Preterm birth and disruptive cerebellar development: assessment of perinatal risk factors

Brain age predicted using graph convolutional neural network explains neurodevelopmental trajectory in preterm neonates

OBJECTIVES

Dramatic brain morphological changes occur throughout the third trimester of gestation. In this study, we investigated whether the predicted brain age (PBA) derived from graph convolutional network (GCN) that accounts for cortical morphometrics in third trimester is associated with postnatal abnormalities and neurodevelopmental outcome.

METHODS

In total, 577 T1 MRI scans of preterm neonates from two different datasets were analyzed; the NEOCIVET pipeline generated cortical surfaces and morphological features, which were then fed to the GCN to predict brain age. The brain age index (BAI; PBA minus chronological age) was used to determine the relationships among preterm birth (i.e., birthweight and birth age), perinatal brain injuries, postnatal events/clinical conditions, BAI at postnatal scan, and neurodevelopmental scores at 30 months.

RESULTS

Brain morphology and GCN-based age prediction of preterm neonates without brain lesions (mean absolute error [MAE]: 0.96 weeks) outperformed conventional machine learning methods using no topological information. Structural equation models (SEM) showed that BAI mediated the influence of preterm birth and postnatal clinical factors, but not perinatal brain injuries, on neurodevelopmental outcome at 30 months of age.

CONCLUSIONS

Brain morphology may be clinically meaningful in measuring brain age, as it relates to postnatal factors, and predicting neurodevelopmental outcome.

CLINICAL RELEVANCE STATEMENT

Understanding the neurodevelopmental trajectory of preterm neonates through the prediction of brain age using a graph convolutional neural network may allow for earlier detection of potential developmental abnormalities and improved interventions, consequently enhancing the prognosis and quality of life in this vulnerable population.

KEY POINTS

•Brain age in preterm neonates predicted using a graph convolutional network with brain morphological changes mediates the pre-scan risk factors and post-scan neurodevelopmental outcomes. •Predicted brain age oriented from conventional deep learning approaches, which indicates the neurodevelopmental status in neonates, shows a lack of sensitivity to perinatal risk factors and predicting neurodevelopmental outcomes. •The new brain age index based on brain morphology and graph convolutional network enhances the accuracy and clinical interpretation of predicted brain age for neonates.

40 years neonatology : An academic life

BACKGROUND

A complete review of the development of neonatology in the last 40 years would probably require a compendium with several volumes, to bring to view the remarkable improvements in survival rates and neurodevelopmental outcomes of ill babies in Austria, most industrial countries and to some extent worldwide. The challenge I had to solve here was to integrate my own contributions to the field of neonatology during this period and particularly the contributions of my team from the Division of Neonatology and Pediatric Intensive Care Medicine, Department of Pediatrics and Adolescence Medicine, Medical University Vienna where I was working first as an intern and resident and later had the privilege to become head of department.

AIM

This very personal review was conceived to showcase the milestones of neonatology where, in my opinion, our department made some meaningful contributions in research and clinical practice during the past 40 years.

METHODS

A total of 10 areas of interest were selected which most likely influenced survival rates of preterm infants born at increasingly younger gestational ages and ameliorated long-term clinical and neurodevelopmental outcomes, including: 1) Construction and continuous modernization of neonatal intensive care units (NICUs). 2) Installation of the "Regionalization Program for NICUs in Vienna". 3) Treatment of respiratory distress syndrome (RDS) of premature babies. 4) Fine tuning of glucose metabolism for growth and outcome. 5) Neurodevelopmental care. 6) Neonatal hematology. 7) Infection control. 8) The toxoplasma screening program. 9) The newborn screening program. 10) Quality control: the Vermont Oxford Neonatal Network (VONN).

RESULTS

Over the past four decades advancements in research and technology have allowed a transformative development of neonatal medicine. Survival rates without increased morbidity for very premature infants with gestational ages reaching to what we consider nowadays the border of viability have constantly increased. In my professional life as a neonatologist in Austria I have had the possibility to support and shape some of these developments together with my team.

CONCLUSION

As we look ahead it is imperative to build upon the progress made, harnessing the power of science and technology to further improve the survival and quality of life for preterm infants in Austria and worldwide. At the same time, neonatology must continue to prioritize ethical reflection and education, fostering a culture of integrity, interdisciplinary collaboration, and the development of guidelines and protocols that uphold ethical standards while addressing the evolving needs and complexities of neonatal medicine.

Cerebellar injury in preterm infants less than 28 weeks gestational age

BACKGROUND

Cerebellar injury is one of the perinatal complications in preterm infants. Recent studies have highlighted the effect of perinatal complications on neurological morbidity. We investigated the perinatal risk factors and morbidity for cerebellar injury in extremely premature infants.

METHODS

This retrospective cohort study included 285 infants born between April 2009 and December 2020 at gestational age <28 weeks at our institution. The infants were divided into two groups based on magnetic resonance imaging findings: those with and without cerebellar injury. We performed a statistical analysis of the perinatal background and short-term morbidity of the two groups.

RESULTS

Significant differences (p < 0.05) were observed between the groups with respect to the perinatal background, especially gestational weeks, birthweight, and hemoglobin values at birth. In the short-term morbidity, significant differences (p < 0.05) were observed in the incidence of respiratory distress syndrome, chronic lung disease, hydrocephalus, severe intraventricular hemorrhage (IVH), and cerebellar hemorrhage. Extensive cerebellar lesions, such as cerebellar agenesis or global cerebellar hypoplasia, accounted for 11 of the 22 cases of cerebellar injury; seven of the 11 cases had severe IVH in addition to cerebellar hemorrhage.

CONCLUSIONS

Gestational age was significantly lower in the cerebellar injury group. The combination of severe IVH and cerebellar hemorrhage may promote cerebellar injury.

Function and dysfunction of the dystonia network: an exploration of neural circuits that underlie the acquired and isolated dystonias

Dystonia is a highly prevalent movement disorder that can manifest at any time across the lifespan. An increasing number of investigations have tied this disorder to dysfunction of a broad "dystonia network" encompassing the cerebellum, thalamus, basal ganglia, and cortex. However, pinpointing how dysfunction of the various anatomic components of the network produces the wide variety of dystonia presentations across etiologies remains a difficult problem. In this review, a discussion of functional network findings in non-mendelian etiologies of dystonia is undertaken. Initially acquired etiologies of dystonia and how lesion location leads to alterations in network function are explored, first through an examination of cerebral palsy, in which early brain injury may lead to dystonic/dyskinetic forms of the movement disorder. The discussion of acquired etiologies then continues with an evaluation of the literature covering dystonia resulting from focal lesions followed by the isolated focal dystonias, both idiopathic and task dependent. Next, how the dystonia network responds to therapeutic interventions, from the "geste antagoniste" or "sensory trick" to botulinum toxin and deep brain stimulation, is covered with an eye towards finding similarities in network responses with effective treatment. Finally, an examination of how focal network disruptions in mouse models has informed our understanding of the circuits involved in dystonia is provided. Together, this article aims to offer a synthesis of the literature examining dystonia from the perspective of brain networks and it provides grounding for the perspective of dystonia as disorder of network function.

Brain Abnormalities in Patients with Germline Variants in H3F3: Novel Imaging Findings and Neurologic Symptoms Beyond Somatic Variants and Brain Tumors

BACKGROUND AND PURPOSE

Pathogenic somatic variants affecting the genes Histone 3 Family 3A and 3B (H3F3) are extensively linked to the process of oncogenesis, in particular related to central nervous system tumors in children. Recently, H3F3 germline missense variants were described as the cause of a novel pediatric neurodevelopmental disorder. We aimed to investigate patterns of brain MR imaging of individuals carrying H3F3 germline variants.

MATERIALS AND METHODS

In this retrospective study, we included individuals with proved H3F3 causative genetic variants and available brain MR imaging scans. Clinical and demographic data were retrieved from available medical records. Molecular genetic testing results were classified using the American College of Medical Genetics criteria for variant curation. Brain MR imaging abnormalities were analyzed according to their location, signal intensity, and associated clinical symptoms. Numeric variables were described according to their distribution, with median and interquartile range.

RESULTS

Eighteen individuals (10 males, 56%) with H3F3 germline variants were included. Thirteen of 18 individuals (72%) presented with a small posterior fossa. Six individuals (33%) presented with reduced size and an internal rotational appearance of the heads of the caudate nuclei along with an enlarged and squared appearance of the frontal horns of the lateral ventricles. Five individuals (28%) presented with dysgenesis of the splenium of the corpus callosum. Cortical developmental abnormalities were noted in 8 individuals (44%), with dysgyria and hypoplastic temporal poles being the most frequent presentation.

CONCLUSIONS

Imaging phenotypes in germline H3F3-affected individuals are related to brain features, including a small posterior fossa as well as dysgenesis of the corpus callosum, cortical developmental abnormalities, and deformity of lateral ventricles.

A Closer Look at a Small Brain: Transnuchal Ultrasound Facilitates High-Resolution Imaging of the Cerebellum in Preterm Infants

PURPOSE

 Very preterm infants are at risk for cerebellar injury and impaired cerebellar growth with adverse neurodevelopmental outcome. Ultrasound through the mastoid fontanel (MF) with a curved-array or sector probe is the most established method for the sonographic examination of the cerebellum. The goal of our study was to examine the validity of transnuchal ultrasound through the foramen occipitale magnum (FOM) with a linear probe for monitoring postnatal cerebellar growth.

METHODS

 Retrospective analysis of routine ultrasound scans through FOM and MF in 105 preterm infants born between 23 and 36 weeks of gestation with a birthweight of less than 1500 g.

RESULTS

 Diameters of the cerebellar hemispheres obtained through the two acoustic windows mastoid fontanel and foramen occipitale magnum showed high correlations (r's = 0.981 and 0.983, p's < 0.001). Corrected gestational age was significantly associated with transverse cerebellar diameter (TCD) on the first scan (r = 0.908, p < 0.001) as well as postnatal cerebellar growth (r = 0.920, p < 0.001). Postnatal growth was slightly decreased resulting in cerebellar growth restriction on serial scans. Both associations exceeded the calculated ratio of TCD to head circumference (r = 0.657, p < 0.001) and TCD to biparietal diameter with gestational age (r = 0.705, p < 0.001).

CONCLUSION

 Transnuchal ultrasound is feasible for examination of the preterm cerebellum and improves image quality compared to scans through the MF with higher resolution at a very short distance. Monitoring cerebellar growth during early postnatal life via transnuchal ultrasound can help to identify children at high risk for neurodevelopmental impairment.

Post-hemorrhagic ventricular dilatation: inter-observer reliability of ventricular size measurements in extremely preterm infants

BACKGROUND

Post-hemorrhagic ventricular dilatation (PHVD) in preterm infants can be assessed with ventricular size indices from cranial ultrasound. We explored inter-observer reliability of these indices for prediction of severe PHVD.

METHODS

For all 139 infants with IVH, serial neonatal ultrasound at 3 time points (days 4-7, day 14, 36 weeks PMA) were assessed independently by 3 observers with differing levels of training/experience. Ventricular index (VI), anterior horn width (AHW), and fronto-temporal horn ratio (FTHR) were measured and used to diagnose PHVD. For all, inter-observer reliability and predictive values for receipt of surgical intervention were calculated.

RESULTS

Inter-observer reliability for all observers varied from poor to excellent, with higher reliability for VI/AHW (ICC 0.49-0.84/0.51-0.81) than FTHR (0.41-0.82), particularly from the second week. Good-excellent inter-expertise reliability was found between observers with ample experience/training (0.65-0.99), particularly for VI and AHW, while poor-moderate when comparing with an inexperienced observer (0.28-0.88). Slightly higher predictive value for PHVD intervention (n = 12) was found for AHW (AUC 0.86-0.96) than for VI and FTHR (0.80-0.96/0.80-0.95).

CONCLUSIONS

AHW and VI are highly reproducible in experienced hands compared to FTHR, with AHW from the second week onwards being the strongest predictor for receiving surgical intervention for severe PHVD. AHW may aid in early PHVD diagnosis and decision-making on intervention.

IMPACT

While ventricular size indices from serial cUS are superior to clinical signs of increased intracranial pressure to assess PHVD, questions remained on their inter-observer reproducibility and reliability to predict severity of PHVD. AHW and VI are highly reproducible when performed by experienced clinicians. AHW from the second week of birth is the strongest predictor of PHVD onset and severity. AHW, combined with VI, may aid in early PHVD diagnosis and decision-making on need for surgical intervention. Consistent use of these indices has the potential to improve PHVD management and therewith the long-term outcomes in preterm infants.

Abnormal Cerebellar Development in Autism Spectrum Disorders

Autism spectrum disorders (ASD) comprise a group of heterogeneous neurodevelopmental conditions characterized by impaired social interactions and repetitive behaviors with symptom onset in early infancy. The genetic risks for ASD have long been appreciated: concordance of ASD diagnosis may be as high as 90% for monozygotic twins and 30% for dizygotic twins, and hundreds of mutations in single genes have been associated with ASD. Nevertheless, only 5-30% of ASD cases can be explained by a known genetic cause, suggesting that genetics is not the only factor at play. More recently, several studies reported that up to 40% of infants with cerebellar hemorrhages and lesions are diagnosed with ASD. These hemorrhages are overrepresented in severely premature infants, who are born during a period of highly dynamic cerebellar development that encompasses an approximately 5-fold size expansion, an increase in structural complexity, and remarkable rearrangements of local neural circuits. The incidence of ASD-causing cerebellar hemorrhages during this window supports the hypothesis that abnormal cerebellar development may be a primary risk factor for ASD. However, the links between developmental deficits in the cerebellum and the neurological dysfunctions underlying ASD are not completely understood. Here, we discuss key processes in cerebellar development, what happens to the cerebellar circuit when development is interrupted, and how impaired cerebellar function leads to social and cognitive impairments. We explore a central question: Is cerebellar development important for the generation of the social and cognitive brain or is the cerebellum part of the social and cognitive brain itself?

Rare Abnormality of the Posterior Fossa: Unilateral İsolated Cerebellar Hypoplasia

The cerebellum abnormalities may be hypoplastic, dysplastic, or hypoplastic. It is very rare that the cerebellar hemisphere is affected unilaterally in the posterior fossa abnormalities. The reason for this effect is mostly sequela. This pathology presents with neuromotor developmental abnormalities. In this presentation, isolated left cerebellar hypoplasia is described radiologically in a 21-month-old male patient with neuromotor development defects. Dysplastic appearance was noticeable in the observable part of the left cerebellar hemisphere and folia. The cerebellar vermis could not be shaped. The right cerebellar hemisphere, other posterior fossa formations, and supratentorial area were natural. In patients with neuromuscular abnormalities, the posterior fossa is applied with care. It should be remembered that cerebellar hypoplasia and dysplasia can be unilateral.

Preterm Birth Impedes Structural and Functional Development of Cerebellar Purkinje Cells in the Developing Baboon Cerebellum

Human cerebellar development occurs late in gestation and is hindered by preterm birth. The fetal development of Purkinje cells, the primary output cells of the cerebellar cortex, is crucial for the structure and function of the cerebellum. However, morphological and electrophysiological features in Purkinje cells at different gestational ages, and the effects of neonatal intensive care unit (NICU) experience on cerebellar development are unexplored. Utilizing the non-human primate baboon cerebellum, we investigated Purkinje cell development during the last trimester of pregnancy and the effect of NICU experience following premature birth on developmental features of Purkinje cells. Immunostaining and whole-cell patch clamp recordings of Purkinje cells in the baboon cerebellum at different gestational ages revealed that molecular layer width, driven by Purkinje dendrite extension, drastically increased and refinement of action potential waveform properties occurred throughout the last trimester of pregnancy. Preterm birth followed by NICU experience for 2 weeks impeded development of Purkinje cells, including action potential waveform properties, synaptic input, and dendrite extension compared with age-matched controls. In addition, these alterations impact Purkinje cell output, reducing the spontaneous firing frequency in deep cerebellar nucleus (DCN) neurons. Taken together, the primate cerebellum undergoes developmental refinements during late gestation, and NICU experience following extreme preterm birth influences morphological and physiological features in the cerebellum that can lead to functional deficits.

Resilience and Vulnerability: Neurodevelopment of Very Preterm Children at Four Years of Age

Children born very preterm (VPT) are at high-risk for altered brain development and impaired neurodevelopmental outcomes but are not well-studied before school-age. We investigated 64 four-year-olds: 37 VPT children [<32 weeks gestational age [GA]; 22 males; mean GA: 28.8 weeks ± 1.6], 25 full-term (FT) children (12 males), plus two VPT cases with ventriculomegaly and exceptionally resilient outcomes. All children underwent high-resolution structural magnetic resonance imaging and developmental assessments. Measures of brain volume, cortical thickness, and surface area were obtained. Children born VPT demonstrated reduced cerebral and cerebellar white matter volumes yet increased cerebral gray matter, temporal lobe, occipital lobe and ventricle volumes after adjusting for total brain volume. Cortical thickness was greater in the VPT children compared to FT children across all lobes. On developmental assessments, the VPT children scored lower on average than FT children while the two cases had intact cognitive abilities. In addition to larger ventricle volumes, the two cases had white matter and gray matter volumes within the ranges of the FT children. The VPT children displayed distinct differences in structural brain volumes at 4 years of age, consistent with delayed maturation. The cases with persistent ventriculomegaly and good cognitive outcomes displayed typical gray matter and increased white matter volumes, indicating a potential protective developmental phenomenon contributing to their intact cognitive abilities.

Resilience and Vulnerability: Neurodevelopment of Very Preterm Children at Four Years of Age

Children born very preterm (VPT) are at high-risk for altered brain development and impaired neurodevelopmental outcomes but are not well-studied before school-age. We investigated 64 four-year-olds: 37 VPT children [<32 weeks gestational age [GA]; 22 males; mean GA: 28.8 weeks ± 1.6], 25 full-term (FT) children (12 males), plus two VPT cases with ventriculomegaly and exceptionally resilient outcomes. All children underwent high-resolution structural magnetic resonance imaging and developmental assessments. Measures of brain volume, cortical thickness, and surface area were obtained. Children born VPT demonstrated reduced cerebral and cerebellar white matter volumes yet increased cerebral gray matter, temporal lobe, occipital lobe and ventricle volumes after adjusting for total brain volume. Cortical thickness was greater in the VPT children compared to FT children across all lobes. On developmental assessments, the VPT children scored lower on average than FT children while the two cases had intact cognitive abilities. In addition to larger ventricle volumes, the two cases had white matter and gray matter volumes within the ranges of the FT children. The VPT children displayed distinct differences in structural brain volumes at 4 years of age, consistent with delayed maturation. The cases with persistent ventriculomegaly and good cognitive outcomes displayed typical gray matter and increased white matter volumes, indicating a potential protective developmental phenomenon contributing to their intact cognitive abilities.

Impact of prematurity on neurodevelopment

The consequences of prematurity on brain functional development are numerous and diverse, and impact all brain functions at different levels. Prematurity occurs between 22 and 36 weeks of gestation. This period is marked by extreme dynamics in the physiologic maturation, structural, and functional processes. These different processes appear sequentially or simultaneously. They are dependent on genetic and/or environmental factors. Disturbance of these processes or of the fine-tuning between them, when caring for premature children, is likely to induce disturbances in the structural and functional development of the immature neural networks. These will appear as impairments in learning skills progress and are likely to have a lasting impact on the development of children born prematurely. The level of severity depends on the initial alteration, whether structural or functional. In this chapter, after having briefly reviewed the neurodevelopmental, structural, and functional processes, we describe, in a nonexhaustive manner, the impact of prematurity on the different brain, motor, sensory, and cognitive functions.

Age-Dependent White Matter Characteristics of the Cerebellar Peduncles from Infancy Through Adolescence

Cerebellum-cerebrum connections are essential for many motor and cognitive functions and cerebellar disorders are prevalent in childhood. The middle (MCP), inferior (ICP), and superior cerebellar peduncles (SCP) are the major white matter pathways that permit communication between the cerebellum and the cerebrum. Knowledge about the microstructural properties of these cerebellar peduncles across childhood is limited. Here, we report on a diffusion magnetic resonance imaging tractography study to describe age-dependent characteristics of the cerebellar peduncles in a cross-sectional sample of infants, children, and adolescents from newborn to 17 years of age (N = 113). Scans were collected as part of clinical care; participants were restricted to those whose scans showed no abnormal findings and whose history and exam had no risk factors for cerebellar abnormalities. A novel automated tractography protocol was applied. Results showed that mean tract-FA increased, while mean tract-MD decreased from infancy to adolescence in all peduncles. Rapid changes were observed in both diffusion measures in the first 24 months of life, followed by gradual change at older ages. The shape of the tract profiles was similar across ages for all peduncles. These data are the first to characterize the variability of diffusion properties both across and within cerebellar white matter pathways that occur from birth through later adolescence. The data represent a rich normative data set against which white matter alterations seen in children with posterior fossa conditions can be compared. Ultimately, the data will facilitate the identification of sensitive biomarkers of cerebellar abnormalities.

Cerebellar hypoplasia of prematurity: Causes and consequences

As magnetic resonance imaging has been increasingly used to study brain injury and brain development in premature newborns, the prevalence of cerebellar abnormalities is increasingly recognized. The preterm cerebellum is highly vulnerable to a number of insults during its critical phase of growth and development throughout the period of prematurity and beyond. Direct cerebellar injury and additional factors such as supratentorial brain injury and glucocorticoid exposure adversely impact cerebellar growth and, consequently, increase the risk of neurodevelopmental disabilities. In this chapter the causes and consequences of cerebellar hypoplasia of prematurity are reviewed.

Preterm brain injury: Germinal matrix-intraventricular hemorrhage and post-hemorrhagic ventricular dilatation

Germinal matrix hemorrhage and intraventricular hemorrhages (GMH-IVH) remain a common and clinically significant problem in preterm infants, particularly extremely preterm infants. A large GMH-IVH is often complicated by posthemorrhagic ventricular dilation (PHVD) or parenchymal hemorrhagic infarction and is associated with an increased risk of adverse neurologic sequelae. The widespread use of cranial ultrasonography since the early 1980s has shown a gradual decrease in the incidence of GMH-IVH and has helped with the identification of antenatal and perinatal risk factors and timing of the lesion. The increased use of magnetic resonance imaging (MRI) has contributed to more detailed visualization of the site and extent of the GMH-IVH. In addition, MRI has contributed to the awareness of associated white matter changes as well as associated cerebellar hemorrhages. Although GMH-IVH and PHVD still cannot be prevented, cerebrospinal fluid drainage initiated in the early stage of PHVD development seems to be associated with a better neurodevelopmental outcome. Further studies are underway to improve treatment strategies for PHVD and to potentially prevent and repair GMH-IVH and PHVD and associated brain injury. This chapter discusses the pathogenesis, incidence, risk factors, and management, including preventive measures, of GHM-IVH and PHVD.

Cerebellar Ataxia in Children: A Clinical and MRI Approach to the Differential Diagnosis

: The cerebellum has long been recognized as a fundamental structure in motor coordination. Structural cerebellar abnormalities and diseases involving the cerebellum are relatively common in children. The not always specific clinical presentation of ataxia, incoordination, and balance impairment can often be a challenge to attain a precise diagnosis. Continuous advances in genetic research and moreover the constant development in neuroimaging modalities, particularly in the field of magnetic resonance imaging, have promoted a better understanding of cerebellar diseases and led to several modifications in their classification in recent years. Thorough clinical and neuroimaging investigation is recommended for proper diagnosis. This review outlines an update of causes of cerebellar disorders that present clinically with ataxia in the pediatric population. These conditions were classified in 2 major groups, namely genetic malformations and acquired or disruptive disorders recognizable by neuroimaging and subsequently according to their features during the prenatal and postnatal periods.

Mild cerebellar injury does not significantly affect cerebral white matter microstructural organization and neurodevelopmental outcome in a contemporary cohort of preterm infants

BackgroundPreterm birth is associated with an increased risk of cerebellar injury. The aim of this study was to assess the impact of cerebellar hemorrhages (CBH) on cerebral white matter microstructural tissue organization and cerebellar volume at term-equivalent age (TEA) in extremely preterm infants. Furthermore, we aimed to evaluate the association between CBH and neurodevelopmental outcome in late infancy.MethodsA total of 24 preterm infants with punctate CBH were included and each matched to two preterm control infants. T1-, T2-weighted images and diffusion-weighted imaging were acquired on a 3T magnetic resonance imaging (MRI) system. Regions of interest were drawn on a population-specific neonatal template and automatically registered to individual fractional anisotropy (FA) maps. Brain volumes were automatically computed. Neurodevelopmental outcome was assessed using the Bayley scales of Infant and Toddler Development at 2 years of corrected age.ResultsCBHs were not significantly related to FA in the posterior limb of the internal capsule and corpus callosum or to cerebellar volume. Infants with CBH did not have poorer neurodevelopmental outcome compared with control infants.ConclusionThese findings suggest that the impact of mild CBH on early macroscale brain development may be limited. Future studies are needed to assess the effects of CBH on long-term neurodevelopment.

Posthemorrhagic ventricular dilatation in preterm infants: When best to intervene?

OBJECTIVE

To compare neurodevelopmental outcomes of preterm infants with and without intervention for posthemorrhagic ventricular dilatation (PHVD) managed with an "early approach" (EA), based on ventricular measurements exceeding normal (ventricular index [VI] <+2 SD/anterior horn width <6 mm) with initial temporizing procedures, followed, if needed, by permanent shunt placement, and a "late approach" (LA), based on signs of increased intracranial pressure with mostly immediate permanent intervention.

METHODS

Observational cohort study of 127 preterm infants (gestation <30 weeks) with PHVD managed with EA (n = 78) or LA (n = 49). Ventricular size was measured on cranial ultrasound. Outcome was assessed at 18-24 months.

RESULTS

Forty-nine of 78 (63%) EA and 24 of 49 (49%) LA infants received intervention. LA infants were slightly younger at birth, but did not differ from EA infants for other clinical measures. Initial intervention in the EA group occurred at younger age (29.4/33.1 week postmenstrual age; p < 0.001) with smaller ventricles (VI 2.4/14 mm >+2 SD; p < 0.01), and consisted predominantly of lumbar punctures or reservoir taps. Maximum VI in infants with/without intervention was similar in EA (3/1.5 mm >+2 SD; p = 0.3) but differed in the LA group (14/2.1 mm >+2 SD; p < 0.001). Shunt rate (20/92%; p < 0.001) and complications were lower in EA than LA group. Most EA infants had normal outcomes (>-1 SD), despite intervention. LA infants with intervention had poorer outcomes than those without (p < 0.003), with scores <-2 SD in 81%.

CONCLUSION

In preterm infants with PHVD, those with early intervention, even when eventually requiring a shunt, had outcomes indistinguishable from those without intervention, all being within the normal range. In contrast, in infants managed with LA, need for intervention predicted worse outcomes. Benefits of EA appear to outweigh potential risks.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that for preterm infants with PHVD, an EA to management results in better neurodevelopmental outcomes than a LA.

Ultrasound and CT of the posterior fossa in neonates

Ultrasound, CT and MRI may all be used in the evaluation of the posterior fossa in neonates depending on the clinical scenario. Ultrasonography is particularly valuable for the evaluation of the neonatal brain because of the lack of ionizing radiation and the ability to perform exams at the bedside and, importantly, advancements in ultrasound technology now allow for diagnostic-quality imaging. While CT is still the initial imaging modality of choice in most neurologic emergencies, in the neonate, ultrasound is the first line in nontraumatic emergencies. The goal of this chapter is to discuss the ultrasound technique for evaluation of the cerebellum, to describe the normal sonographic and CT appearance of posterior fossa and to provide the classical findings of the most common cerebellar abnormalities. While ultrasound is able to accurately diagnosis a majority of cerebellar abnormalities in neonates, subsequent MR imaging remains essential to confirm findings and to detect associated abnormalities.

Systemic inflammation combined with neonatal cerebellar haemorrhage aggravates long-term structural and functional outcomes in a mouse model

BACKGROUND

Despite the increased recognition of cerebellar injury in survivors of preterm birth, the neurodevelopmental consequences of isolated cerebellar injury have been largely unexplored and our current understanding of the functional deficits requires further attention in order to translate knowledge to best practices. Preterm infants are exposed to multiple stressors during their postnatal development including perinatal cerebellar haemorrhage (CBH) and postnatal infection, two major risk factors for neurodevelopmental impairments.

METHODS

We developed a translational mouse model of CBH and/or inflammation to measure the short- and long-term outcomes in cerebellar structure and function.

RESULTS

Mice exposed to early combined insults of CBH and early inflammatory state (EIS) have a delay in grasping acquisition, neonatal motor deficits and deficient long-term memory. CBH combined with late inflammatory state (LIS) does not induce neonatal motor problems but leads to poor fine motor function and long-term memory deficits at adulthood. Early combined insults result in poor cerebellar growth from postnatal day 15 until adulthood shown by MRI, which are reflected in diminished volumes of cerebellar structures. There are also decreases in volumes of gray matter and hippocampus. Cerebellar microgliosis appears 24h after the combined insults and persists until postnatal day 15 in the cerebellar molecular layer and cerebellar nuclei in association with a disrupted patterning of myelin deposition, a delay of oligodendrocyte maturation and reduced white matter cerebellar volume.

CONCLUSIONS

Together, these findings reveal poor outcomes in developing brains exposed to combined cerebellar perinatal insults in association with cerebellar hypoplasia, persistence of microgliosis and alterations of cerebellar white matter maturation and growth.

Cerebellar Exposure to Cell-Free Hemoglobin Following Preterm Intraventricular Hemorrhage: Causal in Cerebellar Damage?

Decreased cerebellar volume is associated with intraventricular hemorrhage (IVH) in very preterm infants and may be a principal component in neurodevelopmental impairment. Cerebellar deposition of blood products from the subarachnoid space has been suggested as a causal mechanism in cerebellar underdevelopment following IVH. Using the preterm rabbit pup IVH model, we evaluated the effects of IVH induced at E29 (3 days prior to term) on cerebellar development at term-equivalent postnatal day 0 (P0), term-equivalent postnatal day 2 (P2), and term-equivalent postnatal day 5 (P5). Furthermore, the presence of cell-free hemoglobin (Hb) in cerebellar tissue was characterized, and cell-free Hb was evaluated as a causal factor in the development of cerebellar damage following preterm IVH. IVH was associated with a decreased proliferative (Ki67-positive) portion of the external granular layer (EGL), delayed Purkinje cell maturation, and activated microglia in the cerebellar white matter. In pups with IVH, immunolabeling of the cerebellum at P0 demonstrated a widespread presence of cell-free Hb, primarily distributed in the white matter and the molecular layer. Intraventricular injection of the Hb scavenger haptoglobin (Hp) resulted in a corresponding distribution of immunolabeled Hp in the cerebellum and a partial reversal of the damaging effects observed following IVH. The results suggest that cell-free Hb is causally involved in cerebellar damage following IVH and that blocking cell-free Hb may have protective effects.

Brainstem shape is affected by clinical course in the neonatal intensive care unit

The brainstem, critical for motor function, autonomic regulation, and many neurocognitive functions, undergoes rapid development from the third trimester. Accordingly, we hypothesized it would be vulnerable to insult during this period, and that a difficult clinical course in the neonatal intensive care unit (NICU) would affect development, and be reflected through atypical shape. Our study population consisted of 66 neonates - all inpatients from the NICU at Victoria Hospital, London Health Sciences Centre, ON, Canada, of which 45 entered the final analysis. The cohort varied in gestational age (GA) and ranged from neurologically healthy to severely brain-injured. Structural MRI was used to quantify brainstem shape at term-equivalent age. From these images, brainstems were semi-automatically segmented and co-registered across subjects. The anterior-posterior dimensions on a sagittal maximum intensity projection were used as the basis for shape comparison. Factor analysis was used to summarize variation in shape and in clinical course to determine three shape factors and three clinical factors, and their relationship assessed using correlation. A factor driven by low GA and associated complications correlated with alterations in the posterior medulla, while a factor driven by complications independent of GA correlated with alterations in the midbrain. Additionally, single clinical measures most representative of their respective clinical factor (days in NICU; days on ventilation) predicted the changes. Thus, different clinical courses in the NICU may have different effects on the shape of the brainstem, and may mediate some of the distinct neurodevelopmental profiles observed in premature and brain-injured neonates.

A rare case of cerebellar agenesis: a probabilistic Constrained Spherical Deconvolution tractographic study

Aim of this study is to show the potential of probabilistic tractographic techniques, based on the Constrained Spherical Deconvolution (CSD) algorithms, in recognizing white matter fiber bundle anomalies in patients with complex cerebral malformations, such as cerebellar agenesis. The morphological and tractographic study of a 17-year-old male patient affected by cerebellar agenesis was performed by using a 3Tesla MRI scanner. Genetic and neuropsychological tests were carried out. An MRI morphological study showed the absence of both cerebellar hemispheres and the flattening of the anterior side of the pons. Moreover, it showed a severe vermian hypoplasia with a minimal vermian residual. The study recognized two thin cerebellar remnants, medially in contact with the small vermian residual, at the pontine level. The third ventricle, morphologically normal, communicated with a permagna cerebello-medullary cistern. Probabilistic CSD tractography identified some abnormal and aberrant infratentorial tracts, symmetrical on both sides. In particular, the transverse pontine fibers were absent and the following tracts with aberrant trajectories have been identified: "cerebello-thalamic" tracts; "fronto-cerebellar" tracts; and ipsilateral and contralateral "spino-cerebellar" tracts. Abnormal tracts connecting the two thin cerebellar remnants have also been detected. There were no visible alterations in the main supratentorial tracts in either side. Neuropsychiatric evaluation showed moderate cognitive-motor impairment with discrete adaptive compensation. Probabilistic CSD tractography is a promising technique that overcome reconstruction biases of other diffusion tensor-based approaches and allowed us to recognize, in a patient with cerebellar agenesis, abnormal tracts and aberrant trajectories of normally existing tracts.

Novel insights from quantitative imaging of the developing cerebellum

There is increasing evidence that points to the central role of the cerebellum in many areas of human behaviour - in health and in illness. The findings reviewed here shed further light on the developmental vulnerability of cerebellar cell types, and highlight the new imaging techniques being used in this research. This article reviews some new advances in our understanding of the normal cerebellar growth trajectory, and how this may become disturbed by pathological processes. Cerebellar development is now being implicated in many conditions, from autism and other neuropsychiatric disorders to diabetes.

Preterm birth and cerebellar neuropathology

Improved survival rates in premature infants and more sensitive neuroimaging techniques have expanded the scope of recognized neurodevelopmental disabilities in this vulnerable population and have implicated a role for cerebellar pathology in their origin. Although supratentorial pathologies are well studied, cerebellar pathology has been under-recognized in premature infants. The purpose of this review is to provide a concise description of established acquired cerebellar pathologies in premature infants including cerebellar atrophy/hypoplasia, hemorrhage, and infarction. The cerebellum develops over an extended period during which time cerebellar injury tends to occur with the potential to derail the cerebellum from its expected growth trajectory and perturb the establishment of cerebellar neural circuitry. The occurrence of cerebellar injury in this vulnerable period may have life-long implications that extend beyond the immediate damage sustained by the cerebellum, all of which needs to be considered as we research the causes and effects of neurodevelopmental disabilities in these patients.

Tract Profiles of the Cerebellar White Matter Pathways in Children and Adolescents

Intact development of cerebellar connectivity is essential for healthy neuromotor and neurocognitive development. To date, limited knowledge about the microstructural properties of the cerebellar peduncles, the major white matter tracts of the cerebellum, is available for children and adolescents. Such information would be useful as a comparison for studies of normal development, clinical conditions, or associations of cerebellar structures with cognitive and motor functions. The goal of the present study was to evaluate the variability in diffusion measures of the cerebellar peduncles within individuals and within a normative sample of healthy children. Participants were 19 healthy children and adolescents, aged 9-17 years, mean age 13.0 ± 2.3. We analyzed diffusion magnetic resonance imaging (dMRI) data with deterministic tractography. We generated tract profiles for each of the cerebellar peduncles by extracting four diffusion properties (fractional anisotropy (FA) and mean, radial, and axial diffusivity) at 30 equidistant points along each tract. We were able to identify the middle cerebellar peduncle and the bilateral inferior and superior cerebellar peduncles in all participants. The results showed that within each of the peduncles, the diffusion properties varied along the trajectory of the tracts. However, the tracts showed consistent patterns of variation across individuals; the coefficient of variation for FA across individual profiles was low (≤20%) for each tract. We observed no systematic variation of the diffusion properties with age. These cerebellar tract profiles of the cerebellar peduncles can serve as a reference for future studies of children across the age range and for children and adolescents with clinical conditions that affect the cerebellum.

Mental health and cerebellar volume during adolescence in very-low-birth-weight infants: a longitudinal study

BACKGROUND

Preterm birth at very low birth weight (VLBW) poses a risk for cerebellar abnormalities and increased psychiatric morbidity compared with reference populations. We aimed to study cerebellar volumes (grey and white matter; GM, WM) and mental health in VLBW individuals and controls at 15 and 19 years of age, as well as changes between the two time points.

METHODS

Forty VLBW (≤1500 g) and 56 control adolescents were included in the study at 15 years of age, and 44 VLBW and 60 control adolescents at 19 years of age. We had longitudinal data for 30 VLBW participants and for 37 controls. Clinical diagnoses were assessed following the schedule for affective disorders and schizophrenia for school-age children (KSADS). Psychiatric symptoms and function were further investigated with the Achenbach System of Empirically Based Assessment (ASEBA), ADHD Rating Scale-IV and the children's global assessment scale (CGAS). An automatic segmentation of cerebellar GM and WM volumes was performed in FreeSurfer. The MRI scans were obtained on the same 1.5T scanner at both ages.

RESULTS

The VLBW group had higher rates of psychiatric disorders at both ages. Cerebellar growth trajectories did not differ between VLBW adolescents and controls, regardless of psychiatric status. However, VLBW adolescents who had a psychiatric diagnosis at both ages or developed a psychiatric disorder from 15 to 19 years had maintained smaller cerebellar WM and GM volumes than controls and also smaller volumes than VLWB adolescents who were or became healthy in this period. Moreover, there were no differences in cerebellar WM and GM volumes between controls and those VLBW who were healthy or became healthy. In the VLBW group, cerebellar WM and GM volumes correlated positively with psycho-social function at both 15 and 19 years of age, and smaller GM volumes were associated with inattention at 15 years.

CONCLUSIONS

Smaller cerebellar volume in adolescents born very preterm and with VLBW may be a biomarker of increased risk of psychiatric problems in young adulthood.

Effects of Posthemorrhagic Ventricular Dilatation in the Preterm Infant on Brain Volumes and White Matter Diffusion Variables at Term-Equivalent Age

OBJECTIVE

To evaluate the differential impact of germinal matrix-intraventricular hemorrhage (GMH-IVH) and posthemorrhagic ventricular dilatation (PHVD) on brain and cerebrospinal fluid (CSF) volumes and diffusion variables in preterm born infants at term-equivalent age (TEA).

STUDY DESIGN

Nineteen infants (gestational age <31 weeks) with GMH-IVH grade II-III according to Papile et al and subsequent PHVD requiring intervention were matched against 19 controls with GMH-IVH grade II but no PHVD and 19 controls without GMH-IVH. Outcome variables on magnetic resonance imaging (MRI) including diffusion weighted imaging at TEA were volumes of white matter, cortical gray matter, deep gray matter, brainstem, cerebellum, ventricles, extracerebral CSF, total brain tissue, and intracranial volume (ICV), as well as white matter and cerebellar apparent diffusion coefficients (ADCs). Effects of GMH-IVH and PHVD on TEA-MRI measurements were evaluated using multivariable regression analysis. Brain and CSF volumes were adjusted for ICV to account for differences in bodyweight at TEA-MRI and ICV between cases and controls.

RESULTS

PHVD was independently associated with volumes of deep gray matter (β [95% CI]: -1.4 cc [-2.3; -.5]), cerebellum (-2.7 cc [-3.8; -1.6]), ventricles (+12.7 cc [7.9; 17.4]), and extracerebral CSF (-11.2 cc [-19.2; -3.3]), and with ADC values in occipital, parieto-occipital, and parietal white matter (β: +.066-.119×10(-3) mm(2)/s) on TEA-MRI (P < .05). No associations were found between GMH-IVH grade II-III and brain and CSF volumes or ADC values at TEA.

CONCLUSIONS

PHVD was negatively related to deep gray matter and cerebellar volumes and positively to white matter ADC values on TEA-MRI, despite early intervention for PHVD in the majority of the infants. These relationships were not observed for GMH-IVH.

Hindbrain regional growth in preterm newborns and its impairment in relation to brain injury

Premature birth globally affects about 11.1% of all newborns and is a risk factor for neurodevelopmental disability in surviving infants. Histology has suggested that hindbrain subdivisions grow differentially, especially in the third trimester. Prematurity-related brain injuries occurring in this period may selectively affect more rapidly developing areas of hindbrain, thus accompanying region-specific impairments in growth and ultimately neurodevelopmental deficits. The current study aimed to quantify regional growth of the cerebellum and the brainstem in preterm neonates (n = 65 with individually multiple scans). We probed associations of the regional volumes with severity of brain injury. In neonates with no imaging evidence of injury, our analysis using a mixed-effect linear model showed faster growth in the pons and the lateral convexity of anterior/posterior cerebellar lobes. Different patterns of growth impairment were found in relation to early cerebral intraventricular hemorrhage and cerebellar hemorrhage (P < 0.05), likely explaining different mechanisms through which neurogenesis is disrupted. The pattern of cerebellar growth identified in our study agreed excellently with details of cerebellar morphogenesis in perinatal development, which has only been observed in histological data. Our proposed analytic framework may provide predictive imaging biomarkers for neurodevelopmental outcome, enabling early identification and treatment of high-risk patients. Hum Brain Mapp 37:678-688, 2016. © 2015 Wiley Periodicals, Inc.

Systemic glycerol decreases neonatal rabbit brain and cerebellar growth independent of intraventricular hemorrhage

BACKGROUND

Cerebellar hypoplasia is a common problem in preterm infants and infants suffering from intraventricular hemorrhage (IVH). To evaluate the effects of IVH on cerebellar growth and development, we used a neonatal rabbit model of systemic glycerol to produce IVH.

METHODS

New Zealand White rabbit kits were surgically delivered 2 d preterm and treated with intraperitoneal glycerol (3.25-6.5 g/kg). Controls were born at term. IVH was documented by ultrasonography. Brain volumes determined by magnetic resonance imaging, cerebellar foliation, proliferation (Ki-67), and Purkinje cell density were assessed at 2 wk of life. Tissue glycerol and glutathione concentrations were measured.

RESULTS

Glycerol increased IVH, subarachnoid hemorrhages, and mortality in a dose-dependent manner. Total cerebellar volumes, cerebellar foliation, and cerebellar proliferation were decreased in a dose-dependent manner. Glycerol accumulated rapidly in blood, brain, and liver and was associated with increased glutathione concentration. All of these results were independent of IVH status.

CONCLUSION

Cerebellar hypoplasia was induced after glycerol administration in a dose-dependent manner. Given the rapid tissue accumulation of glycerol, dose-dependent decrease in brain growth, and lack of IVH effect on measured outcomes, we question the validity of this model because glycerol toxicity cannot be ruled out. A better physiological model of IVH is needed.

Preterm cerebellum at term age: ultrasound measurements are not different from infants born at term

BACKGROUND

Reduced supratentorial brain growth has been shown in preterm-born infants at term-equivalent age (TEA), but cerebellar growth may be preserved in the absence of supratentorial injury. Our study aims to compare cerebellar size assessed using cerebral ultrasound (cUS) at TEA between preterm infants and term-born controls.

METHODS

Cerebellar dimensions (including transverse cerebellar diameter (TCD), cerebellar vermis height, anteroposterior vermis diameter (APVD), and cerebellar vermis area (CVA)) were measured using Image Arena software (TomTec Imaging Systems, Unterschleissheim, Germany) in 71 infants <32-wk gestation without significant scan abnormality at TEA and in 58 term-born control infants. Intra- and interobserver agreement were evaluated.

RESULTS

In comparison with controls, preterms at TEA had smaller TCDs (4.9 vs. 5.2 cm; P < 0.001) but larger CVAs (4.7 vs. 4.3 cm(2); P < 0.005) and APVDs (2.4 vs. 2.2 cm; P < 0.001); however, these differences were no longer seen after accounting for head shape. In <28-wk gestational age infants, CVA was statistically similar to controls, as were for small-for-gestational-age infants.

CONCLUSION

Our data support neonatal sparing of preterm cerebellar growth that is measureable using cUS, and this includes the most immature and small-for-gestational-age infants. We suggest cUS can be used to assess cerebellar size at TEA, with measures of both width and height being taken into account, and thus may be a useful tool for detecting infants with poorer cerebellar growth who are at increased risk of disability.

The effect of hemorrhage on the development of the postnatal mouse cerebellum

Recent studies have shown that hemorrhagic injury in the preterm cerebellum leads to long-term neurological sequelae, such as motor, affective, and cognitive dysfunction. How cerebellar hemorrhage (CBH) affects the development and function of the cerebellum is largely unknown. Our study focuses on developing a mouse model of CBH to determine the anatomical, behavioral, and molecular phenotypes resulting from a hemorrhagic insult to the developing cerebellum. To induce CBH in the postnatal mouse cerebellum, we injected bacterial collagenase, which breaks down surrounding blood vessel walls, into the fourth ventricle at postnatal day two. We found a reduction in cerebellar size during postnatal growth, a decrease in granule cells, and persistent neurobehavioural abnormalities similar to abnormalities reported in preterm infants with CBH. We further investigated the molecular pathways that may be perturbed due to postnatal CBH and found a significant upregulation of genes in the inflammatory and sonic hedgehog pathway. These results point to an activation of endogenous mechanisms of injury and neuroprotection in response to postnatal CBH. Our study provides a preclinical model of CBH that may be used to understand the pathophysiology of preterm CBH and for potential development of preventive therapies and treatments.

Cerebellar hemorrhagic injury in premature infants occurs during a vulnerable developmental period and is associated with wider neuropathology

BACKGROUND

Cerebellar hemorrhagic injury (CHI) is being recognized more frequently in premature infants. However, much of what we know about CHI neuropathology is from autopsy studies that date back to a prior era of neonatal intensive care. To update and expand our knowledge of CHI we reviewed autopsy materials and medical records of all live-born preterm infants (<37 weeks gestation) autopsied at our institution from 1999-2010 who had destructive hemorrhagic injury to cerebellar parenchyma (n = 19) and compared them to matched non-CHI controls (n = 26).

RESULTS

CHI occurred at a mean gestational age of 25 weeks and involved the ventral aspect of the posterior lobe in almost all cases. CHI arose as a large hemorrhage or as multiple smaller hemorrhages in the emerging internal granule cell layer of the developing cortex or in the nearby white matter. Supratentorial germinal matrix hemorrhage occurred in 95% (18/19) of CHI cases compared to 54% (14/26) of control cases (p = 0.003). The cerebellar cortex frequently showed focal neuronal loss and gliosis (both 15/19, 79%) in CHI cases compared to control cases (both 1/26, 4% p < 0.0001). The cerebellar dentate had more neuronal loss (8/15, 53%) and gliosis (9/15, 60%) in CHI cases than controls (both 0/23, 0%; p < 0.0001). The inferior olivary nuclei showed significantly more neuronal loss in CHI (10/17, 59%) than in control cases (5/26, 19%) (p = 0.0077). All other gray matter sites examined showed no significant difference in the incidence of neuronal loss or gliosis between CHI and controls.

CONCLUSIONS

We favor the possibility that CHI represents a primary hemorrhage arising due to the effects of impaired autoregulation in a delicate vascular bed. The incidences of neuronal loss and gliosis in the inferior olivary and dentate nuclei, critical cerebellar input and output structures, respectively were higher in CHI compared to control cases and may represent a transsynpatic degenerative process. CHI occurs during a critical developmental period and may render the cerebellum vulnerable to additional deficits if cerebellar growth and neuronal connectivity are not established as expected. Therefore, CHI has the potential to significantly impact neurodevelopmental outcome in survivors.

Potential mechanisms of cerebellar hypoplasia in prematurity

INTRODUCTION

The cerebellum undergoes dramatic growth and maturation over the neonatal period after preterm birth and is thus particularly sensitive to impaired development due to various clinical factors.

METHODS

Impairments in growth can occur independent of cerebellar parenchymal damage, such as from local hemorrhage, resulting from reduced expression of sonic hedgehog signaling to trigger the appropriate expansion of the granule precursor cells.

RESULTS

The primary risk factors for impaired cerebellar development include postnatal glucocorticoid exposure, which has direct effects on the sonic hedgehog pathway, and supratentorial brain injury, including intraventricular hemorrhage and white matter injury, which may result in crossed cerebellar diaschisis and local toxic effects of blood products on the external granular layer. Other cardiorespiratory and nutritional factors may also exist. Impaired cerebellar development is associated with adverse outcomes in motor and cognitive development.

CONCLUSION

New approaches to care to counteract these risk factors may help improve long-term outcome after preterm birth.

Pontocerebellar hypoplasia in extreme prematurity: clinical and neuroimaging findings

The involvement of the cerebellum in unfavorable outcomes of extreme prematurity is increasingly recognized. Evidence implicates both cerebellar injury and cerebellar growth failure, which, along with supratentorial lesions, aggravate motor and developmental outcomes. We describe clinical and neuroradiologic findings of 12 extremely premature patients with acquired pontocerebellar hypoplasia (mean follow-up, 4 years). Patients' neuromotor outcomes involved combined motor abnormalities (spasticity, dystonia, and ataxia), whereas 25% were ambulatory by age 4 years. All patients exhibited developmental delays of variable degrees. One patient died at age 7.5 years. The possible etiopathogenesis, presentations, sequelae, and differential diagnoses of acquired pontocerebellar hypoplasia are discussed.

Impaired brain growth and neurodevelopment in preterm infants with posthaemorrhagic ventricular dilatation

AIM

To correlate volumetric magnetic resonance imaging at term with neurodevelopmental outcome at 2 years in infants with posthaemorrhagic ventricular dilatation. Preterm infants with posthaemorrhagic ventricular dilatation have high risk of disabilities, but the range is wide and predicting severity of motor and mental disability is difficult.

METHODS

Twenty-five preterm infants with posthaemorrhagic ventricular dilatation had cerebral magnetic resonance imaging at term age. Total and regional brain volumes were calculated using a manual segmentation technique. Bayley Scales of Infant Development II were assessed at 2 years post-term. Developmental Quotients (DQ) were calculated from Developmental Age Equivalent scores.

RESULTS

Total cerebral volume, excluding ventricles, correlated positively with Motor (r = 0.7, p < 0.0001) and Mental DQ (r = 0.4, p = 0.02). Only three of 16 infants with cerebral volume <336 cm(3) were ambulant at 2 years. Cerebellar volumes correlated strongly with Motor DQ (r = 0.6, p = 0.002) but only with Mental DQ after adjustment. Thalamic volumes correlated strongly with Motor DQ (r = 0.7, p = 0.0002).

CONCLUSION

Brain growth is significantly impaired in posthaemorrhagic ventricular dilatation. Volumetric measurements at term of total cerebral and cerebellar volume may have a role in predicting severity of disability.

[Cerebellar injury in premature infants less than 30 weeks of gestation]

Traditionally, the cerebellum has been regarded as a central component of the motor system. Recent studies suggest an important role played by the cerebellum in the development of cognitive and social functions. The objective of this study was to evaluate the incidence of cerebellar injury and to define the obstetrical, neonatal, and radiologic characteristics, as well as the functional outcomes in a population of very preterm infants.

METHODS

This retrospective study included neonates born before 30 weeks of gestational age between March 2004 and July 2007. Infants underwent MRI studies at a term-adjusted age; for each preterm infant with cerebellar injury, we identified two infants for the control group with normal MRI, matched on the basis of gestational age. We collected pertinent demographic, prenatal, and acute postnatal data for all infants. Follow-up assessment was performed at 2 years, using the Brunet-Lezine scale.

RESULTS

A total of 148 ex-preterm infants were studied. Cerebellar injury was present in 14 (9 %) cases and associated with supratentorial parenchymal injury in 90 %. Duration of ventilation was longer in children with cerebellar injury, compared to controls (19.5 days vs 16.5 days; P=0.03). The other neonatal criteria analyzed were comparable between the two groups. Global developmental, functional, and social-behavioral deficits were more common and profound in preterm infants with cerebellar injury, with no significant difference.

CONCLUSION

This study confirms the high incidence of cerebellar injury in very preterm infants and the importance of a specific neurobehavioral follow-up.

Molecular and neuroimaging findings in pontocerebellar hypoplasia type 2 (PCH2): is prenatal diagnosis possible?

The pontocerebellar hypoplasias (PCH) are a group of early-onset, autosomal recessive disorders resulting in abnormal growth and function of the brainstem and cerebellum. PCH type 2 (PCH2) is characterized by respiratory and feeding difficulties at birth, extrapyramidal dyskinesia, severe developmental impairment, progressive microcephaly and frequent death in childhood. Neuropathologic findings include diffuse cerebral gliosis with white matter changes, hypoplastic pons with depletion of neurons in the pontine nuclei, hypoplastic cerebellar hemispheres due to short cerebellar folia with poor branching, segmental loss of dentate, inferior olivary, and ventral pontine nuclei, and near absence of transverse pontine fibers with preservation of long fiber tracts and spinal anterior horn cells. On brain imaging, the cerebellar hemispheres appear very flat, and are more severely involved than the vermis. Most patients with PCH2 have mutations in TSEN54, with occasional mutations found in TSEN34 or TSEN2, genes that encode subunits of tRNA splicing endonuclease. Although this is a congenital disorder of pontocerebellar dysgenesis with fetal onset of neurodegeneration and symptoms at birth, prenatal imaging is unreliable in diagnosing this disorder in utero. We report on IVF dizygous twins with detailed prenatal imaging that failed to reveal any cerebellar abnormalities. Direct sequence analysis of TSEN54 showed homozygosity for c.919G>T, the common founder mutation in most PCH2 patients, and both parents were heterozygous for this mutation. We found no evidence of cerebellar dysgenesis on prenatal ultrasounds, but MRI tractography showed absence of pontine crossing fibers, a unique feature that might be useful for prenatal diagnosis of this condition.

Comparison of neonatal MRI examinations with and without an MR-compatible incubator: advantages in examination feasibility and clinical decision-making

PURPOSE

To assess the utility of an MRI-compatible incubator (INC) by comparing.

METHODS

In a retrospective study, the clinical and radiological aspects of 129 neonatal MRI examinations during a 3 year period were analyzed. Routine protocols including fast spin-echo T2-weighted (w) sequences, axial T1w, Gradient-echo, diffusion sequences, and 3D T1 gradient-echo sequences were performed routinely, angiography and spectroscopy were added in some cases. Diffusion-tensor imaging was done in 50% of the babies examined in the INC and 26% without INC. Sequences, adapted from fetal MR-protocols were done in infants younger than 32 gestational weeks. Benefit from MR-information with respect to further management was evaluated.

RESULTS

The number of the examinations increased (30-99), while the mean age (43-38, 8 weeks of gestational age) and weight (3308-2766 g) decreased significantly with the use of the MR-compatible incubator. The mean imaging time (34, 43-30, 29 min) decreased, with a mean of one additionally performed sequence in the INC group. All infants received sedatives according to our anaesthetic protocol preceding imaging, but a repeated dose was never necessary (10% without INC) using the INC. Regarding all cases, MR-based changes in clinical management were initiated in 58%, while in 57% of cases the initial ultrasound diagnosis was changed or further specified.

CONCLUSIONS

The use of the INC enables the MR access of unstable infants with suspect CNS problems to the management, of whom is improved by MR information to significantly higher percentage, than without INC.

Effects of gestational age and birth weight on brain volumes in healthy 9 year-old children

OBJECTIVE

To assess the effects of gestational age and birth weight on brain volumes in a population-based sample of normal developing children at the age of 9 years.

STUDY DESIGN

A total of 192 children from twin births were included in the analyses. Data on gestational age and birth weight were reported shortly after birth. Total brain, cerebellum, cerebrum, gray and white matter, and lateral ventricle volumes were assessed with structural magnetic resonance imaging. The Wechsler Intelligence Scale for Children-III was administered to assess general cognitive abilities. Structural equation modeling was used to analyze the effects of gestational age and birth weight on brain volumes.

RESULTS

Shorter gestational age was associated with a relatively smaller cerebellar volume (P = .002). This effect was independent of IQ scores. Lower birth weight was associated with lower IQ score (P = .03). Birth weight was not associated with brain volumes.

CONCLUSION

The effect of gestational age on cerebellar volume is not limited to children with very premature birth or very low birth weight, but is also present in children born >32 weeks of gestation and with birth weight >1500 g.

Morphological spectrum of prenatal cerebellar disruptions

There is increasing evidence that the cerebellum is susceptible to both prenatal infections and haemorrhages as well as being vulnerable in extremely preterm babies, but not to perinatal and postnatal hypoxic-ischaemic injuries. Starting with the imaging appearance we describe and illustrate a spectrum of prenatal cerebellar disruptions: cerebellar agenesis; unilateral cerebellar hypoplasia; unilateral cerebellar cleft; global cerebellar hypoplasia; vanishing cerebellum in myelomeningocele; and disruption of cerebellar development in preterm infants. We discuss neuroradiological characteristics, possible disruptive events, and clinical findings in the different morphological patterns. Remarkably, the same disruptive agent can cause different neuroradiological patterns, which appear likely to represent a morphological spectrum. The analysis of imaging patterns is crucial in recognising cerebellar disruptions. Recognition of cerebellar disruptions and their differentiation from cerebellar malformations is important in terms of diagnosis, prognosis, and genetic counselling.

Cerebellum of the premature infant: rapidly developing, vulnerable, clinically important

Brain abnormality in surviving premature infants is associated with an enormous amount of neurodevelopmental disability, manifested principally by cognitive, behavioral, attentional, and socialization deficits, most commonly with only relatively modest motor deficits. The most recognized contributing neuropathology is cerebral white matter injury. The thesis of this review is that acquired cerebellar abnormality is a relatively less recognized but likely important cause of neurodevelopmental disability in small premature infants. The cerebellar disease may be primarily destructive (eg, hemorrhage, infarction) or primarily underdevelopment. The latter appears to be especially common and relates to a particular vulnerability of the cerebellum of the small premature infant. Central to this vulnerability are the extraordinarily rapid and complex developmental events occurring in the cerebellum. The disturbance of development can be caused either by direct adverse effects on the cerebellum, especially the distinctive transient external granular layer, or by indirect remote trans-synaptic effects. This review describes the fascinating details of cerebellar development, with an emphasis on events in the premature period, the major types of cerebellar abnormality acquired during the premature period, their likely mechanisms of occurrence, and new insights into the relation of cerebellar disease in early life to subsequent cognitive/behavioral/attentional/socialization deficits.