Cranial ultrasound in metabolic disorders presenting in the neonatal period: characteristic features and comparison with MR imaging

Prenatal molecular diagnosis of pyruvate dehydrogenase complex deficiency enables rapid initiation of ketogenic diet

Pyruvate dehydrogenase complex deficiency (PDCD) is a mitochondrial disorder of carbohydrate oxidation characterized by lactic acidosis and central nervous system involvement. Knowledge of the affected metabolic pathways and clinical observations suggest that early initiation of the ketogenic diet may ameliorate the metabolic and neurologic course of the disease. We present a case in which first trimester ultrasound identified structural brain abnormalities prompting a prenatal molecular diagnosis of PDCD. Ketogenic diet, thiamine, and N-acetylcysteine were initiated in the perinatal period with good response, including sustained developmental progress. This case highlights the importance of a robust neurometabolic differential diagnosis for prenatally diagnosed structural anomalies and the use of prenatal molecular testing to facilitate rapid, genetically tailored intervention.

Developmental anatomy of the thalamus, perinatal lesions, and neurological development

The thalamic nuclei develop before a viable preterm age. GABAergic neuronal migration is especially active in the third trimester. Thalamic axons meet cortical axons during subplate activation and create the definitive cortical plate in the second and third trimesters. Default higher-order cortical driver connections to the thalamus are then replaced by the maturing sensory networks, in a process that is driven by first-order thalamic neurons. Surface electroencephalographic activity, generated first in the subplate and later in the cortical plate, gradually show oscillations based on the interaction of the cortex with thalamus, which is controlled by the thalamic reticular nucleus. In viable newborn infants, in addition to sensorimotor networks, the thalamus already contributes to visual, auditory, and pain processing, and to arousal and sleep. Isolated thalamic lesions may present as clinical seizures. In addition to asphyxia and stroke, infection and network injury are also common. Cranial ultrasound can be used to classify neonatal thalamic injuries based on functional parcelling of the mature thalamus. We provide ample illustration and a detailed description of the impact of neonatal focal thalamic injury on neurological development, and discuss the potential for neuroprotection based on thalamocortical plasticity.

Imaging of Inherited Metabolic and Endocrine Disorders

"Inherited metabolic disorders represent a large group of disorders of which approximately 25% present in neonatal period with acute metabolic decompensation, rapid clinical deterioration, and often nonspecific imaging findings. Neonatal onset signifies the profound severity of the metabolic abnormality compared with cases with later presentation and necessitates rapid diagnosis and urgent therapeutic measures in an attempt to decrease the extent of brain injury and prevent grave neurologic sequela or death. Here, the authors discuss classification and clinical and imaging findings in a spectrum of metabolic and endocrine disorders with neonatal presentation."

High-resolution neurosonographic examination of the lenticulostriate vessels in neonates with hypoxic-ischemic encephalopathy

OBJECTIVE

To assess the feasibility of visualizing lenticulostriate vessels (LV) using a linear high-resolution ultrasound probe and characterize LV morphology to determine whether morphological alterations in LV are present in neonatal hypoxic-ischemic encephalopathy (HIE) as compared to the unaffected infants.

METHODS

We characterized LV by their echogenicity, width, length, tortuosity, and numbers of visualized stems/branches in neurosonographic examinations of 80 neonates. Our population included 45 unaffected (non-HIE) and 35 with clinical and/or imaging diagnosis of HIE. Of the neonates with clinical diagnosis of HIE, 16 had positive MRI findings for HIE (HIE+MRI) and 19 had negative MRI findings (HIE-MRI). Annotations were performed twice with shuffled data sets at a 1-month interval and intrarater reliability was assessed. Focused comparison was conducted between non-HIE, HIE+MRI and HIE-MRI neonates whose images were acquired with a high frequency linear transducer.

RESULTS

Studies acquired with the two most frequently utilized transducers significantly differed in number of branches (p = 0.002), vessel thickness (p = 0.007) and echogenicity (p = 0.009). Studies acquired with the two transducers also significantly differed in acquisition frequency (p < 0.001), thermal indices (p < 0.001) and use of harmonic imaging (p < 0.001). Groupwise comparison of vessels imaged with the most frequently utilized transducer found significantly fewer branches in HIE + MRI compared to HIE-MRI negative and non-HIE patients (p = 0.005).

CONCLUSION

LV can be visualized in the absence of pathology using modern high-resolution neurosonography. Visualization of LV branches varies between HIE + MRI, HIE-MRI neonates and controls.

ADVANCES IN KNOWLEDGE

High-resolution neurosonography is a feasible technique to assess LV morphology in healthy neonates and neonates with HIE.

Clinical and molecular data in cases of prenatal localized overgrowth disorder: major implication of genetic variants in PI3K-AKT-mTOR signaling pathway

OBJECTIVES

To describe clinical and molecular findings in a French multicenter cohort of fetuses with prenatal diagnosis of congenital abnormality and suspicion of a localized overgrowth disorder (LOD) suggestive of genetic variants in the PI3K-AKT-mTOR signaling pathway.

METHODS

We analyzed retrospectively data obtained between 1 January 2013 and 1 May 2020 from fetuses with brain and/or limb overgrowth referred for molecular diagnosis of PI3K-AKT-mTOR pathway genes by next-generation sequencing (NGS) using pathological tissue obtained by fetal autopsy. We also assessed the diagnostic yield of amniotic fluid.

RESULTS

During the study period, 21 subjects with LOD suspected of being secondary to a genetic variant of the PI3K-AKT-mTOR pathway were referred for analysis. Of these, 17 fetuses had brain overgrowth, including six with isolated megalencephaly (MEG) and 11 with hemimegalencephaly (HMEG). Of the six with MEG, germline variants were identified in four cases, in either PIK3R2, AKT3 or MTOR, and a postzygotic PIK3R2 variant was found in the other two cases. Of the 11 with HMEG, a postzygotic PIK3CA variant was found in three fetuses with extracerebral features of PIK3CA-related overgrowth spectrum, and in seven fetuses with isolated HMEG. No pathogenic variant was identified in the 11^th case with HMEG. Four fetuses with limb overgrowth also had one or more lymphatic malformations (LM) and harbored a postzygotic PIK3CA variant. NGS on cultured amniocytes performed in 10 cases, of which nine had been found positive on analysis of pathological fetal tissue, showed variants in four, in either PIK3CA, PIK3R2 or AKT3.

CONCLUSIONS

Isolated MEG or HMEG may lead to identification of genetic variants in the PI3K-AKT-mTOR signaling pathway. Cases of limb overgrowth and LM or isolated HMEG are likely associated with PIK3CA variants. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

The Effects of Prenatal Diagnosis on the Interaction of the Mother-Infant Dyad: A Longitudinal Study of Prenatal Care in the First Year of Life

Introduction

Mother-child interactions during the first years of life have a significant impact on the emotional and cognitive development of the child. In this work, we study how a prenatal diagnosis of malformation may affect maternal representations and the quality of these early interactions. To this end, we conducted a longitudinal observational study of mother-child interactions from the gestational stage until the baby completed 12 months of age.

Participants and Methods

We recruited 250 pregnant women from a local university hospital. Among them, 50 mother-infant dyads participated in all stages of the study. The study group consisted of 25 pregnant women with fetuses with some structural alteration and the control group consisted of 25 pregnant women with fetuses without structural anomalies. We collected obstetric and socio demographic data and pregnancy outcomes. Anxiety and depressive state data were collected using the COVI and Raskin Scales. We video-recorded the mother-infant interactions during several stages, including when the child was a newborn and when the child was 2, 4, 6, 9, and 12 months of age. The quality of the mother infant interactions were measured using the Coding Interactive Behavior (CIB). The interactive moments recorded on video was composed of three different activities, each one lasting appoximately 3 min, which included (1) Free Interaction, where the mother was instructed to interact "as usual" without any toy, (2) Toy Interaction, where the mother and baby played with a puppv, and (3) Song Interaction, where the mother and baby interacted while the mother sang the "Happy Birthday" song.

Results

In the gestational phase, there was a significant difference between the groups with respect to anxiety and depression scores, which were significantly higher for the study group. In the postnatal phase, we found significant differences between the groups with respect to CIB scales after the child completed 6 months of age: the study group presented significantly higher values of Maternal Sensitivity at 6 months of age, of Baby Involvement at 9 and 12 months of age, and of Dyadic Reciprocity at 6, 9, and 12 months of age, while the control group presented significantly higher values of Withdrawal of the Baby at 6 months of age, and of Dyadic Negative States at 6 and 9 months of age.

Conclusion

The support offered by the study favored the mother-infant bond and had a positive effect on the quality of interaction during the first year of life, despite the presence of prenatal diagnosis.

Neuromonitoring in Rare Disorders of Metabolism

Inborn errors of metabolism (IEM) are a unique class of genetic diseases due to mutations in genes involved in key metabolic pathways. The combined incidence of IEM has been estimated to be as high as 1:1000. Urea Cycle disorders (UCD), one class of IEM, can present with cerebral edema and represent a possible target to explore the utility of different neuromonitoring techniques during an hyperammonemic crisis. The last two decades have brought advances in the early identification and comprehensive management of UCD, including further understanding of neuroimaging patterns associated with neurocognitive function. Nonetheless, very important questions remain about the potential acute neurotoxic effects of hyperammonemia to better understand how to treat and prevent secondary brain injury. In this review, we describe existing neuromonitoring techniques that have been used in rare metabolic disorders to assess and allow amelioration of ongoing brain injury. Directions of future research should be focused on identifying new diagnostic approaches in the management of metabolic crises to optimize care and reduce long term morbidity and mortality in patients with IEM.

Superficial anatomy of the neonatal cerebrum - an ultrasonographic roadmap

Neurosonography is an essential imaging modality for assessing the neonatal brain, particularly as a screening tool to evaluate intracranial hemorrhage, hydrocephalus and periventricular leukomalacia. The primary advantages of neurosonography include portability, accessibility and lack of ionizing radiation. Its main limitations are intrinsic operator dependence and the need for an open fontanelle. Neurosonographic imaging acquisition is typically performed by placing a sector transducer over the anterior fontanelle and following sagittal and coronal sweeps. The sensitivity of neurosonography has markedly improved thanks to the adoption of modern imaging equipment, the use of dedicated head probes, and the employment of advanced diagnostic US techniques. These developments have facilitated more descriptive identification of specific cerebral anatomical details, improving understanding of the cerebral anatomy by conventional US. Such knowledge is fundamental for enhanced diagnostic sensitivity and is a key to understanding pathological states. Furthermore, familiarity with normal anatomy is crucial for understanding pathological states. Our primary goal in this review was to supplement these technological developments with a roadmap to the cerebral landscape. We accomplish this by presenting a systematic approach to using routine US for consistent identification of the most crucial cerebral landmarks, reviewing their relationship with adjacent structures, and briefly describing their primary function.

Neuroimaging Findings of Organic Acidemias and Aminoacidopathies

Although individual cases of inherited metabolic disorders are rare, overall they account for a substantial number of disorders affecting the central nervous system. Organic acidemias and aminoacidopathies include a variety of inborn errors of metabolism that are caused by defects in the intermediary metabolic pathways of carbohydrates, amino acids, and fatty acid oxidation. These defects can lead to the abnormal accumulation of organic acids and amino acids in multiple organs, including the brain. Early diagnosis is mandatory to initiate therapy and prevent permanent long-term neurologic impairments or death. Neuroimaging findings can be nonspecific, and metabolism- and genetics-based laboratory investigations are needed to confirm the diagnosis. However, neuroimaging has a key role in guiding the diagnostic workup. The findings at conventional and advanced magnetic resonance imaging may suggest the correct diagnosis, help narrow the differential diagnosis, and consequently facilitate early initiation of targeted metabolism- and genetics-based laboratory investigations and treatment. Neuroimaging may be especially helpful for distinguishing organic acidemias and aminoacidopathies from other more common diseases with similar manifestations, such as hypoxic-ischemic injury and neonatal sepsis. Therefore, it is important that radiologists, neuroradiologists, pediatric neuroradiologists, and clinicians are familiar with the neuroimaging findings of organic acidemias and aminoacidopathies. ^©RSNA, 2018.

Imaging the term neonatal brain

Brain imaging is important for the diagnosis and management of sick term neonates. Although ultrasound and computed tomography may provide some information, magnetic resonance imaging is now the brain imaging modality of choice because it is the most sensitive technique for detecting and quantifying brain abnormalities and does not expose infants to radiation. This statement describes the principles, roles and limitations of these three imaging modalities and makes recommendations for appropriate use in term neonates. The primary focus is the brain of term infants with neonatal encephalopathy, many of whom are diagnosed with hypoxic-ischemic encephalopathy.

Diagnosis of an Intraventricular Cyst Using Point-of-Care Cranial Ultrasound in the Pediatric Emergency Department

A 2-month-old previously healthy male infant presents with 2 days of unusual eye movements and increased fatigue. During evaluation in the pediatric emergency department, point-of-care cranial ultrasound identified a cyst-like mass. Subsequent magnetic resonance imaging confirmed the presence of a cyst within the third ventricle causing obstructive hydrocephalus.

Cranial Ultrasonography in Infantile Encephalitic Beriberi: A Useful First-Line Imaging Tool for Screening and Diagnosis in Suspected Cases

BACKGROUND AND PURPOSE

Brain imaging is central to the diagnosis of infantile encephalitic beriberi. Because cranial sonography findings have not been described in infantile encephalitic beriberi, our aim was to investigate its role in the diagnosis of this condition.

MATERIALS AND METHODS

We performed a retrospective review of head sonography of infants (admitted between November 1, 2014, and March 31, 2015) who presented with encephalopathy. Cranial ultrasonography scans were studied for the alteration of echogenicity of the basal ganglia.

RESULTS

Of the 145 consecutive infants who presented with encephalopathy, 58 had thiamine-responsive encephalopathy (infantile encephalitic beriberi) and 87 had encephalopathy due to other causes. Forty-eight of 145 infants with encephalopathy showed hyperechoic basal ganglia. A hyperechoic appearance of the basal ganglia on cranial ultrasonography was found to have a sensitivity of 71% (41/58) and a specificity of 92% (80/87) in diagnosing infantile encephalitic beriberi. The sensitivity of cranial sonography increased with age. It was a maximum of 93% (14/15) in the 5 months and older age group. Specificity was a maximum of 100% (18/18) in infants older than 5 months of age. Sensitivity was maximum in Wernicke encephalopathy at 90% (18/20) and least in the acidotic form at 43% (10/23). Follow-up showed gradual normalization of the hyperechoic appearance of the basal ganglia during 8 weeks in 26/41 (63%), with mild atrophy of the basal ganglia in 6/41 (15%)

CONCLUSIONS

Hyperechogenicity of the basal ganglia on cranial ultrasonography is a sensitive finding for the diagnosis of infantile encephalitic beriberi in infants who present with Wernicke encephalopathy.

Neurometabolic diseases of childhood

Metabolic diseases affecting the pediatric brain are complex conditions, the underlying mechanisms leading to structural damage are diverse and the diagnostic imaging manifestations are often non-specific; hence early, sensitive and specific diagnosis can be challenging for the radiologist. However, misdiagnosis or a delayed diagnosis can result in a devastating, irreversible injury to the developing brain. Based upon the inborn error, neurometabolic diseases can be subdivided in various groups depending on the predominantly involved tissue (e.g., white matter in leukodystrophies or leukoencephalopathies), the involved metabolic processes (e.g., organic acidurias and aminoacidopathies) and primary age of the child at presentation (e.g., neurometabolic disorders of the newborn). This manuscript summarizes these topics.

Structural brain defects

Up to 14% of patients with congenital metabolic disease may show structural brain abnormalities from perturbation of cell proliferation, migration, and/or organization. Most inborn errors of metabolism have a postnatal onset. Abnormalities from genetic disease processes have a prenatal onset. Energy impairment, substrate insufficiency, cell membrane receptor and cell signaling abnormalities, and toxic byproduct accumulation are associations between genetic disorders and structural brain anomalies. Collective imaging patterns of brain abnormalities can provide clues to the underlying etiology. We review selected metabolic diseases associated with brain malformations and highlight characteristic clinical and imaging manifestations that help narrow the differential diagnosis.

Posterior fossa abnormalities in high-risk term infants: comparison of ultrasound and MRI

Objectives

We aimed to assess the characteristics of posterior fossa (PF) abnormalities in a cohort of high-risk term neonates, as well as the diagnostic performance of cranial ultrasound (CUS) with additional mastoid fontanelle (MF) views for the detection of these abnormalities, with magnetic resonance imaging (MRI) being the reference standard.

Methods

In this retrospective study, 113 term neonates with CUS and subsequent MRI were included. Sensitivity, specificity, and predictive values of routine CUS and CUS with MF views were calculated.

Results

Posterior fossa abnormalities were diagnosed on CUS in 46 of 113 infants. MRI confirmed these findings in 43 and showed additional abnormalities in 32 infants. The sensitivity and specificity of anterior fontanelle views for major PF abnormalities as seen on MRI were 16 % and 99 %. Adding MF views increased the sensitivity of US to 82 %. The sensitivity and specificity of MF views for the detection of any (major or minor) PF abnormality were 57 % and 95 %. Especially acute hypoxic-ischemic injury and small subdural and punctate cerebellar haemorrhage remained undetected by CUS.

Conclusions

PF abnormalities are frequent in high-risk term infants. MF-CUS enables early diagnosis of major PF abnormalities. We therefore advocate to perform MF-CUS in high-risk term neonates.

Key Points

• Posterior fossa abnormalities are a frequent finding in high-risk term infants.

• Adding mastoid fontanelle views improves ultrasound detection of clinically relevant abnormalities.

• Hypoxic-ischemic injury and small posterior fossa haemorrhages are better detected with MRI.

• Cranial ultrasound examination should include mastoid fontanelle views in high-risk term neonates.

The aetiology of neonatal seizures and the diagnostic contribution of neonatal cerebral magnetic resonance imaging

AIM

The aim of this study was to delineate aetiologies and explore the diagnostic value of cerebral magnetic resonance imaging (MRI) in addition to cranial ultrasonography (cUS) in infants presenting with neonatal seizures.

METHOD

This retrospective cohort study comprised infants (gestational age 35.0-42.6wks) with seizures, confirmed by either continuous amplitude-integrated electroencephalography (aEEG) or standard EEG and admitted during a 14-year period to a level three neonatal intensive care unit (n=378; 216 males, 162 females; mean [SD] birthweight 3334g [594]). All infants underwent cUS and MRI (MRI on median of 5 days after birth, range 0-58d) within the first admission period.

RESULTS

An underlying aetiology was identified in 354 infants (93.7%). The most common aetiologies identified were hypoxic-ischaemic encephalopathy (46%), intracranial haemorrhage (12.2%), and perinatal arterial ischaemic stroke (10.6%). When comparing MRI with cUS in these 354 infants MRI showed new findings which did not become apparent on cUS, contributing to a diagnosis in 42 (11.9%) infants and providing additional information to cUS, contributing to a diagnosis in 141 (39.8%). cUS alone would have allowed a diagnosis in only 37.9% of infants (134/354).

INTERPRETATION

Cerebral MRI contributed to making a diagnosis in the majority of infants. In 11.9% of infants the diagnosis would have been missed if only cUS were used and cerebral MRI added significantly to the information obtained in 39.8% of infants. These data suggest that cerebral MRI should be performed in all newborn infants presenting with EEG- or aEEG-confirmed seizures.

Imaging manifestations of the leukodystrophies, inherited disorders of white matter

The leukodystrophies are a diverse set of inherited white matter disorders and are uncommonly encountered by radiologists in everyday practice. As a result, it is challenging to recognize these disorders and to provide a useful differential for the referring physician. In this article, leukodystrophies are reviewed from the perspective of 4 imaging patterns: global myelination delay, periventricular/deep white matter predominant, subcortical white matter predominant, and mixed white/gray matter involvement patterns. Special emphasis is placed on pattern recognition and unusual combinations of findings that may suggest a specific diagnosis.

Neonatal neuroimaging findings in inborn errors of metabolism

Individually, metabolic disorders are rare, but overall they account for a significant number of neonatal disorders affecting the central nervous system. The neonatal clinical manifestations of inborn errors of metabolism (IEMs) are characterized by nonspecific systemic symptoms that may mimic more common acute neonatal disorders like sepsis, severe heart insufficiency, or neonatal hypoxic-ischemic encephalopathy. Certain IEMs presenting in the neonatal period may also be complicated by sepsis and cardiomyopathy. Early diagnosis is mandatory to prevent death and permanent long-term neurological impairments. Although neuroimaging findings are rarely specific, they play a key role in suggesting the correct diagnosis, limiting the differential diagnosis, and may consequently allow early initiation of targeted metabolic and genetic laboratory investigations and treatment. Neuroimaging may be especially helpful to distinguish metabolic disorders from other more common causes of neonatal encephalopathy, as a newborn may present with an IEM prior to the availability of the newborn screening results. It is therefore important that neonatologists, pediatric neurologists, and pediatric neuroradiologists are familiar with the neuroimaging findings of metabolic disorders presenting in the neonatal time period.

State-of-the-art cranial sonography: Part 2, pitfalls and variants

OBJECTIVE

In the first part of this article, modern cranial sonography techniques and interpretation were discussed, emphasizing ways in which the application of modern imaging technology and techniques are able to enhance detection of pathologic abnormalities on cranial sonography.

CONCLUSION

In this part of the article, we will describe pitfalls and variants that may be confused with pathologic abnormalities. Emphasis will be placed on recognizing normal variations and distinguishing them from pathologic abnormalities that may require additional imaging or clinical follow-up.

Patterns of neonatal hypoxic-ischaemic brain injury

Enormous progress has been made in assessing the neonatal brain, using magnetic resonance imaging (MRI). In this review, we will describe the use of MRI and proton magnetic resonance spectroscopy in detecting different patterns of brain injury in (full-term) human neonates following hypoxic–ischaemic brain injury and indicate the relevance of these findings in predicting neurodevelopmental outcome.

Patterns of neonatal hypoxic-ischaemic brain injury

Enormous progress has been made in assessing the neonatal brain, using magnetic resonance imaging (MRI). In this review, we will describe the use of MRI and proton magnetic resonance spectroscopy in detecting different patterns of brain injury in (full-term) human neonates following hypoxic-ischaemic brain injury and indicate the relevance of these findings in predicting neurodevelopmental outcome.

Routine TORCH screening is not warranted in neonates with subependymal cysts

BACKGROUND

Congenital infections are associated with a wide variety of clinical symptoms, including subependymal cysts (SEC).

OBJECTIVE

To determine the co-occurrence of SEC and congenital infections, as diagnosed by TORCH serologic tests and/or cytomegalovirus (CMV) urine culture.

METHODS

We performed a retrospective study of all neonates admitted to our neonatal intensive care unit from 1998 to 2009 in whom SEC were detected on cranial ultrasound and TORCH serologic tests and/or CMV urine cultures were performed.

RESULTS

Fifty-nine neonates fulfilled the inclusion criteria. TORCH serologic tests were performed in 69% (41/59) of cases. Urine CMV culture was performed in 68% (40/59) of cases. None of the neonates tested positive for IgM Toxoplasma gondii, Rubella and Herpes simplex virus. Positive CMV IgM titers and/or a positive urine CMV culture were detected in 2% (1/59) of neonates.

CONCLUSION

The co-occurrence of TORCH congenital infections in infants with SEC is rare. Routine TORCH screening in neonates with SEC does not seem warranted.

Cranial ultrasonography in neonates: role and limitations

In experienced hands, cranial ultrasonography (cUS) is an excellent tool to detect the most frequently occurring brain abnormalities in preterm and full-term neonates, to study the evolution of lesions, and to follow brain maturation. It enables screening of the brain and serial imaging in high-risk neonates. However, cUS also has limitations and magnetic resonance imaging is needed in most neonates with (suspected) parenchymal brain injury and/or neurological symptoms and in very preterm infants. In this review, we discuss the applications, possibilities, indications, predictive value, and limitations of neonatal cUS. We will pay attention to the standard cUS procedure and expand on optimizing the possibilities of cUS by using supplemental acoustic windows and changing transducers and focus points. For illustration numerous cUS images are provided.

Tethered cord, corpus callosum abnormalities, and periventricular cysts in Wolf-Hirschhorn syndrome. Report of two cases and review of the literature

Wolf-Hirschhorn syndrome (4p-) is a rare disorder with characteristic physical findings. Neuroimaging findings are relatively scarce. We performed a literature search and found 22 reports of neuroimaging findings. We present findings in our two cases, each with the previously unreported finding of a tethered cord. The most common abnormalities were of the corpus callosum, occurring in 71% of all cases. There appears to be a high association in the syndrome between corpus callosal abnormalities and periventricular cysts formation in the first year of life. These cysts eventually fuse with the frontal horns during late infancy with enlargement of the frontal horns. Absence of other causes for periventricular cyst formation, such as perinatal distress, prematurity, or cytomegalovirus infection, appears to strengthen the association. With further studies, neuroimaging findings may eventually assist in the diagnosis of patients with Wolf-Hirschhorn syndrome.

Evolving understanding of hypoxic-ischemic encephalopathy in the term infant

Our aim was to document changes in the evaluation and prognosis of term-born infants with neonatal encephalopathy of hypoxic-ischemic origin, with particular reference to our own experiences and influences, and to summarize the debate on causation and the relative importance of antenatal and perinatal factors. High quality neonatal cranial ultrasound and magnetic resonance imaging and spectroscopy have enabled the accurate early visualization of different patterns of hypoxic-ischemic brain injury and prediction of their associated outcomes. Long-term follow-up shows that cognitive and memory difficulties may follow even in children without motor deficits. The very early use of electrophysiologic methods has allowed broad prognostic categorization of infants when this is not possible from clinical assessment or imaging, providing a rationale for entry into intervention trials, such as therapeutic hypothermia. This work has also shown that most of these infants have evidence of acute hypoxic-ischemic brain injury that explains their symptoms and outcomes.

Inborn errors of metabolism for the diagnostic radiologist

Inherited metabolic disorders are becoming more important with the increasing availability of diagnostic methods and therapies for these conditions. The radiologist has become an important link in making the diagnosis or collaborating with the specialist centre to diagnose these disorders and monitor effects of therapy. The modes of presentation, disease-specific groups, classic radiological features and investigations are explored in this article to try and give the general radiologist some crucial background knowledge. The following presentations are covered: acute intoxication, hypoglycaemia, developmental delay and storage features. Specific groups of disorders covered are the abnormalities of intermediary metabolism, disorders of fatty acid oxidation and ketogenesis, mitochondrial disorders, lysosomal storage disorders, and, briefly, other groups such as peroxisomal disorders, disorders of glycosylation, and creatine synthesis disorders. New advances and the demands for monitoring are also briefly explored.

Brain imaging findings in very preterm infants throughout the neonatal period: part I. Incidences and evolution of lesions, comparison between ultrasound and MRI

This study describes the incidence and evolution of brain imaging findings in very preterm infants (GA<32 weeks), assessed with sequential cranial ultrasound (cUS) throughout the neonatal period and MRI around term age. The accuracy of both tools is compared for findings obtained around term. Periventricular echodensities and intraventricular haemorrhage were the most frequent cUS findings during admission. Frequent findings on both cUS and MRI around term included ventricular dilatation, widened extracerebral spaces, and decreased cortical complexity. MRI additionally showed punctate white matter lesions and diffuse and excessive high signal intensity, but did not depict lenticulostriate vasculopathy and calcifications, and was less reliable for germinolytic and plexus cysts. cUS detected most abnormalities that have been associated with abnormal neurodevelopmental outcome.

Serial brain MRI and ultrasound findings: relation to gestational age, bilirubin level, neonatal neurologic status and neurodevelopmental outcome in infants at risk of kernicterus

AIMS

To describe cranial ultrasound (cUS) and magnetic resonance imaging (MRI) findings in neonates at risk of kernicterus, in relation to gestational age (GA), total serum bilirubin (TSB), age at imaging and neurodevelopmental outcome.

PATIENTS AND METHODS

Neonates with peak TSB > 400 micromol/L and/or signs of bilirubin encephalopathy. Review of neonatal data, cUS, preterm, term and later MRI scans and neurodevelopmental outcome.

RESULTS

11 infants were studied, two < 31, four 34-36 and five 37-40 weeks GA. TSB levels: 235-583 micromol/L (preterms); 423-720 micromol/L (terms). Neonatal neurological examination was abnormal in 8/10. cUS showed increased basal ganglia (BG) in 4/9 infants and white matter (WM) echogenicity, lenticulostriate vasculopathy (LSV) and caudothalamic hyperechogencity/cysts (GLCs) in 5/9 infants. MRI showed abnormal signal intensity (SI) in the globus pallidum (GP) in 1/2 preterm, 8/9 term and 9/11 later scans. Abnormal WM SI occurred in 2 preterm, 7 term and 10/11 later scans. Seven infants developed athetoid/dystonic cerebral palsy (CP) and 6 hearing loss (HL). Adverse outcome was associated with abnormal BG on cUS (3/4 CP, 4/4 HL), with high SI in GP (7/9 CP, 6/9 HL) on late T2-weighted MRI (all GA) and on T1/T2-weighted term MRI, mainly in term-born infants. WM abnormalities, GLCs and LSV did not correlate with outcome.

CONCLUSIONS

Severe CP occurred with relatively low TSB levels in preterms but only at high levels in full-terms; HL was difficult to predict. Early scans did not reliably predict motor deficits whilst all children with CP had abnormal central grey matter on later scans. Abnormal WM was seen early suggesting primary involvement rather than change secondary to grey matter damage. Why characteristic central grey matter MRI features of kernicterus are not seen early remains unexplained.

Neonatal pyruvate dehydrogenase deficiency due to a R302H mutation in the PDHA1 gene: MRI findings

Pyruvate dehydrogenase (PDH) deficiency is one of the most common causes of congenital lactic acidosis. Correlations between the genetic defect and neuroimaging findings are lacking. We present conventional and diffusion-weighted MRI findings in a 7-day-old male neonate with PDH deficiency due to a mosaicism for the R302H mutation in the PDHA1 gene. Corpus callosum dysgenesis, widespread increased diffusion in the white matter, and bilateral subependymal cysts were the main features. Although confirmation of PDH deficiency depends on specialized biochemical analyses, neonatal MRI plays a role in evaluating the pattern and extent of brain damage, and potentially in early diagnosis and clinical decision making.