Associations Between Early Structural Magnetic Resonance Imaging, Hammersmith Infant Neurological Examination, and General Movements Assessment in Infants Born Very Preterm

Application of the Hammersmith Infant Neurological Examination in the developmental follow-up of high-risk infants

AIM

To investigate the independent influences affecting the global score of the Hammersmith Infant Neurological Examination (HINE) in the early life of high-risk infants and to provide evidence for early effective screening and for evaluating interventions.

METHOD

We conducted a prospective cohort study of 258 high-risk infants assessed by the HINE and Gesell Developmental Diagnosis Schedule at 3, 6, 9, and 12 months corrected age. A multiple linear regression model was developed to investigate independent influences on HINE global score at 3 months corrected age. The accuracy of the HINE global score was analysed by calculating the discriminant, concurrent, and predictive validities according to ages.

RESULTS

There were nine independent influences affecting the HINE global score at 3 months corrected age in high-risk infants. The discriminant, concurrent, and predictive validities of the HINE for gross motor developmental delays at 12 months corrected age were all statistically significant (p < 0.05).

INTERPRETATION

Different neonatal clinical settings are related to the HINE global score of high-risk infants early in life. The HINE can be used for longitudinal monitoring of neurological development in the first year of life in a typical Chinese clinical setting and the findings at all four ages tested relate to neuromotor outcomes at 12 months corrected age.

Hammersmith

目的

探讨影响高危儿生命早期Hammersmith婴儿神经学检查(HINE)总分的独立影响因素，并为早期有效筛查和评估干预疗效提供证据。

方法

我们对258名高危儿进行了前瞻性队列研究，分别在矫正3、6、9 和12月龄时接受了 HINE和Gesell发育诊断表的评估。一个多元线性回归模型被建立以探究矫正3月龄时HINE总分的独立影响因素。通过计算不同年龄段的区分效度、同时效度和预测效度，分析HINE 总分的准确性。

结果

高危儿HINE总分在矫正3月龄时有9个独立影响因素。在矫正2月龄时，HINE总分对粗大运动发育迟缓的区分效度、同时效度和预测效度均有统计学意义(P < 0.05)。

结果

不同的新生儿临床状况与其生命早期HINE总分有关。在典型的中国临床环境中，HINE可用于纵向监测高危儿出生后第一年的神经系统发育情况，而且四个年龄段的筛查结果都与矫正12月龄时的神经运动发育结果有关。

A Simple MRI Score Predicts Pathological General Movements in Very Preterm Infants with Brain Injury-Retrospective Cohort Study

BACKGROUND/OBJECTIVES

Very preterm infants are at increased risk of brain injury and impaired brain development. The Total Abnormality Score and biometric parameters, such as biparietal width, interhemispheric distance and transcerebellar diameter, are simple measures to evaluate brain injury, development and growth using cerebral magnetic resonance imaging data at term-equivalent age. The aim of this study was to evaluate the association between the Total Abnormality Score and biometric parameters with general movements in very preterm infants with brain injury.

METHODS

This single-center retrospective cohort study included 70 very preterm infants (≤32 weeks' gestation and/or <1500 g birth weight) born between January 2017 and June 2021 in a level-three neonatal intensive care unit with brain injury-identified using cerebral magnetic resonance imaging data at term-equivalent age. General movements analysis was carried out at corrected age of 8-16 weeks. Binary logistic regression and Spearman correlation were used to examine the associations between the Total Abnormality Score and biometric parameters with general movements.

RESULTS

There was a significant association between the Total Abnormality Score and the absence of fidgety movements [OR: 1.19, 95% CI = 1.38-1.03] as well as a significant association between the transcerebellar diameter and fidgety movements (Spearman ρ = -0.269, p < 0.05).

CONCLUSIONS

Among very preterm infants with brain injury, the Total Abnormality Score can be used to predict the absence of fidgety movements and may be an easily accessible tool for identifying high-risk very preterm infants and planning early interventions accordingly.

Practice Variations for Therapeutic Hypothermia in Neonates with Hypoxic-ischemic Encephalopathy: An International Survey

OBJECTIVE

To evaluate variations in management of therapeutic hypothermia (TH) for neonatal hypoxic-ischemic encephalopathy (HIE) among international clinical sites and to identify areas for harmonization.

STUDY DESIGN

An electronic survey was sent to Children's Hospitals Neonatal Consortium site sponsors, Canadian Neonatal Network site investigators, members of the Newborn Brain Society, and American Academy of Pediatrics Neonatology chiefs.

RESULTS

One hundred five sites responded, with most from high-income regions (n = 95). Groupings were adapted from the United Nations regional groups: US (n = 52 sites); Canada (n = 20); Western Europe and other states excluding Canada and US Group (WEOG, n = 18); and non-WEOG (central and eastern Europe, Asia, Africa, Latin America, and Caribbean, n = 15). Regional variations were seen in the eligibility criteria for TH, such as the minimum gestational age, grading of HIE severity, use of electroencephalography, and the frequency of providing TH for mild HIE. Active TH during transport varied among regions and was less likely in smaller volume sites. Amplitude-integrated electroencephalogram and/or continuous electroencephalogram to determine eligibility for TH was used by most sites in WEOG and non-WEOG but infrequently by the US and Canada Groups. For sedation during TH, morphine was most frequently used as first choice but there was relatively high (33%) use of dexmedetomidine in the US Group. Timing of brain magnetic resonance imaging and neurodevelopmental follow-up were variable. Neurodevelopmental follow occurred earlier and more frequently, although for a shorter duration, in the non-WEOG.

CONCLUSIONS

We found significant variations in practices for TH for HIE across regions internationally. Future guidelines should incorporate resource availability in a global perspective.

Diffusion Tensor Imaging to Predict Neurodevelopmental Impairment in Infants after Hypoxic-Ischemic Injury

OBJECTIVE

Magnetic resonance imaging (MRI) is the standard of care for evaluation of brain injury after hypoxic-ischemic encephalopathy (HIE) in term newborns. This study utilizes diffusion tensor imaging (DTI) to (1) identify infants at highest risk of development of cerebral palsy (CP) following HIE and to (2) identify regions of the brain critical to normal fidgety general movements (GMs) at 3 to 4 months of postterm. Absence of these normal, physiological movements is highly predictive of CP.

STUDY DESIGN

Term infants treated with hypothermia for HIE from January 2017 to December 2021 were consented for participation and had brain MRI with DTI after rewarming. The Prechtl's General Movements Assessment was performed at 12 to 16 weeks of age. Structural MRIs were reviewed for abnormalities, and DTI data were processed with the FMRIB Software Library. Infants underwent the Bayley Scales of Infant and Toddler Development III test at 24 months.

RESULTS

Forty-five infant families were consented; three infants died prior to MRI and were excluded, and a fourth infant was excluded due to diagnosis of a neuromuscular disorder. Twenty-one infants were excluded due to major movement artifact on diffusion images. Ultimately, 17 infants with normal fidgety GMs were compared with 3 infants with absent fidgety GMs with similar maternal and infant characteristics. Infants with absent fidgety GMs had decreased fractional anisotropy of several important white matter tracts, including the posterior limb of the internal capsule, optic radiations, and corpus callosum (p < 0.05). All three infants with absent fidgety GMs and two with normal GMs went on to be diagnosed with CP.

CONCLUSION

This study identifies white matter tracts of the brain critical to development of normal fidgety GMs in infants at 3 to 4 months of postterm using advanced MRI techniques. These findings identify those at highest risk for CP among infants with moderate/severe HIE prior to hospital discharge.

KEY POINTS

· HIE has devastating impacts on families and infants.. · Diffusion MRI identifies infants at highest risk for developing neurodevelopmental impairment.. · Normal general movements of infancy are generated by key white matter tracts..

Structural connectivity at term equivalent age and language in preterm children at 2 years corrected

We previously reported interhemispheric structural hyperconnectivity bypassing the corpus callosum in children born extremely preterm (<28 weeks) versus term children. This increased connectivity was positively associated with language performance at 4-6 years of age in our prior work. In the present study, we aim to investigate whether this extracallosal connectivity develops in extremely preterm infants at term equivalent age by leveraging a prospective cohort study of 350 very and extremely preterm infants followed longitudinally in the Cincinnati Infant Neurodevelopment Early Prediction Study. For this secondary analysis, we included only children born extremely preterm and without significant brain injury (n = 95). We use higher-order diffusion modelling to assess the degree to which extracallosal pathways are present in extremely preterm infants and predictive of later language scores at 22-26 months corrected age. We compare results obtained from two higher-order diffusion models: generalized q-sampling imaging and constrained spherical deconvolution. Advanced MRI was obtained at term equivalent age (39-44 weeks post-menstrual age). For structural connectometry analysis, we assessed the level of correlation between white matter connectivity at the whole-brain level at term equivalent age and language scores at 2 years corrected age, controlling for post-menstrual age, sex, brain abnormality score and social risk. For our constrained spherical deconvolution analyses, we performed connectivity-based fixel enhancement, using probabilistic tractography to inform statistical testing of the hypothesis that fibre metrics at term equivalent age relate to language scores at 2 years corrected age after adjusting for covariates. Ninety-five infants were extremely preterm with no significant brain injury. Of these, 53 had complete neurodevelopmental and imaging data sets that passed quality control. In the connectometry analyses adjusted for covariates and multiple comparisons (P < 0.05), the following tracks were inversely correlated with language: bilateral cerebellar white matter and middle cerebellar peduncles, bilateral corticospinal tracks, posterior commissure and the posterior inferior fronto-occipital fasciculus. No tracks from the constrained spherical deconvolution/connectivity-based fixel enhancement analyses remained significant after correction for multiple comparisons. Our findings provide critical information about the ontogeny of structural brain networks supporting language in extremely preterm children. Greater connectivity in more posterior tracks that include the cerebellum and connections to the regions of the temporal lobes at term equivalent age appears to be disadvantageous for language development.

Prenatal Opioid Exposure and Risk for Adverse Brain and Motor Outcomes in Infants Born Premature

OBJECTIVE

To compare brain magnetic resonance imaging (MRI) biomarkers and neurodevelopmental test scores in infants born preterm with and without prenatal opioid exposure (POE).

STUDY DESIGN

We examined 395 preterm infants (≤32 weeks gestational age) who had term-equivalent brain MRIs, composite scores from the Bayley Scales of Infant and Toddler Development-III at 2 years corrected age, and POE data. MRI parameters included total/regional brain volumes and severe punctate white matter lesions (PWMLs). We conducted bivariable analysis and multivariable logistic regression analyses.

RESULTS

The mean ± SD gestational age was 29.3 ± 2.5 weeks; 35 (8.9%) had POE and 20 (5.1%) had severe PWML. Compared with unexposed infants, those with POE exhibited higher rates of severe PWML (17.1% vs 3.9%, respectively; P = .002); findings remained significant with an OR of 4.16 (95% CI, 1.26-13.68) after adjusting for confounders. On mediation analysis, the significant relationship between POE and severe PWML was not indirectly mediated through preterm birth/gestational age (OR, 0.93; 95% CI, 0.78-1.10), thus suggesting the association was largely driven by a direct adverse effect of POE on white matter. In multivariable analyses, POE was associated with a significantly lower score by -6.2 (95% CI, -11.8 to -0.6) points on the Bayley Scales of Infant and Toddler Development-III Motor subscale compared with unexposed infants.

CONCLUSIONS

POE was associated with severe PWML; this outcome may be a direct effect of POE rather than being mediated by premature birth. POE was also associated with worse motor development. Continued follow-up to understand the long-term effects of POE is warranted.

Identifying and Evaluating Young Children with Developmental Central Hypotonia: An Overview of Systematic Reviews and Tools

Children with developmental central hypotonia have reduced muscle tone secondary to non-progressive damage to the brain or brainstem. Children may have transient delays, mild or global functional impairments, and the lack of a clear understanding of this diagnosis makes evaluating appropriate interventions challenging. This overview aimed to systematically describe the best available evidence for tools to identify and evaluate children with developmental central hypotonia aged 2 months to 6 years. A systematic review of systematic reviews or syntheses was conducted with electronic searches in PubMed, Medline, CINAHL, Scopus, Cochrane Database of Systematic Reviews, Google Scholar, and PEDro and supplemented with hand-searching. Methodological quality and risk-of-bias were evaluated, and included reviews and tools were compared and contrasted. Three systematic reviews, an evidence-based clinical assessment algorithm, three measurement protocols, and two additional measurement tools were identified. For children aged 2 months to 2 years, the Hammersmith Infant Neurological Examination has the strongest measurement properties and contains a subset of items that may be useful for quantifying the severity of hypotonia. For children aged 2-6 years, a clinical algorithm and individual tools provide guidance. Further research is required to develop and validate all evaluative tools for children with developmental central hypotonia.

Reliability, Knowledge Translation, and Implementability of the Spanish Version of the Hammersmith Infant Neurological Examination

Purpose. This study aimed to: (a) translate and cross-culturally adapt the Hammersmith Infant Neurological Examination (HINE) into Spanish; (b) evaluate its intra- and inter-examiner reliability; (c) support a knowledge translation and tool implementation program in early intervention; and (d) evaluate its reliability and implementation for professionals one year after receiving training. Materials and methods. The translation followed the World Health Organization's recommendations. Reliability was assessed in 25 infants aged between 3 and 15 months with identifiable risks of cerebral palsy (CP). The implementation was also evaluated by analyzing the reliability of professionals without previous experience of the tool by using a pre-survey and a follow-up survey one year after training. The survey covered aspects related to the use of early detection tools of CP and the use of HINE, including attitudes, opinions, and perceptions. Results. An excellent intra- and inter-examiner agreement was obtained for the total score of the HINE intra-class correlation coefficient (ICC = 0.98 in both indices). One year after training, the professionals also showed excellent reliability values (ICC = 0.99), as well as an increase in sensitization and skills in evidence-based practices for the early detection of "high risk" of CP. Conclusions. The Spanish version of HINE is a reliable measure for the neurological evaluation of "high risk" of CP and can be administered after standardized training and without costs to acquire the evaluation. This allows its accessible and widespread implementation in the clinical context.

Hammersmith Infant Neurological Examination Subscores Are Predictive of Cerebral Palsy

BACKGROUND

The Hammersmith Infant Neurological Examination (HINE) is a standardized assessment that identifies early signs of cerebral palsy (CP). In practice, the clinician performs this assessment in its entirety, yielding a global score. This study aimed to investigate the individual HINE subscores and "asymmetries" as predictive indicators of CP.

METHODS

In this retrospective nested case-control study, a pediatric neurologist performed the HINE on a cohort of three- to four-month-old former neonatal intensive care unit infants. The infants' neurodevelopmental outcomes were determined by chart review when they were aged two to three years. We performed univariate and multivariable logistic regression analyses to yield the accuracy of the global HINE score, HINE subscores, and "asymmetries" in classifying infants with and without CP.

RESULTS

Of the 108 infants on whom HINE was performed, 50 were either discharged due to normal developmental progress or were lost to follow-up. Of the remaining 58 subjects, 17 had CP and 41 did not. Receiver operator characteristic (ROC) curves of univariate models yielded the following area under the curve (AUC) scores: global HINE score (AUC = 0.75), "reflexes and reactions" (AUC = 0.80), "cranial nerve function" (AUC = 0.76), "asymmetries" (AUC = 0.75), and "movements" (AUC = 0.71). The ROC for our multivariable model (AUC = 0.91) surpassed the global HINE score's predictive value for CP.

CONCLUSIONS

The weighted combination of HINE subscores and "asymmetries" outperforms the global HINE score in predicting CP. These findings suggest the need for revisiting HINE, but further validation with a larger dataset is required.

Prenatal tobacco smoke exposure and risk of brain abnormalities on magnetic resonance imaging at term in infants born very preterm

BACKGROUND

Prenatal tobacco smoke exposure and preterm birth are associated with abnormal brain and neurodevelopmental outcomes in infants. Studies that can disentangle indirect mediating effects from direct effects of prenatal tobacco smoke exposure on sensitive early brain magnetic resonance imaging biomarkers in very preterm infants are needed.

OBJECTIVE

This study aimed to determine whether prenatal tobacco smoke exposure in preterm infants posed any direct effects on magnetic resonance imaging-determined global brain abnormality score and secondary measures of brain abnormalities after removing any indirect mediating effects of preterm birth on neurostructural outcomes.

STUDY DESIGN

We examined brain magnetic resonance imaging findings collected at 39 to 44 weeks postmenstrual age from a prospective cohort of 395 infants born very preterm (gestational age of ≤32 weeks). The primary outcome was global brain abnormality score, and the secondary outcomes were global efficiency of structural connectome, diffuse white matter abnormality volume, total brain tissue volume, total gray and white matter volumes, and cerebellar volume. Maternal reports of smoking during pregnancy were obtained. We performed multivariable linear regression analyses to examine the association between prenatal tobacco smoke exposure and our magnetic resonance imaging outcomes, controlling for prospectively collected confounders. Moreover, we performed a mediation analysis to estimate the direct effects of prenatal tobacco smoke exposure on brain abnormalities and any indirect effects through preterm birth.

RESULTS

Overall, 12.6% of infants had prenatal tobacco smoke exposure. Infants with prenatal tobacco smoke exposure had a higher median global brain abnormality score than nonexposed infants (7 [interquartile range, 0-41] vs 5 [interquartile range, 0-34]; P≤.001); the findings remained significant (P<.001) after controlling for antenatal confounders. Global efficiency (P<.001), diffuse white matter volume (P=.037), and total brain tissue volume (P=.047) were significantly different between TSE groups in multivariable analyses. On mediation analysis, preterm birth mediated between 0% and 29% of the indirect effect of prenatal tobacco smoke exposure on several measures of brain abnormality outcomes. Thus, prenatal tobacco smoke exposure had a direct adverse effect between 71% and 100% on brain injury or abnormal development.

CONCLUSION

Our study has identified multiple adverse effects of prenatal tobacco smoke exposure on sensitive and objective measures of neonatal brain injury and abnormal development; most cases seemed to be a direct effect of prenatal tobacco smoke exposure on fetal brain development. The results underscored the significant adverse neurostructural effects of prenatal tobacco smoke exposure to tobacco smoke pollutants.

Smartphone application links severity of retinopathy of prematurity to early motor behavior in a cohort of high-risk preterm infants

PURPOSE

To evaluate the General Movement Assessment (GMA) with the Motor Optimality Score-Revised (MOS-R) as a neurodevelopmental marker in infants with retinopathy of prematurity (ROP).

METHODS

Infants screened prospectively for ROP were evaluated at 3 months' post-term age using a smartphone application to complete the GMA and MOS-R. Results were analyzed by ROP severity.

RESULTS

Of 105 enrolled infants, 83 completed the study. Of these, 54 (65%) had any ROP, 32 (39%) had severe ROP, and 13 (16%) had type 1 ROP. The proportion with aberrant GMA was significantly higher in infants with severe ROP (14/32 [44%]) compared with infants who had milder ROP (8/51 [16%]; P = 0.006). Of those with severe ROP, there was no significant difference comparing infants with type 1 ROP treated with bevacizumab (7/13 [54%]) to infants with type 2 ROP without treatment (7/19 [37%]; P = 0.47). Although the presence of any ROP, stage of ROP, and severe ROP each predicted lower MOS-R scores on univariate analyses, only severe bronchopulmonary dysplasia and markers of brain injury remained significant in the multivariate analysis.

CONCLUSIONS

The GMA was a convenient, short-term method of data collection with low attrition. Although severe ROP initially appeared linked to poor early motor scores, this association is likely confounded by neurological and respiratory complications, which frequently accompany severe ROP.

Long-term predictivity of early neurological assessment and developmental trajectories in low-risk preterm infants

Prematurity represents 10.6% of all births, and although preterm infants usually show adequate neurodevelopmental outcomes, some may develop significant and long-lasting neurological sequelae. Many studies have analyzed predictive factors for developing severe neurodevelopmental impairments (cerebral palsy, other motor and socio-relational disorders such as autism). In this study, 148 preterm infants were enrolled to investigate the neurodevelopmental trajectories in a population of low-risk premature infants using standardized assessment methods. Significant correlations were found between the general movements, the Hammersmith Infant Neurological Examination, and the Griffiths Mental and Development Scales. Moreover, this study showed their validity and predictivity for adverse neurodevelopmental outcomes even in low-risk infants.

Hammersmith Infant Neurological Examination in low-risk infants born very preterm: a longitudinal prospective study

AIM

To describe the profile of global and single items of the Hammersmith Infant Neurological Examination (HINE) in a population of low-risk infants born very preterm during the first year of life.

METHOD

The HINE was performed at 3, 6, 9, and 12 months' corrected age in a population of low-risk infants born preterm with a gestational age of fewer than 32 weeks and with normal or minimal changes on neuroimaging.

RESULTS

A total of 174 infants born preterm (96 males, 78 females; mean gestational age = 27 weeks [SD = 1.8], range 23-31 weeks) fulfilled the inclusion criteria. The 10th centile cut-off score with median and range was reported for the HINE global and subsection scores. A progressive increase in global HINE scores was observed. Most of the single items, especially those related to tone, posture, and reflexes, showed progressive maturation.

INTERPRETATION

Our results, which provide longitudinal data for single-item and global scores in a population of low-risk infants born very preterm, can be used as a reference in both clinical and research settings to monitor early neurological signs in these infants. These data could be used as normative data when examining low-risk infants born preterm.

Assessing the Utility of Neonatal Screening Assessments in Early Diagnosis of Cerebral Palsy in Preterm Infants

Background: Early diagnosis of cerebral palsy (CP) in high-risk infants is possible at 3−4 months’ corrected age (CA) using standardised assessments. Aim: To assess the utility of neonatal screening assessments—writhing general movements (GMs) and the Hammersmith Neonatal Neurological Examination (HNNE)—to predict CP/high-risk status at 3−4 months’ CA in extremely preterm infants. Methods: Retrospective cohort study of high-risk preterm infants (born < 29 weeks’ gestation and/or birth weight < 1000 g) attending an Early Neurodevelopment Clinic. Data from neonatal assessments were compared with CP/high-risk diagnosis at 3−4 months’ CA, fidgety GMs, and Hammersmith Infant Neurological Examinations (HINE) using logistic regression, linear regression, and Spearman rank correlation. Results: Two hundred and two preterm infants (median gestation age at birth 27.3 (IQR 25.4−28.3) weeks, mean birth weight 870.3 (SD 248.4) grams) were included. A total of 26 (12.8%) infants received early CP/high-risk diagnoses at 3−4 months’ CA. A lower gestational age (GA) (OR = 0.78; p = 0.029, 95% CI [0.26, 0.97]) and abnormal writhing GMs (OR 1.56; p = 0.019, 95% CI [1.07, 2.27]) were predictive of CP/high-risk diagnosis. Although after adjustment for sex, GA, birth weight, and growth restriction, GA (aOR = 0.67; p = 0.068, 95% CI [0.44, 1.03]) and writhing GMs (aOR = 1.44; p = 0.087, 95% CI [0.95, 2.20]) were not significant, a strong trend still persisted. The HNNE scores significantly correlated with both the HINE evaluation (rs = 0.43, p < 0.001, 95% CI [0.31, 0.56]) and fidgety GMs (rs = −0.10, p = 0.012, 95% CI [−0.32, −0.04]). Linear regression confirmed the HNNE was highly predictive of the HINE (correlation coefficient 0.82; p < 0.001, 95% CI [0.48, 1.15]). Writhing GMs did not significantly correlate with either fidgety GMs (p = 0.723, 95% CI [−0.12, 0.17]) or the HINE (p = 0.173, 95% CI [−0.24, 0.04]). Conclusions: Abnormal writhing GMs in the neonatal period were non-significantly associated with early CP/high-risk diagnoses in extremely preterm infants in a multivariate analysis. Additionally, the HNNE significantly correlated with both fidgety GMs and the HINE.

Brain microstructural antecedents of visual difficulties in infants born very preterm

Infants born very preterm (VPT) are at risk of later visual problems. Although neonatal screening can identify ophthalmologic abnormalities, subtle perinatal brain injury and/or delayed brain maturation may be significant contributors to complex visual-behavioral problems. Our aim was to assess the micro and macrostructural antecedents of early visual-behavioral difficulties in VPT infants by using diffusion MRI (dMRI) at term-equivalent age. We prospectively recruited a cohort of 262 VPT infants (≤32 weeks gestational age [GA]) from five neonatal intensive care units. We obtained structural and diffusion MRI at term-equivalent age and administered the Preverbal Visual Assessment (PreViAs) questionnaire to parents at 3-4 months corrected age. We used constrained spherical deconvolution to reconstruct nine white matter tracts of the visual pathways with high reliability and performed fixel-based analysis to derive fiber density (FD), fiber-bundle cross-section (FC), and combined fiber density and cross-section (FDC). In multiple logistic regression analyses, we related these tract metrics to visual-behavioral function. Of 262 infants, 191 had both high-quality dMRI and completed PreViAs, constituting the final cohort: mean (SD) GA was 29.3 (2.4) weeks, 90 (47.1%) were males, and postmenstrual age (PMA) at MRI was 42.8 (1.3) weeks. FD and FC of several tracts were altered in infants with (N = 59) versus those without retinopathy of prematurity (N = 132). FDC of the left posterior thalamic radiations (PTR), left inferior longitudinal fasciculus (ILF), right superior longitudinal fasciculus (SLF), and left inferior fronto-occipital fasciculus (IFOF) were significantly associated with visual attention scores, prior to adjusting for confounders. After adjustment for PMA at MRI, GA, severe retinopathy of prematurity, and total brain volume, FDC of the left PTR, left ILF, and left IFOF remained significantly associated with visual attention. Early visual-behavioral difficulties in VPT infants are preceded by micro and macrostructural abnormalities in several major visual pathways at term-equivalent age.

Profile of minor neurological findings after perinatal asphyxia

Aim

To characterise the spectrum of findings in sequential neurological examinations, general movements (GM) assessment and magnetic resonance imaging (MRI) of infants with perinatal asphyxia.

Methods

The prospective cohort study of term infants with perinatal asphyxia treated at Helsinki University Hospital's neonatal units in 2016–2020 used Hammersmith Neonatal Neurological Examination (HNNE) and brain MRI at 2 weeks and Hammersmith Infant Neurological Examination (HINE) and GM assessment at 3 months of age.

Results

Analysis included 50 infants: 33 displaying perinatal asphyxia without hypoxic‐ischaemic encephalopathy (HIE), seven with HIE1 and 10 with HIE2. Of the infants with atypical HNNE findings, 24/25 perinatal asphyxia without HIE cases, 5/6 HIE1 cases and all 10 HIE2 cases showed atypical findings in the HINE. The HINE identified atypical spontaneous movements significantly more often in infants with white matter T2 hyperintensity.

Conclusion

In this cohort, most infants with perinatal asphyxia, with or without HIE, presented atypical neurological findings in sequential examinations. The profile of neurological findings for children with perinatal asphyxia without HIE resembled that of children with HIE. White matter T2 hyperintensity was associated with atypical spontaneous movements in the HINE and was a frequent MRI finding also in perinatal asphyxia without HIE.

Association between brain structural network efficiency at term-equivalent age and early development of cerebral palsy in very preterm infants

Very preterm infants (born at less than 32 weeks gestational age) are at high risk for serious motor impairments, including cerebral palsy (CP). The brain network changes that antecede the early development of CP in infants are not well characterized, and a better understanding may suggest new strategies for risk-stratification at term, which could lead to earlier access to therapies. Graph theoretical methods applied to diffusion MRI-derived brain connectomes may help quantify the organization and information transfer capacity of the preterm brain with greater nuance than overt structural or regional microstructural changes. Our aim was to shed light on the pathophysiology of early CP development, before the occurrence of early intervention therapies and other environmental confounders, to help identify the best early biomarkers of CP risk in VPT infants. In a cohort of 395 very preterm infants, we extracted cortical morphometrics and brain volumes from structural MRI and also applied graph theoretical methods to diffusion MRI connectomes, both acquired at term-equivalent age. Metrics from graph network analysis, especially global efficiency, strength values of the major sensorimotor tracts, and local efficiency of the motor nodes and novel non-motor regions were strongly inversely related to early CP diagnosis. These measures remained significantly associated with CP after correction for common risk factors of motor development, suggesting that metrics of brain network efficiency at term may be sensitive biomarkers for early CP detection. We demonstrate for the first time that in VPT infants, early CP diagnosis is anteceded by decreased brain network segregation in numerous nodes, including motor regions commonly-associated with CP and also novel regions that may partially explain the high rate of cognitive impairments concomitant with CP diagnosis. These advanced MRI biomarkers may help identify the highest risk infants by term-equivalent age, facilitating earlier interventions that are informed by early pathophysiological changes.

Diffuse white matter abnormality in very preterm infants at term reflects reduced brain network efficiency

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Most preterm infants exhibit regions of high signal intensity on T2 MRI at term.

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Debate remains as to whether this signal (DWMA) is pathological.

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We quantified DWMA and used graph theory to measure brain network efficiency.

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Whole-brain and regional network efficiency at term decreased with greater DWMA.

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DWMA in very preterm infants is associated with reduced brain efficiency at term.

Between 50 and 80% of very preterm infants (<32 weeks gestational age) exhibit increased white matter signal intensity on T2-weighted MRI at term-equivalent age, known as diffuse white matter abnormality (DWMA). A few studies have linked DWMA with microstructural abnormalities, but the exact relationship remains poorly understood. We related DWMA extent to graph theory measures of network efficiency at term in a representative cohort of 343 very preterm infants. We performed anatomic and diffusion MRI at term and quantified DWMA volume with our novel, semi-automated algorithm. From diffusion-weighted structural connectomes, we calculated the graph theory metrics local efficiency and clustering coefficient, which measure the ability of groups of nodes to perform specialized processing, and global efficiency, which assesses the ability of brain regions to efficiently combine information. We computed partial correlations between these measures and DWMA volume, adjusted for confounders. Increasing DWMA volume was associated with decreased global efficiency of the entire very preterm brain and decreased local efficiency and clustering coefficient in a variety of regions supporting cognitive, linguistic, and motor function. We show that DWMA is associated with widespread decreased brain network efficiency, suggesting that it is pathologic and likely has adverse developmental consequences.

Effects of intraventricular hemorrhage on white matter microstructural changes at term and early developmental outcomes in infants born very preterm

PURPOSE

Very preterm (VPT) infants are at high risk for motor and behavioral deficits. We investigated microstructural differences using diffusion tensor imaging (DTI) among VPT infants with different grades of intraventricular hemorrhage (IVH), their association with early motor function and temperament ratings, and the potential moderating effect of IVH severity on the above structure-function relations.

METHODS

Fifty-seven VPT (≤32 weeks gestational age) infants with IVH (Low Grade (Papile grading I/II): 42; High Grade (III/IV): 15) were studied. DTI was acquired between 39 and 44 weeks postmenstrual age and was analyzed using the tract-based spatial statistics approach. Early motor function and temperament were assessed at 3-month corrected age based on the Hammersmith Infant Neurological Examination (HINE) and Infant Behavioral Questionnaire - Revised, Short Version (IBQ-R-S), respectively.

RESULTS

Significantly lower fractional anisotropy and higher mean, axial, and/or radial diffusivity were found in VPT infants with High Grade IVH compared to Low Grade IVH (p < 0.05). Significant associations were found between DTI metrics and motor function in both IVH groups and between DTI and Fear temperament ratings in the High Grade IVH Group (all p < 0.05). IVH severity had a significant moderating effect on the relation between DTI and motor and Fear ratings (p < 0.05).

CONCLUSION

DTI is a sensitive neuroimaging biomarker providing a refined understanding of the impact and location of differing severities of IVH on the developing white matter of VPT infants. Early motor and behavioral outcomes are associated with microstructural changes that are influenced by severity of IVH.