame scores of the children with CP with those of the neurologically intact children, concurrent validity by correlations with clinical scores and therapists' opinions, and relative and absolute test-retest reliability.

RESULTS

We included 20 children with CP (mean age 12 years and 5 months, SD 3 years and 4 months; Gross Motor Function Classification System levels I to IV) and 31 neurologically intact children (mean age 11 years and 1 month, SD 3 years and 6 months). The assessgame could distinguish between the children with CP and neurologically intact children. The correlations between the assessgame's involuntary movement score and the therapist's rating of the occurrence of involuntary movements during the game were moderate (Spearman ρ=0.56; P=.01), whereas the correlations of the assessgame outcomes with the Selective Control Assessment of the Lower Extremity and Gross Motor Function Classification System were low and not significant (|ρ|≤0.39). The intraclass correlation coefficients were >0.85 and indicated good relative test-retest reliability. Minimal detectable changes amounted to 25% (accuracy) and 44% (involuntary movement score) of the mean total scores. The percentage of children able to improve by the minimal detectable change without reaching the maximum score was 100% (17/17) for the accuracy score and 94% (16/17) for the involuntary movement score.

CONCLUSIONS

The assessgame proved reliable and showed discriminative validity in this preliminary evaluation. Concurrent validity was moderate with the therapist's opinion but relatively poor with the Selective Control Assessment of the Lower Extremity. We assume that the assessment's gamelike character demanded various other motor control aspects that are less considered in current clinical assessments.

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.

Muscle synergy structure and gait patterns in children with spastic cerebral palsy

AIM

To determine if muscle synergy structure (activations and weights) differs between gait patterns in children with spastic cerebral palsy (CP).

METHOD

In this cross-sectional study, we classified 188 children with unilateral (n=82) or bilateral (n=106) spastic CP (mean age: 9y 5mo, SD: 4y 3mo, range: 3y 9mo-17y 7mo; 75 females; Gross Motor Function Classification System [GMFCS] level I: 106, GMFCS level II: 55, GMFCS level III: 27) into a minor deviations (n=34), drop foot (n=16), genu recurvatum (n=26), apparent equinus (n=53), crouch (n=39), and jump gait pattern (n=20). Surface electromyography recordings from eight lower limb muscles of the most affected side were used to calculate synergies with weighted non-negative matrix factorization. We compared synergy activations and weights between the patterns.

RESULTS

Synergy structure was similar between gait patterns, although weights differed in the more impaired children (crouch and jump gait) when compared to the other patterns. Variability in synergy structure between participants was high.

INTERPRETATION

The similarity in synergy structure between gait patterns suggests a generic motor control strategy to compensate for the brain lesion. However, the differences in weights and high variability between participants indicate that this generic motor control strategy might be individualized and dependent on impairment level.

Validity and reliability of an electromyography-based similarity index to quantify lower extremity selective voluntary motor control in children with cerebral palsy

•

The SI_SCALE is a new electromyography-based measure to quantify selective voluntary motor control.

•

There is a need for precise, interval-scaled measures of selective voluntary motor control in children with cerebral palsy.

•

Concurrent and discriminative validity of the new measure was affirmed and test–retest reliability was acceptable.

Objective

To quantify selective voluntary motor control (SVMC) objectively and more precisely, we combined the “Selective Control Assessment of the Lower Extremity” (SCALE) with surface electromyography. The resulting Similarity Index (SI) measures the similarity of muscle activation patterns. This study evaluated the preliminary validity and reliability of this novel SI_SCALE measure in children with cerebral palsy (CP).

Methods

We investigated concurrent validity by correlating the SI_SCALE of 24 children with CP (median age 10.6 years) with comparator assessments. For discriminative validity, the patients’ SI_SCALE scores were compared to 31 neurologically intact age-matched peers. Test-retest reliability was quantified using intraclass correlation coefficients (ICC) and minimal detectable change (MDC) values.

Results

The SI_SCALE correlated strongly with the SCALE (ρ = 0.90, p < .001) and the Gross Motor Function Classification System (ρ = −0.74, p < .001). SI_SCALE scores were significantly lower in children with CP compared to healthy peers. Test-retest reliability appeared good (for the more and less affected leg, ICC ≥ 0.84, and MDC ≤ 0.17).

Conclusions

Validity and reliability of the SI_SCALE leg and total scores lay within clinically acceptable ranges. Further clinimetric analyses should include responsiveness.

Significance

A neurophysiology-based assessment could contribute to a more refined assessment of SVMC impairments.

From Hemispheric Asymmetry through Sensorimotor Experiences to Cognitive Outcomes in Children with Cerebral Palsy

Recent neuroimaging studies allowed us to explore abnormal brain structures and interhemispheric connectivity in children with cerebral palsy (CP). Behavioral researchers have long reported that children with CP exhibit suboptimal performance in different cognitive domains (e.g., receptive and expressive language skills, reading, mental imagery, spatial processing, subitizing, math, and executive functions). However, there has been very limited cross-domain research involving these two areas of scientific inquiry. To stimulate such research, this perspective paper proposes some possible neurological mechanisms involved in the cognitive delays and impairments in children with CP. Additionally, the paper examines the ways motor and sensorimotor experience during the development of these neural substrates could enable more optimal development for children with CP. Understanding these developmental mechanisms could guide more effective interventions to promote the development of both sensorimotor and cognitive skills in children with CP.

Effect of extracorporeal shock wave therapy on spastic equinus foot in children with unilateral cerebral palsy

Objectives

This study aims to investigate the effects of radial extracorporeal shock wave therapy on selective motor control, spasticity, gross motor function, and balance in children with unilateral cerebral palsy.

Methods

This randomised controlled study recruited 34 children aged 7–9 with spastic unilateral cerebral palsy. They were randomly allocated to either the control or study group. Both groups undertook traditional exercises for 12 weeks. The study group received shock waves (one session/week) on the calf muscle (1500 shocks, frequency of 4 Hz, energy of 0.030 mJ/mm²). All children were evaluated at baseline and after 12 weeks using the Modified Ashworth Scale, a Biodex System 4 isokinetic dynamometer, dimensions D (standing) and E (walking) of the Gross Motor Function Measure – 88, the Trost Selective Motor Control test, and the single leg standing test.

Results

Mixed analysis of variance and Mann–Whitney results showed significant improvement in eccentric peak torque, torque threshold angles, gross motor function, selective motor control, and balance in the study group compared with the control group (p < 0.05).

Conclusions

Shock wave therapy may be a valuable instrument for reducing spasticity, improving the ability to isolate and control movement, and consequently, improving balance and gross motor function in children with unilateral cerebral palsy.

Motivating Selective Motor Control of Infants at High Risk of Cerebral Palsy Using an In-Home Kicking-Activated Mobile Task: A Pilot Study

OBJECTIVE

Decreased selective motor control limits gait function of children with spastic cerebral palsy (CP). Infants at high risk of CP demonstrate decreased selective motor control by 1 month of age. To motivate more selective hip-knee control, infants at high risk of CP participated in an in-home kicking-activated mobile task. The purpose of this study was to determine whether infants at high risk of CP and infants with typical development (TD) demonstrated increased selective hip-knee control during 2-minute intervals of the mobile task when they demonstrated learning of the association between their leg movement and mobile activation vs during 2-minute intervals when they did not demonstrate learning.

METHODS

Participants in this cohort study included 10 infants at high risk of CP based on neuroimaging and 11 infants with TD at 3.5 to 4.5 months of age. Each infant participated in the in-home kicking-activated mobile task for 8 to 10 min/d, 5 d/wk, for 6 weeks. Over 80,000 kicks were extracted and classified for each infant as occurring during 2-minute intervals of the task when the infant demonstrated learning vs not learning based on mobile activation time above baseline.

RESULTS

Infants demonstrated kicks with more selective hip-knee control during 2-minute intervals of the mobile task when they demonstrated learning compared with when they did not demonstrate learning for 4 of 6 weeks in the cohort at high risk of CP and for 2 of 6 weeks in the cohort with TD.

CONCLUSION

Participation in the in-home kicking-activated mobile task may motivate more selective hip-knee control of infants at high risk of CP.

IMPACT

This study is a first step toward developing an intervention to promote selective hip-knee control of infants at high risk of CP, with the ultimate goal of optimizing future walking function.

LAY SUMMARY

This study showed that playing with an in-home infant kicking-activated mobile may motivate infants at high risk of CP to produce more age-appropriate leg movements.

Relationship between ankle function and walking ability for children and young adults with cerebral palsy: A systematic review of deficits and targeted interventions

BACKGROUND

A primary goal of treatment for children with cerebral palsy is improved walking ability to allow for a more active and independent lifestyle. With the importance of ankle function to walking ability, and the deficits in ankle function associated with cerebral palsy, there is good rationale for targeting this joint in an effort to improve walking ability for this population.

RESEARCH QUESTION

How do deficits and targeted interventions of the ankle joint influence walking ability in children with cerebral palsy?

METHODS

A specific search criteria was used to identify articles that either (1) provided information on the relationship between ankle function and walking ability or (2) investigated the effect of a targeted ankle intervention on walking ability in cerebral palsy. PubMed, Embase, CINAHL, and Web of Science databases were searched from 1980-April, 2020. Resulting citations were compared against a prospective set of inclusion and exclusion criteria. Data relevant to the original research question was extracted, and the level of evidence for each intervention study was scored. Interpretation was focused on specific, pre-determined mobility measures.

RESULTS

Sixty-one citations met all criteria for data extraction, six of which were observational, and fifty-five of which were interventional. Level of evidence ranged from 2 to 4. Self-selected walking speed was the most common measure of walking ability, while physical activity level was the least common.

SIGNIFICANCE

Ankle function is an important contributor to the walking ability of children with cerebral palsy, and most interventions targeting the ankle seem to demonstrate a benefit on walking ability, but future higher-powered and/or controlled studies are necessary to confirm these findings.

Variability in lower extremity motor function in spina bifida only partially associated with spinal motor level

PURPOSE

Previous studies have found motor function to correlate with spinal motor level and, accordingly, individuals with spina bifida are frequently categorized clinically in this manner. The aim of the current study was to describe how lower extremity functions including strength, selective motor control, and mirror movements vary by motor level in children and young adults with spina bifida.

METHODS

A single center, retrospective, cross-sectional, descriptive study using data collected in the National Spina Bifida Patient Registry and by a gait laboratory was performed.

RESULTS

Seventy-seven individuals with spina bifida were included with the majority having myelomeningocele (59 lumbar, 18 sacral motor level). Lower extremity strength and selective motor control varied to a certain extent with motor level. However, 90% of individuals showed strength or weakness in at least one muscle group that was unexpected based on their motor level. Mirror movements did not clearly vary with motor level.

CONCLUSION

Lower extremity strength, selective motor control, and mirror movements in individuals with spina bifida were not entirely predicted by motor level. This highlights the possible need for an improved spina bifida classification system that describes not only spinal motor level but more clearly defines a particular individual's functional motor abilities.

Reliability and Validity of the Turkish Version of the Selective Control of the Upper Extremity Scale in Children with Cerebral Palsy

AIMS

To investigate the psychometric properties of the Selective Control of the Upper Extremity Scale (SCUES).

METHODS

Fifty-two children (27 females and 25 males; mean age 9.8 ± 4.4 years) with spastic type of cerebral palsy (CP) participated in the study. Psychometric analyses included reliability, concurrent validity, construct validity, and discriminant validity. Upper Limb Physician's Rating Scale (ULPRS), Modified Ashworth Scale (MAS), Quality of Upper Extremity Skills Test (QUEST) were used for concurrent validity. Manual Ability Classification System (MACS) was used for construct validity. Differences in SCUES scores were determined between participants categorized according to their limb distribution and MACS levels.

RESULTS

Intra-rater reliability (intraclass correlation coefficient [ICC] = 0.98) of the SCUES was excellent. SCUES and ULPRS (r = 0.87, p < 0.001), SCUES and MAS (r=-0.93, p < 0.001), SCUES and QUEST (r=0.81, p < 0.001) were highly correlated. SCUES and MACS (r=-0.67, p < 0.001) was moderately correlated. SCUES scores differed significantly between children classifed as MACS levels I versus II and III and between children with hemiparetic and diparetic CP.

CONCLUSION

The SCUES appears to be a valid and reliable tool to assess selective voluntary motor control of the upper extremities in children with spastic CP, which may be useful in selecting and planning interventions.

Game-based training of selective voluntary motor control in children and youth with upper motor neuron lesions: protocol for a multiple baseline design study

Background

Impairments of selective control of joint movements can have consequences for many activities of daily life, but there are only a few interventions to improve selective voluntary motor control (SVMC). We have developed a treatment option to specifically enhance SVMC exploiting the advantages of interactive computer play technology. It targets SVMC by training selective activation of a muscle or a selective joint movement while it provides immediate feedback about involuntary muscle activations/movements at an (unwanted) joint. This study aims to investigate the effectiveness of this game-based intervention to enhance SVMC in children and youth with upper motor neuron lesions.

Methods

We will conduct a randomized, non-concurrent, multiple baseline design study. Patients aged between 6 and 20 years with reduced SVMC due to an upper motor neuron lesion will be included. During the baseline phase of random length, participants will attend their regular intensive rehabilitation program, and in the intervention phase, they will additionally complete 10 therapy sessions (à 40 min) of the game-based SVMC training. The primary outcome will be a short SVMC assessment conducted repeatedly throughout both phases, which quantifies movement accuracy and involuntary movements. Changes in clinical SVMC measures, muscle strength, cortical excitability, motor control of the inhibited/unwanted movement, and functional independence will be assessed as secondary outcomes. We will use a mixed-effect model to determine the change in the course of the primary outcome when the intervention is introduced, and we will compare changes between phases for secondary outcomes with paired tests.

Discussion

This study will provide first evidence whether SVMC can be improved with our game-based training. The single-case design takes into account the individualization required for this intervention, and it can help to address the challenges of intervention trials in our setting.

Trial registration

German Clinical Trials Register: DRKS00025184, registered on 28.04.2021.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-021-02983-8.

Determining the relationship between the impairment of selective voluntary motor control and gait deviations in children with cerebral palsy using simple video-based analyses

BACKGROUND

The impairment of selective voluntary motor control (SVMC) in children with cerebral palsy (CP) has been shown to correlate with their gait characteristics using complex 3D gait analysis systems (3DGA); however, this relationship has not been investigated using simple video-based observational gait analysis (VBOGA). The aim of this study was to determine the relationship between VBOGA and SVMC of the lower extremities in children with CP.

METHODS

Forty-two CP children 10.9 ± 5.7 years old with Gross Motor Function Classification System (GMFCS) levels I-III participated in the study. Their gait characteristics were assessed using the Edinburgh Visual Gait Score (EVGS), and selective voluntary motor control was tested using the Selective Control Assessment of the Lower Extremity (SCALE). Spearman's rho correlation test with Cohen's classification were used in the statistical analyses.

RESULTS

The GMFCS levels (r = 0.604, p < 0.001), foot clearance (r = -0.584. p < 0.001), and maximum ankle dorsiflexion (r =-0.567, p < 0.001) during the swing phase had strong correlations with total SCALE scores. There was also a moderate correlation between total SCALE scores and total EVGS (r =-0.494, p < 0.001), knee extension in the terminal swing phase (r = -0.353, p < 0.001), peak sagittal trunk position (r = -0.316, p < 0.005), and maximum lateral shift (r = -0.37, p < 0.001).

CONCLUSION

Impaired lower extremity SVMC was noticeably related to the foot and ankle movements in the swing phase and initial stance during walking as well as the total EVGS scores and sagittal and frontal trunk movements. The SCALE correlations with VBOGA were similar those observed in the complex 3DGA in the literature; therefore, we suggest that SVMC impairment of gait could be evaluated using simple VBOGA. These findings may help to tailor physical therapy programs for CP children to increase their motor control and walking quality.

Recording activity in proximal muscle networks with surface EMG in assessing infant motor development

OBJECTIVE

To develop methods for recording and analysing infant's proximal muscle activations.

METHODS

Surface electromyography (sEMG) of truncal muscles was recorded in three months old infants (N = 18) during spontaneous movement and controlled postural changes. The infants were also divided into two groups according to motor performance. We developed an efficient method for removing dynamic cardiac artefacts to allow i) accurate estimation of individual muscle activations, as well as ii) quantitative characterization of muscle networks.

RESULTS

The automated removal of cardiac artefacts allowed quantitation of truncal muscle activity, which showed predictable effects during postural changes, and there were differences between high and low performing infants.The muscle networks showed consistent change in network density during spontaneous movements between supine and prone position. Moreover, activity correlations in individual pairs of back muscles linked to infant́s motor performance.

CONCLUSIONS

The hereby developed sEMG analysis methodology is feasible and may disclose differences between high and low performing infants. Analysis of the muscle networks may provide novel insight to central control of motility.

SIGNIFICANCE

Quantitative analysis of infant's muscle activity and muscle networks holds promise for an objective neurodevelopmental assessment of motor system.

Correlation between the Korean Version of the Trunk Control Measurement Scale and the Selective Control Assessment of the Lower Extremity Scores in Children with Cerebral Palsy

Background and Objectives: The purpose of this study was to investigate the correlation between the Korean version of the trunk control measurement scale (K-TCMS) and the selective control assessment of the lower extremity (SCALE). Through this, we tried to find out the effect of proximal stabilization on distal motor development. Materials and Methods: Fifty-one children with gross motor function classification system level I–III, diagnosed with cerebral palsy (CP), were studied. The K-TCMS was used to evaluate the body control ability of the children. SCALE was used to quantify selective voluntary motor control (SVMC). Results: Analysis of SCALE and K-TCMS showed a significant positive correlation in all items. Multiple regression analysis showed that the SCALE score decreased as age increased, and that it increased as the static sitting balance ability score and the dynamic sitting balance ability score of the K-TCMS increased significantly (p < 0.05). Conclusions: In children with cerebral palsy, there was a close correlation between trunk control and selective voluntary motor control of the lower extremities. Therefore, when trying to improve the lower extremity function of a child with cerebral palsy, a trunk control intervention should be considered.

Clinical Characteristics Associated with Reduced Selective Voluntary Motor Control in the Upper Extremity of Individuals with Spastic Cerebral Palsy

BACKGROUND

Selective voluntary motor control (SVMC) in the upper extremity is often impaired in individuals with cerebral palsy (CP) and can be assessed quantitatively and qualitatively using the Test of Arm Selective Control (TASC).

METHODS

Fifty-six individuals with spastic CP (5-18 years old) were included. Descriptors associated with administration of the TASC were analyzed according to the type of CP and arm joint using Chi-square and Kruskal-Wallis tests. ABILHAND-Kids scores were compared between participants with and without mirror movements using a t-test.

RESULTS

All groups of children with spastic CP had incidence of TASC movement descriptors. There was a main effect of topography of CP on extra movements, decreased active range of motion, tightness, spasticity, and mirroring, and an additional main effect of joint on mirroring. Participants with mirroring had lower ABILHAND-Kids scores than those without mirroring.

CONCLUSIONS

Systematically observing arm movements using the TASC revealed differences across participants.

Neuromuscular Control before and after Independent Walking Onset in Children with Cerebral Palsy

Early brain lesions which produce cerebral palsy (CP) may affect the development of walking. It is unclear whether or how neuromuscular control, as evaluated by muscle synergy analysis, differs in young children with CP compared to typically developing (TD) children with the same walking ability, before and after the onset of independent walking. Here we grouped twenty children with (high risk of) CP and twenty TD children (age 6.5–52.4 months) based on their walking ability, supported or independent walking. Muscle synergies were extracted from electromyography data of bilateral leg muscles using non-negative matrix factorization. Number, synergies’ structure and variability accounted for when extracting one (VAF₁) or two (VAF₂) synergies were compared between CP and TD. Children in the CP group recruited fewer synergies with higher VAF₁ and VAF₂ compared to TD children in the supported and independent walking group. The most affected side in children with asymmetric CP walking independently recruited fewer synergies with higher VAF₁ compared to the least affected side. Our findings suggest that early brain lesions result in early alterations of neuromuscular control, specific for the most affected side in asymmetric CP.

Quantifying age-related differences in selective voluntary motor control in children and adolescents with three assessments

BACKGROUND

Neurophysiological development of selective voluntary motor control (SVMC) is assumed but has not been quantified objectively. We assessed SVMC with (i) clinical assessments, (ii) a combination of these assessments with surface electromyography (sEMG) and, (iii) a playful computer game. The aim of this study was to describe and compare age-related differences in SVMC, quantified with these tools, in neurologically intact children, adolescents, and adults.

METHODS

We measured upper and lower extremity SVMC with three assessments in 31 children and adolescents. A sample of 33 and 31 adults provided reference values for the upper and lower extremity assessments, respectively. The Selective Control of the Upper Extremity Scale (SCUES) or the Selective Control Assessment of the Lower Extremity (SCALE) were combined with simultaneous sEMG recordings. We quantified SVMC by a similarity index that compared an individual's muscle activation pattern with those of an adult reference group. The SVMC Assessgame required isolated joint movements to steer an avatar and quantified the accuracy of the selective movement and the extent of involuntary movements occurring in not involved joints.

RESULTS

Results from the conventional clinical assessments correlated low to moderately with age (SCUES: r = 0.55, p = 0.013; SCALE: r = 0.44, p = 0.001), while the correlation between the sEMG based similarity index and age was negligible (r ≤ 0.25). The outcomes of the Assessgame correlated highly with age (r ≥ 0.80, p ≤ 0.001). Older children and adolescents performed movements more accurately and with fewer involuntary movements compared to younger participants.

CONCLUSIONS

The tools assess and quantify SVMC differently, affecting the way they capture age-related differences in SVMC. Some assessments require reference values from neurologically intact children and adolescents to correctly classify impairments of SVMC in patients with neuromotor disorders.

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.

A Systematic Review of Training Methods That May Improve Selective Voluntary Motor Control in Children With Spastic Cerebral Palsy

Background: Impaired selective voluntary motor control is defined as “the reduced ability to isolate the activation of muscles in response to demands of a voluntary posture or movement.” It is a negative motor sign of an upper motor neuron lesion.

Objective: This paper reviews interventions that may improve selective motor control in children and youths with spastic cerebral palsy. The aim was to systematically evaluate the methodological quality and formulate the level of evidence from controlled studies.

Methods: Six databases (Scopus, Web of Science, PubMed, Embase, MEDLINE, and CINAHL) were searched with predefined search terms for population, interventions, and outcomes. Two reviewers independently completed study selection and ratings of methodological quality and risk of bias. Evidence was summarized in a best evidence synthesis.

Results: Twenty-three studies from initially 2,634 papers were included. The interventions showed a wide variety of approaches, such as constraint-induced movement therapy (CIMT), electrical stimulation, robot-assisted therapy, and functional training. The evidence synthesis revealed conflicting evidence for CIMT, robot-assisted rehabilitation and mirror therapy for the upper extremities in children with cerebral palsy.

Conclusions: Final recommendations are difficult due to heterogeneity of the reviewed studies. Studies that include both an intervention and an outcome that specifically focus on selective voluntary motor control are needed to determine the most effective therapy.

The Upper Extremity Flexion Synergy Is Minimally Expressed in Young Individuals With Unilateral Cerebral Palsy Following an Early Brain Injury

Hemiparetic stroke in adulthood often results in the grouped movement pattern of the upper extremity flexion synergy thought to arise from an increased reliance on cortico-reticulospinal pathways due to a loss of lateral corticospinal projections. It is well established that the flexion synergy induces reaching constraints in individuals with adult-onset hemiplegia. The expression of the flexion synergy in individuals with brain injuries onset earlier in the lifespan is currently unknown. An early unilateral brain injury occurring prior to six months post full-term may preserve corticospinal projections which can be used for independent joint control and thus minimizing the expression of the flexion synergy. This study uses kinematics of a ballistic reaching task to evaluate the expression of the flexion synergy in individuals with pediatric hemiplegia (PH) ages six to seventeen years. Fifteen individuals with brain injuries before birth (n = 8) and around full-term (n = 7) and nine age-matched controls with no known neurological impairment completed a set of reaches in an admittance controlled robotic device. Descending drive, and the possible expression of the upper extremity flexion synergy, was modulated by increasing shoulder abduction loading. Individuals with early-onset PH achieved lower peak velocities when reaching with the paretic arm compared to controls; however, no differences in reaching distance were found between groups. Relative maintenance in reaching seen in individuals with early brain injuries highlights minimal expression of the flexion synergy. We interpret this conservation of independent control of the paretic shoulder and elbow as the use of more direct corticospinal projections instead of indirect cortico-reticulospinal pathways used in individuals with adult-onset hemiplegia.

Functional near-infrared spectroscopy to assess sensorimotor cortical activity during hand squeezing and ankle dorsiflexion in individuals with and without bilateral and unilateral cerebral palsy

Significance: Our study is the first comparison of brain activation patterns during motor tasks across unilateral cerebral palsy (UCP), bilateral cerebral palsy (BCP), and typical development (TD) to elucidate neural mechanisms and inform rehabilitation strategies. Aim: Cortical activation patterns were compared for distal upper and lower extremity tasks in UCP, BCP, and TD using functional near-infrared spectroscopy (fNIRS) and related to functional severity. Approach: Individuals with UCP ( n = 10 , 18.8 ± 6.8    years ), BCP ( n = 14 , 17.5 ± 9.6    years ), and TD ( n = 16 , 17.3 ± 9.1    years ) participated in this cross-sectional cohort study. The fNIRS was used to noninvasively monitor the hemodynamic response to task-related cortical activation. The block design involved repetitive nondominant hand squeezing and ankle dorsiflexion. Results: Individuals with UCP demonstrated the highest levels of activation for the squeeze task ( UCP > BCP q = 0.049 ; BCP > TD q < 0.001 ; and UCP > TD q = 0.001 ) and more activity in the ipsilateral versus contralateral hemisphere. Individuals with BCP showed the highest levels of cortical activation in the dorsiflexion task ( BCP > UCP q < 0.001 ; BCP > TD ). Conclusions: Grouping by CP subtype and manual function or mobility level demonstrated significant differences from TD, even for individuals with the mildest forms of CP. Hemispheric activation patterns showed hypothesized but nonsignificant trends.

Brain Metabolism During A Lower Extremity Voluntary Movement Task in Children With Spastic Cerebral Palsy

Reduced selective voluntary motor control (SVMC) is a primary impairment due to corticospinal tract (CST) injury in spastic cerebral palsy (CP). There are few studies of brain metabolism in CP and none have examined brain metabolism during a motor task. Nine children with bilateral spastic CP [Age: 6-11 years, Gross Motor Function Classification System (GMFCS) Levels II-V] completed this study. SVMC was evaluated using Selective Control Assessment of the Lower Extremity (SCALE) ranging from 0 (absent) to 10 (normal). Brain metabolism was measured using positron emission tomography (PET) scanning in association with a selective ankle motor task. Whole brain activation maps as well as ROI averaged metabolic activity were correlated with SCALE scores. The contralateral sensorimotor and superior parietal cortex were positively correlated with SCALE scores (p < 0.0005). In contrast, a negative correlation of metabolic activity with SCALE was found in the cerebellum (p < 0.0005). Subsequent ROI analysis showed that both ipsilateral and contralateral cerebellar metabolism correlated with SCALE but the relationship for the ipsilateral cerebellum was stronger (R ² = 0.80, p < 0.001 vs. R ² = 0.46, p = 0.045). Decreased cortical and increased cerebellar activation in children with less SVMC may be related to task difficulty, activation of new motor learning paradigms in the cerebellum and potential engagement of alternative motor systems when CSTs are focally damaged. These results support SCALE as a clinical correlate of neurological impairment.

Pyramidal tract and alternate motor fibers complementarily mediate motor compensation in patients after hemispherotomy

Motor function after hemispheric lesions has been associated with the structural integrity of either the pyramidal tract (PT) or alternate motor fibers (aMF). In this study, we aimed to differentially characterize the roles of PT and aMF in motor compensation by relating diffusion-tensor-imaging-derived parameters of white matter microstructure to measures of proximal and distal motor function in patients after hemispherotomy. Twenty-five patients (13 women; mean age: 21.1 years) after hemispherotomy (at mean age: 12.4 years) underwent Diffusion Tensor Imaging and evaluation of motor function using the Fugl-Meyer Assessment and the index finger tapping test. Regression analyses revealed that fractional anisotropy of the PT explained (p = 0.050) distal motor function including finger tapping rate (p = 0.027), whereas fractional anisotropy of aMF originating in the contralesional cortex and crossing to the ipsilesional hemisphere in the pons explained proximal motor function (p = 0.001). Age at surgery was found to be the only clinical variable to explain motor function (p < 0.001). Our results are indicative of complementary roles of the PT and of aMF in motor compensation of hemispherotomy mediating distal and proximal motor compensation of the upper limb, respectively.

Differential involvement of rubral branches in chronic capsular and pontine stroke

•

Rubral branches were differentially involved in chronic capsular and pontine stroke.

•

The impairment severity of each rubral branch was dependent on lesion locations.

•

The integrity of the rubral branches is related to the severity of motor impairment.

Background and Purpose

Early studies have indicated that the cortico-rubro-spinal tracts play important roles in motor dysfunction after stroke. However, the differential involvement of the rubral branches in capsular and pontine stroke, and their associations with the motor impairment are still unknown.

Methods

The present study recruited 144 chronic stroke patients and 91 normal controls (NC) from three hospitals, including 102 cases with capsular stroke (CS) and 42 cases with pontine stroke (PS). The rubral branches, including bilateral corticorubral tracts (CRT), dentatorubral tracts (DRT), and rubrospinal tracts (RST), and the cortico-spinal tract (CST) were reconstructed based on the dataset of the Human Connectome Project. Group differences in diffusion scalars of each rubral branch were compared, and the associations between the diffusion measures of rubral branches and the Fugl-Meyer assessment (FMA) scores were tested.

Results

The bilateral CRT of the CS cases showed significantly lower factional anisotropy (FA) than in the NC. The bilateral DRT of the PS cases had lower FA than in the NC. Both CS and PS cases had significantly lower FA of the bilateral RST than the NC. Besides, the stroke patients demonstrated significantly lower FA in bilateral CSTs than the NC. Partial correlation analysis identified significantly positive correlations between the FA of the ipsilesional and CRT and the FMA scores in the CS group, and significantly positive correlations between the FA of the RST bilaterally and the FMA scores in the CS and PS groups. Furthermore, the association between RST integrity and FMA scores still survived after controlling for the effect of the CST. Finally, multiple regression modelling found that rubral tract FA explained 39.2% of the variance in FMA scores for CS patients, and 48.8% of the variance in FMA scores for PS patients.

Conclusions

The bilateral rubral branches were differentially involved in the chronic capsular and pontine stroke, and the impairment severity of each rubral branch was dependent on lesion locations. The integrity of the rubral branches is related to motor impairment in both the chronic capsular and pontine stroke.

Gait synergetic neuromuscular control in children with cerebral palsy at different gross motor function classification system levels

Cerebral palsy (CP) is a neural developmental disease featured with gait abnormalities. CP gait assessment is usually performed with the Gross Motor Function Classification System (GMFCS) in clinics, which does not involve a thorough assessment of neuromuscular control. To understand how the neuromuscular control disorders lead to gait abnormalities, we explored the relationship between GMFCS levels and the gait synergetic control characteristics in this study. In total, 18 children with CP at different GMFCS levels (mean age: 4.41±1.30 yr) and 8 age-matched typically developing (TD) children (mean age: 4.43±1.36 yr) were recruited to perform a straight walking task, and the surface electromyographic (sEMG) signals from eight lower limb muscles on each side and accelerometer data were collected. A nonnegative matrix factorization method was applied to obtain the muscle synergies from the sEMG signals. Next, synergy structures were projected onto the basic gait synergies to test the completeness of those structures. Subsequently, synergy activation parameters, including total activation duration and coactivation index, were compared across the participants. This study showed that children with CP at GMFCS levels I and II and the TD children had similar synergy structures, but the synergy activations of these children with CP were different from those of TD children. In addition, similar to previous research, we also found that children with CP at GMFCS level III could not access all four basic synergies on both sides. Based on the synergy analysis results, a gait assessment paradigm was proposed to facilitate the clinical CP gait evaluation.

NEW & NOTEWORTHY Understanding the mechanism of gait abnormality has important clinical significance for the diagnosis, prognosis, and possible treatment of motor dysfunction in children with cerebral palsy (CP). In this study, the comparisons of the lower limb muscle synergies among different groups of children with CP at different Gross Motor Function Classification System levels might provide some new insight into the mechanism underlying the gait disorder. In particular, the discrepancies of gait synergy structure and activation patterns across the study groups may indicate different neurophysiological and pathological attributes in different groups of patients.

How does upper extremity Fugl-Meyer motor score relate to resting-state EEG in chronic stroke? A power spectral density analysis

OBJECTIVE

We investigated the potential added value of high-density resting-state EEG by addressing differences with healthy individuals and associations with Fugl-Meyer motor assessment of the upper extremity (FM-UE) scores in chronic stroke.

METHODS

Twenty-one chronic stroke survivors with initial upper limb paresis and eleven matched controls were included. Group differences regarding resting-state EEG parameters (Delta Alpha ratio (DAR) and pairwise-derived Brain Symmetry Index (BSI)) and associations with FM-UE were investigated, as well as lateralization of BSI and the value of different frequency bands.

RESULTS

Chronic stroke survivors showed higher BSI compared to controls (p < 0.001), most pronounced in delta and theta frequency bands (p < 0.0001; p < 0.001). In the delta and theta band, BSI was significantly negatively associated with FM-UE (both p = 0.008) corrected for confounding factors. DAR showed no differences between groups nor association with FM-UE. Directional BSI showed increased power in the affected versus the unaffected hemisphere.

CONCLUSIONS

Asymmetry in spectral power between hemispheres was present in chronic stroke, most pronounced in low frequencies and related to upper extremity motor function deficit.

SIGNIFICANCE

BSI is related to motor impairment and higher in chronic stroke patients compared to healthy controls, suggesting that BSI may be a marker of selective motor control.

Influence of impaired selective motor control on gait in children with cerebral palsy

PURPOSE

Spastic cerebral palsy (CP) is characterized by four neuromuscular deficits: weakness, short muscle-tendon unit, muscle spasticity and impaired selective motor control (SMC). We examined the influence of impaired SMC on gait in children with bilateral spastic CP. Delineating the influence of neuromuscular deficits on gait abnormalities can guide surgical and therapeutic interventions to reduce long-term debilitating effects of CP.

METHODS

The relationship between impaired SMC and gait was assessed using multivariate linear regression analysis of Selective Control Assessment of the Lower Extremity (SCALE) in relation to stance phase knee flexion and temporal-spatial gait parameters calculated using 3D kinematics for 57 children with bilateral spastic CP, ages seven to 11 years.

RESULTS

Mean SCALE values were 5.8 (0 to 10, sd 3.0) and 5.7 (0 to 10, sd 2.9) for right and left legs, respectively. Multivariate linear regression models, including right and left SCALE and height, significantly predicted right and left knee flexion at initial contact (R = 0.479, p = 0.003; R = 0.452, p = 0.007, respectively) and right and left knee flexion in midstance (R = 0.428, p = 0.013; R = 0.407, p = 0.022, respectively). The model significantly predicted right and left step length (R = 0.645, p = 0.000; R = 0.523, p = 0.001, respectively) and predicted gait velocity (R = 0.444, p = 0.008). The model including SCALE did not predict step width.

CONCLUSION

Results indicate impaired SMC predicts increased knee flexion at initial contact, and reduces step length and velocity. Understanding the influence of impaired SMC on gait can inform decisions regarding therapy and surgery, such as hamstring lengthening.

LEVEL OF EVIDENCE

Level II Retrospective Study.

Full Activation Profiles and Integrity of Corticospinal Pathways in Adults With Bilateral Spastic Cerebral Palsy

Background. Dysfunction of corticospinal pathways has been implicated in motor impairments in people with bilateral spastic cerebral palsy (CP). While structural damage to corticospinal pathways in people with CP is known, its impact on the activation of these pathways is not. Objective. To provide the first, complete activation profile of corticospinal pathways in adults with CP using a full range of transcranial magnetic stimulation (TMS) intensities and voluntary contractions. Methods. TMS targeted the soleus muscle of 16 adults with bilateral spastic CP and 15 neurologically intact (NI) control participants. Activation profiles were generated using motor-evoked potentials (MEPs) produced by varying both stimulation intensity and degree of voluntary muscle activity. Anatomical integrity of corticospinal pathways was also measured with diffusion tractography. Results. Participants with CP had smaller MEPs produced by TMS at 1.2× active motor threshold during submaximal (20%) muscle activity and smaller maximal MEPs produced under any combination of stimulation intensity and voluntary muscle activity. At a fixed stimulation intensity, increasing voluntary muscle activity facilitated MEP amplitudes to a lesser degree in the participants with CP. Consistent differences in diffusion tractography suggested structural abnormalities in the corticospinal pathways of participants with CP that correlated with maximal MEPs. Conclusion. People with bilateral spastic CP have impaired activation of low and high-threshold corticospinal pathways to soleus motoneurons by TMS and reduced facilitation by voluntary activity that may be associated with structural damage to these pathways. These impairments likely contribute to impaired voluntary movement.

Perinatal hypoxic-ischemic brain injury in large animal models: Relevance to human neonatal encephalopathy

Perinatal hypoxia-ischemia resulting in death or lifelong disabilities remains a major clinical disorder. Neonatal models of hypoxia-ischemia in rodents have enhanced our understanding of cellular mechanisms of neural injury in developing brain, but have limitations in simulating the range, accuracy, and physiology of clinical hypoxia-ischemia and the relevant systems neuropathology that contribute to the human brain injury pattern. Large animal models of perinatal hypoxia-ischemia, such as partial or complete asphyxia at the time of delivery of fetal monkeys, umbilical cord occlusion and cerebral hypoperfusion at different stages of gestation in fetal sheep, and severe hypoxia and hypoperfusion in newborn piglets, have largely overcome these limitations. In monkey, complete asphyxia produces preferential injury to cerebellum and primary sensory nuclei in brainstem and thalamus, whereas partial asphyxia produces preferential injury to somatosensory and motor cortex, basal ganglia, and thalamus. Mid-gestational fetal sheep provide a valuable model for studying vulnerability of progenitor oligodendrocytes. Hypoxia followed by asphyxia in newborn piglets replicates the systems injury seen in term newborns. Efficacy of post-insult hypothermia in animal models led to the success of clinical trials in term human neonates. Large animal models are now being used to explore adjunct therapy to augment hypothermic neuroprotection.

Inter-Limb Muscle Synergies and Kinematic Analysis of Hands-and-Knees Crawling in Typically Developing Infants and Infants With Developmental Delay

Hands-and-knees-crawling is an important motor developmental milestone and a unique window into the development of central nervous system (CNS). Mobility during crawling is regularly used in clinical assessments to identify delays in motor development. However, possible contribution from CNS impairments to motor development delay is still unknown. The aim of this study was to quantify and compare inter-limb muscle synergy and kinematics during crawling among infants at a similar developmental age, however, clinically determined to be typically developing (TD, N = 20) infants, infants at risk of developmental delay (ARDD, N = 33), or infants with confirmed developmental delay (CDD, N = 13). We hypothesized that even though all of the groups are at a similar developmental age, there would be differences in kinematic measures during crawling, and such differences would be associated with CNS impairment as measured by electromyography (EMG) features. Surface EMG of eight arm and leg muscles and the corresponding joint kinematic data were collected while participants crawled on hands and knees at their self-selected velocity. Temporal-spatial parameters and normalized Jerk-Cost (JC) function (i.e., smoothness of movement) were computed from the measured kinematics. The inter-limb muscle synergy and the number of co-activating muscles per synergy were measured using EMGs. We found that the infants with CDD demonstrated higher normalized JC values (less movement smoothness), fewer muscle synergies, and more co-activating muscles per synergy, compared to infants with TD (p < 0.05) and ARDD (p < 0.05). Furthermore, the normalized JC values were correlated (p < 0.05) with the number of co-activation muscles per synergy. Our results suggest a constrained neuromuscular control strategy due to neurological injury in infants with CDD, and such constrain may contribute to the reduced movement smoothness in infant crawling.

Associations Between Muscle Synergies and Treatment Outcomes in Cerebral Palsy Are Robust Across Clinical Centers

OBJECTIVE

To determine whether patient-specific differences in motor control quantified using muscle synergy analysis were associated with changes in gait after treatment of cerebral palsy (CP) across 2 clinical centers with different treatments and clinical protocols.

DESIGN

Retrospective cohort study.

SETTING

Clinical medical center.

PARTICIPANTS

Center 1: children with CP (n=473) and typically developing (TD) children (n=84). Center 2: children with CP (n=163) and TD children (n=12).

INTERVENTIONS

Standard clinical care at each center.

MAIN OUTCOME MEASURES

The Dynamic Motor Control Index During Walking (walk-DMC) was computed from electromyographic data during gait using muscle synergy analysis. Regression analysis was used to evaluate whether pretreatment walking speed or kinematics, muscle synergies, treatment group, prior treatment, or age were associated with posttreatment changes in gait at both clinical centers.

RESULTS

Walk-DMC was significantly associated with changes in speed and kinematics after treatment with similar regression models at both centers. Children with less impaired motor control were more likely to have improvements in walking speed and gait kinematics after treatment, independent of treatment group.

CONCLUSIONS

Dynamic motor control evaluated with synergy analysis was associated with changes in gait after treatment at both centers, despite differences in treatments and clinical protocols. This study further supports the finding that walk-DMC provides additional information, not captured in traditional gait analysis, that may be useful for treatment planning.

Relative phase measures of intersegmental coordination describe motor control impairments in children with cerebral palsy who exhibit stiff-knee gait

BACKGROUND

The purpose of this retrospective study was to explore lower limb intersegmental coordination as a clinically important indicator of motor control mechanisms in individuals with cerebral palsy exhibiting stiff-knee gait. We used the relative phase of thigh and foot segments around foot-off to describe motor control, given the relevance of the pre-swing phase of gait to the existence of stiff-knee gait.

METHODS

Traditional gait parameters and thigh/foot intersegmental coordination were calculated using pre-and postoperative kinematic data from a cohort of 54 subjects (92 legs) with spastic cerebral palsy. All participants had stiff-knee gait, walked without assistive devices, and underwent rectus femoris transfer surgery to improve swing period knee flexion. Analyses included correlations between a) preoperative intersegmental coordination and gait variables (knee flexion range, rate and gait performance) and b) pre-to-postoperative intersegmental coordination change and change in gait variables.

FINDINGS

Thigh/foot intersegmental coordination significantly (P < 0.001) correlated with knee flexion range, rate and walking speed. Postoperative intersegmental coordination was significantly more uncoupled than preoperative. Pre-to-postoperative intersegmental coordination improvement also significantly correlated with improvements in knee flexion range, rate and walking speed. Pre-to-postoperative changes in intersegmental coordination accounted for 43% and 36% of variance in knee flexion range change and knee flexion rate change respectively.

INTERPRETATION

Intersegmental coordination is a clinically important factor in knee flexion limitations associated with stiff-knee gait for individuals with cerebral palsy. These findings are a foundation for further study of intersegmental coordination measures as complements to traditional instrumented gait analysis.

Relationship between sensorimotor cortical activation as assessed by functional near infrared spectroscopy and lower extremity motor coordination in bilateral cerebral palsy

Background

Evaluation of task-evoked cortical responses during movement has been limited in individuals with bilateral cerebral palsy (CP), despite documented alterations in brain structure/function and deficits in motor control.

Objective

To systematically evaluate cortical activity associated with lower extremity tasks, and relate activation parameters to clinical measures in CP.

Methods

28 ambulatory participants (14 with bilateral CP and 14 with typical development) completed five motor tasks (non-dominant ankle dorsiflexion, hip flexion and leg cycling as well as bilateral dorsiflexion and cycling) in a block design while their sensorimotor cortex was monitored using functional near infrared spectroscopy (fNIRS), in addition to laboratory and clinical measures of performance.

Results

Main effects for group and task were found for extent of fNIRS activation (number of active channels; p < 0.001 and p = 0.010, respectively), magnitude of activation (sum of beta values; p < 0.001 for both), and number of active muscles (p = 0.001 and p < 0.001, respectively), but no group by task interactions. Collectively, subgroups with CP and especially those with greater impairments, showed higher extent and magnitude of cortical sensorimotor activation as well as higher amounts of concurrent activity in muscles not required for task performance. Magnitude of fNIRS activation during non-dominant dorsiflexion correlated with validated measures of selective control (r = −0.60, p = 0.03), as well as mobility and daily activity (r = −0.55, p = 0.04 and r = −0.52, p = 0.05, respectively) and self-reported gait function (r = −0.68, p = 0.01) in those with CP.

Conclusions

The association between higher activity in the sensorimotor cortex and decreased selectivity in cortical organization suggests a potential neural mechanism of motor deficits and target for intervention.

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First fNIRS comparison of a range of lower extremity tasks in children with and without bilateral CP.

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FNIRS showed a greater amount and extent of activation of sensorimotor cortices in CP.

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Greater activation correlated with a greater number of muscles involved in the task.

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fNIRS results correlated to clinical measures of motor control and function.