Neuroimaging of pediatric intracranial infection--part 2: TORCH, viral, fungal, and parasitic infections

Diagnostic work-up in malformations of cortical development

Malformations of cortical development (MCDs) represent a heterogeneous spectrum of disorders characterized by atypical development of the cerebral cortex. MCDs are most often diagnosed on the basis of imaging, although subtle lesions, such as focal cortical dysplasia, may only be revealed on neuropathology. Different subtypes have been defined, including lissencephaly, heterotopia, cobblestone malformation, polymicrogyria, and dysgyria. Many MCDs are of genetic origin, although acquired factors, such as congenital cytomegalovirus infections and twinning sequence, can lead to similar phenotypes. In this narrative review, we provide an overview of the diagnostic approach to MCDs, which is illustrated with clinical vignettes, on diagnostic pitfalls such as somatic mosaicism and consanguinity, and recognizable phenotypes on imaging, such as tubulinopathies, the lissencephaly spectrum, tuberous sclerosis complex, and FLNA-related periventricular nodular heterotopia.

A Novel Neuroimaging Phenotype in the X-Linked Intellectual Disability with a Missense Mutation of CNKSR2 Gene

Background

Mental retardation, X-linked, syndromic, Houge type (MRXSHG) is a form of mental retardation characterized by intellectual disability, speech and language impairments, and early-onset seizures. It has been recently recorded in Online Mendelian Inheritance in Man (OMIM), and only 10 cases have been reported in the literature so far.

Objective

To highlight the novel neuroimaging findings in the pediatric X-linked intellectual disability with a missense mutation of connector enhancer of kinase suppressor of RAS2 (CNKSR2) gene.

Material and Methods

We present a case of intellectual disability, refractory epilepsy, speech and language delay with subtle dysmorphism, and behavioral issues in an 11-year-old boy with novel neuroimaging findings in a CNKSR2 gene with missense mutation.

Results

Brain MRI revealed involvement of the basal ganglia, predominantly the neostriatum, and along with the subependymal aspects with focal cavitations involving, especially the bilateral caudate heads. There was relative sparing of the globus pallidi and posterior putamina bilaterally. Whole-exome sequencing identified a hemizygous missense pathogenic variant in the CNKSR2 gene. The mother was found to be an asymptomatic carrier.

Conclusion

This case report highlights the rare missense mutation in the CNKSR2 gene and abnormal neuroimaging findings, which further provide information about the phenotypic characteristics of X-linked syndromic intellectual disability.

From Fetal to Neonatal Neuroimaging in TORCH Infections: A Pictorial Review

Congenital infections represent a challenging and varied clinical scenario in which the brain is frequently involved. Therefore, fetal and neonatal neuro-imaging plays a pivotal role in reaching an accurate diagnosis and in predicting the clinical outcome. Congenital brain infections are characterized by various clinical manifestations, ranging from nearly asymptomatic diseases to syndromic disorders, often associated with severe neurological symptoms. Brain damage results from the complex interaction among the infectious agent, its specific cellular tropism, and the stage of development of the central nervous system at the time of the maternal infection. Therefore, neuroradiological findings vary widely and are the result of complex events. An early detection is essential to establishing a proper diagnosis and prognosis, and to guarantee an optimal and prompt therapeutic perinatal management. Recently, emerging infective agents (i.e., Zika virus and SARS-CoV2) have been related to possible pre- and perinatal brain damage, thus expanding the spectrum of congenital brain infections. The purpose of this pictorial review is to provide an overview of the current knowledge on fetal and neonatal brain neuroimaging patterns in congenital brain infections used in clinical practice.

Cytomegalovirus infections in infants in Uganda: Newborn-mother pairs, neonates with sepsis, and infants with hydrocephalus

OBJECTIVES

To estimate the prevalence of cytomegalovirus (CMV) infections among newborn-mother pairs, neonates with sepsis, and infants with hydrocephalus in Uganda.

DESIGN AND METHODS

Three populations-newborn-mother pairs, neonates with sepsis, and infants (≤3 months) with nonpostinfectious (NPIH) or postinfectious (PIH) hydrocephalus-were evaluated for CMV infection at 3 medical centers in Uganda. Quantitative PCR (qPCR) was used to characterize the prevalence of CMV.

RESULTS

The overall CMV prevalence in 2498 samples across all groups was 9%. In newborn-mother pairs, there was a 3% prevalence of cord blood CMV positivity and 33% prevalence of maternal vaginal shedding. In neonates with clinical sepsis, there was a 2% CMV prevalence. Maternal HIV seropositivity (adjusted odds ratio [aOR] 25.20; 95% confidence interval [CI] 4.43-134.26; p = 0.0001), residence in eastern Uganda (aOR 11.06; 95% CI 2.30-76.18; p = 0.003), maternal age <25 years (aOR 4.54; 95% CI 1.40-19.29; p = 0.02), and increasing neonatal age (aOR 1.08 for each day older; 95% CI 1.00-1.16; p = 0.05), were associated risk factors for CMV in neonates with clinical sepsis. We found a 2-fold higher maternal vaginal shedding in eastern (45%) vs western (22%) Uganda during parturition (n = 22/49 vs 11/50, the Fisher exact test; p = 0.02). In infants with PIH, the prevalence in blood was 24% and in infants with NPIH, it was 20%. CMV was present in the cerebrospinal fluid (CSF) of 13% of infants with PIH compared with 0.5% of infants with NPIH (n = 26/205 vs 1/194, p < 0.0001).

CONCLUSIONS

Our findings highlight that congenital and postnatal CMV prevalence is substantial in this African setting, and the long-term consequences are uncharacterized.

Central Nervous System Mold Infections in Children with Hematological Malignancies: Advances in Diagnosis and Treatment

The incidence of invasive mold disease (IMD) has significantly increased over the last decades, and IMD of the central nervous system (CNS) is a particularly severe form of this infection. Solid data on the incidence of CNS IMD in the pediatric setting are lacking, in which Aspergillus spp. is the most prevalent pathogen, followed by mucorales. CNS IMD is difficult to diagnose, and although imaging tools such as magnetic resonance imaging have considerably improved, these techniques are still unspecific. As microscopy and culture have a low sensitivity, non-culture-based assays such as the detection of fungal antigens (e.g., galactomannan or beta-D-glucan) or the detection of fungal nucleic acids by molecular assays need to be validated in children with suspected CNS IMD. New and potent antifungal compounds helped to improve outcome of CNS IMD, but not all agents are approved for children and a pediatric dosage has not been established. Therefore, studies have to rapidly evaluate dosage, safety and efficacy of antifungal compounds in the pediatric setting. This review will summarize the current knowledge on diagnostic tools and on the management of CNS IMD with a focus on pediatric patients.

Neurologic complications in children under five years with sickle cell disease

INTRODUCTION

Sickle Cell Disease (SCD) is one of the most common genetic diseases in the world affecting every organ. The major challenge in the medical care of children with SCD is preventing end-organ dysfunction, particularly the brain. Major neurologic complications in children less than five years with SCD include, but are not limited to, Silent cerebral infarct, cerebral sinus thrombosis, epilepsy, reversible encephalopathy syndrome, and ischemic and hemorrhagic stroke. Recurrent headaches and migraine are not rare in children under five years with SCD. This review will focus on the neurologic complications and the description of the modifiable risk factors in children less than 5 years of age with emphasis on differences between high and low resource settings.

AREAS COVERED

Neurologic complications of children under 5 years of age and the modifiable risk factors. The PUBMED database was searched using medical subject headings (MeSH) and keywords for articles regarding neurologic complications in children under 5 years of age.

CONCLUSION

Neurologic complications in children under five years of age with SCD may be more frequent than currently reported, among which Silent cerebral infarct and cognitive impairment are the most common.

An assessment of public health surveillance of Zika virus infection and potentially associated outcomes in Latin America

BACKGROUND

We evaluated whether outbreaks of Zika virus (ZIKV) infection, newborn microcephaly, and Guillain-Barré syndrome (GBS) in Latin America may be detected through current surveillance systems, and how cases detected through surveillance may increase health care burden.

METHODS

We estimated the sensitivity and specificity of surveillance case definitions using published data. We assumed a 10% ZIKV infection risk during a non-outbreak period and hypothetical increases in risk during an outbreak period. We used sensitivity and specificity estimates to correct for non-differential misclassification, and calculated a misclassification-corrected relative risk comparing both periods. To identify the smallest hypothetical increase in risk resulting in a detectable outbreak we compared the misclassification-corrected relative risk to the relative risk corresponding to the upper limit of the endemic channel (mean + 2 SD). We also estimated the proportion of false positive cases detected during the outbreak. We followed the same approach for microcephaly and GBS, but assumed the risk of ZIKV infection doubled during the outbreak, and ZIKV infection increased the risk of both diseases.

RESULTS

ZIKV infection outbreaks were not detectable through non-serological surveillance. Outbreaks were detectable through serologic surveillance if infection risk increased by at least 10%, but more than 50% of all cases were false positive. Outbreaks of severe microcephaly were detected if ZIKV infection increased prevalence of this condition by at least 24.0 times. When ZIKV infection did not increase the prevalence of severe microcephaly, 34.7 to 82.5% of all cases were false positive, depending on diagnostic accuracy. GBS outbreaks were detected if ZIKV infection increased the GBS risk by at least seven times. For optimal GBS diagnosis accuracy, the proportion of false positive cases ranged from 29 to 54% and from 45 to 56% depending on the incidence of GBS mimics.

CONCLUSIONS

Current surveillance systems have a low probability of detecting outbreaks of ZIKV infection, severe microcephaly, and GBS, and could result in significant increases in health care burden, due to the detection of large numbers of false positive cases. In view of these limitations, Latin American countries should consider alternative options for surveillance.

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.

Follow-up brain imaging of 37 children with congenital Zika syndrome: case series study

Objective To compare initial brain computed tomography (CT) scans with follow-up CT scans at one year in children with congenital Zika syndrome, focusing on cerebral calcifications.Design Case series study.Setting Barão de Lucena Hospital, Pernambuco state, Brazil.Participants 37 children with probable or confirmed congenital Zika syndrome during the microcephaly outbreak in 2015 who underwent brain CT shortly after birth and at one year follow-up.Main outcome measure Differences in cerebral calcification patterns between initial and follow-up scans.Results 37 children were evaluated. All presented cerebral calcifications on the initial scan, predominantly at cortical-white matter junction. At follow-up the calcifications had diminished in number, size, or density, or a combination in 34 of the children (92%, 95% confidence interval 79% to 97%), were no longer visible in one child, and remained unchanged in two children. No child showed an increase in calcifications. The calcifications at the cortical-white matter junction which were no longer visible at follow-up occurred predominately in the parietal and occipital lobes. These imaging changes were not associated with any clear clinical improvements.Conclusion The detection of cerebral calcifications should not be considered a major criterion for late diagnosis of congenital Zika syndrome, nor should the absence of calcifications be used to exclude the diagnosis.

Infectious, atopic and inflammatory diseases, childhood adversities and familial aggregation are independently associated with the risk for mental disorders: Results from a large Swiss epidemiological study

AIM

To examine the associations between mental disorders and infectious, atopic, inflammatory diseases while adjusting for other risk factors.

METHODS

We used data from PsyCoLaus, a large Swiss Population Cohort Study (n = 3720; age range 35-66). Lifetime diagnoses of mental disorders were grouped into the following categories: Neurodevelopmental, anxiety (early and late onset), mood and substance disorders. They were regressed on infectious, atopic and other inflammatory diseases adjusting for sex, educational level, familial aggregation, childhood adversities and traumatic experiences in childhood. A multivariate logistic regression was applied to each group of disorders. In a complementary analysis interactions with sex were introduced via nested effects.

RESULTS

Associations with infectious, atopic and other chronic inflammatory diseases were observable together with consistent effects of childhood adversities and familial aggregation, and less consistent effects of trauma in each group of mental disorders. Streptococcal infections were associated with neurodevelopmental disorders (men), and measles/mumps/rubella-infections with early and late anxiety disorders (women). Gastric inflammatory diseases took effect in mood disorders (both sexes) and in early disorders (men). Similarly, irritable bowel syndrome was prominent in a sex-specific way in mood disorders in women, and, moreover, was associated with early and late anxiety disorders. Atopic diseases were associated with late anxiety disorders. Acne (associations with mood disorders in men) and psoriasis (associations with early anxiety disorders in men and mood disorders in women) contributed sex-specific results. Urinary tract infections were associated with mood disorders and, in addition, in a sex-specific way with late anxiety disorders (men), and neurodevelopmental and early anxiety disorders (women).

CONCLUSION

Infectious, atopic and inflammatory diseases are important risk factors for all groups of mental disorders. The sexual dimorphism of the associations is pronounced.

Fifteen-minute consultation: diagnosis and management of congenital CMV

Congenital cytomegalovirus (cCMV) infection can result in permanent neurological problems and is a potentially preventable cause of sensorineural hearing loss in the UK. There is an urgency to diagnose and assess cCMV as antiviral treatment and has only been shown to be effective if started in the first 4 weeks of life. A recent randomised controlled trial of 6 months of treatment using oral valganciclovir has shown modest benefit in preventing hearing deterioration and in improving some neurodevelopmental outcomes. Parents and clinicians need to make a timely and informed choice regarding antiviral treatment and ensure that relevant non-pharmaceutical interventions are considered. This paper brings together the current evidence regarding the diagnosis and treatment of cCMV, consensus from two paediatric infectious diseases centres and outlines research priorities.

The clinical, biochemical and genetic features associated with RMND1-related mitochondrial disease

Background

Mutations in the RMND1 (Required for Meiotic Nuclear Division protein 1) gene have recently been linked to infantile onset mitochondrial disease characterised by multiple mitochondrial respiratory chain defects.

Methods

We summarised the clinical, biochemical and molecular genetic investigation of an international cohort of affected individuals with RMND1 mutations. In addition, we reviewed all the previously published cases to determine the genotype–phenotype correlates and performed survival analysis to identify prognostic factors.

Results

We identified 14 new cases from 11 pedigrees that harbour recessive RMND1 mutations, including 6 novel variants: c.533C>A, p.(Thr178Lys); c.565C>T, p.(Gln189*); c.631G>A, p.(Val211Met); c.1303C>T, p.(Leu435Phe); c.830+1G>A and c.1317+1G>T. Together with all previously published cases (n=32), we show that congenital sensorineural deafness, hypotonia, developmental delay and lactic acidaemia are common clinical manifestations with disease onset under 2 years. Renal involvement is more prevalent than seizures (66% vs 44%). In addition, median survival time was longer in patients with renal involvement compared with those without renal disease (6 years vs 8 months, p=0.009). The neurological phenotype also appears milder in patients with renal involvement.

Conclusions

The clinical phenotypes and prognosis associated with RMND1 mutations are more heterogeneous than that were initially described. Regular monitoring of kidney function is imperative in the clinical practice in light of nephropathy being present in over 60% of cases. Furthermore, renal replacement therapy should be considered particularly in those patients with mild neurological manifestation as shown in our study that four recipients of kidney transplant demonstrate good clinical outcome to date.

Social Phobia Is Associated with Delayed Onset of Chickenpox, Measles, and Mumps Infections

OBJECTIVE

Evidence showing that infectious diseases in childhood play an important role in the etiopathogenesis of neurodevelopmental and other mental disorders is growing. The aim of this study was to explore the timing of common childhood diseases in early-onset anxiety disorders.

MATERIALS AND METHODS

We analyzed data from PsyCoLaus, a large Swiss Population Cohort Study (N = 3720). In this study, we regressed overanxious disorder, separation anxiety disorder, social phobia, and specific phobias on the age of onset of several childhood diseases, always adjusting for the other anxiety disorders listed above and for sex.

RESULTS

The timing of viral childhood diseases (chickenpox, measles, and mumps) was consistently delayed in social phobia, notably both in men and women. We found no evidence for a reversed sequence of onset of phobia symptoms before that of the infections included.

CONCLUSION

Social phobia was the only early anxiety disorder to show an association with a delayed onset of common viral childhood diseases.

Infections

"Children are not little adults," and while this is a well-worn aphorism, it is especially true in the context of infection, where the same organism may evoke a different immune response in the pediatric central nervous system (CNS) and clinical presentation may be clouded by the lack of a good history or paucity of clinical information. The chronology and natural history of different organisms/infections will be laid out together with the preferred use of different imaging modalities. This chapter will use illustrative examples of some of the more common infections and their complications, in addition to several more rare conditions as well as mimics of childhood CNS infection. Challenges in the imaging of children, including strategies to minimize the use of radiation, are discussed. Some of the more recently voiced concerns regarding the use of anesthetic agents in children are also addressed, along with the contrast agents that are typically required for imaging. With a global increase in worldwide travel the anticipation is that pediatricians will increasingly see unusual organisms presenting with CNS infection while dealing with the ever-present risk of drug resistance with inappropriately treated common or garden infections.

Brain stones revisited-between a rock and a hard place

OBJECTIVES AND METHODS

Large intracranial calcifications are occasionally encountered in routine computed tomography (CT) scans of the brain. These calcifications, also known as "brain stones", can be classified according to location and aetiology. Combining imaging findings with relevant clinical history and physical examination can help narrow down the differential diagnosis and may allow confident diagnosis in certain situations.

RESULTS

This article provides a pictorial review illustrating various clinical entities resulting in brain stones.

DISCUSSION

Based on location, brain stones can be classified as extra- or intra-axial. Extra-axial brain stones comprise tumours and exaggerated physiological calcifications. Intra-axial brain stones can further be classified according to aetiology, namely neoplastic, vascular, infectious, congenital and endocrine/metabolic. Imaging findings combined with essential clinical information can help in narrowing the differential diagnosis, determining disease state and evaluating effect of therapy.

TEACHING POINTS

• Based on location, brain stones can be either extra- or intra-axial. • Extra-axial brain stones comprise tumours and exaggerated physiological calcifications. • Intra-axial aetiologies include neoplastic, vascular, infectious, congenital and endocrine/metabolic. • CT scan is the mainstay in identifying and characterising brain stones. • Certain MRI sequences (gradient echo T2* and susceptibility-weighted imaging) are considered adjunctive.