Quantitative gait assessment in children with 16p11.2 syndrome

Checks and balances: a meta-analysis on the known-groups validity of functional postural control tests in children

INTRODUCTION

Pediatric physical therapists commonly treat children with postural control deficits. Ideally, pediatric functional postural control tests should therefore be able to identify postural control deficits in children with various disorders. Despite a plethora of available tests, evidence for their validity - especially known-groups - remains scarce. This review aims to determine the known-group validity of available functional postural control tests to differentiate various pediatric pathological groups of different ages from their typically developing (TD) peers.

EVIDENCE ACQUISITION

PubMed, Web of Science and Scopus were systematically searched (last update: February 2023; PROSPERO: CRD42023408982). Forty case-control studies with a pathological pediatric sample (N.=1331) and TD peers (N.=1889) were included and selected for data-extraction and -analysis. Risk of bias was assessed using the SIGN checklist and level of evidence was scored using GRADE. Random-effect meta-analyses were performed to estimate pooled standardized mean differences (SMD) for the various test types and subclassified based on pathology and/or age.

EVIDENCE SYNTHESIS

When compared with TD peers, children with underlying pathologies performed significantly worse on pediatric functional postural control test batteries (SMD=-2.21), the Timed Up and Go Test and variants (SMD=2.30), the One Leg Stance test and variants (SMD=-2.14), while the Reach tests showed a smaller difference (SMD=-1.19). Subclassification within the meta-analyses showed that pathology was an influencing factor for the test batteries and the one leg stance test and variants. Age was an influencing factor for the reach tests. None of the included functional postural control tests exceeded a low level of evidence.

CONCLUSIONS

Pediatric functional postural control tests that assess multiple aspects of postural control (such as test batteries) seem to offer higher known-groups validity than single-task tests (e.g. reach tests). The underlying pathology has a larger impact on the validity of these tests than age. There remains an overall low level of evidence for the known-groups validity of pediatric functional postural control tests indicating the need for research with more homogenous groups and norm reference data.

Characterizing ambulatory function in children with PPP2R5D-related neurodevelopmental disorder

BACKGROUND

Individuals with PPP2R5D-related neurodevelopmental disorder have an atypical gait pattern characterized by ataxia and incoordination. Structured, quantitative assessments are needed to further understand the impact of these impairments on function.

RESEARCH QUESTION

How do gait parameters and ambulatory function of individuals with PPP2R5D-related neurodevelopmental disorder compare to age and sex matched healthy norms?

METHODS

Twenty-six individuals with PPP2R5D pathogenic genetic variants participated in this observational, single visit study. Participants completed at least one of the following gait assessments: quantitative gait analysis at three different speeds (preferred pace walking (PPW), fast paced walking (FPW) and running, six-minute walk test (6MWT), 10-meter walk run (10MWR), and timed up and go (TUG). Descriptive statistics were used to summarize gait variables. Percent of predicted values were calculated using published norms. Paired t-tests and regression analyses were used to compare gait variables.

RESULTS

The median age of the participants was 8 years (range 4-27) and eighteen (69.2 %) were female. Individuals with PPP2R5D-related neurodevelopmental disorder walked slower and with a wider base of support than predicted for their age and sex. Stride velocity ranged from 48.9 % to 70.1 % and stride distance from 58.5 % to 81.9 % of predicted during PPW. Percent of predicted distance walked on the 6MWT ranged from 30.6 % to 71.1 % representing varied walking impairment. Increases in stride distance, not cadence, were associated with changes in stride velocity in FPW (R2 = 0.675, p =< 0.001) and running conditions (R2 = 0.918, p =< 0.001).

SIGNIFICANCE

We quantitatively assessed the abnormal gait in individuals with PPP2R5D-related neurodevelopmental disorder. These impairments may affect ability to adapt to environmental changes and participation in daily life. Rehabilitative interventions targeting gait speed and balance may improve function and safety for individuals with PPP2R5D-related neurodevelopmental disorder.

Motor difficulties in 16p11.2 copy number variation

The rare genetic variants 16p11.2 duplication and 16p11.2 deletion have opposing effects on brain structure and function, yet are associated with broadly similar clinical phenotypes that include autism, intellectual impairment, psychiatric illness, and motor difficulties. In recent years, studies have identified subtle distinctions between the phenotypic effects of 16p11.2 duplication and 16p11.2 deletion with respect to patterns of autism, intellectual impairment, and psychiatric illness. However, although divergent phenotypic findings in some motor domains have been reported, no study has yet made a comprehensive comparison of motor difficulties between 16p11.2 deletion and 16p11.2 duplication carriers to elucidate points of convergence and divergence. We sought to make such a comparison in a group of 133 16p11.2 deletion carriers, 122 duplication carriers, and 388 familial controls, hypothesizing that motor impairment would overall be greater in deletion than duplication carriers. In a series of regression models, we found that 16p11.2 deletion status tended to predict greater impairment along indices of gross motor function, but less impairment along indices of fine motor function. These findings point to a potential pattern of performance difficulties that could be investigated in future studies. Elucidating motor differences between 16p11.2 duplication and 16p11.2 deletion carriers may help in understanding the complex effect of 16p11.2 copy number variation and other rare genetic causes of autism.

Analysis of gait synchrony and balance in neurodevelopmental disorders using computer vision techniques

Gait tasks are commonly administered during motor assessments of children with neurodevelopmental disorders (NDDs). Gait analyses are often conducted in laboratory settings using costly and cumbersome experiments. In this paper, we propose a computational pipeline using computer vision techniques as an ecological and precise method to quantify gait in children with NDDs with challenging behaviors. We analyzed videos of 15 probands (PB) and 12 typically developing (TD) siblings, engaged in a preferred-pace walking task, using pose estimation software to track points of interest on their bodies over time. Analyzing the extracted information revealed that PB children had significantly less whole-body gait synchrony and poorer balance compared to their TD siblings. Our work offers a cost-effective method while preserving the validity of its results. This remote approach increases access to more diverse and distant cohorts and thus lowers barriers to research participation, further enriching our understanding of motor outcomes in NDDs.

Assessing Child Postural Variability: Development, Feasibility, and Reliability of a Video Coding System

AIMS

Postural variability is central to children's locomotion, motor control, and environmental exploration, and lacks standardized methods for systematic assessment. The purpose of this study was to develop and evaluate the feasibility and interrater reliability of Child Posture Variability Coding (CPVC), a method of quantifying postural variability in young children.

METHOD

Videos of parent-child play interactions obtained from a longitudinal study investigating language acquisition in typically developing (TD) children and children with autism spectrum disorder (ASD) were used to develop 33 codes for children's voluntary changes in static and dynamic postures. Interrater reliability was calculated for three raters who independently coded 10 randomly selected videos of children aged 23 to 48 months (TD: n = 5, median = 35, IQR = 12.5; ASD: n = 5, median = 35, IQR = 6.75).

RESULTS

Overall, CPVC demonstrated excellent interrater reliability (Krippendorff's α > 0.90). Among all codes developed, five codes (i.e., sit-half, sit-other, crawl, cruise, and supported walk) were not observed by any coders in the sample, but were kept in the coding scheme to reflect normal developmental milestones.

CONCLUSIONS

CPVC is a reliable, feasible method of quantifying postural variability in young children with and without neurodevelopmental disorders in naturalistic contexts.

16p11.2 Copy Number Variations and Neurodevelopmental Disorders

Copy number variations (CNVs) of the human 16p11.2 genetic locus are associated with a range of neurodevelopmental disorders, including autism spectrum disorder, intellectual disability, and epilepsy. In this review, we delineate genetic information and diverse phenotypes in individuals with 16p11.2 CNVs, and synthesize preclinical findings from transgenic mouse models of 16p11.2 CNVs. Mice with 16p11.2 deletions or duplications recapitulate many core behavioral phenotypes, including social and cognitive deficits, and exhibit altered synaptic function across various brain areas. Mechanisms of transcriptional dysregulation and cortical maldevelopment are reviewed, along with potential therapeutic intervention strategies.

Adaptive Skills in FXS: A Review of the Literature and Evaluation of the PEDI-Computer Adaptive Test (PEDI-CAT) to Measure Adaptive Skills

As adaptive skills (AS) are dynamic and may indicate the success of an intervention, they are a common domain measured in clinical trials. Typical interview tools for measuring AS are time-consuming, and questionnaire measures often lead to inconsistent information. The present study was designed to evaluate the feasibility, validity and test-retest performance of the Pediatric Evaluation of Disability Inventory Computer Adaptive Test (PEDI-CAT) in Fragile X syndrome (FXS). The PEDI-CAT is administered via tablet and uses the item response theory to efficiently determine the items administered. The PEDI-CAT was administered to 42 individuals with FXS (27 males; 15 females) aged 1.6-50.9 years (M = 14.9; SD = 11.2), followed by the Vineland-3 (VABS-3) interview for comparison. Administration was efficient (M = 21.7 min; SD = 9.5; range 8-45 min; mode = 19). Males and females did not significantly differ on the PEDI-CAT domains, except for daily activities (t(40) = -2.22, p = 0.037). Floor effects were significant for both measures, although the PEDI-CAT showed more floor effects in the mobility (35.7%) and social-cognitive (50%) domains. PEDI-CAT daily activities, mobility, social-cognitive and responsibility domains were all significantly correlated with most of the VABS-3 domains (all rho > 0.5; p < 0.01). Test-rest of the PEDI-CAT was comparable to the VABS-3. Results suggest that the PEDI-CAT is efficient, and minimal training is needed to administer it; however, it lacks specificity and shares a high rate of floor effects with the VABS-3.