Do mirror movements relate to hand function and timing of the brain lesion in children with unilateral cerebral palsy?

Neuroanatomical correlates of gross manual dexterity in children with unilateral spastic cerebral palsy

Unilateral spastic Cerebral Palsy (UCP) results from congenital brain injury, and Magnetic Resonance Imaging (MRI) has a role in understanding the etiology and severity of brain insult. In UCP, functional impairment predominantly occurs in the upper limb (UL) of the more affected side, where manual ability and dexterity are typically reduced. Also, mirror movements (MMs), are often present in UCP, with a further possible negative functional impact. This study aims to investigate the relationships among neuroanatomical characteristics of brain injury at MRI, manual functional impairment and MMs, in children with UCP. Thirty-five children with UCP participated in the study (20, M = 15, F, mean age 9.2 ± 3.5 years). Brain lesions at MRI were categorized according to the Magnetic Resonance Classification System (MRICS) and by using a semi-quantitative MRI (sqMRI) scale. Gross manual performance was assessed through Manual Ability Classification System (MACS) and the Box and Block Test (BBT), and MMs by Woods and Teuber scale, for both hands. Non-parametric correlation analyses were run to determine the relationship between neuroanatomical and functional features. Regression models were run to explore the contribution of neuroanatomical features and MMs to UL function. Correlation analyses revealed moderate to strong associations between sqMRI scores contralateral to the more affected side and UL functional impairment on MACS and BBT, with more severe brain injuries significantly correlating with poorer function in the more affected hand. No association emerged between brain lesion severity scores and MMs. MRICS showed no association with MACS or BBT, while a significant correlation emerged between MRICS category and MMs in the more affected hand, with brain lesion category that are suggestive of presumed earlier injury being associated with more severe MMs. Finally, exploratory regression analyses showed that neuroanatomical characteristics of brain injury and MMs contributed to the variability of UL functional impairment. This study contributes to the understanding of the neuroanatomical and neurological correlates of some aspects of manual functional impairment in UCP by using a simple clinical brain MRI assessment.

An Exploration of Tri-Axial Accelerometers in Assessing the Therapeutic Efficacy of Constraint-Induced Movement Therapy in Children with Unilateral Cerebral Palsy

This study aimed to elucidate the role of tri-axial accelerometers in assessing therapeutic interventions, specifically constraint-induced movement therapy (CIMT), in children with unilateral cerebral palsy (UCP). The primary focus was understanding the correlation between the actigraphy metrics recorded during CIMT sessions and the resultant therapeutic outcomes. Children with UCP, aged between 4 and 12 years, participated in this study from July 2021 to December 2022. In conjunction with in-clinic sessions, during which participants wore tri-axial accelerometers on both limbs, we analyzed actigraphy data over three days of routine activities pre- and post-CIMT. While not all metrics derived from the accelerometers indicated significant improvements post-intervention, there was a clear trend towards a more balanced usage of both limbs, particularly evident in Axis 3, associated with vertical movement (p = 0.017). Additionally, a discernible correlation was observed between changes in the magnitude ratio derived from actigraphy data during CIMT (Δweek3-week1) and variations in traditional assessments pre- and post-intervention (ΔT0-T1), specifically the Assisting Hand Assessment grasp and release. Using tri-axial accelerometers has helped clarify the potential impacts of CIMT on children with UCP. The preliminary results suggest a possible link between actigraphy metrics taken during CIMT and the subsequent therapeutic outcomes determined by standardized tests.

Mirror movements and brain pathology in children with unilateral cerebral palsy

AIM

We systematically examined the relationship between mirror movements and brain lesion type, corticospinal tract (CST) organization, and hand function to determine the relevance between mirror movements, brain lesion, the CST pattern, and hand function in children with unilateral cerebral palsy (CP).

METHOD

Forty-eight children (mean age 9y 9mo [SD 3y 3mo], range 6-18y; 30 males, 18 females) with unilateral CP participated. Mirror movements, brain lesion type, CST pattern identified by transcranial magnetic stimulation, and clinical outcomes were evaluated. Children performed four unilateral tasks: hand opening/closing, finger opposition, individuation, and finger 'walking'. Mirror movements induced in the contralateral hand were scored using standardized criteria (scores 0-4 using the Woods and Teuber scale).

RESULTS

We found that children with periventricular lesion may have stronger mirror movement scores induced in either hand than those with middle cerebral artery lesion (more affected hand: p=0.02; less affected hand: p<0.01). The highest mirror movement score a child exhibits across the tested tasks (i.e. scores of 3-4 using the Woods and Teuber scoring criteria) may potentially be an indicator of an ipsilateral CST connectivity pattern (p=0.03). Significant correlations were observed between higher mirror movement scores when performing hand opening/closing as well as finger walking and better unimanual dexterity (Spearman's rank correlation coefficient r_s =0.44, p=0.002; r_s =0.46, p=0.002 respectively).

INTERPRETATION

Brain lesions may be predictive of the strength of mirror movements in either hand in children with unilateral CP. Our findings warrant further studies to extensively investigate the relationship between mirror movements and the underlying brain pathology.

WHAT THIS PAPER ADDS

Brain lesion type may be predictive of mirror movement scores induced in either hand in children with unilateral cerebral palsy. The highest mirror movement score a child exhibits across the tested tasks may indicate corticospinal tract connectivity pattern in children with unilateral cerebral palsy.

Mirror movements after bimanual intensive therapy in children with unilateral cerebral palsy: A randomized controlled trial

AIM

To investigate potential changes in mirror movements after Hand and Arm Bimanual Intensive Therapy Including Lower Extremity (HABIT-ILE) training in children with unilateral cerebral palsy (CP).

METHOD

Thirty-one children with unilateral CP (mean age 9 years 4 months, SD 4 years 3 months; range 5 years 4 months-17 years 3 months; 14 females, 17 males) were randomized to either a control or treatment group. After allocation, children were assessed three times: before (T1, baseline) and after (T2) a 2-week interval and again at 3 months after T1 (T3) as follow-up. Between T1 and T2, the treatment group received 90 hours of HABIT-ILE training, while the control group continued their customary treatment. Mirror movements were assessed in all children using the Woods and Teuber Scale, as well as the Assisting Hand Assessment, Pediatric Evaluation of Disability Inventory, and Canadian Occupational Performance Measure.

RESULTS

Repeated measures analysis of variance indicated a significant decrease in mirror movements in the more-affected (mean difference = 0.97; 95% confidence interval [CI] = 0.51-1.42; p < 0.001) and less-affected (mean difference = 0.71; 95% CI = 0.37-1.0; p < 0.001) hands of children after HABIT-ILE; these improvements were maintained at the 3-month follow-up. Moreover, the mirror movement changes observed at the second assessment (T2) were inversely correlated with changes in the assessment of activities of daily living, especially in the less-affected hand.

INTERPRETATION

HABIT-ILE decreased the intensity of mirror movements in a group of children with CP. Furthermore, mirror movement changes were associated with bimanual performance and activities of daily living in these children.

WHAT THIS PAPER ADDS

The intensity of mirror movements decreased in both hands after 2 weeks of Hand and Arm Bimanual Intensive Therapy Including Lower Extremity (HABIT-ILE) training. Mirror movement changes were maintained at the 3-month follow-up after HABIT-ILE. Mirror movement changes were associated with improvements in bimanual performance and activities of daily living.

Time-matched accelerometers on limbs and waist in children with CP give new insights into real-life activities after botulinum toxin treatment: A proof of concept study

PURPOSE

This study aimed to explore the feasibility of using time-matched uniaxial accelerometers for measuring movement in daily life in children with cerebral palsy (CP) before and after botulinum toxin injections.

METHODS

This observational study of clinical care with a pre-post design was set in the home and school environment. Participants included eleven children (4-13 years of age) with CP (GMFCS I-III). The children wore uniaxial accelerometers (ActiGraph, model GT1M) for 4 days on both wrists, the right ankle and around the waist before, 3 weeks and 3 months after BoNT-A injections in the legs. Five children also got BoNT-A in the most affected arm. All injections were given according to clinical indications and routine. The accelerometers were all time-matched to define ambulation, arm swing, voluntary activity of arms, and bimanual activity. The feasibility of wearing accelerometers with this setup was evaluated. A linear mixed model was used for analysis of the percentage time and at which intensity the different activities were performed. The confidence interval demonstrated any difference between the dominant and non-dominant arm.

RESULTS

Time-matching of accelerometers placed on both wrists, the waist, and one ankle is a feasible method of registering ambulation, arm swing during gait, and arm movements while not ambulating. Before injections, the children spent 5.6% of their time ambulating. This value declined to 3.9% at 3 months. Contrary to clinical goals, arm movement did not increase after injecting the most affected arm with BoNT-A, however, injections may have decreased mirror movements, which are often bothersome for the child.

CONCLUSION

A time-matched 4-accelerometer set-up is feasible in children with cerebral palsy. A future study including time-matched multi-axial accelerometers on all four limbs, could provide important information on the effect of BoNT-A in daily life.

The impact of brain lesion characteristics and the corticospinal tract wiring on mirror movements in unilateral cerebral palsy

Mirror movements (MM) influence bimanual performance in children with unilateral cerebral palsy (uCP). Whilst MM are related to brain lesion characteristics and the corticospinal tract (CST) wiring pattern, the combined impact of these neurological factors remains unknown. Forty-nine children with uCP (mean age 10y6mo) performed a repetitive squeezing task to quantify similarity (MM-similarity) and strength (MM-intensity) of the MM activity. We used MRI data to evaluate lesion type (periventricular white matter, N = 30; cortico-subcortical, N = 19), extent of ipsilesional damage, presence of bilateral lesions, and damage to basal ganglia, thalamus and corpus callosum. The CST wiring was assessed with Transcranial Magnetic Stimulation (17 CSTcontralateral, 16 CSTipsilateral, 16 CSTbilateral). Data was analyzed with regression analyses. In the more-affected hand, MM-similarity and intensity were higher with CSTbilateral/ipsilateral. In the less-affected hand, MM-similarity was higher in children with (1) CSTcontra with CSC lesions, (2) CSTbilat/ipsi with PVL lesions and (3) CSTbilat/ipsi with unilateralized lesions. MM-intensity was higher with larger damage to the corpus callosum and unilateral lesions. A complex combination of neurological factors influences MM characteristics, and the mechanisms differ between hands.

Increased intensity of unintended mirror muscle contractions after cervical spinal cord injury is associated with changes in interhemispheric and corticomuscular coherences

Mirror contractions refer to unintended contractions of the contralateral homologous muscles during voluntary unilateral contractions or movements. Exaggerated mirror contractions have been found in several neurological diseases and indicate dysfunction or lesion of the cortico-spinal pathway. The present study investigates mirror contractions and the associated interhemispheric and corticomuscular interactions in adults with spinal cord injury (SCI) - who present a lesion of the cortico-spinal tract - compared to able-bodied participants (AB). Eight right-handed adults with chronic cervical SCI and ten age-matched right-handed able-bodied volunteers performed sets of right elbow extensions at 20% of maximal voluntary contraction. Electromyographic activity (EMG) of the right and left elbow extensors, interhemispheric coherence over cerebral sensorimotor regions evaluated by electroencephalography (EEG) and corticomuscular coherence between signals over the cerebral sensorimotor regions and each extensor were quantified. Overall, results revealed that participants with SCI exhibited (1) increased EMG activity of both active and unintended active limbs, suggesting more mirror contractions, (2) reduced corticomuscular coherence between signals over the left sensorimotor region and the right active limb and increased corticomuscular coherence between the right sensorimotor region and the left unintended active limb, (3) decreased interhemispheric coherence between signals over the two sensorimotor regions. The increased corticomuscular communication and decreased interhemispheric communication may reflect a reduced inhibition leading to increased communication with the unintended active limb, possibly resulting to exacerbated mirror contractions in SCI. Finally, mirror contractions could represent changes of neural and neuromuscular communication after SCI.

Development of Laterality and Bimanual Interference of Fine Motor Movements in Childhood and Adolescence

Drawing and handwriting are fine motor skills acquired during childhood. We analyzed the development of laterality by comparing the performance of the dominant with the nondominant hand and the effect of bimanual interference in kinematic hand movement parameters (speed, automation, variability, and pressure). Healthy subjects (n = 187, 6-18 years) performed drawing tasks with both hands on a digitizing tablet followed by performance in the presence of an interfering task of the nondominant hand. Age correlated positively with speed, automation, and pressure, and negatively with variability for both hands. As task complexity increased, differences between both hands were less pronounced. Playing an instrument had a positive effect on the nondominant hand. Speed and automation showed a strong association with lateralization. Bimanual interference was associated with an increase of speed and variability. Maturation of hand laterality and the extent of bimanual interference in fine motor tasks are age-dependent processes.

Impact of Upper Extremity Impairment and Trunk Control on Self-Care Independence in Children With Upper Motor Neuron Lesions

OBJECTIVE

The purpose of this study was to evaluate the relative importance of different approaches to measure upper extremity selective voluntary motor control (SVMC), spasticity, strength, and trunk control for explaining self-care independence in children affected by upper motor neuron lesions.

METHODS

Thirty-one patients (mean [SD] age = 12.5 [3.2] years) with mild to moderate arm function impairments participated in this observational study. Self-care independence was evaluated with the Functional Independence Measure for children (WeeFIM). Upper extremity SVMC was quantified with the Selective Control of the Upper Extremity Scale (SCUES), a similarity index (SISCUES) calculated from simultaneously recorded surface electromyography muscle activity patterns, and an accuracy and involuntary movement score derived from an inertial-measurement-unit-based assessgame. The Trunk Control Measurement Scale was applied and upper extremity spasticity (Modified Ashworth Scale) and strength (dynamometry) were assessed. To determine the relative importance of these factors for self-care independence, 3 regression models were created: 1 included only upper extremity SVMC measures, 1 included upper extremity and trunk SVMC measures (overall SVMC model), and 1 included all measures (final self-care model).

RESULTS

In the upper extremity SVMC model (total variance explained 52.5%), the assessgame (30.7%) and SCUES (16.5%) were more important than the SISCUES (4.5%). In the overall SVMC model (75.0%), trunk SVMC (39.0%) was followed by the assessgame (21.1%), SCUES (11.0%), and SISCUES (4.5%). In the final self-care model (82.1%), trunk control explained 43.2%, upper extremity SVMC explained 23.1%, spasticity explained 12.3%, and strength explained 2.3%.

CONCLUSION

Although upper extremity SVMC explains a substantial portion of self-care independence, overall trunk control was even more important. Whether training trunk control and SVMC can translate to improved self-care independence should be the subject of future research.

IMPACT

This study highlights the importance of trunk control and selective voluntary motor control for self-care independence in children with upper motor neuron lesions.

Between Limb Muscle Co-activation Patterns in the Paretic Arm During Non-paretic Arm Tasks in Hemiparetic Cerebral Palsy

Tasks of daily life require the independent use of the arms and hands. Individuals with hemiparetic cerebral palsy (HCP) often experience difficulty with fine motor tasks demonstrating mirrored movements between the arms. In this study, bilateral muscle activations were quantified during single arm isometric maximum efforts and submaximal reaching tasks. The magnitude and direction of mirrored activation was examined in 14 individuals with HCP and 9 age-matched controls. Participants generated maximum voluntary torques (MVTs) in five different directions and completed ballistic reaches while producing up to 80% of shoulder abduction MVT. Electromyography (EMG) signals were recorded from six upper extremity muscles bilaterally. Participants with HCP demonstrated more mirrored activation when volitionally contracting the non-paretic (NP) arm than the paretic arm (F = 83.543, p < 0.001) in isometric efforts. Increased EMG activation during reach acceleration resulted in a larger increase in rest arm co-activation when reaching with the NP arm compared to the paretic arm in the HCP group (t = 8.425, p < 0.001). Mirrored activation is more pronounced when driving the NP arm and scales with effort level. This directionality of mirroring is indicative of the use of ipsilaterally terminating projections of the corticospinal tract (CST) originating in the non-lesioned hemisphere. Peripheral measures of muscle activation provide insight into the descending pathways available for control of the upper extremity after early unilateral brain injury.

Tyneside Pegboard Test for unimanual and bimanual dexterity in unilateral cerebral palsy: association with sensorimotor impairment

AIM

We explored the psychometric properties of the recently developed Tyneside Pegboard Test (TPT) for unimanual and bimanual dexterity in children with unilateral cerebral palsy (CP) and investigated the impact of sensorimotor impairments on manual dexterity.

METHOD

In this cross-sectional study, the TPT was assessed in 49 children with unilateral CP (mean age 9y 8mo, SD 1y 11mo, range 6-15y; 30 males, 19 females; 23 with right unilateral CP). All participants additionally underwent a standardized upper limb evaluation at body function and activity level. We investigated: (1) known-group, concurrent, and construct validity and (2) impact of sensorimotor impairments including spasticity, grip force, stereognosis, and mirror movements using analysis of covariance, Spearman's rank correlation (r), and multiple linear regression (R² ) respectively.

RESULTS

TPT outcomes significantly differed according to the Manual Ability Classification System (p<0.001, known-group validity). Relationships were found between the unimanual TPT tasks and the Jebsen-Taylor Hand Function Test (r=0.86-0.88, concurrent validity). Bimanual TPT tasks were negatively correlated with the Assisting Hand Assessment, ABILHAND-Kids, and Children's Hand-use Experience Questionnaire (r=-0.38 to -0.78, construct validity). Stereognosis was the main determinant influencing all tasks (p<0.001, R² =37-50%). Unimanual dexterity was additionally determined by grip strength (p<0.05, R² =8-9%) and mirror movements in the more impaired hand (p<0.05, R² =4-8%). Bimanual dexterity was also explained by mirror movements in the more impaired hand (p<0.01, R² =10-16%) and spasticity (p=0.04, R² =5%).

INTERPRETATION

The TPT is a valid test to measure unimanual and bimanual dexterity in unilateral CP. The results further emphasize the importance of somatosensory impairments in children with unilateral CP. What this paper adds The Tyneside Pegboard Test is valid for measuring unimanual and bimanual dexterity in unilateral cerebral palsy. Children with poorer manual ability show worse unimanual and bimanual dexterity. Stereognosis is the main predictor of both unimanual and bimanual dexterity. Stronger mirror movements in the more impaired hand result in worse bimanual dexterity.

Neuromotor examination in unilateral cerebral palsy: Bilateral impairments in different levels of motor integration

Unilateral cerebral palsy (UCP) usually results in damage to the unilateral pyramidal system. However, the clinical presentation of neuromotor deficits also suggests lesions to the extrapyramidal and cerebellar systems bilaterally. In this study, we developed and tested a behavioral neuromotor examination protocol assessing impairments at three levels of motor integration for children with UCP, also considering impairments of the non-paretic upper limb as well as the influences of the laterality of the lesion. We included 30 children with UCP (10.79 ± 2.61 years) and 60 healthy children (8.27 ± 1.57 years) in the study. All children were assessed on general cognitive ability and classified according to the manual ability classification system (MACS). Our neuromotor examination protocol incorporated specific tasks for each level of motor integration: pyramidal, extrapyramidal and cerebellar. Children with UCP and controls did not differ with respect to general cognitive abilities and sex but children with UCP were significantly older. Controls performed significantly better than children with UCP on neuromotor tasks at all levels of motor integration. Additionally, performance of the non-plegine hand in children with UCP was significantly inferior to controls. With the exception of fine motor skills (pyramidal level), children with right and left UCP did not differ. Our behavioral neuromotor examination was sensitive to reveal impairments at all three levels of motor integration bilaterally in children with UCP-although more subtle for the non-paretic limb.

Assessment of mirror movements in children and adolescents with unilateral cerebral palsy: reliability of the Woods and Teuber scale

AIM

To investigate the inter- and intrarater reliability of the Woods and Teuber scale to detect mirror movements in children and adolescents with unilateral cerebral palsy (CP).

METHOD

A convenience sample of children and adolescents with unilateral CP (n=68; 31 males, 37 females; mean age 12y 2mo, SD 3y 6mo) in Manual Ability Classification levels I to III was recruited from Norway, Australia, and Belgium. Three therapists scored mirror movements according to the Woods and Teuber scale from three video-recorded tasks at two separate time points. A two-way, mixed model regression was used to calculate intraclass correlation coefficients (ICCs) reflecting overall inter- and intrarater reliability. In addition, ICCs for each hand and task were calculated separately.

RESULTS

The overall interrater reliability ICC was 0.90 and the corresponding intrarater reliability ICC was 0.92. The ICCs for each hand ranged from 0.86 to 0.92 and for each task from 0.63 to 0.89.

INTERPRETATION

The Woods and Teuber scale shows excellent reliability for scoring mirror movements in children and adolescents with unilateral CP. The assessment is easy to administer with no need for specific equipment and scoring can be determined from short video recordings, making it a feasible instrument in research and clinical practice.

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.

Validity and reliability of an electromyography-based upper limb assessment quantifying selective voluntary motor control in children with upper motor neuron lesions

Current clinical assessments evaluating selective voluntary motor control are measured on an ordinal scale. We combined the Selective Control of the Upper Extremity Scale (SCUES) with surface electromyography to develop a more objective and interval-scaled assessment of selective voluntary motor control. The resulting Similarity Index (SI) quantifies the similarity of muscle activation patterns. We aimed to evaluate the validity and reliability of this new assessment named SISCUES (Similarity Index of the SCUES) in children with upper motor neuron lesions. Thirty-three patients (12.2 years [8.8;14.9]) affected by upper motor neuron lesions with mild to moderate impairments and 31 typically developing children (11.6 years [8.5;13.9]) participated. We calculated reference muscle activation patterns for the SISCUES using data of 33 neurologically healthy adults (median [1st; 3rd quantile]: 32.5 [27.9; 38.3]). We calculated Spearman correlations (ρ) between the SISCUES and the SCUES and the Manual Ability Classification System (MACS) to establish concurrent validity. Discriminative validity was tested by comparing scores of patients and healthy peers with a robust ANCOVA. Intraclass correlation coefficients2,1 and minimal detectable changes indicated relative and absolute reliability. The SISCUES correlates strongly with SCUES (ρ = 0.76, p < 0.001) and moderately with the MACS (ρ = -0.58, p < 0.001). The average SISCUES can discriminate between patients and peers. The intraclass correlation coefficient2,1 was 0.90 and the minimal detectable change was 0.07 (8% of patients' median score). Concurrent validity, discriminative validity, and reliability of the SISCUES were established. Further studies are needed to evaluate whether it is responsive enough to detect changes from therapeutic interventions.

Validity and reliability of the Selective Control of the Upper Extremity Scale in children with upper motor neuron lesions

PURPOSE

We evaluated the validity and intra-, inter-, and test-retest reliability of the Selective Control of the Upper Extremity Scale (SCUES) sum and item scores in patients with upper motor neuron lesions.

METHODS

Thirty-one boys and 15 girls (mean age ± SD: 11 years 1 month ± 3 years 9 month) with upper motor neuron lesions participated. We correlated SCUES scores with the range of motion items of the Melbourne Assessment 2 (MA2) and Box and Block Test (BBT) to establish concurrent validity and compared scores between the more and less affected side for discriminative validity. Intra-class correlation coefficients (ICC) and smallest detectable changes (SDC) indicated relative and absolute reliability.

RESULTS

For the more affected side, SCUES sum scores correlated well with MA2 (ρ = 0.83) and BBT (ρ = 0.77), and reliability proved high for intra-rater (ICC = 0.93, SDC = 2.55), inter-rater (ICC = 0.86, SDC = 3.58), and test-retest (ICC = 0.98, SDC = 1.41) reliability. Reliability of single items varied from 0.64 (inter-rater elbow) to 0.98 (intra-rater elbow). Limb and item scores were lower for the more affected side.

CONCLUSION

The SCUES limb and item scores seem valid and reliable in children with upper motor neuron lesions. While future studies should evaluate the responsiveness of the SCUES, we recommend that the same rater should score a patient twice.Implications for rehabilitationThe SCUES assesses selective voluntary motor control and appears valid and reliable in patients with upper motor neuron lesions.Test-retest reliability of the SCUES seems excellent.SCUES single item scores show concurrent validity and acceptable reliability.Limb and item scores are significantly lower for the more affected side.

Neuroimaging Patterns and Function in Cerebral Palsy-Application of an MRI Classification

Background: Cerebral palsy (CP) is a disorder of movement and posture and every child with CP has a unique composition of neurological symptoms, motor severity, and associated impairments, constituting the functional profile. Although not part of the CP definition, magnetic resonance imaging (MRI) sheds light on the localization, nature, and severity of brain compromise. The MRI classification system (MRICS), developed by the Surveillance of Cerebral Palsy in Europe (SCPE), describes typical MRI patterns associated with specific timing of vulnerability in different areas of the brain. The classification has proven to be reliable and easy to use. Aims: The aim of this study is to apply the MRICS on a large dataset and describe the functional profile associated with the different MRI patterns of the MRICS. Materials and Methods: Data on children with CP born in 1999-2009 with a post-neonatal MRI from 20 European registers in the JRC-SCPE Central Registry was included. The CP classification and the MRICS was applied, and The Gross Motor Function Classification (GMFCS) and the Bimanual Fine Motor Function (BFMF) classification were used. The following associated impairments were documented: intellectual impairment, active epilepsy, visual impairment, and hearing impairment. An impairment index was used to characterize severity of impairment load. Results: The study included 3,818 children with post-neonatal MRI. Distribution of CP type, motor, and associated impairments differed by neuroimaging patterns. Functional profiles associated with neuroimaging patterns were described, and the impairment index showed that bilateral findings were associated with a more severe outcome both regarding motor impairment and associated impairments than unilateral compromise. The results from this study, particularly the differences in functional severity regarding uni- and bilateral brain compromise, may support counseling and service planning of support of children with CP.

Lateralized EEG mu power during action observation and motor imagery in typically developing children and children with unilateral Cerebral Palsy

OBJECTIVE

During motor execution (ME), mu power is diminished over the contralateral hemisphere and increased over the ipsilateral hemisphere, which has been associated with cortical activation of the contralateral motor areas and inhibition of the ipsilateral motor areas respectively. The influence of action observation (AO) and motor imagery (MI) on mu power is less clear, especially in children, and remains to be studied in children with unilateral cerebral palsy (uCP).

METHODS

We determined mu power during ME, AO, and MI of 45 typically developing (TD) children and 15 children with uCP over both hemispheres, for each hand.

RESULTS

In TD children, over the left hemisphere mu power was lowered during ME when the right hand was used. In line, over the right hemisphere mu power was lowered when the left hand was addressed. In addition, during AO and MI increased mu power was observed when the right hand was addressed. In children with uCP, over the spared hemisphere mu power was diminished during ME when the less-affected hand was used. However, over the lesioned hemisphere, no mu changes were observed.

CONCLUSIONS

The results of TD children fit the activation/inhibition model of mu power.

SIGNIFICANCE

The results of children with uCP suggest that the lesioned hemisphere is unresponsive to the motor tasks.

Validity and reliability of an accelerometer-based assessgame to quantify upper limb selective voluntary motor control

INTRODUCTION

Current clinical assessments measure selective voluntary motor control (SVMC) on an ordinal scale. We introduce a playful, interval-scaled method to assess SVMC in children with brain lesions and evaluate its validity and reliability.

METHODS

Thirty-one neurologically intact children (median [1st-3rd quartile]: 11.6 years [8.5-13.9]) and 33 patients (12.2 years [8.8-14.9]) affected by upper motor neuron lesions with mild to moderate impairments participated. Using accelerometers, they played a movement tracking game (assessgame) with isolated joint movements (shoulder, elbow, lower arm [pro-/supination], wrist, and fingers), yielding an accuracy score. Involuntary movements were recorded simultaneously and resulted in an involuntary movement score. Both scores were normalized to the performance of 33 neurologically intact adults (32.5 years [27.9; 38.3]), which represented physiological movement patterns. We correlated the assessgame outcomes with the Manual Ability Classification System, Selective Control of the Upper Extremity Scale, and a therapist rating of involuntary movements. Furthermore, a robust ANCOVA was performed with age as covariate, comparing patients to their healthy peers at the age levels of 7.5, 9, 10.5, 12, and 15 years. Intraclass correlation coefficients and smallest real differences indicated relative and absolute reliability.

RESULTS

Correlations (Kendall/Spearman) for the accuracy score were τ = 0.29 (p = 0.035; Manual Ability Classification System), ρ = - 0.37 (p = 0.035; Selective Control of the Upper Extremity Scale), and ρ = 0.64 (p < 0.001; therapist rating). Correlations for the involuntary movement metric were τ = 0.37 (p = 0.008), ρ = - 0.55 (p = 0.001), and ρ = 0.79 (p < 0.001), respectively. The robust ANCOVAs revealed that patients performed significantly poorer than their healthy peers in both outcomes and at all age levels except for the dominant/less affected arm, where the youngest age group did not differ significantly. Robust intraclass correlation coefficients and smallest real differences were 0.80 and 1.02 (46% of median patient score) for the accuracy and 0.92 and 2.55 (58%) for involuntary movements, respectively.

CONCLUSION

While this novel assessgame is valid, the reliability might need to be improved. Further studies are needed to determine whether the assessgame is sensitive enough to detect changes in SVMC after a surgical or therapeutic intervention.

The relationship between neuroimaging and motor outcome in children with cerebral palsy: A systematic review - Part A. Structural imaging

BACKGROUND

Conventional Structural Magnetic Resonance Imaging (sMRI) is a mainstay in Cerebral Palsy (CP) diagnosis.

AIMS

A systematic literature review was performed with the aim to investigate the relationship between structural brain lesions identified by sMRI and motor outcomes in children with CP.

METHODS

Fifty-eight studies were included. The results were analysed in terms of population characteristics, sMRI (classified according to Krägeloh-Mann & Horber, 2007), gross and fine motor function and their interrelation.

OUTCOMES

White matter lesions were the most common brain lesion types and were present in 57.8 % of all children with uCP, in 67.0 % of all children with bCP and in 33 % of the group of mixed subtypes. Grey matter lesions were most frequently registered in children with dyskinesia (n = 42.2 %). No structural anomalies visualized by sMRI were reported in 5.7 % of all cases. In all lesion types, an equal distribution over the different gross motor function classification system categories was present. The included studies did not report sufficient information about fine motor function to relate these results to structural imaging.

CONCLUSIONS AND IMPLICATIONS

The relationship between brain structure and motor outcome needs to be further elucidated in a representative cohort of children with CP, using a more standardized MRI classification system.

Ipsilateral Corticospinal Tract Excitability Contributes to the Severity of Mirror Movements in Unilateral Cerebral Palsy: A Case Series

Mirror movements (MM) can be a clinical manifestation of unilateral cerebral palsy (UCP) causing involuntary movements when attempting to use either hand for functional activities. Atypical development of the corticospinal tract (CST) contributes to impairments in observed motor movements and functional activities. However, little is known about the underlying neurophysiology and contribution of the CST to MM. The current case study characterizes MM in 13 children and young adults with UCP ranging in age from 7 to 19 years and includes clinical and neurophysiologic variables. Clinical profiles included MM of each hand (ie, Woods and Teuber), bimanual coordination and hand use (Assisting Hand Assessment [AHA]), and perception of performance (Canadian Occupational Performance Measure [COPM]). We measured the strength of motor-evoked potentials (MEP) elicited from single-pulse transcranial magnetic stimulation (TMS) of each hemisphere to create a ratio of hemispheric responses. Our sample included three types of CST circuitry: ipsilateral (n = 5), bilateral (n = 3), and contralateral (n = 4). The MEP ratio ranged from 0 to 1.45 (median 0.11) with greater MM observed in participants with ratios greater than 0.5. We observed a positive relationship between the MEP ratio and the more-affected MM score, meaning participants with larger ipsilateral responses from contralesional stimulation (eg, the contralesional hemisphere was stimulated with TMS resulting in an ipsilateral MEP response), as compared with contralateral responses, displayed greater MM than those that did not. There was no relationship between MM and function as measured by the AHA or COPM. These findings suggest a role of the contralesional hemisphere to MM, which could serve as a therapeutic target for interventions.

Contra-Lateral Unintended Upper Arm Movement during Unimanual Tasks in Children with Cerebral Palsy

PURPOSE

To characterize associated reactions (ARs) in the contralateral arm across multiple muscles during unimanual tasks and to identify factors related to ARs in children with cerebral palsy (CP).

MATERIALS AND METHODS

This was a prospective, cross-sectional study of 35 children with CP. The extent of ARs of the contra-lateral, non-task hand was assessed while performing three unimanual tasks (opening and clenching the fist, a finger opposition task, and tapping fingers). The occurrence of ARs in each trial was evaluated separately for each task using a four-point scale (total scores ranged from 0 to 12). Surface electromyography (SEMG) was used to measure the firing activity of the muscles of the opposite arm during the task. The Manual Ability Classification System and Melbourne Assessment 2 (MA-2) were used to evaluate upper limb function.

RESULTS

AR scores were higher in the more-affected limb than in the less-affected limb. SEMG data on the non-task hand showed motor overflow up to the elbow muscles in the more-affected limb. Root mean square ratios of EMG signals were significantly higher in children with ARs than in children without ARs. Multiple regression analysis showed both age and MA-2 to be significant factors related to ARs in the more-affected limb.

CONCLUSION

Children with visible ARs showed motor overflow in the non-task limb during unimanual hand tasks. Age and upper limb function were significantly related to the extent of ARs in the more-affected limb of children with CP.

Randomized controlled trial combining constraint-induced movement therapy and action-observation training in unilateral cerebral palsy: clinical effects and influencing factors of treatment response

Introduction:

Constraint-induced movement therapy (CIMT) improves upper limb (UL) motor execution in unilateral cerebral palsy (uCP). As these children also show motor planning deficits, action-observation training (AOT) might be of additional value. Here, we investigated the combined effect of AOT to CIMT and identified factors influencing treatment response.

Methods:

A total of 44 children with uCP (mean 9 years 6 months, SD 1 year 10 months) participated in a 9-day camp wearing a splint for 6 h/day and were allocated to the CIMT + AOT (n = 22) and the CIMT + placebo group (n = 22). The CIMT + AOT group received 15 h of AOT (i.e. video-observation) and executed the observed tasks, whilst the CIMT + AOT group watched videos free of biological motion and executed the same tasks. The primary outcome measure was bimanual performance. Secondary outcomes included measures of body function and activity level assessed before (T1), after the intervention (T2), and at 6 months follow-up (T3). Influencing factors included behavioural and neurological characteristics.

Results:

Although no between-groups differences were found (p > 0.05; η² = 0–16), the addition of AOT led to higher gains in children with initially poorer bimanual performance (p = 0.02; η² = 0.14). Both groups improved in all outcome measures after the intervention and retained the gains at follow up (p < 0.01; η² = 0.02–0.71). Poor sensory function resulted in larger improvements in the total group (p = 0.03; η² = 0.25) and high amounts of mirror movements tended to result in a better response to the additional AOT training (p = 0.06; η² = 0.18). Improvements were similar irrespective of the type of brain lesion or corticospinal tract wiring pattern.

Conclusions:

Adding AOT to CIMT, resulted in a better outcome for children with poor motor function and high amounts of mirror movements. CIMT with or without AOT seems to be more beneficial for children with poor sensory function.

Trial registration:

Registered at ClinicalTrials.gov on 22nd August 2017 (ClinicalTrials.gov identifier: NCT03256357).

Upper limb impairments, process skills, and outcome in children with unilateral cerebral palsy

AIM

To examine the relationships between upper limb impairments and independence in self-care (ISC) in children with unilateral cerebral palsy (CP).

METHOD

One hundred and eight children with unilateral CP (46 females, 62 males; mean age 8y 7mo, SD 3y 9mo) recruited from a population register were assessed for upper limb muscle power, spasticity, sensation, motor control, and process skills, and for ISC as the functional outcome using structural equation modelling.

RESULTS

The model showed good fit indices and explained 90% of the variance in ISC. Direct effects were significant between manual ability and ISC (β=0.47), and process skills and ISC (β=0.63). Sensation had a significant positive indirect effect on ISC through manual ability (β=0.24) and a positive but marginally non-significant indirect effect through process skills (β=0.21, bootstrapped 95% confidence interval -0.05 to 0.55). Spasticity had a significant negative indirect effect on ISC through its effect on manual ability (β=-0.21). Age had a significant positive indirect effect on ISC, as did intellect, through their effect on process skills (β=0.34 and 0.21 respectively).

INTERPRETATION

ISC is affected by upper limb impairments and process skill. Sensation influences ISC through its effects on manual and process skill abilities. Both sensation and process skills require further evaluation to assist ISC in children with unilateral CP.

WHAT THIS PAPER ADDS

Process skills and manual ability most strongly positively influence independence in self-care (ISC) in children with unilateral cerebral palsy. Sensation influences ISC through manual ability and process skill.

Mirror movements in children with unilateral cerebral palsy due to perinatal stroke: clinical correlates of plasticity reorganization

AIM

We aimed to determine if the mirror movements that often result in children with unilateral cerebral palsy (CP) after perinatal stroke represent a clinical biomarker of developmental plasticity.

METHOD

This was a prospective, controlled cohort study. Mirror movements in children with unilateral CP from a population-based cohort were compared to those of typically developing controls. The population with stroke was assessed further via electromyography (EMG), motor function, and corticospinal organization investigations. Mirror movements were quantified (0-5) bidirectionally. EMG mirror movements were quantified during voluntary contraction. Motor function was quantified by validated measures including the Assisting Hand Assessment (AHA). Corticospinal organization was categorized as ipsilateral or contralateral using transcranial magnetic stimulation (TMS). The relationships between mirror movements, function, and corticospinal organization were assessed (t-tests, Pearson rank correlation coefficients).

RESULTS

Ninety-two participants were scored (55 males, 37 females, mean [SD] 12y [5y 6mo], range 4-17y), 63 with complete motor outcomes and 39 with TMS data. EMG ratios correlated with clinical mirror movements (r=0.562, p=0.008). Mild mirror activity in controls declined with age (r=-0.459, p<0.001). Mirroring was stronger with tasks performed by the affected hand (p<0.001). Mirror movements correlated with AHA scores (r=-0.255, p=0.04) and poor motor outcome (p<0.001). Unaffected hand mirror activity was higher in children with ipsilateral corticospinal tract arrangements (p<0.001).

INTERPRETATION

Clinical mirror movements correlate with disability and corticospinal organization in children with unilateral CP with perinatal stroke. This simple bedside biomarker could facilitate patient selection for personalized rehabilitation.

WHAT THIS PAPER ADDS

Mirror movements are a clinical indicator of corticospinal organization in children with unilateral cerebral palsy with perinatal stroke. Mirroring is strongest in children with ipsilateral corticospinal tract reorganization. The concept of a 'directionality factor' to mirror movements highlights additional, clinically relevant functional correlations.

Perinatal stroke syndromes: Similarities and diversities in aetiology, outcome and management

With a birth-prevalence of 37-67/100,000 (mostly term-born), perinatal stroke encompasses distinct disease-states with diverse causality, mechanism, time of onset, mode of presentation and outcome. Neonatal primary haemorrhagic stroke and ischemic events (also divided into neonatal arterial ischemic stroke and neonatal cerebral sinus venous thrombosis) that manifest soon after birth are distinguished from presumed perinatal - ischemic or haemorrhagic - stroke. Signs of the latter become apparent only beyond the neonatal period, most often with motor asymmetry or milestones delay, and occasionally with seizures. Acute or remote MRI defines the type of stroke and is useful for prognosis. Acute care relies on homeostatic maintenance. Seizures are often self-limited and anticonvulsant agents might be discontinued before discharge. Prolonged anticoagulation for a few weeks is an option in some cases of sinovenous thrombosis. Although the risk of severe impairment is low, many children develop mild to moderate multimodal developmental issues that require a multidisciplinary approach.

Learning to cope with mirror movements in unilateral spastic cerebral palsy: a brief report

PURPOSE

Mirror movements (MM) in unilateral spastic cerebral palsy (USCP) interfere with many bimanual activities of daily living.

METHODS

Here, we developed a specific bimanual therapeutic regimen, focusing on asymmetric simultaneous movements of the two hands. Twelve children (6-17 years old; complete data available in ten children) with USCP and MM were included.

RESULTS

After three weeks of inpatient rehabilitation, we observed significant improvements for two self-defined bimanual goal activities (Goal Attainment Scaling, Canadian Occupational Performance Measure) and for bimanual performance in general (Assisting Hand Assessment). These improvements were still present 6 months later. In contrast, even immediately after therapy, the severity of MM had not changed.

CONCLUSIONS

Hence, targeted bimanual therapy improved bimanual performance, but did not lead to a reduction of MM. The results of this pilot study might suggest that children with MM benefit more from acquiring strategies to cope with MM than by an active training which aimed to reduce MM.

Neurophysiological mechanisms and functional impact of mirror movements in children with unilateral spastic cerebral palsy

Children with unilateral spastic cerebral palsy (CP) often have mirror movements, i.e. involuntary imitations of unilateral voluntary movements of the contralateral upper extremity. The pathophysiology of mirror movements has been investigated in small and heterogeneous cohorts in the literature. Specific pathophysiology of mirror movements and their impact on upper extremity function require systematic investigation in larger and homogeneous cohorts of children with unilateral spastic CP. Here we review two possible neurophysiological mechanisms underlying mirror movements in children with CP and those with typical development: (1) an ipsilateral corticospinal tract projecting from the contralesional motor cortex (M1) to both upper extremities; (2) insufficient interhemispheric inhibition between the two M1s. We also discuss clinical implications of mirror movements in children with unilateral CP and suggest that a thorough examination of the relationship between the pathophysiology and clinical manifestations of mirror movements is warranted. We suggest two premises: (1) the presence of mirror movements is indicative of an ipsilateral corticospinal tract reorganization; and (2) the corticospinal tract organization may affect patients' responses to certain treatment. If these premises are supported through future research, mirror movements should be clinically evaluated for patient selection to maximize benefits of therapy, hence promoting individualized medicine in this population.

WHAT THIS PAPER ADDS

Mirror movements may be indicative of the underlying corticospinal tract reorganization in children with unilateral spastic cerebral palsy (CP). Future research will benefit from systematic investigations of the relationship between mirror movements and its pathophysiology. Mirror movements may be a potential biomarker for individualized medicine in children with unilateral spastic CP.

The Relationship Between Hand Function and Overlapping Motor Representations of the Hands in the Contralesional Hemisphere in Unilateral Spastic Cerebral Palsy

BACKGROUND

In many children with unilateral spastic cerebral palsy (USCP), the corticospinal tract to the affected hand atypically originates in the hemisphere ipsilateral to the affected hand. Such ipsilateral connectivity is on average a predictor of poor hand function. However, there is high variability in hand function in these children, which might be explained by the complexity of motor representations of both hands in the contralesional hemisphere.

OBJECTIVE

To measure the link between hand function and the size and excitability of motor representations of both hands, and their overlap, in the contralesional hemisphere of children with USCP.

METHODS

We used single-pulse transcranial magnetic stimulation to measure the size and excitability of motor representations of both hands, and their overlap, in the contralesional hemisphere of 50 children with USCP. We correlated these measures with manual dexterity of the affected hand, bimanual performance, and mirror movement strength.

RESULTS

The main and novel findings were (1) the large overlap in contralesional motor representations of the 2 hands and (2) the moderate positive associations of the size and excitability of such shared-site representations with hand function. Such functional associations were not present for overall size and excitability of representations of the affected hand.

CONCLUSIONS

Greater relative overlap of the affected hand representation with the less-affected hand representation within the contralesional hemisphere was associated with better hand function. This association suggests that overlapping representations might be adaptively "yoked," such that cortical control of the child's less-affected hand supports that of the affected hand.

Understanding the relationship between brain and upper limb function in children with unilateral motor impairments: A multimodal approach

Atypical brain development and early brain injury have profound and long lasting impact on the development, skill acquisition, and subsequent independence of a child. Heterogeneity is present at the brain level and at the motor level; particularly with respect to phenomena of bilateral activation and mirrored movements (MMs). In this multiple case study we consider the feasibility of using several modalities to explore the relationship between brain structure and/or activity and hand function: Electroencephalography (EEG), both structural and functional Magnetic Resonance Imaging (sMRI, fMRI), diffusion tensor imaging (DTI), transcranial magnetic stimulation (TMS), Electromyography (EMG) and hand function assessments.

METHODS

15 children with unilateral CP (ages: 9.4 ± 2.5 years) undertook hand function assessments and at least two additional neuroimaging and/or neurophysiological procedures: MRI/DTI/fMRI (n = 13), TMS (n = 11), and/or EEG/EMG (n = 8). During the fMRI scans and EEG measurements, a motor task was performed to study cortical motor control activity during simple hand movements. DTI tractography analysis was used to study the corpus-callosum (CC) and cortico-spinal tracts (CST). TMS was used to study cortico-spinal connectivity pattern.

RESULTS

Type and range of severity of brain injury was evident across all levels of manual ability with the highest radiological scores corresponded to children poorer manual ability. Evidence of MMs was found in 7 children, mostly detected when moving the affected hand, and not necessarily corresponding to bilateral brain activation. When moving the affected hand, bilateral brain activation was seen in 6/11 children while 3/11 demonstrated unilateral activation in the contralateral hemisphere, and one child demonstrated motor activation predominantly in the supplementary motor area (SMA). TMS revealed three types of connectivity patterns from the cortex to the affected hand: a contralateral (n = 3), an ipsilateral (n = 4) and a mixed (n = 1) connectivity pattern; again without clear association with MMs. No differences were found between children with and without MMs in lesion scores, motor fMRI laterality indices, CST diffusivity values, and upper limb function. In the genu, midbody, and splenium of the CC, higher fractional anisotropy values were found in children with MMs compared to children without MMs. The EEG data indicated a stronger mu-restoration above the contralateral hemisphere in 6/8 children and above the ipsilateral hemisphere in 2/8 children.

CONCLUSION

The current results demonstrate benefits from the use of different modalities when studying upper-limb function in children with CP; not least to accommodate to the variations in tolerance and feasibility of implementation of the differing methods. These exposed multiple individual brain-reorganization patterns corresponding to different functional motor abilities. Additional research is warranted to understand the transactional influences of early brain injury, neuroplasticity and developmental and environmental factors on hand function in order to develop targeted interventions.

Less-Affected Hand Function in Children With Hemiparetic Unilateral Cerebral Palsy: A Comparison Study With Typically Developing Peers

BACKGROUND

Neurorehabilitation interventions in children with unilateral cerebral palsy (UCP) target motor abilities in daily life yet deficits in hand skills persist. Limitations in the less-affected hand may affect overall bimanual hand skills.

OBJECTIVE

To compare hand function, by timed motor performance on the Jebsen-Taylor Test of Hand Function (JTTHF) and grip strength of children with UCP to children with typical development (CTD), aged 8 to 18 years old. Exploratory analyses compared hand function measures with regard to neurophysiological outcomes measured by transcranial magnetic stimulation and between group comparisons of hemispheric motor threshold.

METHODS

Baseline hand skills were evaluated in 47 children (21 UCP; 26 CTD). Single-pulse transcranial magnetic stimulation testing assessed corticospinal tract and motor threshold.

RESULTS

The mean difference of the less-affected hand of children with UCP to the dominant hand of CTD on the JTTHF was 21.4 seconds (95% CI = 9.32-33.46, P = .001). The mean difference in grip strength was -30.8 N (95% CI = -61.9 to 0.31, P = .052). Resting motor thresholds between groups were not significant, but age was significantly associated with resting motor threshold ( P < .001; P = .001). Children with UCP ipsilateral pattern of motor representation demonstrated greater mean differences between hands than children with contralateral pattern of motor representation ( P < .001). All results were adjusted for age and sex.

CONCLUSIONS

The less-affected hand in children with UCP underperformed the dominant hand of CTD. Limitations were greater in children with UCP ipsilateral motor pattern. Rehabilitation in the less-affected hand may be warranted. Bilateral hand function in future studies may help identify the optimal rehabilitation and neuromodulatory intervention.

Impaired Voluntary Movement Control and Its Rehabilitation in Cerebral Palsy

Cerebral palsy is caused by early damage to the developing brain, as the most common pediatric neurological disorder. Hemiplegia (unilateral spastic cerebral palsy) is the most common subtype, and the resulting impairments, lateralized to one body side, especially affect the upper extremity, limiting daily function. This chapter first describes the pathophysiology and mechanisms underlying impaired upper extremity control of cerebral palsy. It will be shown that the severity of impaired hand function closely relates to the integrity of the corticospinal tract innervating the affected hand. It will also shown that the developing corticospinal tract can reorganize its connectivity depending on the timing and location of CNS injury, which also has implications for the severity of hand impairments and rehabilitation. The mechanisms underlying impaired motor function will be highlighted, including deficits in movement execution and planning and sensorimotor integration. It will be shown that despite having unimanual hand impairments, bimanual movement control deficits and mirror movements also impact function. Evidence for motor learning-based therapies including Constraint-Induced Movement Therapy and Bimanual Training, and the possible pathophysiological predictors of treatment outcome and plasticity will be described. Finally, future directions for rehabilitations will be presented.

The relation between mirror movements and non-use of the affected hand in children with unilateral cerebral palsy

AIM

In children with unilateral cerebral palsy (CP), it is widely believed that mirror movements contribute to non-use of the affected hand despite preserved capacity, a phenomenon referred to as developmental disregard. We aimed to test whether mirror movements are related to developmental disregard, and to clarify the relation between mirror movements and bimanual function.

METHOD

A repetitive squeezing task simultaneously measuring both hands' grip-forces was developed to assess mirror movements by using maximum cross-correlation coefficient (CCC_max ) as well as strength measures (MM_strength ). Developmental disregard, bimanual performance, and capacity were assessed using a validated video-observation method. Twenty-one children with unilateral CP participated (Median age 10y 7mo, interquartile range [IQR] 10y 1mo-12y 9mo). Outcome measures of mirror movements were correlated to developmental disregard, bimanual performance, and capacity scores using Spearman's correlations (significance level: α<0.05).

RESULTS

Mirror movements were not related to developmental disregard. However, enhanced mirror movements in the less-affected hand were related to reduced performance (CCC_max : ρ=-0.526, p=0.007; MM_strength : ρ=-0.750, p<0.001) and capacity (CCC_max : ρ=-0.410, p=0.033; MM_strength : ρ=-0.679, p<0.001). These relations were only moderate (performance:MM_strength : ρ=-0.504, p=0.010), low (capacity: MM_strength : ρ=-0.470, p=0.016) or absent for mirror movements in the affected hand. Additionally, seven children showed stronger movements in their less-affected hands when actually being asked to move their affected hand.

INTERPRETATION

These findings show no relation between mirror movements and developmental disregard, but support an association between mirror movements and bimanual function.

Mirror therapy in children with hemiparesis: a randomized observer-blinded trial

AIM

To determine the efficacy of mirror therapy in children with hemiparesis.

METHOD

The design was an observer-blinded parallel-group randomized controlled trial (International Standard Randomised Controlled Trial Number 48748291). Randomization was computer-generated, 1:1 allocation to mirror therapy or comparison groups. The settings were home-based intervention and tertiary centre assessments. Participants were 90 children with hemiparesis aged 7 to 17 years. Intervention was 15 minutes per day of simultaneous arm training, 5 days a week, for 5 weeks. The mirror therapy group used a mirror; those in the comparison group looked at their paretic limb. Assessments comprised measures of upper limb strength, function (Melbourne Assessment 2), daily performance (ABILHAND-Kids), and sensory function at weeks 0 (T0 ), 5 (T1 ), and 10 (T2 ).

RESULTS

There were no significant differences in outcomes and their progression over time between the mirror therapy and comparison groups. Post-hoc intention-to-treat analyses showed significant improvements in both groups for grasp strength (T0 -T1 +12.6%), pinch strength (T0 -T2 +9.1%), upper limb function in terms of accuracy (T0 -T2 +2.7%) and fluency (T0 -T2 +5.0%), as well as daily performance (T0 -T2 +16.6%). Per protocol analyses showed additional improvements in dexterity (T0 -T2 +4.0%).

INTERPRETATION

The use of the mirror illusion during therapy had no significant effect on treatment outcomes. However, 5 weeks of daily simultaneous arm training significantly improved paretic upper limb strength, function, and daily use.

The Corticospinal Tract: A Biomarker to Categorize Upper Limb Functional Potential in Unilateral Cerebral Palsy

Children with unilateral cerebral palsy (CP) typically present with largely divergent upper limb sensorimotor deficits and individual differences in response to upper limb rehabilitation. This review summarizes how early brain damage can cause dramatic deviations from the normal anatomy of sensory and motor tracts, resulting in unique "wiring patterns" of the sensorimotor system in CP. Based on the existing literature, we suggest that corticospinal tract (CST) anatomy and integrity constrains sensorimotor function of the upper limb and potentially also the response to treatment. However, it is not possible to infer CST (re)organization from clinical presentation alone and conventional biomarkers, such as time of insult, location, and lesion extent seem to have limited clinical utility. Here, we propose a theoretical framework based on a detailed examination of the motor system using behavioral, neurophysiological, and magnetic resonance imaging measures, akin to those used to predict potential for upper limb recovery of adults after stroke. This theoretical framework might prove useful because it provides testable hypotheses for future research with the goal to develop and validate a clinical assessment flowchart to categorize children with unilateral CP.