Kinematic quality of reaching movements in preterm infants

Postural Control Measurements to Predict Future Motor Impairment in Preterm Infants: A Systematic Review

Preterm infants are more likely to demonstrate developmental delays than fullterm infants. Postural measurement tools may be effective in measuring the center of pressure (COP) and asymmetry, as well as predicting future motor impairment. The objective of this systematic review was to evaluate existing evidence regarding use of pressure mats or force plates for measuring COP and asymmetry in preterm infants, to determine how measures differ between preterm and fullterm infants and if these tools appropriately predict future motor impairment. The consulted databases included PubMed, Embase, Scopus, and CINAHL. The quality of the literature and the risk of bias were assessed utilizing the ROB2: revised Cochrane risk-of bias tool. Nine manuscripts met the criteria for review. The postural control tools included were FSA UltraThin seat mat, Conformat Pressure-Sensitive mat, Play and Neuro-Developmental Assessment, and standard force plates. Studies demonstrated that all tools were capable of COP assessment in preterm infants and support the association between the observation of reduced postural complexity prior to the observation of midline head control as an indicator of future motor delay. Postural measurement tools provide quick and objective measures of postural control and asymmetry. Based on the degree of impairment, these tools may provide an alternative to standardized assessments that may be taxing to the preterm infant, inaccessible to therapists, or not sensitive enough to capture motor delays.

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.

Quantifying interaction with robotic toys in pre-term and full-term infants

Infants born pre-term are at an increased risk for developmental, behavioral, and motor delay and subsequent disability. When these problems are detected early, clinical intervention can be effective at improving functional outcomes. Current methods of early clinical assessment are resource intensive, require extensive training, and do not always capture infants' behavior in natural play environments. We developed the Play and Neuro Development Assessment (PANDA) Gym, an affordable, mechatronic, sensor-based play environment that can be used outside clinical settings to capture infant visual and motor behavior. Using a set of classification codes developed from the literature, we analyzed videos from 24 pre-term and full-term infants as they played with each of three robotic toys designed to elicit different types of interactions-a lion, an orangutan, and an elephant. We manually coded for frequency and duration of toy interactions such as kicking, grasping, touching, and gazing. Pre-term infants gazed at the toys with similar frequency as full-term infants, but infants born full-term physically engaged more frequently and for longer durations with the robotic toys than infants born pre-term. While we showed we could detect differences between full-term and pre-term infants, further work is needed to determine whether differences seen were primarily due to age, developmental delays, or a combination.

TwinEDA: a sustainable deep-learning approach for limb-position estimation in preterm infants' depth images

Early diagnosis of neurodevelopmental impairments in preterm infants is currently based on the visual analysis of newborns' motion patterns by trained operators. To help automatize this time-consuming and qualitative procedure, we propose a sustainable deep-learning algorithm for accurate limb-pose estimation from depth images. The algorithm consists of a convolutional neural network (TwinEDA) relying on architectural blocks that require limited computation while ensuring high performance in prediction. To ascertain its low computational costs and assess its application in on-the-edge computing, TwinEDA was additionally deployed on a cost-effective single-board computer. The network was validated on a dataset of 27,000 depth video frames collected during the actual clinical practice from 27 preterm infants. When compared to the main state-of-the-art competitor, TwinEDA is twice as fast to predict a single depth frame and four times as light in terms of memory, while performing similarly in terms of Dice similarity coefficient (0.88). This result suggests that the pursuit of efficiency does not imply the detriment of performance. This work is among the first to propose an automatic and sustainable limb-position estimation approach for preterm infants. This represents a significant step towards the development of broadly accessible clinical monitoring applications.

Generating depth images of preterm infants in given poses using GANs

BACKGROUND AND OBJECTIVES

The use of deep learning for preterm infant's movement monitoring has the potential to support clinicians in early recognizing motor and behavioural disorders. The development of deep learning algorithms is, however, hampered by the lack of publicly available annotated datasets.

METHODS

To mitigate the issue, this paper presents a Generative Adversarial Network-based framework to generate images of preterm infants in a given pose. The framework consists of a bibranch encoder and a conditional Generative Adversarial Network, to generate a rough image and a refined version of it, respectively.

RESULTS

Evaluation was performed on the Moving INfants In RGB-D dataset which has 12.000 depth frames from 12 preterm infants. A low Fréchet inception distance (142.9) and an inception score (2.8) close to that of real-image distribution (2.6) are obtained. The results achieved show the potentiality of the framework in generating realistic depth images of preterm infants in a given pose.

CONCLUSIONS

Pursuing research on the generation of new data may enable researchers to propose increasingly advanced and effective deep learning-based monitoring systems.

Outcomes and Hand Use of Reaching Attempts: Comparison of Infants at Risk for Developmental Disability and Infants With Typical Development

Background

Infants at risk for developmental disabilities often show signs of motor delay. Reaching is a skill that can help us identify atypical motor trajectories in early infancy. Researchers have studied performance after onset of reaching, but none have followed infants at risk from pre-reaching to skilled reaching.

Aims

We assessed differences in reaching outcomes and hand use as reaching skill emerged in infants at risk for developmental disabilities and with typical development.

Methods and Procedures

We followed infants at risk for developmental disabilities (n = 11) and infants with typical development (n = 21) longitudinally as they developed reaching skill. Infants reached for a toy at midline while sitting in the caregiver's lap. Video data were coded for reach outcome (miss, touch, partial grasp, and whole-hand grasp) and hand use (right, left, and bilateral).

Outcomes and Results

Infants at risk had a larger proportion of missed reaches across visits compared to infants with typical development. Infants at risk also showed less variability in hand use when grasping over the study period.

Conclusion and Implications

Our results provide information to support early differences in reaching performance to inform identification of typical and atypical developmental trajectories. Future studies should assess how the missed reaches are different and consider other quantitative measures of movement variability in infants at risk.

Infant Reaching in the First Year of Life: A Scoping Review of Typical Development and Examples of Atypical Development

AIMS

Our objective was to identify the most common variables used for infant reaching assessment, describe values of these variables across the first year of life, and identify methodological considerations and knowledge gaps for future research.

METHODS

Studies were included if they met the following criteria: (1) assessed infant reaching in any position, (2) included a sample of infants with typical development: healthy, full-term, with no known impairments, (3) infants were under one year old at the first data collection, and (4) counted successful reaches resulting in object contact.

RESULTS

We identified 6 commonly assessed kinematic reaching variables: frequency, duration, movement units, peak velocity, average velocity, and straightness index. Methodological inconsistencies limit our ability to interpret values of these variables across studies.

CONCLUSIONS

Eliminating inconsistencies in study design and data analysis methods is the next step to defining a normative reference standard for reaching development. Establishing a normative reference standard for reaching in the first year of life will be important for assessment of typical and atypical reaching development.

Improving Preterm Infants' Joint Detection in Depth Images Via Dense Convolutional Neural Networks

Preterm infants' spontaneous motility is a valuable diagnostic and prognostic index of motor and cognitive impairments. Despite being recognized as crucial, preterm infant's movement assessment is mostly based on clinicians' visual inspection. The aim of this work is to present a 2D dense convolutional neural network (denseCNN) to detect preterm infant's joints in depth images acquired in neonatal intensive care units. The denseCNN allows to improve the performance of our previous model in the detection of joints and joint connections, reaching a median recall value equal to 0.839. With a view to monitor preterm infants in a scenario where computational resources are scarce, we tested the architecture on a mid-range laptop. The prediction occurs in real-time (0.014 s per image), opening up the possibility of integrating such monitoring system in a domestic environment.

Reaching skills in six-month-old infants at environmental and biological risk

OBJECTIVES

To assess kinematic parameters and proximal and distal reaching adjustments of infants at biological or environmental risk and compare with reaching performance of six-month-old full-term infants without known risk factors.

METHODS

This blinded cross-sectional study included 62 infants at six months of age divided into three independent groups: Group with no known risk factor (NRF), 28 full-terms with no risk factors; Low SES group (LSES):19 full-terms classified as low socioeconomic status and no biological risk; Very preterm group (VPT), 15 very preterm infants at six months corrected age and no environmental risk. Infants were placed in a reclined baby chair at 45°, and a malleable and unfamiliar object was presented to the infant at 5-second intervals to elicit reaching movements.

RESULTS

Infants from LSES presented reaching duration (p = 0.032, Cohen's f = 0.349) and movement unit (p = 0.033, Cohen's f = 0.351) significantly higher than VPT group. Horizontal hand orientation was moderately associated with infants at environmental risk (p = 0.031; Cramer's V = 0.30).

CONCLUSION

Infants of low socioeconomic status perform less functional reaching movements than very preterm infants at six months corrected age. Socioeconomic status may impact more on reaching skills than biological risk. Given the importance of reaching for infant development, low-cost public health strategies are needed to identify possible delays.

The babyPose dataset

The database here described contains data relevant to preterm infants' movement acquired in neonatal intensive care units (NICUs). The data consists of 16 depth videos recorded during the actual clinical practice. Each video consists of 1000 frames (i.e., 100s). The dataset was acquired at the NICU of the Salesi Hospital, Ancona (Italy). Each frame was annotated with the limb-joint location. Twelve joints were annotated, i.e., left and right shoul- der, elbow, wrist, hip, knee and ankle. The database is freely accessible at http://doi.org/10.5281/zenodo.3891404. This dataset represents a unique resource for artificial intelligence researchers that want to develop algorithms to provide healthcare professionals working in NICUs with decision support. Hence, the babyPose dataset is the first annotated dataset of depth images relevant to preterm infants' movement analysis.

Preterm Infants' Pose Estimation With Spatio-Temporal Features

OBJECTIVE

Preterm infants' limb monitoring in neonatal intensive care units (NICUs) is of primary importance for assessing infants' health status and motor/cognitive development. Herein, we propose a new approach to preterm infants' limb pose estimation that features spatio-temporal information to detect and track limb joints from depth videos with high reliability.

METHODS

Limb-pose estimation is performed using a deep-learning framework consisting of a detection and a regression convolutional neural network (CNN) for rough and precise joint localization, respectively. The CNNs are implemented to encode connectivity in the temporal direction through 3D convolution. Assessment of the proposed framework is performed through a comprehensive study with sixteen depth videos acquired in the actual clinical practice from sixteen preterm infants (the babyPose dataset).

RESULTS

When applied to pose estimation, the median root mean square distance, computed among all limbs, between the estimated and the ground-truth pose was 9.06 pixels, overcoming approaches based on spatial features only (11.27 pixels).

CONCLUSION

Results showed that the spatio-temporal features had a significant influence on the pose-estimation performance, especially in challenging cases (e.g., homogeneous image intensity).

SIGNIFICANCE

This article significantly enhances the state of art in automatic assessment of preterm infants' health status by introducing the use of spatio-temporal features for limb detection and tracking, and by being the first study to use depth videos acquired in the actual clinical practice for limb-pose estimation. The babyPose dataset has been released as the first annotated dataset for infants' pose estimation.

Reaching skills of infants born very preterm predict neurodevelopment at 2.5 years

The purpose was to investigate associations between quality of reaching for moving objects at 8 months corrected age and neurodevelopment at 2.5 years in children born very preterm (gestational age (GA), 24-31 weeks). Thirtysix infants were assessed while reaching for moving objects. The movements were recorded by a 3D motion capture system. Reaching parameters included aiming, relative length of the reach, number of movement units, proportion of bimanual coupled reaches and number of hits. Neurodevelopment was assessed at 2.5 years by the Bayley Scales of Infant Development III. There were strong associations between infant reaching kinematics and neurodevelopment of cognition and language but the patterns differed: in children born extremely preterm (GA < 28 weeks), planning and control of reaching was strongly related to outcome, while in children born very preterm (GA 28-31 weeks) number of hits and bimanual strategies were of greater relevance. In conclusion, for extremely preterm infants, basic problems on how motion information is incorporated with action planning prevail, while in very preterm infants the coordination of bimanual reaches is more at the focus. We conclude that the results reflect GA related differences in neural vulnerability and that early motor coordination deficits have a cascading effect on neurodevelopment.

Developmental progression and side specialization in upper-limb movements from 4 to 8 years in children born preterm and fullterm

This study investigated developmental changes and differences in upper-limb movement organization from 4 to 8 years of age in children born preterm (PT) and fullterm (FT). Kinematic recordings of precision-demanding unimanual movements and lateral assessments were carried out in 37 children (18 PT). All children, particularly children born PT, displayed considerable gain in movement kinematics. Contrary to controls, children born PT displayed persistently less-evident side preference. Gestational age (GA) contributed significantly to kinematic differences shown, with larger upper-limb deviances in the lowest GAs, in agreement with cross-sectional findings of altered hemispheric connections and delayed side-specialization among children born very PT.

Are postural adjustments during reaching related to walking development in typically developing infants and infants at risk of cerebral palsy?

BACKGROUND

In typical development, postural adjustments during reaching change in the second half of infancy, including increasing rates of direction-specific adjustments. These changes are absent or different in infants at risk of cerebral palsy (CP). To discover whether these changes are related to acquisition of independent walking, we studied postural adjustments during reaching in infants before and after they learned to walk.

METHODS

Ten typically developing (TD) infants and 11 infants at very high risk (VHR) of CP were assessed before and after they learned to walk. Reaching movements were elicited during supported sitting, while surface electromyography was recorded of arm, neck, and trunk muscles. Percentages of direction-specific adjustments (first level of control), and recruitment patterns and anticipatory activation (second level of control) were calculated.

RESULTS

In both groups, postural adjustments during reaching were similar before and after acquisition of independent walking. Direction-specificity increased with age in typically developing infants but not in VHR-infants.

CONCLUSION

Increasing age rather than the transition to independent walking is associated with increasing direction-specificity of TD-infants during reaching while sitting, while infants at very high risk of CP show no increase in direction-specificity, suggesting that they gradually grow into a postural deficit.

Development of the quality of reaching in infants with cerebral palsy: a kinematic study

AIM

To assess development of reaching and head stability in infants at very high risk (VHR-infants) of cerebral palsy (CP) who did and did not develop CP.

METHOD

This explorative longitudinal study assessed the kinematics of reaching and head sway in sitting in 37 VHR-infants (18 CP) one to four times between 4.7 months and 22.6 months corrected age. Developmental trajectories were calculated using linear mixed effect models. Motor function was evaluated with the Infant Motor Profile (IMP) around 13 months corrected age.

RESULTS

Throughout infancy, VHR-infants with CP had a worse reaching quality than infants without CP, reflected for example by more movement units (factor 1.52, 95% CI 1.16-1.99) and smaller transport movement units (factor 1.86, 95% CI 1.20-2.90). Total head sway of infants with and without CP was similar, but infants with CP used more head movement units to achieve stability. The rate of developmental change in infants with and without CP was similar. Around 13 months, head control and reaching quality were interrelated; both were associated with IMP-scores.

INTERPRETATION

Infants with CP showed a worse kinematic reaching quality and head stability throughout infancy from early age onwards than VHR-infants without CP, implying that kinematically they do not grow into a deficit, but exhibit deficits from early infancy on.

WHAT THIS PAPER ADDS

Reaching quality improves throughout infancy in all infants at high risk (VHR-infants). Infants with cerebral palsy (CP) show a worse reaching quality than VHR-infants without CP. Infants with CP achieve head stability differently from infants without CP. Infants with CP exhibit kinematic reaching problems from early age onwards.

Alterations in white matter microstructure are associated with goal-directed upper-limb movement segmentation in children born extremely preterm

Altered white matter microstructure is commonly found in children born preterm (PT), especially those born at an extremely low gestational age (GA). These children also commonly show disturbed motor function. This study explores the relation between white matter alterations and upper-limb movement segmentation in 41 children born PT (19 girls), and 41 children born at term (18 girls) at 8 years. The PT group was subdivided into extremely PT (E-PT; GA = 25-27 weeks, N = 10), very PT (V-PT; GA = 28-32 weeks, N = 13), and moderately PT (M-PT; GA = 33-35 weeks, N = 18). Arm/hand preference (preferred/non-preferred) was determined through object interactions and the brain hemispheres were designated accordingly. White matter alterations were assessed using diffusion tensor imaging in nine areas, and movement segmentation of the body-parts head, shoulder, elbow, and wrist were registered during a unimanual goal-directed task. Increased movement segmentation was demonstrated consistently on the preferred side in the E-PT group compared with the term born group. Also compared with the term born peers, the E-PT group demonstrated reduced fractional anisotropy (FA) in the cerebral peduncle (targeting the corticospinal tract) in the hemisphere on the non-preferred side and in the splenium of corpus callosum. In contrast, in the anterior internal capsule on the preferred side, the E-PT group had increased FA. Lower FA in the cerebral peduncle, but higher FA in the anterior internal capsule, was associated with increased movement segmentation across body-parts in a contralateral manner. The results suggest that impaired development of sensorimotor tracts in E-PT children could explain a sub-optimal spatiotemporal organization of upper-limb movements. Hum Brain Mapp 38:5051-5068, 2017. © 2017 Wiley Periodicals, Inc.

Coupling Timing of Interventions With Dose to Optimize Plasticity and Participation in Pediatric Neurologic Populations

PURPOSE

The purpose of this article is to propose that coupling of timing of interventions with dosing of interventions optimizes plasticity and participation in pediatric neurologic conditions, specifically cerebral palsy. Dosing includes frequency, intensity, time per session, and type of intervention. Interventions focus on body structures and function and activity and participation, and both are explored. Known parameters for promoting bone, muscle, and brain plasticity and evidence supporting critical periods of growth during development are reviewed. Although parameters for dosing participation are not yet established, emerging evidence suggests that participation at high intensities has the potential for change. Participation interventions may provide an additional avenue to promote change through the life span. Recommendations for research and clinical practice are presented to stimulate discussions and innovations in research and practice.

Stereo 3D tracking of infants in natural play conditions

This paper describes the design and implementation of a multiple view stereoscopic 3D vision system and a supporting infant tracker pipeline to track limb movement in natural play environments and identify potential metrics to quantify movement behavior. So far, human pose estimation and tracking with 3D cameras has been focused primarily on adults and cannot be directly extended to infants because of differences in visual features such as shapes, sizes and appearance. With rehabilitation in mind, we propose a portable, compact, markerless, low cost and high resolution 3D vision system and a tracking algorithm that exploits infant appearance attributes and depth information. This approach achieved a mean 3D tracking error of 8.21cm and a standard deviation of 8.75cm. We also identify two potential metrics for movement behavior analysis - approximate entropy and interaction events.

Development of a Wearable Sensor Algorithm to Detect the Quantity and Kinematic Characteristics of Infant Arm Movement Bouts Produced across a Full Day in the Natural Environment

We developed a wearable sensor algorithm to determine the number of arm movement bouts an infant produces across a full day in the natural environment. Full-day infant arm movement was recorded from 33 infants (22 infants with typical development and 11 infants at risk of atypical development) across multiple days and months by placing wearable sensors on each wrist. Twenty second sections of synchronized video data were used to compare the algorithm against visual observation as the gold standard for counting the number of arm movement bouts. Overall, the algorithm counted 173 bouts and the observer identified 180, resulting in a sensitivity of 90%. For each bout produced across the day, we then calculated the following kinematic characteristics: duration, average and peak acceleration, average and peak angular velocity, and type of movement (one arm only, both arms for some portion of the bout, or both arms for the entire bout). As the first step toward developing norms, we present average values of full-day arm movement kinematic characteristics across the first months of infancy for infants with typical development. Identifying and quantifying infant arm movement characteristics produced across a full day has potential application in early identification of developmental delays and the provision of early intervention therapies to support optimal infant development.

[Evaluation of coordination and balance in preterm children]

INTRODUCTION

Recent studies show that many preterm children without apparent neurological sequelae present some difficulties in different areas, such as coordination or balance during their school years. The Movement Assessment Battery for Children-2 (MABC-2) has demonstrated to be a useful tool to validate the coordination, while the stabilometric platform was the reference standard test for validating the balance.

PATIENTS AND METHOD

Case-control study carried out on preterm children from 7 to 10 years old and healthy term infant controls of the same ages. The same age band of MABC-2 was applied and the static balance by the stabilometric platform was analysed.

RESULTS

A total of 89 subjects were included, 30 preterm children≤1,500g birthweight, 29 preterm children>1,500g birthweight, and 30 controls. Preterm children obtained the lowest scores on an overall basis in hand dexterity and balance tests in MABC-2, regardless of their birthweight. Lower gestational age was associated with poorer outcomes in hand dexterity and total scores in MABC-2. Balance results were similar using the stabilometric platform, regardless of prematurity.

CONCLUSIONS

A little more than 10% preterm and term children could have coordination disorders or be at risk of developing them using the MABC-2. Despite the visual-motor coordination being similar, preterm children could face greater difficulties in hand dexterity while, in the absence of neurological comorbidity, preterm and term children balance could be comparable.

Immediate Effect of Training at the Onset of Reaching in Preterm Infants: Randomized Clinical Trial

The authors' aim was to investigate the immediate effect of a single specific training session (serial varied practice), of short duration on the kinematic parameters of reaching, in the period of the emergence of the skill in preterm and low birth weight infants. The study included 16 infants of both sexes, born at a mean gestational age of 32.13 (±1.36) weeks and mean birth weight of 1720.94 (±358.46) g. The infants were randomly divided into 2 groups: experimental and control. The experimental group was given a 5-min training session in reaching, while the control group received no training. The results showed significant differences in peak velocity in the intra (Z = -2.10, p = .036) and intergroup (U = 9.00, p = .016) evaluations, which decreased in the experimental group after training. Cohen's d test for clinical relevance suggested that the specific, short duration training proved effective in promoting slower reaches, with greater adjustment and lower number of units of movement. These results are positive for preterm infants given that these parameters more closely resemble the typical development of mature reaching behaviors in term infants, which suggests that this protocol of reaching training (serial varied practice) could be used as an evidence-based intervention strategy.

Characterization and intervention for upper extremity exploration & reaching behaviors in infancy

This article aims to: 1) highlight general exploration, reaching, and object exploration behaviors as key activities of daily living in infancy, 2) describe how knowledge of early warning signs for these behaviors may improve early assessment, and 3) discuss interventions that may advance performance of these behaviors. Early intervention should focus on improving performance of these behaviors because: a) these early, interrelated upper extremity behaviors serve an integral role in global learning and development in infancy, b) among at-risk populations, differences have been observed in the quantity and quality of performance of these behaviors and, in many cases, these differences are associated with related perceptual-motor and cognitive delays. This article highlights how early assessment and intervention can target these key early behaviors in populations at risk for upper extremity disabilities, such as those born preterm, with Down syndrome, brachial plexus palsy, or arthrogryposis multiplex congentia.

Associations between developmental trajectories of movement variety and visual attention in fullterm and preterm infants during the first six months postterm

BACKGROUND

During early infancy major developmental changes, both in the variety of body movements and in visual attention, help the infant to explore its surroundings. Both behaviours depend on a gradual shift from subcortical to cortical functioning.

AIMS

First, to determine whether preterms reach mature levels of movement variety (the number of different movement patterns) and visual attention earlier than fullterms. Second, to determine whether individual developmental trajectories of movement variety and visual attention were associated. Finally, we compared the associations of developmental trajectories between fullterm and preterm infants.

STUDY DESIGN

In this longitudinal study, 20 fullterm and 9 low-risk preterm infants performed a visual disengagement task every four weeks from six weeks until six months postterm. For each infant we drew up developmental trajectories for movement variety, and for frequencies and latencies of looks. We analyzed the developmental trajectories by means of general linear model (GLM) repeated measures and Monte Carlo analyses.

RESULTS

In comparison to fullterms, preterm infants showed a similar increase in movement variety over time (F(4,108)=0.27; partial eta(2)=0.01; P=.90). Visual attention reached mature levels four weeks earlier than movement variety. This effect was stronger in fullterm infants. Neither in fullterm nor in preterm infants did we find an association between the developmental trajectories of movement variety and visual attention. P values ranged from .37 to .99.

CONCLUSIONS

During the first 6 months postterm, movement variety and visual attention developed independently. Temporarily, preterm exposure to the extrauterine environment led to shorter latencies of looks but it did not affect developmental trajectories of frequencies of looks and movement variety.

Infants born preterm demonstrate impaired object exploration behaviors throughout infancy and toddlerhood

BACKGROUND

Object exploration behaviors form the foundation for future global development, but little is known about how these behaviors are exhibited by infants born preterm.

OBJECTIVE

The study objective was to longitudinally compare a comprehensive set of object exploration behaviors in infants born preterm and infants born full-term from infancy into toddlerhood.

DESIGN

Twenty-two infants born full-term and 28 infants born preterm were monitored as they interacted with objects throughout their first 2 years.

METHODS

Infants were provided up to 30 seconds to interact with each of 7 objects across 9 visits. Experimenters coded videos of infants' behaviors. Growth modeling and t tests were used to compare how much infants exhibited behaviors and how well they matched their behaviors to the properties of objects.

RESULTS

Infants born preterm explored objects less in the first 6 months, exhibited less visual-haptic multimodal exploration, displayed reduced variability of exploratory behavior in a manner that reflected severity of risk, and were less able to match their behaviors to the properties of objects in a manner that reflected severity of risk. Infants born preterm with significant brain injury also had impaired bimanual abilities.

LIMITATIONS

There was a limited sample of infants born preterm with significant brain injury.

CONCLUSIONS

Infants born preterm have impaired abilities to interact with objects even in the first months of life. This impairment likely limits the knowledge they acquire about objects and about how they can act on them; this limited knowledge may, in turn, impair their early learning abilities. These results highlight the need for assessment and intervention tools specific for object exploration in young infants.

Kinematic analysis of preterm newborns' spontaneous movements for postural activity assessment

AIMS

The objectives of this pilot study were to assess the potential use of 3D videography for analyzing the motion of the body center of mass (COM) in newborns and to determine differences in spontaneous movements between preterm and full-term infants.

METHODS

The group comprised 10 preterm newborns (gestational age at birth between 26 and 37 weeks; birth weight 800 to 2960 g; gestational age at the time of examination 34 to 39 weeks) and 10 full-term infants (gestational week 38 to 41; birth weight 2810 to 4360 g). To determine the range of motion of the COM, 3D videography was used (2 cameras, 25 Hz). When recording their movements, the infants were in the supine position, calm and awake. The recordings were processed using the APAS software. Selected points on the body were marked to obtain data for calculating the basic parameters of COM trajectories.

RESULTS

The range of motion of the COM in both craniocaudal and anteroposterior directions was significantly greater in premature infants (P < 0.05 and P < 0.01, respectively) than in full-term babies. The variability of motion of the COM was significantly greater in the craniocaudal (P < 0.01) and anteroposterior (P < 0.05) directions in preterm babies. This was also valid for the velocity of motion of the COM in the craniocaudal direction (P < 0.05).

CONCLUSIONS

3D videography can be used for experimental assessment of motor behavior in preterm infants. Basic kinematic characteristics of the motion of the COM (range, variability, velocity) are greater in preterm infants.

Early influence of auditory stimuli on upper-limb movements in young human infants: an overview

Given that the auditory system is rather well developed at the end of the third trimester of pregnancy, it is likely that couplings between acoustics and motor activity can be integrated as early as at the beginning of postnatal life. The aim of the present mini-review was to summarize and discuss studies on early auditory-motor integration, focusing particularly on upper-limb movements (one of the most crucial means to interact with the environment) in association with auditory stimuli, to develop further understanding of their significance with regard to early infant development. Many studies have investigated the relationship between various infant behaviors (e.g., sucking, visual fixation, head turning) and auditory stimuli, and established that human infants can be observed displaying couplings between action and environmental sensory stimulation already from just after birth, clearly indicating a propensity for intentional behavior. Surprisingly few studies, however, have investigated the associations between upper-limb movements and different auditory stimuli in newborns and young infants, infants born at risk for developmental disorders/delays in particular. Findings from studies of early auditory-motor interaction support that the developing integration of sensory and motor systems is a fundamental part of the process guiding the development of goal-directed action in infancy, of great importance for continued motor, perceptual, and cognitive development. At-risk infants (e.g., those born preterm) may display increasing central auditory processing disorders, negatively affecting early sensory-motor integration, and resulting in long-term consequences on gesturing, language development, and social communication. Consequently, there is a need for more studies on such implications.

Influence of additional weight on the frequency of kicks in infants with Down syndrome and infants with typical development

BACKGROUND:

Infants with Down syndrome present with organic and neurological changes that may lead to a delay in the acquisition of motor skills such as kicking, a fundamental skill that is a precursor of gait and is influenced by intrinsic and extrinsic factors. Therefore, this movement should be taken into account in early physical therapy interventions in infants.

OBJECTIVE:

To analyze and to compare the effect of additional weight on the frequency of kicks in infants with Down syndrome and infants with typical development at 3 and 4 months of age.

METHOD:

Five infants with Down syndrome and five with typical development at 3 and 4 months of age were filmed. The experiment was divided into four experimental conditions lasting 1 minute each: training, baseline, weight (addition of ankle weight with 1/3 the weight of the lower limb), and post-weight.

RESULTS:

There were significant differences between groups for all variables (p<0.05), with lower frequencies observed for infants with Down syndrome in all variables. There were significant differences between the experimental conditions baseline and post-weight (p<0.001) for both groups in the frequency of contact and success, with a higher frequency in the post-weight condition.

CONCLUSIONS:

The weight acted as an important stimulus for both groups, directing the kicks toward the target and improving the infants' performance in the task through repetition, however, the infants with Down syndrome had lower frequencies of kicks.

Long-term influences of a preterm birth on movement organization and side specialization in children at 4-8 years of age

This study explored upper-limb and head kinematics during unimanual goal-directed movements in children born preterm (PT) and full-term (FT) aged 4-8 years. Further, functional lateralization was investigated through side-specific kinematics and hand preference observations. Altogether, 141 children were included, divided into three sub-groups based on gestation week at birth (GW). Children born FT (38-41 GW) and moderately PT (33-35 GW) showed faster, smoother, and shorter movement trajectories than children born very PT (V-PT < 33 GW). Only children born FT expressed evident side differences that were characterized by smoother movements with the preferred side. Regarding hand preference, the children born V-PT showed increased rates of non-right-handedness compared with the other groups. Regardless of hand preference, the children born V-PT showed less well organized movements compared with the other groups. These findings suggest that spatio-temporal movement organization and side specialization at pre-/early school-age are affected by a PT birth, and more frequently so for children born before 33 GWs, indicating long-lasting influences on neuromotor development and specialization.

Typical and atypical development of reaching and postural control in infancy

Successful reaching requires postural control, either by active regulation or by postural support. The present paper reviews literature on typical and atypical development of reaching and postural control during infancy. Typically, reaching movements end in grasping around 4 months of age. Initially, reaches are characterized by large variation, including many trajectory corrections. During the first year, the movements get increasingly straight and smooth. Reaching in low-risk preterm infants is initially characterized by advanced development, but minor impairments may emerge in the second half of infancy. In high-risk preterm infants, development of reaching is characterized by delay and non-optimal reaching performance. Typical development of postural adjustments is characterized by variation and an increasing ability to adapt the variable repertoire to the specifics of the situation. The latter is facilitated by an increasing role of anticipatory mechanisms in the second half of infancy. Atypically developing infants may have a reduced repertoire and usually have difficulties in adapting postural adjustments. In infancy, most reaching movements are performed during sitting. The postural challenge of sitting may interfere in particular with the development of reaching in atypically developing infants. The practical implications of this suggestion are discussed.

Imitation of 'bye-bye' in very low-birthweight infants

BACKGROUND

The aim of this study was to clarify the development of imitation skills in very low-birthweight (VLBW) infants compared with full-term infants with regard to the onset of 'bye-bye'.

METHODS

A total of 597 full-term infants (age, 6-21 months) and 95 VLBW infants (corrected age, 6-21 months) participated in this study. The time at which the infants began to imitate bye-bye and how they moved their hands were investigated by direct observations of their behaviors.

RESULT

Some full-term infants began to imitate bye-bye at 9 months, and all full-term infants could imitate bye-bye by 16 months old. The imitation of bye-bye was delayed in VLBW infants, but all of them could imitate it at 17 months old. Bye-bye motions were divided into five types. The 'moving wrist up and down' motion was observed most frequently at the initial bye-bye in both groups, but it was more frequent in VLBW infants at the early stage. The motion types changed with age, with the 'palm facing others' motion observed exclusively at 16 months in full-term infants. All infants of both groups could imitate this type at 17 months old.

CONCLUSION

The development of the ability to imitate bye-bye was delayed in VLBW infants even after correction for gestational age. It was suspected that the fine motor development delay might contribute to the late appearance of bye-bye in VLBW infants. Further follow-up study is required to clarify the clinical significance.

Relations among upper-limb movement organization and cognitive function at school age in children born preterm

OBJECTIVE

To explore relations between aspects of upper-body spatiotemporal movement organization and intelligence in children born preterm at school age.

METHODS

Three-dimensional (3D) kinematic recordings of arm and head movements during a unimanual precision task were related to performance on the Wechsler Intelligence Scale for Children, 4th edition, in a sample of 32 children born preterm (gestational age, mean: 31.5 weeks [range: 22-35 weeks]; birth weight, mean: 1699 g [range: 404-2962 g]) at 6 years to 8 years with no diagnosed cognitive, sensory, or motor impairments compared with 40 age-matched control children born fullterm.

RESULTS

In the children born preterm, upper-limb movement duration and segmentation of movement trajectories were significantly associated with full-scale intelligence quotient independent of gestational age (GA) and sex. These effects pertained to the preferred side, characterized by more effective movement organization being linked with increased intelligence scores. The same relations were not seen in the controls. Within the children born preterm, a significant effect of GA was also found for some aspects of upper-limb movement organization. Full-scale intelligence quotient was within normal limits for both groups but significantly lower in the preterm (mean: 94.5 [range: 72-120]) compared with the fullterm (mean: 101.7 [range: 76-119]) born children.

CONCLUSIONS

The findings demonstrate that, independent of GA, the spatiotemporal organization of upper-limb movements is partly associated with cognitive performance in children born preterm.

Physical therapy intervention in the neonatal intensive care unit

This article presents the elements of the Intervention section of the Infant Care Path for Physical Therapy in the Neonatal Intensive Care Unit (NICU). The types of physical therapy interventions presented in this path are evidence-based and the suggested timing of these interventions is primarily based on practice knowledge from expert therapists, with supporting evidence cited. Physical therapy intervention in the NICU is infant-driven and focuses on providing family-centered care. In this context, interventions to facilitate a calm behavioral state and motor organization in the infant, address positioning and handling of the infant, and provide movement therapy are presented.

Early manifestations of manual specialisation in infants: a longitudinal study from 20 to 30 weeks

This longitudinal study examined lateral differences between latency time of the two hands during the development of prehension in 12 infants from 20 to 30 weeks. Latency time (LT) is defined as the delay between the visual localisation of a reachable target and the beginning of the movement and could be considered as a phase in the preparation of action. If LT varies with the hand used and the type of movement, this would suggest differences in information processing (nature and/or quantity). Results show that the latency time is shorter for the left hand approach movements and shorter for the right hand grasping movements. These findings are in favour of a manual specialisation--clearly present from 20 weeks--and are discussed in a possible hemispheric specialisation perspective.

Proximal and distal adjustments of reaching behavior in preterm infants

The authors aimed to investigate proximal and distal adjustments of reaching behavior and grasping in 5-, 6-, and 7-month-old preterm infants. Nine low-risk preterm and 10 full-term infants participated. Both groups showed the predominance of unimanual reaching, an age-related increase in the frequency of vertical-oriented and open hand movement, and also an increase in successful grasping from 6 to 7 months. The frequency of open hand was higher in the preterm group at 6 months. Intrinsic restrictions imposed by prematurity did not seem to have impaired reaching performance of preterm infants throughout the months of age.

Goal-directed arm movements in children with fetal alcohol syndrome: a kinematic approach

BACKGROUND

Although many studies have documented deficits in general motor functioning in children with fetal alcohol syndrome (FAS), few have employed detailed measurements to explore the specific nature of such disabilities. This pilot study explores whether three-dimensional (3D) kinematic analysis may generate increased knowledge of the effect of intrauterine alcohol exposure on motor control processes by detecting atypical upper-limb movement pattern specificity in children with FAS relative to typically developing (TD) children.

METHODS

Left and right arm and head movements during a sequential unimanual goal-directed precision task in a sample of children with FAS and in TD children were registered by an optoelectronic tracking system (ProReflex, Qualisys Inc.).

RESULTS

Children with FAS demonstrated evidently poorer task performance compared with TD children. Additionally, analyses of arm movement kinematics revealed atypical spatio-temporal organization in the children with FAS. In general, they exhibited longer arm movement trajectories at both the proximal and distal level, faster velocities at the proximal level but slower at the distal level, and more segmented distal movements. Children with FAS also showed atypically augmented and fast head movements during the task performance.

CONCLUSIONS

Findings indicate neuromotor deficits and developmental delay in goal-directed arm movements because of prenatal alcohol exposure. It is suggested that 3D kinematic analysis is a valid technique for furthering the understanding of motor control processes in children with FAS/fetal alcohol spectrum disorders. A combination with relevant neuroimaging techniques in future studies would enable a more clear-cut interpretation of how atypical movement patterns relate to underlying brain abnormalities.

Reaching strategies of very preterm infants at 8 months corrected age

Reaching strategies and kinematics for a group of very preterm infants were investigated and compared with a group of full-term infants when reaching for a moving object. Eight-month-old (corrected-age) infants were presented with small toys moving on a semicircular path in the vertical plane. The trajectories of the target and the hands of the infants were measured using a 3D motion analysis system. No differences were found in how often the infants encountered the target. The very preterm group, however, used bimanual strategies more often and had more curved reaching paths than the full-term group. These results suggest that very preterm infants are equally successful as healthy full-term infants in catching a moving object but their reaching strategies are less efficient compared with full-term infants at 8 months (corrected age).

Clinimetric properties of the alberta infant motor scale in infants born preterm

PURPOSE

The Alberta Infant Motor Scale (AIMS) is a standardized motor assessment for young infants. This study aimed to examine the reliability of the AIMS in a group of infants born at or before 29 weeks of gestation.

METHODS

Fifty-nine infants born preterm were recruited. Two experienced pediatric physical therapists participated in this reliability study. Infants were assessed at 4, 8, 12, and 18 months corrected age (CA).

RESULTS

Intrarater reliability was high (intraclass correlation coefficient [ICC] > or =0.99). The ICC for interrater reliability varied from 0.85 to 0.97. The ICC was low at 4 and 18 months CA.

CONCLUSIONS

The AIMS is reliable in evaluating motor development in infants born preterm. Clinicians should be cautious about using the AIMS in infants at very young ages and those approaching independent ambulation. Accurate placement of the window on a movement repertoire is crucial. Attention is required when using the AIMS in infants developing atypically.

The assessment of minor neurological dysfunction in infancy using the Touwen Infant Neurological Examination: strengths and limitations

AIM

Little is known of minor neurological dysfunction (MND) in infancy. This study aimed to evaluate the inter-assessor reliability of the assessment of MND with the Touwen Infant Neurological Examination (TINE) and the construct and predictive validity of MND in infancy.

METHOD

Inter-assessor agreement was determined in a sample of 40 infants (24 males, 16 females) aged 3 to 12 months (25 born at term: gestational age 37-41wks, median 39; and 15 born preterm, gestational age 24-35wks, median 32). Thirty typically developing term infants (18 males, 12 females; gestational age 37-42wks, median 40) and 59 preterm infants (34 males, 25 females) born at <35 weeks' gestation (gestational age 25-34wks, median 29) participated in the validity study. They were neurologically assessed with the TINE at the corrected ages of 4, 6, 10, and 12 months and with the Hempel assessment at 18 months.

RESULTS

The findings indicated that MND can be assessed reliably (inter-assessor agreement: kappa=0.83). MND during infancy was related to prenatal, perinatal, and social factors, and in particular to preterm birth. Neurological condition during infancy was prone to change, but was related to neurological condition at 18 months at all ages tested.

INTERPRETATION

We conclude that MND can be determined reliably in infancy. Important considerations in the construct of MND in infancy are its relation to prenatal and perinatal factors, its limited stability, and its moderate predictive value.

Exploring objects with feet advances movement in infants born preterm: a randomized controlled trial

BACKGROUND

Previous work has shown that full-term infants who were healthy contacted a toy with their feet several weeks before they did so with their hands and that movement training advanced feet reaching. Certain populations of preterm infants are delayed in hand reaching; however, feet reaching has not been investigated in any preterm population.

OBJECTIVE

The primary purpose of this study was to determine whether preterm infants born at less than 33 weeks of gestational age contacted a toy with their feet at 2 months of corrected age, before doing so with their hands, and whether movement training advanced feet reaching.

DESIGN

This study was a randomized controlled trial.

METHODS

Twenty-six infants born preterm were randomly assigned to receive daily movement training or daily social training. During the 8-week training period, the infants were videotaped in a testing session every other week from 2 to 4 months of age.

RESULTS

Both groups contacted the toy with their feet at 2 months of age during the first testing session prior to training, at an age when no infants consistently contacted the toy with their hands. After 8 weeks of training, the movement training group displayed a greater number and longer duration of foot-toy contacts compared with the social training group.

CONCLUSIONS

These results suggest that movement experiences advance feet reaching as they do for hand reaching. For clinicians, feet-oriented play may provide an early intervention strategy to encourage object interaction for movement impairments within the first months of postnatal life. Future studies can build on these results to test the long-term benefit of encouraging early purposeful leg movements.

Reaching and grasping movements in infants at risk: a review

Although the influence of intrinsic and extrinsic factors on the development of reaching and grasping skills in typical infants has been extensively described in the literature, the effect of such factors on at-risk infants is still poorly understood. Therefore, the aims of the present study were to analyze the scientific publications, from 1980 to 2008, about factors influencing reaching and grasping movements in infants at risk and to describe methodological procedures used in the studies under review. A bibliographical review on empirical studies indexed on Medline, Lilacs and Science Direct data bases was done, using as keywords the terms: "reaching movements", "grasping", "catching", "prehension", "infants", "children", "risk", "deficit", "impairment" and "delay". 127 articles were identified, and 11 were selected. The following risk conditions were assessed in the papers: prematurity, cerebral palsy, Down syndrome, intrauterine cocaine exposure and agenesis of corpus callosum. Methodological issues as well as the intrinsic and extrinsic factors manipulated in the experiments are discussed in the light of changes in theoretical approach to motor behavior.

Motor development from 4 to 8 months corrected age in infants born at or less than 29 weeks' gestation

AIM

Clinically, preterm infants show motor delay and atypical postures compared with their peers born at term. A longitudinal cohort study was designed to describe the motor development of very preterm infants from 4 to 18 months corrected age (CA). The study was also designed to investigate how the atypical postures observed in early infancy in the preterm infants might be related to their later motor development. Here we report the findings in early motor skills from 4 to 8 months CA.

METHOD

Early motor skills were assessed in 62 preterm infants (32 males, 30 females, mean gestation 26.94wks, SD 1.11) and 53 term infants (32 males, 21 females, mean gestation 39.55wks, SD 1.17) using the Alberta Infant Motor Scale (AIMS).

RESULTS

The preterm infants demonstrated different motor behaviours from their term peers, with an uneven progression of motor skills in different positions from 4 to 8 months CA. At 8 months CA, 90%of the term infants were able to sit without arm support, but only 56%of the preterm infants could maintain sitting very briefly without arm support.

INTERPRETATION

This uneven progression may have been due to an imbalance between the active flexor and extensor strength and hence inadequate postural control in these positions. The AIMS has also been shown to be a valid assessment tool to demonstrate unique characteristics in movement quality in the preterm population.

Effects of preterm experience on the developing visual system: a longitudinal study of shifts of attention and gaze in early infancy

Several studies on visual development support the notion that healthy, low-risk preterm infants benefit from their early exposure to the visual world. It has been suggested, however, that mainly early developing sensory and motor processes are enhanced as a result of visual experience and early exercise, whereas later maturing processes might not. This study investigates whether preterm infants' visual and attentional development is accelerated as a consequence of their early visual experience and whether early and later maturing processes are affected differently. Preterm and full-term infants' performance on a gaze and attention shifting task was examined during the first six months of life. Until about 16 weeks post- term, preterm infants were faster in disengaging and shifting their attention and gaze from a stimulus in their central visual field to the periphery, whereas no difference was found for simple gaze shifts without disengagement. This finding is in contrast to earlier accounts that only early developing mechanisms might be advanced as a result of additional visual experience, whereas later developing cortical processes might depend mainly on preprogrammed maturation processes. However, it is consistent with a number of findings on visual, motor, and speech development, which have indicated accelerated cortical functioning in healthy preterm infants before.

The development of reaching behavior in low-risk preterm infants

This longitudinal study investigated the development of reaching behavior in the seated position in preterm infants at the ages of 5-7 months by analyzing kinematic variables (straightness and adjustment indexes, movement unit, mean and final velocities). The correlation between kinematic variables and grasping was verified. The participants were nine low-risk preterm infants with no cerebral lesions. Ten fullterm infants served as control. In both groups, kinematic variables remained unchanged over age, except for the adjustment index, which was higher at 6 months in the preterm group. Successful grasping increased in both groups over age and it was shown to be negatively correlated with mean velocity in the preterm infants. At the ages of 6 and 7 months, preterms showed lower mean and final velocities and higher adjustment index when compared with fullterms. The relative constancy in the kinematic variables suggests that, after having explored the action possibilities during the acquisition phase, the infants selected an adaptative pattern to perform the reaching movements. Slower movements and greater adjustments may be functional strategies of preterms to achieve successful grasps.

Movement training advances the emergence of reaching in infants born at less than 33 weeks of gestational age: a randomized clinical trial

BACKGROUND AND PURPOSE

This study had 2 purposes: (1) to compare the emergence of reaching in infants born full-term and infants born at less than 33 weeks of gestational age and (2) to evaluate the effectiveness of a movement training program on the emergence of reaching in this preterm population.

PARTICIPANTS

Twenty-six infants born at less than 33 weeks of gestational age and with a birth weight less than 2,500 g were randomly assigned to receive 20 minutes of daily movement training (PT-M group) or daily social training (PT-S group) and were compared with 13 infants born full-term (FT-S group).

METHODS

Reaching and hand-object interactions were tested every other week for 8 weeks. At each visit, infants were allowed six 30-second opportunities to contact a midline toy.

RESULTS

The FT-S and PT-M groups reached earlier and more consistently than the PT-S group. Specifically, the subjects in the FT-S group contacted the toy for longer durations and with an open, ventral surface of their hand. The PT-M group demonstrated increases in the number of hand-object contacts, the number of consistent reaches, and the percentage of time interacting with the toy and the surface of hand-object contact.

DISCUSSION AND CONCLUSION

This project demonstrates that there are early gross motor skill differences in infants born at less than 33 weeks of gestational age. A caregiver-based daily training program, however, is effective at lessening some, but not all, of these differences over the short term.