Head ultrasound, CT or MRI? The choice of neuroimaging in the assessment of infants with congenital cytomegalovirus infection.

BACKGROUND: Despite growing interest in universal screening for congenital CMV infection (cCMV), and data to support treatment for cases with central nervous system (CNS) involvement, there is limited regarding the optimal imaging modalities to identify CNS involvement. The objective of this study was to assess the concordance between head ultrasound (US) and magnetic resonance imaging (MRI) or computed tomography (CT), in identifying neurological abnormalities in infants with cCMV infection, and to determine whether the addition of advanced neuroimaging after US had an impact on clinical management. METHODS: Retrospective review of infants with cCMV infection, referred to the Centre d'Infectiologie Mère-Enfant (CIME) at Sainte-Justine Hospital Center in Montreal, between 2008 and 2016. Only patients who underwent head US followed by and brain MRI or CT scan were included in this analysis. RESULTS: Of 46 cases of cCMV identified during the study period, 34 (74%) had a head US followed by MRI (n = 28, 61%), or CT scan (n = 6, 13%). In the majority of cases (n = 24, 71%), both images were concordant (11 both reported abnormal, 13 both reported normal). In 5 cases, US was reported normal and subsequent imaging (MRI = 4, CT = 1); reported abnormal. In all 5 cases patients were clinically symptomatic and met treatment criteria even in the absence of neuroimaging findings. In 5 cases, US was reported abnormal with a subsequent normal MRI (4) or CT (1); in 2 of these cases, patients were clinically symptomatic and met treatment criteria regardless of neuroimaging findings. However, in 3 cases, the patients were clinically asymptomatic, and in 2 of these cases, treated based only on the abnormal US findings. CONCLUSIONS: In this study, we found that that sequential US and MRI were concordant in the majority (71%) of cases in detecting abnormalities potentially associated with cCMV infection. While the addition of MRI to baseline head ultrasound did not influence the decision to treat in clinically symptomatic infants, the addition of MRI to infants with abnormal HUS imaging who are clinically asymptomatic could help refine treatment decisions in these cases.

Prolonged activation of cytomegalovirus early gene e1-promoter exclusively in neurons during infection of the developing cerebrum.

The brain is the major target of congenital cytomegalovirus (CMV) infection. It is possible that neuron disorder in the developing brain is a critical factor in the development of neuropsychiatric diseases in later life. Previous studies using mouse model of murine CMV (MCMV) infection demonstrated that the viral early antigen (E1 as a product of e1 gene) persists in the postnatal neurons of the hippocampus (HP) and cerebral cortex (CX) after the disappearance of lytic infection from non-neuronal cells in the periventricular (PV) region. Furthermore, neuron-specific activation of the MCMV-e1-promoter (e1-pro) was found in the cerebrum of transgenic mice carrying the e1-pro-lacZ reporter construct. In this study, in order to elucidate the mechanisms of e1-pro activation in cerebral neurons during actual MCMV infection, we have generated the recombinant MCMV (rMCMV) carrying long e1-pro1373- or short e1-pro448-EGFP reporter constructs. The length of the former, 1373 nucleotides (nt), is similar to that of transgenic mice. rMCMVs and wild type MCMV did not significantly differed in terms of viral replication or E1 expression. rMCMV-infected mouse embryonic fibroblasts showed lytic infection and activation of both promoters, while virus-infected cerebral neurons in primary neuronal cultures demonstrated the non-lytic and persistent infection as well as the activation of e1-pro-1373, but not -448. In the rMCMV-infected postnatal cerebrum, lytic infection and the activation of both promoters were found in non-neuronal cells of the PV region until postnatal 8 days (P8), but these disappeared at P12, while the activation of e1-pro-1373, but not -448 appeared in HP and CX neurons at P8 and were prolonged exclusively in these neurons at P12, with preservation of the neuronal morphology. Therefore, e1-pro-448 is sufficient to activate E1 expression in non-neuronal cells, however, the upstream sequence from nt -449 to -1373 in e1-pro-1373 is supposed to work as an enhancer necessary for the neuron-specific activation of e1-pro, particularly around the second postnatal week. This unique activation of e1-pro in developing cerebral neurons may be an important factor in the neurodevelopmental disorders induced by congenital CMV infection.

Neuroimaging of viral infections in infants and young children.

Many viral infections can involve the central nervous systems (CNS) of fetuses, neonates, infants, and children. The pathogenesis, patterns of CNS involvement, and species of viral infection may differ in the developing fetus, infant and neonate, and early childhood. Familiarity with the clinical course and imaging appearances of the variable CNS diseases is helpful in making correct differential diagnoses and in prompting timely treatment. This article reviews the clinical courses, pathologic findings, and imaging features of the most common viral infections that may involve the CNS of neonates and infants, including congenital and neonatal CNS viral infections, common CNS viral infections, and parainfectious encephalomyelitis.

Transplacental murine cytomegalovirus infection in the brain of SCID mice.

BACKGROUND: Congenital cytomegalovirus (CMV) infection is the most common congenital viral infection in humans and the major nonhereditary cause of central nervous system (CNS) developmental disorders. Previous attempts to develop a murine CMV (MCMV) model of natural congenital human CMV (HCMV) infection have failed because MCMV does not cross the placenta in immunocompetent mice. RESULTS: In marked contrast with immunocompetent mice, C.B-17 SCID (severe combined immunodeficient) mice were found to be highly susceptible to natural MCMV transplacental transmission and congenital infection. Timed-pregnant SCID mice were intraperitoneally (IP) injected with MCMV at embryonic (E) stages E0-E7, and vertical MCMV transmission was evaluated using nested polymerase chain reaction (nPCR), in situ hybridization (ISH) and immunohistochemical (IHC) assays. SCID mouse dams IP injected at E0 with 102 PFU of MCMV died or resorbed their fetuses by E18. Viable fetuses collected at E18 from SCID mice IP injected with 102-104 PFU of MCMV at E7 did not demonstrate vertical MCMV transmission. Notably, transplacental MCMV transmission was confirmed in E18 fetuses from SCID mice IP injected with 103 PFU of MCMV at stages E3-E5. The maximum rate of transplacental MCMV transmission (53%) at E18 occurred when SCID mouse dams were IP injected with 103 PFU of MCMV at E4. Congenital infection was confirmed by IHC immunostaining of MCMV antigens in 26% of the MCMV nPCR positive E18 fetuses. Transplacental MCMV transmission was associated with intrauterine growth retardation and microcephaly. Additionally, E18 fetuses with MCMV nPCR positive brains had cerebral interleukin-1alpha (IL-1alpha) expression significantly upregulated and cerebral IL-1 receptor II (IL-1RII) transcription significantly downregulated. However, MCMV-induced changes in cerebral cytokine expression were not associated with any histological signs of MCMV infection or inflammation in the brain. CONCLUSION: Severe T- and B-cell immunodeficiencies in SCID mice significantly enhance the rate of natural MCMV transplacental transmission and congenital infection. During gestation MCMV exhibits a tissue tropism for the developing brain, and vertical MCMV transmission is correlated with fetal growth retardation and abnormal cerebral proinflammatory cytokine expression. These data confirm that natural vertical MCMV infection in SCID mice constitutes a useful new experimental rodent model of congenital HCMV infection.

Congenital cytomegalovirus infection: a retrospective diagnosis in a child with pachygyria.

A 2-year, 6-month-old child with pachygyria demonstrated on magnetic resonance imaging at 12 months of age, psychomotor delay, and deafness who was diagnosed with congenital cytomegalovirus infection by the demonstration of cytomegalovirus DNA in blood from the stored neonatal filter paper is reported. The use of this technique provides an opportunity for the retrospective viral diagnosis in children with neurodevelopmental impairments and abnormalities, such as migration disturbances, in the brain.

Neuroimaging in CMV congenital infected neonates: how and when.

Neonatal congenital infections are an important cause of mortality, morbidity and long-term neurodevelopmental and sensorineural sequelae. Many pathogens can cause in utero infection, and among them, cytomegalovirus (CMV) plays a prominent role. In developed countries, CMV poses major health problems as it is the most common pathogen leading to congenital infection, and the leading cause of nonhereditary deafness in children. Evaluation of central nervous system (CNS) involvement in congenital CMV infected newborns is mandatory to better assess the severity of the disease, to guide adequate treatment, to define prognosis, and to tailor follow-up observations and parents' counselling. Cerebral ultrasonography (cUS), Computed Tomography (CT), and Magnetic Resonance Imaging (MRI) are the currently available techniques to evaluate infants with suspected or proven congenital CMV infection. In congenital CMV infection, their role in early detection and confirmation of cerebral involvement within the first month of life is crucial to initiate specific treatment with antivirals. Neonatologists, paediatricians and radiologists should be aware of the role, the limitations and the inherent risks related to the use of these specific neuroimaging diagnostic tools in these infants. In this article we will discuss from a neonatological perspective the advantages, disadvantages, risks and limitations of each imaging technique.

Human herpesviruses-6 and -7 infections.

PURPOSE OF REVIEW: To summarize the biology and clinical consequences of infection with the closely related human herpesviruses-6 and -7 (HHV-6/7) in children. RECENT FINDINGS: Over the last year there has been a paucity of paediatric publications on HHV-6 and only two studies focused on HHV-7. Steady progress has been made regarding the biology and clinical consequences of HHV-6 infection whereas the effect of HHV-7 infection remains a neglected topic. However, both viruses have been shown to contribute significantly and equally to the burden of disease in young children with suspected encephalitis or severe convulsions with fever. There continues to be uncertainty as to the effects of HHV-6 infection after stem cell transplant, although there is general agreement that it contributes to encephalitis. In contrast, HHV-7 seems to have little clinical impact after stem cell transplant, although central nervous system infection and disease have recently been reported in children. Understanding the contribution of chromosomal integration and inheritance of both HHV-6 variants A and B (HHV-6A/B) and their effect on diagnosis is emerging. SUMMARY: There is an urgent need for more research on HHV-6 and -7 in children, particularly in relation to chromosomal integration of HHV-6A and B, and clinical consequences of HHV-7 infection.

Neuropathogenesis in cytomegalovirus infection: indication of the mechanisms using mouse models.

Cytomegalovirus (CMV) is the most frequent infectious cause of developmental brain disorders and also causes brain damage in immunocompromised individuals. Although the brain is one of the main targets of CMV infection, little is known about the neuropathogenesis of the brain disorders caused by CMV in humans because of the limitations in studying human subjects. Murine CMV (MCMV) is similar to human CMV (HCMV) in terms of genome structure, pattern of gene expressions, cell tropism and infectious dynamics. In mouse models, it has been shown that neural stem/progenitor cells are the most susceptible to CMV infection in developing brains. During brain development, lytic infection tends to occur in immature glial cells, presumably causing structural disorders of the brain. In the prolonged phase of infection, CMV preferentially infects neuronal cells. Infection of neurons may tend to become persistent by evasion of immune reactions, anti-apoptotic effects and neuron-specific activation of the e1-promoter, presumably causing functional neuronal disorders. It has also been shown that CMV infection in developing brains may become latent in neural immature cells. Brain disorders may occur long after infection by reactivation of the latent infection.

Congenital varicella syndrome: a rare case of central nervous system involvement without dermatological features.

An unusual case of congenital varicella syndrome with significant central nervous system involvement, but without dermatological features at birth is described. The mother contracted chicken pox at 15 weeks' gestation. Congenital varicella syndrome involves multiple systems, but rarely without skin lesions identifiable at birth. Although varicella infection in pregnant women is an uncommon complication, the fetal embryopathy that may result can be devastating. Antenatal diagnosis of fetal embryopathy during the first 20 weeks of pregnancy should be established by amniocentesis or cordocentesis when a mother presents in the first trimester with chicken pox, and appropriate risk counselling provided.

Effects of test administration order on children's neuropsychological performance: emerging one-word expressive and receptive language skills.

Differences in neuropsychological performance associated with specific test presentation sequences have been reported in adults. However, these effects have received little attention in children. The EOWPVT-R, a measure of one-word expressive language, and the PPVT-R, a measure of receptive language, were administered to 6- to 14-year-olds (control [n = 17] and experimental [n = 22] groups) in a counterbalanced fashion to investigate the potential effects of test presentation sequence on neuropsychological performance. Group findings were not evidenced subsequent to variation in test administration sequence. In contrast, order of test presentation revealed differences in performance. Administration of the PPVT-R prior to the EOWPVT-R resulted in enhanced EOWPVT-R expressive language scores in both groups of participants. Presentation of the PPVT-R after the EOWPVT-R did not affect performance. Applied and theoretical implications associated with these findings are discussed.

Building a mouse model hallmarking the congenital human cytomegalovirus infection in central nervous system.

To investigate the mechanisms that human cytomegalovirus (HCMV) can vertically transmit from the placenta of mice to infect their offspring in the central nervous system (CNS) and cause congenital anomalies, and in order to provide basic research for preparing HCMV vaccine, we have developed a new type of mouse model of HCMV congenital CNS infection. Pure strain mice were propagated after being infected with HCMV. Then the degree of infection by HCMV to offspring was determined. The experiment shows that in the infection groups the mortality of fetal mice and the fatality of neonatal mice in one week are higher than that of the control groups (P < or = 0.05). At the same time we investigated the CNS of fetus's mice whose mothers were infected by HCMV. Our results showed: 1. The virus was successfully isolated from their cerebral cortex. 2. The signal of HCMV hybridization print was found in their nervous cell through in situ hybridization. 3. Especially human herpes virus-like particles and inclusion bodies in the plasm of nerve cell were found in the tissue of their brain under the electron microscope. This new type of mouse model of HCMV inherent CNS infection will help prepare HCMV vaccine and research HCMV congenital infection in CNS.

Effect of ganciclovir therapy on hearing in symptomatic congenital cytomegalovirus disease involving the central nervous system: a randomized, controlled trial.

OBJECTIVE: To evaluate the efficacy and safety of ganciclovir therapy in neonates with congenital cytomegalovirus (CMV) disease. STUDY DESIGN: Neonates with symptomatic CMV disease involving the central nervous system were randomly assigned to receive 6 weeks of intravenous ganciclovir versus no treatment. The primary end point was improved brainstem-evoked response (BSER) between baseline and 6-month follow-up (or, for patients with normal baseline hearing, normal BSER at both time points). RESULTS: From 1991 to 1999, 100 patients were enrolled. Of these, 42 patients had both a baseline and 6-month follow-up BSER audiometric examination and thus were evaluable for the primary end point. Twenty-one (84%) of 25 ganciclovir recipients had improved hearing or maintained normal hearing between baseline and 6 months versus 10 (59%) of 17 control patients (P=.06). None (0%) of 25 ganciclovir recipients had worsening in hearing between baseline and 6 months versus 7 (41%) of 17 control patients (P<.01). A total of 43 patients had a BSER at both baseline and at 1 year or beyond. Five (21%) of 24 ganciclovir recipients had worsening of hearing between baseline and > or =1 year versus 13 (68%) of 19 control patients (P<.01). A total of 89 patients had absolute neutrophil counts determined during the course of the study; 29 (63%) of 46 ganciclovir-treated patients had grade 3 or 4 neutropenia during treatment versus 9 (21%) of 43 control patients (P<.01). CONCLUSIONS: Ganciclovir therapy begun in the neonatal period in symptomatically infected infants with CMV infection involving the central nervous system prevents hearing deterioration at 6 months and may prevent hearing deterioration at > or =1 year. Almost two thirds of treated infants have significant neutropenia during therapy.