Spontaneous motility in preterm, small-for-gestational age infants. I. Quantitative aspects

Novel AI driven approach to classify infant motor functions

The past decade has evinced a boom of computer-based approaches to aid movement assessment in early infancy. Increasing interests have been dedicated to develop AI driven approaches to complement the classic Prechtl general movements assessment (GMA). This study proposes a novel machine learning algorithm to detect an age-specific movement pattern, the fidgety movements (FMs), in a prospectively collected sample of typically developing infants. Participants were recorded using a passive, single camera RGB video stream. The dataset of 2800 five-second snippets was annotated by two well-trained and experienced GMA assessors, with excellent inter- and intra-rater reliabilities. Using OpenPose, the infant full pose was recovered from the video stream in the form of a 25-points skeleton. This skeleton was used as input vector for a shallow multilayer neural network (SMNN). An ablation study was performed to justify the network's architecture and hyperparameters. We show for the first time that the SMNN is sufficient to discriminate fidgety from non-fidgety movements in a sample of age-specific typical movements with a classification accuracy of 88%. The computer-based solutions will complement original GMA to consistently perform accurate and efficient screening and diagnosis that may become universally accessible in daily clinical practice in the future.

The general movement optimality score: a detailed assessment of general movements during preterm and term age

AIM

To explore the appropriateness of applying a detailed assessment of general movements and characterize the relationship between global and detailed assessment.

METHOD

The analysis was based on 783 video recordings of 233 infants (154 males, 79 females) who had been videoed from 27 to 45 weeks postmenstrual age. Apart from assessing the global general movement categories (normal, poor repertoire, cramped-synchronized, or chaotic general movements), we scored the amplitude, speed, spatial range, proximal and distal rotations, onset and offset, tremulous and cramped components of the upper and lower extremities. Applying the optimality concept, the maximum general movement optimality score of 42 indicates the optimal performance.

RESULTS

General movement optimality scores (GMOS) differentiated between normal general movements (median 39 [25-75th centile 37-41]), poor repertoire general movements (median 25 [22-29]), and cramped-synchronized general movements (median 12 [10-14]; p<0.01). The optimality score for chaotic general movements (mainly occurring at late preterm age) was similar to those for cramped-synchronized general movements (median 14 [12-17]). Short-lasting tremulous movements occurred from very preterm age (<32wks) to post-term age across all general movement categories, including normal general movements. The detailed score at post-term age was slightly lower compared to the scores at preterm and term age for both normal (p=0.02) and poor repertoire general movements (p<0.01).

INTERPRETATION

Further research might demonstrate that the GMOS provides a solid base for the prediction of improvement versus deterioration within an individual general movement trajectory.

Specific characteristics of spontaneous movements in preterm infants at term age are associated with developmental delays at age 3 years

AIM

The aim of this study was to investigate the relationship between the characteristics of spontaneous movements in preterm infants at term age and developmental delay at 3 years of age.

METHOD

We analysed video recordings of the spontaneous movements in the supine position of 124 preterm infants (44 males, 80 females) at 36 to 44 weeks postmenstrual age (PMA). The infants were born preterm (22-36wks PMA; birthweight 489-1696g) and had not received a diagnosis of a neurological or developmental disorder by the age of 3 years. The recorded spontaneous movements were quantified using six movement indices, which were calculated from two-dimensional trajectories of all limbs. The infants were divided into three developmental groups, normal, borderline, or delayed, based on their developmental quotient as calculated using the Kyoto Scale of Psychological Development 2001 (Kyoto Scale) at 3 years of age. Group differences in the movement indices were analysed.

RESULTS

In the delayed group, average velocity of arms and legs were significantly lower (p<0.05 and p<0.01 respectively), the numbers of movement units of arms and legs were significantly lower (p<0.05 and p<0.01 respectively), kurtosis of acceleration of arms and legs was significantly higher (p<0.05 in each case), and correlation between limb velocities was higher (p<0.05) than in the normal group.

INTERPRETATION

In children who exhibited developmental delay at 3 years of age, the spontaneous movements at term age can be described as less active with intermittent occurrences of abrupt and synchronized movements of the limbs. Recognition of these characteristics of spontaneous movements at term age may be used as a predictor for subsequent cognitive and behavioural development in preterm infants.

Neurodevelopment after fetal growth restriction

Fetal growth restriction (FGR) can emerge as a complication of placental dysfunction and increases the risk for neurodevelopmental delay. Marked elevations of umbilical artery (UA) Doppler resistance that set the stage for cardiovascular and biophysical deterioration with subsequent preterm birth characterize early-onset FGR. Minimal, or absent UA Doppler abnormalities and isolated cerebral Doppler changes with subtle deterioration and a high risk for unanticipated term stillbirth are characteristic for late-onset FGR. Nutritional deficiency manifested in lagging head growth is the most powerful predictor of developmental delay in all forms of FGR. Extremes of blood flow resistance and cardiovascular deterioration, prematurity and intracranial hemorrhage increase the risks for psychomotor delay and cerebral palsy. In late-onset FGR, regional cerebral vascular redistribution correlates with abnormal behavioral domains. Irrespective of the phenotype of FGR, prenatal tests that provide precise and independent stratification of risks for adverse neurodevelopment have yet to be determined.

Correlation properties of spontaneous motor activity in healthy infants: a new computer-assisted method to evaluate neurological maturation

Qualitative assessment of spontaneous motor activity in early infancy is widely used in clinical practice. It enables the description of maturational changes of motor behavior in both healthy infants and infants who are at risk for later neurological impairment. These assessments are, however, time-consuming and are dependent upon professional experience. Therefore, a simple physiological method that describes the complex behavior of spontaneous movements (SMs) in infants would be helpful. In this methodological study, we aimed to determine whether time series of motor acceleration measurements at 40-44 weeks and 50-55 weeks gestational age in healthy infants exhibit fractal-like properties and if this self-affinity of the acceleration signal is sensitive to maturation. Healthy motor state was ensured by General Movement assessment. We assessed statistical persistence in the acceleration time series by calculating the scaling exponent α via detrended fluctuation analysis of the time series. In hand trajectories of SMs in infants we found a mean α value of 1.198 (95 % CI 1.167-1.230) at 40-44 weeks. Alpha changed significantly (p = 0.001) at 50-55 weeks to a mean of 1.102 (1.055-1.149). Complementary multilevel regression analysis confirmed a decreasing trend of α with increasing age. Statistical persistence of fluctuation in hand trajectories of SMs is sensitive to neurological maturation and can be characterized by a simple parameter α in an automated and observer-independent fashion. Future studies including children at risk for neurological impairment should evaluate whether this method could be used as an early clinical screening tool for later neurological compromise.

Introduction of a method for quantitative evaluation of spontaneous motor activity development with age in infants

Coordination between perception and action is required to interact with the environment successfully. This is already trained by very young infants who perform spontaneous movements to learn how their body interacts with the environment. The strategies used by the infants for this purpose change with age. Therefore, very early progresses in action control made by the infants can be investigated by monitoring the development of spontaneous motor activity. In this paper, an objective method is introduced, which allows the quantitative evaluation of the development of spontaneous motor activity in newborns. The introduced methodology is based on the acquisition of spontaneous movement trajectories of the feet by 3D movement analysis and subsequent calculation of specific movement parameters from them. With these movement-based parameters, it was possible to provide an objective description of age-dependent developmental steps in healthy newborns younger than 6 months. Furthermore, it has been shown that pathologies like infantile cerebral palsy influence development of motor activity significantly. Since the introduced methodology is objective and quantitative, it is suitable to monitor how newborns train their cognitive processes, which will enable them to cope with their environment by motor interaction.

Neurodevelopment following fetal growth restriction and its relationship with antepartum parameters of placental dysfunction

Placental dysfunction leading to fetal growth restriction (FGR) is an important risk factor for neurodevelopmental delay. Recent observations clarify that FGR evolves prenatally from a preclinical phase of abnormal nutrient and endocrine milieu to a clinical phase that differs in characteristics in preterm and term pregnancies. Relating childhood neurodevelopment to these prenatal characteristics offers potential advantages in identifying mechanisms and timing of critical insults. Based on available studies, lagging head circumference, overall degree of FGR, gestational age, and umbilical artery (UA), aortic and cerebral Doppler parameters are the independent prenatal determinants of infant and childhood neurodevelopment. While head circumference is important independent of gestational age, overall growth delay has the greatest impact in early onset FGR. Gestational age has an overriding negative effect on neurodevelopment until 32-34 weeks' gestation. Accordingly, the importance of Doppler status is demonstrated from 27 weeks onward and is greatest when there is reversed end-diastolic velocity in the UA or aorta. While these findings predominate in early-onset FGR, cerebral vascular impedance changes become important in late onset FGR. Abnormal motor and neurological delay occur in preterm FGR, while cognitive effects and abnormalities that can be related to specific brain areas increase in frequency as gestation advances, suggesting different pathophysiology and evolving vulnerability of the fetal brain. Observational and management studies do not suggest that fetal deterioration has an independent impact on neurodevelopment in early-onset FGR. In late-onset FGR further research needs to establish benefits of perinatal intervention, as the pattern of vulnerability and effects of fetal deterioration appear to differ in the third trimester.

Inter-observer reliability of the "Assessment of Motor Repertoire--3 to 5 Months" based on video recordings of infants

OBJECTIVE

A detailed analysis of infant motor behaviour can show up indicators for later neurological impairment. The "Assessment of Motor Repertoire--3 to 5 Months", which is part of Prechtl's general movement assessment, could potentially be used for this purpose. The aim of the present study was to investigate inter-observer reliability in this instrument.

METHOD

Video recordings of 24 infants (corrected ages 3 to 5 months, gestational ages 24 to 42 weeks) were analysed by four observers. Kappa and ICC statistics were applied in the reliability analysis.

RESULTS

High to very high inter-observer reliability was found in the assessment of "Fidgety Movements" (kappa 0.75-0.91). Agreement on the "Movement Character" was also high (kappa 0.54-0.84), while the assessment of the "Posture" showed the lowest inter-observer reliability (kappa 0.39-0.56). Moderate to high inter-observer reliability (kappa 0.51-0.84) was achieved in the field "Quality of Other Movements", and moderate in "Repertoire of Co-Existent Other Movements" (kappa 0.51-0.69). Inter-observer reliability in the assessment of the total "Motor Optimality Score" was very high between all four observers as intraclass correlation coefficient (2,1) was 0.87, and ICCs for the pairwise analyses ranged between 0.80 and 0.94.

CONCLUSION

Inter-observer reliability in the "Assessment of Motor Repertoire - 3 to 5 Months" was satisfactory in respect of the subcategories and in case of high and low total optimality scores in pairwise assessments. In the total optimality scores, however, there was some inconsistency in the middle range of the scale.

Quantitative aspects of the early motor repertoire in preterm infants: do they predict minor neurological dysfunction at school age?

BACKGROUND

Qualitative aspects of the motor repertoire, at 11-16 weeks post-term are predictive for minor neurological dysfunction (MND) at 7 to 11 years of age. Predictive value of quantitative aspects is unknown so far.

AIM

To investigate whether quantitative aspects of the motor repertoire between 6 and 24 weeks post-term also have predictive value for neurological outcome at 7 to 11 years of age.

STUDY DESIGN

Prospective cohort study.

SUBJECTS

Preterm infants from whom several quantitative aspects of the motor repertoire were assessed between 6 and 24 weeks post-term.

OUTCOME MEASURES

Neurological outcome at 7-11 years of age was assessed according to Touwens' neurological examination. Children were classified as neurologically normal, or as having complex MND or cerebral palsy (CP).

RESULTS

Eighty-two children were included. At 7 to 11 years of age 15 children (18%) had developed CP, 49 (60%) were neurologically normal, and 18 (22%) had MND. Multiple logistic regression analysis showed that, when the qualitative aspects of the motor repertoire known to predict neurological outcome were taken into account, only the asymmetric tonic neck (ATN) posture provided additional predictive value. In case of normal fidgety movements (FMs) accompanied by an abnormal concurrent motor repertoire, the presence of an obligatory ATN increased the risk for developing complex MND to 75%; absence of an obligatory ATN reduced the risk to 15% (p<0.05).

CONCLUSIONS

Quantitative aspects of the motor repertoire at 11-16 weeks post-term, in particular the presence of an obligatory ATN posture, contribute to the prediction of neurological outcome at 7 to 11 years of age.

Functional magnetic resonance imaging of the sensorimotor system in preterm infants

OBJECTIVE

Preterm birth at <32 weeks' gestational age has a specific predilection for periventricular white matter injury. Early prediction of concomitant motor sequelae is a fundamental clinical issue. Recently, functional MRI was introduced as a noninvasive method for investigating the functional integrity of the neonatal brain. We aimed at implementing a unilateral passive forearm extension/flexion functional MRI paradigm in a routine clinical MRI setup to allow noninvasive mapping of the sensorimotor system in preterm infants and to relate the functional data to structural and behavioral data.

PATIENTS AND METHODS

Eight patients (median gestational age: 26.5 weeks; median birth weight: 885 g) were included. The functional MRI was performed at term-equivalent age (median: 39 weeks' postconceptional age) under chloral hydrate (50 mg/kg) sedation. In 5 of 8 patients, functional MRI data acquisition was successful. This resulted in 10 functional data sets (5 for passive stimulation of each forearm).

RESULTS

Unilateral stimulation was associated with mainly bilateral activation of the primary sensorimotor cortex (n = 7 of 10 data sets), the prevailing hemodynamic response being a negative blood oxygenation level-dependent signal. Positive blood oxygenation level-dependent response or failure to activate the sensorimotor cortex (n = 3 of 10 data sets) were seen in those patients with aberrant structural/behavioral indices.

CONCLUSIONS

Our data show the feasibility of passive unilateral sensorimotor stimulation during neonatal clinical MRI protocols. The bilateral activation pattern observed at this age is compatible with a bilaterally distributed sensorimotor system. Our data validate initial accounts for a raised incidence of negative blood oxygenation level-dependent responses in the primary sensorimotor cortex at this developmental stage. The negative blood oxygenation level-dependent response is likely to reflect a reduction of the oxy/deoxy-hemoglobin ratio during a maturational stage characterized by rapid formation of synapses, yet ineffective processing. Positive blood oxygenation level-dependent responses or failure to activate the sensorimotor cortex may be an early indicator of abnormal development and will have to be followed up carefully.

Human Motor Behavior

The spontaneous movements of the newborn infant have a long prenatal history. From 8 weeks postmenstrual age onward the fetus moves in distinct motor patterns. There is no period of amorphic and random movements. The patterns are easily recognizable, as all of them can be seen after birth. The human neonate demonstrates a continuum of motor patterns from prenatal to early postnatal life. Around the 3rd month a major transformation of motor and sensory patterns occurs. This makes the infant more fit to meet the requirements of the extra-uterine environment. The developmental course of spontaneous movements during the first 20 weeks postterm age shows the emergence and disappearance of various movement patterns. The so-called general movements deserve special interest as they are in their altered quality a most reliable indicator of brain (dys)function with a specific prediction of later developing cerebral palsy.

Ontogeny of EEG-sleep from neonatal through infancy periods

Serial neonatal and infant electroencephalographic (EEG)-polysomnographic studies document the ontogeny of cerebral and noncerebral physiologic behaviors based on visual inspection or computer analyses. EEG patterns and their relationship to other physiologic signals serve as templates for normal brain organization and maturation, subserving multiple interconnected neuronal networks. Interpretation of serial EEG-sleep patterns also helps track the continuity of brain functions from intrauterine to extrauterine time periods. Recognition of the ontogeny of behavioral and electrographic patterns provides insight into the developmental neurophysiological expression of neural plasticity. Sleep ontogenesis from neonatal and infancy periods documents expected patterns of postnatal brain maturation, which allows for alterations from genetically programmed neuronal processes under stressful and/or pathological conditions. Automated analyses of cerebral and noncerebral signals provide time- and frequency-dependent computational phenotypes of brain organization and maturation in healthy or diseased states. Research pertaining to the developmental origins of health and disease can use these computational phenotypes to design longitudinal studies for the assessment of gene-environment interactions. Computational strategies may ultimately improve our diagnostic skills to identify special-needs children and to track the neurorehabilitative care of the high-risk fetus, neonate, and infant.

Neonatal general movements: an early predictor for neurodevelopmental outcome in infants with intrauterine growth retardation

Intrauterine growth retardation plays a significant role in neurodevelopmental outcome. The assessment of general movements during the first 20 weeks is a new method for early detection of brain dysfunction. General movements in 31 infants with asymmetric intrauterine growth retardation and their appropriate for gestational age-matched controls were examined. General movements were scored as normal or abnormal by sequential videotape recordings in the writhing (term to 2 weeks), early fidgety (9-11 weeks), and late fidgety (14-16 weeks) periods. Scores were compared between the groups and correlated with neurodevelopmental outcome at 2 years. The incidence of normal general movements was lower in the intrauterine growth retarded infants than in the controls (P < .001). Significant correlations were found between general movement quality and neurodevelopmental scores in the intrauterine growth retarded group. The fidgety movements were the most sensitive and specific for prediction of neurologic outcome. The general movement assessment can, therefore, serve as an additional tool for examining the neurologic status of the preterm and term intrauterine growth retarded infant.

Is a quantitative approach useful in the comparison of spontaneous movements in fullterm and preterm infants?

Spontaneous motility in the first six months of infancy has been examined over the last few decades using both qualitative and quantitative techniques. The major focus of the quantitative research has been to investigate a dynamic systems approach to understanding motor development, and has primarily examined normal development in fullterm infants. Recently, there have been several papers comparing spontaneous kicking in fullterm and preterm infants. These studies were designed to identify developmental differences that may indicate a risk of later motor disability. There has, however, been criticism that the quantitative approach fails to detect developmental differences that are useful in early identification of disability, unlike qualitative approaches which use the principles of Gestalt perception to examine the quality of the total movement pattern in young infants. The current paper describes both qualitative and quantitative techniques and reviews recent studies using motion analysis to compare early motor development in fullterm and preterm infants. New evidence is provided to suggest that the quantitative approach may not only be useful in detecting infants at risk of motor disability, but may also be useful in identifying the underlying processes that determine normal and abnormal motor outcomes.

Spontaneous motility in preterm, small-for-gestational age infants. II. Qualitative aspects

In order to document in detail the developmental course of qualitative aspects of early spontaneous motility in intrauterine growth-retarded infants, sequential videotape recordings were made in 19 preterm infants with a birth weight below the 5th percentile. The quality of general movements (GMs) was studied longitudinally during the preterm and postterm period until approximately 20 weeks corrected age, using Prechtl's method of quality assessment. An abnormal quality of GMs was present in 15 out of 19 infants. Compared to a low-risk group, consisting of appropriate-for-gestational age preterm infants, the proportion of infants with normal findings on brain scans who had an abnormal quality of GMs was high. The presence of 'abrupt chaotic' GMs was related to late fetal heart-rate decelerations and ischaemic alterations of the placenta. The quality of GMs normalized before or during the third month postterm in most infants with abnormal GMs. In four infants, the GMs did not normalize during the study period. The quality of fidgety movements was, in particular, a marker for neurological outcome at 24 months. This study demonstrates that intrauterine growth retardation may cause prolonged, but in most cases transient brain dysfunction; the qualitative assessment of GMs may help to identify infants at increased risk for neurodevelopmental abnormalities.

State of the art of a new functional assessment of the young nervous system. An early predictor of cerebral palsy

The paper provides a survey of the state of the art of a new neurological diagnostic procedure in fetuses, preterm and term infant as well as in young infants. This method consists of a judgement of the movement quality of a particular type of spontaneous movements, the so-called general movements. At a very early age normal and abnormal general movement quality predicts the neurological outcome over 2 years, in particular cerebral palsy. The reliability of this method turned out to be very robust. Recent animal experiments on isolated parts of the central nervous system provide convincing evidence of endogenously generated neural activity. Similar neural mechanisms must provide the basis for spontaneous movements seen in the human at early ages. Those neural defects leading to qualitative changes of general movements are described in detail.