Relationship Between Neonatal Brain Injury and Objective Measures of Head Trauma: A Case-Control Study

BACKGROUND AND OBJECTIVES

Neonatal brain injury is a common and devastating diagnosis conferring lifelong challenges for children and families. The role of mechanical forces applied to the head, often referred to as "birth trauma," are often considered although evidence for this association is lacking. The objective of this study was to investigate the association between common types of neonatal brain injury and scalp swelling using a novel method to quantify scalp swelling as an unbiased proxy for mechanical forces applied to the head.

METHODS

Case-control study using population-based, prospectively collected tertiary care center databases and healthy controls from the Human Connectome Development Project. Included were infants born 32-42 weeks gestational age and MRI in the first 9 days. Outcomes categories included healthy neonates, hypoxic ischemic encephalopathy (HIE) with or without brain injury, or stroke (ischemic or hemorrhagic). Volume of scalp swelling was objectively quantified by a novel imaging method blinded to brain injury. Variables included mode of delivery and use of instrumentation. Statistical tests included Kruskal-Wallis test, chi square, and multivariable and multinomial logistic regression.

RESULTS

There were 309 infants included (55% male): 72 healthy controls, 77 HIE without brain injury on MRI, 78 HIE with brain injury, and 82 with stroke (60 ischemic, 22 hemorrhagic). Scalp swelling was present in 126 (40.8%, 95% confidence interval [CI] 35.2%-46.5%) with no difference in proportions between outcome groups. Compared to healthy controls, median volume was higher in those with HIE without brain injury (17.5 mL, 95% CI 6.8-28.2), HIE with brain injury (12.1 mL, 95% CI 5.5-18.6), but not ischemic stroke (4.7 mL, 95% CI -1.2-10.6) nor hemorrhagic stroke (8.3 mL, 95% CI -2.2-18.8). Scalp swelling was associated with instrumented delivery (OR 2.1, 95% CI 1.0-4.1), but not associated with increased odds of brain injury in those with HIE (OR 1.5, 95% CI 0.76-3.30). Scalp swelling measures were highly reliable (ICC = 0.97).

DISCUSSION

"Birth trauma" quantified by scalp swelling volume was more common in infants with difficult deliveries, but not associated with greater odds of brain injury due to hypoxia or stroke. These results may help parents and practitioners to dissociate the appearance of trauma with the risk of brain injury.

Alterations in cortical morphometry of the contralesional hemisphere in children, adolescents, and young adults with perinatal stroke

Perinatal stroke causes most hemiparetic cerebral palsy and cognitive dysfunction may co-occur. Compensatory developmental changes in the intact contralesional hemisphere may mediate residual function and represent targets for neuromodulation. We used morphometry to explore cortical thickness, grey matter volume, gyrification, and sulcal depth of the contralesional hemisphere in children, adolescents, and young adults after perinatal stroke and explored associations with motor, attention, and executive function. Participants aged 6-20 years (N = 109, 63% male) with unilateral perinatal stroke underwent T1-weighted imaging. Participants had arterial ischemic stroke (AIS; n = 36), periventricular venous infarction (PVI; n = 37) or were controls (n = 36). Morphometry was performed using the Computational Anatomy Toolbox (CAT12). Group differences and associations with motor and executive function (in a smaller subsample) were assessed. Group comparisons revealed areas of lower cortical thickness in contralesional hemispheres in both AIS and PVI and greater gyrification in AIS compared to controls. Areas of greater grey matter volume and sulcal depth were also seen for AIS. The PVI group showed lower grey matter volume in cingulate cortex and less volume in precuneus relative to controls. No associations were found between morphometry metrics, motor, attention, and executive function. Cortical structure of the intact contralesional hemisphere is altered after perinatal stroke. Alterations in contralesional cortical morphometry shown in perinatal stroke may be associated with different mechanisms of damage or timing of early injury. Further investigations with larger samples are required to more thoroughly explore associations with motor and cognitive function.

Structural brain network lateralization across childhood and adolescence

Developmental lateralization of brain function is imperative for behavioral specialization, yet few studies have investigated differences between hemispheres in structural connectivity patterns, especially over the course of development. The present study compares the lateralization of structural connectivity patterns, or topology, across children, adolescents, and young adults. We applied a graph theory approach to quantify key topological metrics in each hemisphere including efficiency of information transfer between regions (global efficiency), clustering of connections between regions (clustering coefficient [CC]), presence of hub-nodes (betweenness centrality [BC]), and connectivity between nodes of high and low complexity (hierarchical complexity [HC]) and investigated changes in these metrics during development. Further, we investigated BC and CC in seven functionally defined networks. Our cross-sectional study consisted of 211 participants between the ages of 6 and 21 years with 93% being right-handed and 51% female. Global efficiency, HC, and CC demonstrated a leftward lateralization, compared to a rightward lateralization of BC. The sensorimotor, default mode, salience, and language networks showed a leftward asymmetry of CC. BC was only lateralized in the salience (right lateralized) and dorsal attention (left lateralized) networks. Only a small number of metrics were associated with age, suggesting that topological organization may stay relatively constant throughout school-age development, despite known underlying changes in white matter properties. Unlike many other imaging biomarkers of brain development, our study suggests topological lateralization is consistent across age, highlighting potential nonlinear mechanisms underlying developmental specialization.

Structural connectivity of the sensorimotor network within the non-lesioned hemisphere of children with perinatal stroke

Perinatal stroke occurs early in life and often leads to a permanent, disabling weakness to one side of the body. To test the hypothesis that non-lesioned hemisphere sensorimotor network structural connectivity in children with perinatal stroke is different from controls, we used diffusion imaging and graph theory to explore structural topology between these populations. Children underwent diffusion and anatomical 3T MRI. Whole-brain tractography was constrained using a brain atlas creating an adjacency matrix containing connectivity values. Graph theory metrics including betweenness centrality, clustering coefficient, and both neighbourhood and hierarchical complexity of sensorimotor nodes were compared to controls. Relationships between these connectivity metrics and validated sensorimotor assessments were explored. Eighty-five participants included 27 with venous stroke (mean age = 11.5 ± 3.7 years), 26 with arterial stroke (mean age = 12.7 ± 4.0 years), and 32 controls (mean age = 13.3 ± 3.6 years). Non-lesioned primary motor (M1), somatosensory (S1) and supplementary motor (SMA) areas demonstrated lower betweenness centrality and higher clustering coefficient in stroke groups. Clustering coefficient of M1, S1, and SMA were inversely associated with clinical motor function. Hemispheric betweenness centrality and clustering coefficient were higher in stroke groups compared to controls. Hierarchical and average neighbourhood complexity across the hemisphere were lower in stroke groups. Developmental plasticity alters the connectivity of key nodes within the sensorimotor network of the non-lesioned hemisphere following perinatal stroke and contributes to clinical disability.

Frontal interhemispheric structural connectivity, attention, and executive function in children with perinatal stroke

Perinatal stroke affects ∼1 in 1000 births and concomitant cognitive impairments are common but poorly understood. Rates of Attention Deficit/Hyperactivity Disorder (ADHD) are increased 5-10× and executive dysfunction can be disabling. We used diffusion imaging to investigate whether stroke-related differences in frontal white matter (WM) relate to cognitive impairments. Anterior forceps were isolated using tractography and sampled along the tract. Resulting metrics quantified frontal WM microstructure. Associations between WM metrics and parent ratings of ADHD symptoms (ADHD-5 rating scale) and executive functioning (Behavior Rating Inventory of Executive Function (BRIEF)) were explored. Eighty-three children were recruited (arterial ischemic stroke [AIS] n = 26; periventricular venous infarction [PVI] n = 26; controls n = 31). WM metrics were altered for stroke groups compared to controls. Along-tract analyses showed differences in WM metrics in areas approximating the lesion as well as more remote differences at midline and in the nonlesioned hemisphere. WM metrics correlated with parental ratings of ADHD and executive function such that higher diffusivity values were associated with poorer function. These findings suggest that underlying microstructure of frontal white matter quantified via tractography may provide a relevant biomarker associated with cognition and behavior in children with perinatal stroke.

Subcortical brain structure in children with developmental coordination disorder: A T1-weighted volumetric study

Developmental coordination disorder (DCD) is a neurodevelopmental disorder occurring in 5-6% of school-aged children. Converging evidence suggests that dysfunction within cortico-striatal and cortico-cerebellar networks may contribute to motor deficits in DCD, yet limited research has examined the brain morphology of these regions. Using T1-weighted magnetic resonance imaging the current study investigated cortical and subcortical volumes in 37 children with DCD, aged 8 to 12 years, and 48 controls of a similar age. Regional brain volumes of the thalamus, basal ganglia, cerebellum and primary motor and sensory cortices were extracted using the FreeSurfer recon-all pipeline and compared between groups. Reduced volumes within both the left and right pallidum (Left: F = 4.43, p = 0.039; Right: F = 5.24, p = 0.025) were observed in children with DCD; however, these results did not withstand correction for multiple comparisons. These findings provide preliminary evidence of altered subcortical brain structure in DCD. Future studies that examine the morphology of these subcortical regions are highly encouraged in order replicate these findings.

Cerebellar lesions disrupt spatial and temporal visual attention

The current study represents the first comprehensive examination of spatial, temporal and sustained attention following cerebellar damage. Results indicated that, compared to controls, cerebellar damage resulted in a larger cueing effect at the longest SOA - possibly reflecting a slowed the onset of inhibition of return (IOR) during a reflexive covert attention task, and reduced the ability to detect successive targets during an attentional blink task. However, there was little evidence to support the notion that cerebellar damage disrupted voluntary covert attention or the sustained attention to response task (SART). Lesion overlay data and supplementary voxel-based lesion symptom mapping (VLSM) analyses indicated that impaired performance on the reflexive covert attention and attentional blink tasks were related to damage to Crus II of the left posterior cerebellum. In addition, subsequent analyses indicated our results are not due to either general motor impairments or to damage to the deep cerebellar nuclei. Collectively these data demonstrate, for the first time, that the same cerebellar regions may be involved in both spatial and temporal visual attention.

Abstract 54: Bilateral Developmental Alterations in Cortical Morphology in Children With Perinatal Stroke

Perinatal stroke (PS) causes hemiparetic cerebral palsy (CP) and lifelong disability. Compensatory changes in the nonlesioned hemisphere may mediate residual function and represent targets for neuromodulation. Region-based approaches may reveal relationships between cortical thickness of nonlesioned primary motor/sensory cortices and motor function. This study uses surface-based morphometry to explore cortical alterations in the nonlesioned hemisphere in children after perinatal stroke. Children aged 6-19 with MRI-confirmed unilateral perinatal stroke and CP underwent T1-weighted anatomical imaging. Participants were classified as arterial ischemic stroke (AIS; n=36), periventricular venous infarction (PVI; n=38), or typically developing controls (TDC; n=53). Group differences in cortical thickness (distance between grey/white matter boundary and pial surface), grey matter volume, gyrification and sulcal depth and relationships between these morphology metrics and validated measures of motor/executive function were explored. Group comparisons revealed less cortical thickness, greater gyrification, and greater surface area in the nonlesioned hemisphere in both AIS and PVI as compared to TDC. Greater volume and sulcal depth were observed in the nonlesioned hemisphere for AIS. The PVI group showed greater volume in the cingulate cortex and less volume in the precuneus relative to TDC. The AIS group showed more widespread differences than the PVI group in volume and other cortical surface parameters when compared with TDC. Only modest correlations were observed between morphometric changes and clinical function. We suggest that broad differences in structural developmental plasticity occur in the nonlesioned hemisphere after perinatal stroke, particularly the larger lesions seen with AIS, and may represent novel targets for therapeutic neuromodulation.

Abstract P581: Neonatal Stroke is Not Associated With Birth Trauma

Acute neonatal stroke causes cerebral palsy, lifelong morbidity and mortality. Neonatal arterial ischemic stroke (NAIS) and hemorrhagic stroke (NHS) are most common. Pathophysiology is poorly understood and causation is often attributed to observed obstetrical factors such as instrumentation (forceps or vacuum) or operative delivery despite no empiric evidence supporting an association. We explored the relationship between birth trauma and neonatal stroke via population-based, prospectively collected registries in Southern Alberta, Canada. Consecutive cases of NAIS (n=59), NHS (n=20), and neonatal hypoxic-ischemic encephalopathy HIE with MRI-confirmed injury (HIE+, n=78)) were compared to neonates without injury (HIE-n=77). Cranial soft tissue swelling was objectively quantified as a trauma score from T1-weighted images using a semi-automatic segmentation method performed by two blinded investigators. Maternal, obstetrical, perinatal, and outcome variables were obtained from medical records. Multinomial regression modeling evaluated the relationship between diagnosis and birth trauma as measured by total soft tissue swelling score and diagnosis (HIE- as controls). Across the 234 infants studied, mean age at MRI (4.1+/-1.3 days) and sex (54% male) were comparable. Measurable scalp trauma was present in 93(40%), the proportion of which did not differ across groups. On univariate analysis, mean trauma scores did not differ between groups, were not associated with NHS or HIE+, and were lower for the NAIS group compared to HIE- (controls). Multinomial modeling revealed no relationship between scalp trauma and outcome. We conclude that the leading forms of acquired neonatal brain injury are not associated with objectively measured birth trauma. The term “birth trauma” should be removed from the perinatal stroke vernacular to help counsel traumatized parents and advance studies of genuine pathophysiology.

Effects of Transcranial Direct Current Stimulation on Motor Function in Children 8-12 Years With Developmental Coordination Disorder: A Randomized Controlled Trial

Background and objectives: Developmental coordination disorder (DCD) is a neurodevelopmental motor disorder occurring in 5-6% of school-aged children. It is suggested that children with DCD show deficits in motor learning. Transcranial direct current stimulation (tDCS) enhances motor learning in adults and children but is unstudied in DCD. We aimed to investigate if tDCS, paired with motor skill training, facilitates motor learning in a pediatric sample with DCD.

Methods: Twenty-eight children with diagnosed DCD (22 males, mean age: 10.62 ± 1.44 years) were randomized and placed into a treatment or sham group. Anodal tDCS was applied (1 mA, 20 min) in conjunction with fine manual training over 5 consecutive days. Children's motor functioning was assessed with the Purdue Pegboard Test and Jebsen-Taylor Hand Function Test at baseline, post-intervention and 6 weeks following intervention. Group differences in rates of motor learning and skill transfer/retention were examined using linear mixed modeling and repeated measures ANOVAs, respectively.

Results: There were no serious adverse events or drop-outs and procedures were well-tolerated. Independent of group, all participants demonstrated improved motor scores over the 5 training days [F_(69.280), p < 0.001, 95% CI (0.152, 0.376)], with no skill decay observed at retention. There was no interaction between intervention group and day [F_(2.998), p = 0.086, 95% CI (−0.020, 0.297)].

Conclusion: Children with DCD demonstrate motor learning with long-term retention of acquired skill. Motor cortex tDCS did not enhance motor learning as seen in other populations. Before conclusions of tDCS efficacy can be drawn, additional carefully designed trials with reproducible results are required.

Clinical Trial Registration:ClinicalTrials.gov: NCT03453983

Structural and functional connectivity of motor circuits after perinatal stroke: A machine learning study

Developmental neuroplasticity allows young brains to adapt via experiences early in life and also to compensate after injury. Why certain individuals are more adaptable remains underexplored. Perinatal stroke is an ideal human model of neuroplasticity with focal lesions acquired near birth in a healthy brain. Machine learning can identify complex patterns in multi-dimensional datasets. We used machine learning to identify structural and functional connectivity biomarkers most predictive of motor function. Forty-nine children with perinatal stroke and 27 controls were studied. Functional connectivity was quantified by fluctuations in blood oxygen-level dependent (BOLD) signal between regions. White matter tractography of corticospinal tracts quantified structural connectivity. Motor function was assessed using validated bimanual and unimanual tests. RELIEFF feature selection and random forest regression models identified predictors of each motor outcome using neuroimaging and demographic features. Unilateral motor outcomes were predicted with highest accuracy (8/54 features r = 0.58, 11/54 features, r = 0.34) but bimanual function required more features (51/54 features, r = 0.38). Connectivity of both hemispheres had important roles as did cortical and subcortical regions. Lesion size, age at scan, and type of stroke were predictive but not highly ranked. Machine learning regression models may represent a powerful tool in identifying neuroimaging biomarkers associated with clinical motor function in perinatal stroke and may inform personalized targets for neuromodulation.

Developmental neuroplasticity of the white matter connectome in children with perinatal stroke

OBJECTIVE

To employ diffusion imaging connectome methods to explore network development in the contralesional hemisphere of children with perinatal stroke and its relationship to clinical function. We hypothesized alterations in global efficiency of the intact hemisphere would correlate with clinical disability.

METHODS

Children with unilateral perinatal arterial (n = 26) or venous (n = 27) stroke and typically developing controls (n = 32) underwent 3T diffusion and T1 anatomical MRI and completed established motor assessments. A validated atlas coregistered to whole-brain tractography for each individual was used to estimate connectivity between 47 regions. Graph theory metrics (assortativity, hierarchical coefficient of regression, global and local efficiency, and small worldness) were calculated for the left hemisphere of controls and the intact contralesioned hemisphere of both stroke groups. Validated clinical motor assessments were then correlated with connectivity outcomes.

RESULTS

Global efficiency was higher in arterial strokes compared to venous strokes (p < 0.001) and controls (p < 0.001) and was inversely associated with all motor assessments (all p < 0.012). Additional graph theory metrics including assortativity, hierarchical coefficient of regression, and local efficiency also demonstrated consistent differences in the intact hemisphere associated with clinical function.

CONCLUSIONS

The structural connectome of the contralesional hemisphere is altered after perinatal stroke and correlates with clinical function. Connectomics represents a powerful tool to understand whole brain developmental plasticity in children with disease-specific cerebral palsy.

Abstract TMP109: Cortico-Ponto-Cerebellar Structural Connectivity in Perinatal Stroke

Introduction: Perinatal stroke (PS) causes hemiparetic cerebral palsy and lifelong disability. As an early cerebrovascular injury, typically involving injury to motor systems, PS represents an ideal model for understanding motor system development. Emerging models demonstrate widespread network alterations but the role of the cerebellum is poorly defined. We used diffusion tractography to explore the development of the cortico-ponto-cerebellar (CPC) tract in children with PS, hypothesizing an association between non-dominant CPC diffusion metrics and motor ability.

Methods: Retrospective, population-based, cross-sectional, controlled study. Participants aged 6-19 years with unilateral MRI confirmed perinatal arterial ischemic stroke (AIS; n=11) or periventricular venous infarction (PVI; n=20), and typically developing controls (TDC; n=31) had a 3T MRI including T1-weighted and diffusion imaging (32 directions; b=750s/mm 2 , 3 b0 volumes). Probabilistic tensor-based tractography was performed using the posterior limb of the internal capsule and contralateral middle cerebellar peduncle as regions of interest for seeding. Tensor-based outcomes were calculated including mean diffusivity (MD) and fractional anisotropy (FA). An asymmetry index (AI) was subsequently calculated (dominant / non-dominant values). PS participants completed motor assessments [Assisting Hand Assessment (AHA), Melbourne Assessment (MA), Box and Blocks Test (BBT)].

Results: Paired-samples t-tests revealed MD was significantly higher for non-dominant versus dominant tracts across all groups (all p<0.001), while FA did not differ (all p>0.05). MD AI differed among groups (F(2,59)=10.117, p <0.001) such that MD AI was significantly lower (less symmetrical) in AIS (AI=0.912±0.04) compared to PVI (AI=0.960±0.05, p =0.01) and TDC (AI=0.977±0.03, p <0.001). FA AI did not differ between groups (F(2,59)=1.045, p =0.358). A positive association was observed between MD AI and BBT performance in the affected hand (r=0.439, p =0.019).

Conclusion: CPC tractography in children with PS is feasible. Development of the CPC appears to be altered following perinatal stroke, the degree of which may relate to motor function.

Thalamic diaschisis following perinatal stroke is associated with clinical disability

BACKGROUND

Perinatal stroke causes most hemiparetic cerebral palsy and leads to lifelong disability. Understanding developmental neuroplasticity following early stroke is increasingly translated into novel therapies. Diaschisis refers to alterations brain structures remote from, but connected to, stroke lesions. Ipsilesional thalamic diaschisis has been described following adult stroke but has not been investigated in perinatal stroke. We hypothesized that thalamic diaschisis occurs in perinatal stroke and its degree would be inversely correlated with clinical motor function.

METHODS

Population-based, controlled cohort study. Participants were children (<19 years) with unilateral perinatal stroke (arterial ischemic stroke [AIS] or periventricular venous infarction [PVI]), anatomical magnetic resonance imaging (MRI) >6 months of age, symptomatic hemiparetic cerebral palsy, and no additional neurologic disorders. Typically developing controls had comparable age and gender proportions. T1-weighted anatomical scans were parcellated into 99 regions of interest followed by generation of regional volumes. The primary outcome was thalamic volume expressed as ipsilesional (ILTV), contralesional (CLTV) and thalamic ratio (CLTV/ILTV). Standardized clinical motor assessments were correlated with thalamic volume metrics.

RESULTS

Fifty-nine participants (12.9 years old ±4.0 years, 46% female) included 20 AIS, 11 PVI, and 28 controls. ILTV was reduced in both AIS and PVI compared to controls (p < .001, p = .029, respectively). Ipsilesional thalamic diaschisis was not associated with clinical motor function. However, CLTV was significantly larger in AIS compared to both controls and PVI (p = .005, p < .001, respectively). CLTV was inversely correlated with all four clinical motor assessments (all p < .003).

CONCLUSION

Bilateral thalamic volume changes occur after perinatal stroke. Ipsilesional volume loss is not associated with clinical motor function. Contralesional volume is inversely correlated with clinical motor function, suggesting the thalamus is involved in the known developmental plasticity that occurs in the contralesional hemisphere after early unilateral injury.

Crossed Cerebellar Atrophy in Perinatal Stroke

Background and Purpose- Perinatal stroke causes most hemiparetic cerebral palsy and lifelong disability. Crossed cerebellar atrophy (CCA) is chronic cerebellar volume loss following contralateral motor pathway injury. We hypothesized that CCA is quantifiable in perinatal stroke and associated with poor motor outcome. Methods- Term-born children with perinatal stroke, magnetic resonance imaging beyond 6 months of age, and no additional neurological disorders were recruited. Blinded scorers measured cerebellar volumes expressed as ratios (contralesional/ipsilesional), with values <1 suggesting CCA. Motor outcomes including perinatal stroke outcome measure (PSOM) motor and cognitive scores (good/poor), Assisting Hand Assessment, and Melbourne Assessment were compared with cerebellar volume measures. Results- Seventy-three children met criteria (53% male). Mean cerebellar ratios were <1.0 (0.975±0.04; range, 0.885-1.079; P<0.001) suggesting occurrence of CCA. Cerebellar ratios did not differ between stroke types or across PSOM motor outcomes. Larger ipsilesional cerebellar volume was associated with poor PSOM cognitive outcome (P=0.042), possibly with poor PSOM motor outcome (P=0.063), and overall PSOM score (P=0.034). Conclusions- CCA occurs in perinatal stroke but is not strongly associated with motor outcome. However, ipsilesional cerebellar volume is associated with poor cognitive and overall outcomes.