Imaging findings in congenital Zika virus infection syndrome: an update

Long-term developmental outcomes of children with congenital Zika syndrome

BACKGROUND

Eight years after the epidemics in Brazil, children with congenital Zika syndrome (CZS) and their families confront ongoing health challenges.

OBJECTIVE

This study aims to characterize how virally induced prenatal brain injury impacts development and functional outcomes among children diagnosed with CZS.

METHODS

We performed a cross-sectional study of a consecutive series of children diagnosed with CZS. Using validated neurodevelopmental assessments, we evaluated gross motor function, manual ability, communication, eating and drinking, and visual function.

RESULTS

Sixty children (29 males, and 31 females) met the inclusion criteria for the study. Comorbidities such as epilepsy (90.0%) and undernutrition (38.3%), along with clinical conditions including dysphagia (68.3%) and dependence on tube feeding (31.7%), were observed. Our results demonstrate a majority of children at level V - the most severe level within a five-tier system - in the Gross Motor Function (86.7%), Manual Ability (85.0%), Communication Function (68.3%), Eating and Drinking Ability (40.0%) Classification Systems, and level IV in the Visual Function Classification System (38.3%).

CONCLUSION

CZS is associated with severe functional impairments and comorbidities, adversely impacting child development and quality of life. These findings reveal persistent challenges affecting the functioning of children with CZS, underscoring the need for continued support and specialized care.

IMPACT

This study aimed to characterize the long-term clinical and functional characteristics of a subset of children with Congenital Zika Syndrome (CZS). We found that eight years after the Brazilian Zika epidemic, this subset of children with CZS continues to demonstrate major functional limitations impacting mobility, vision, and the ability to eat and drink. Our analysis documented a very high level of disability in several key functional classification systems. Notably, applying a new instrument for visual ability among children diagnosed with cerebral palsy, we found that more than 60% of the study group have poor or very poor visual function.

Infectious Diseases and Basal Ganglia Calcifications: A Cross-Sectional Study in Patients with Fahr's Disease and Systematic Review

Background: It is unclear whether patients with basal ganglia calcifications (BGC) should undergo infectious disease testing as part of their diagnostic work-up. We investigated the occurrence of possibly associated infections in patients with BGC diagnosed with Fahr's disease or syndrome and consecutively performed a systematic review of published infectious diseases associated with BGC. Methods: In a cross-sectional study, we evaluated infections in non-immunocompromised patients aged ≥ 18 years with BGC in the Netherlands, who were diagnosed with Fahr's disease or syndrome after an extensive multidisciplinary diagnostic work-up. Pathogens that were assessed included the following: Brucella sp., cytomegalovirus, human herpesvirus type 6/8, human immunodeficiency virus (HIV), Mycobacterium tuberculosis, rubella virus, and Toxoplasma gondii. Next, a systematic review was performed using MEDLINE and Embase (2002-2023). Results: The cross-sectional study included 54 patients (median age 65 years). We did not observe any possible related infections to the BGC in this population. Prior infection with Toxoplasma gondii occurred in 28%, and in 94%, IgG rubella antibodies were present. The positive tests were considered to be incidental findings by the multidisciplinary team since these infections are only associated with BGC when congenitally contracted and all patients presented with adult-onset symptoms. The systematic search yielded 47 articles, including 24 narrative reviews/textbooks and 23 original studies (11 case series, 6 cross-sectional and 4 cohort studies, and 2 systematic reviews). Most studies reported congenital infections associated with BGC (cytomegalovirus, HIV, rubella virus, Zika virus). Only two studies reported acquired pathogens (chronic active Epstein-Barr virus and Mycobacterium tuberculosis). The quality of evidence was low. Conclusions: In our cross-sectional study and systematic review, we found no convincing evidence that acquired infections are causing BGC in adults. Therefore, we argue against routine testing for infections in non-immunocompromised adults with BGC in Western countries.

Congenital Zika Virus Infection Impairs Corpus Callosum Development

Congenital Zika syndrome (CZS) is a set of birth defects caused by Zika virus (ZIKV) infection during pregnancy. Microcephaly is its main feature, but other brain abnormalities are found in CZS patients, such as ventriculomegaly, brain calcifications, and dysgenesis of the corpus callosum. Many studies have focused on microcephaly, but it remains unknown how ZIKV infection leads to callosal malformation. To tackle this issue, we infected mouse embryos in utero with a Brazilian ZIKV isolate and found that they were born with a reduction in callosal area and density of callosal neurons. ZIKV infection also causes a density reduction in PH3+ cells, intermediate progenitor cells, and SATB2+ neurons. Moreover, axonal tracing revealed that callosal axons are reduced and misrouted. Also, ZIKV-infected cultures show a reduction in callosal axon length. GFAP labeling showed that an in utero infection compromises glial cells responsible for midline axon guidance. In sum, we showed that ZIKV infection impairs critical steps of corpus callosum formation by disrupting not only neurogenesis, but also axon guidance and growth across the midline.

Brain MRI segmentation of Zika-Exposed normocephalic infants shows smaller amygdala volumes

BACKGROUND

Infants with congenital Zika syndrome (CZS) are known to exhibit characteristic brain abnormalities. However, the brain anatomy of Zika virus (ZIKV)-exposed infants, born to ZIKV-positive pregnant mothers, who have normal-appearing head characteristics at birth, has not been evaluated in detail. The aim of this prospective study is, therefore, to compare the cortical and subcortical brain structural volume measures of ZIKV-exposed normocephalic infants to age-matched healthy controls.

METHODS AND FINDINGS

We acquired T2-MRI of the whole brain of 18 ZIKV-exposed infants and 8 normal controls on a 3T MRI scanner. The MR images were auto-segmented into eight tissue types and anatomical regions including the white matter, cortical grey matter, deep nuclear grey matter, corticospinal fluid, amygdala, hippocampus, cerebellum, and brainstem. We determined the volumes of these regions and calculated the total intracranial volume (TICV) and head circumference (HC). We compared these measurements between the two groups, controlling for infant age at scan, by first comparing results for all subjects in each group and secondly performing a subgroup analysis for subjects below 8 weeks of postnatal age at scan. ZIKV-exposed infants demonstrated a significant decrease in amygdala volume compared to the control group in both the group and subgroup comparisons (p<0.05, corrected for multiple comparisons using FDR). No significant volume differences were observed in TICV, HC, or any specific brain tissue structures or regions. Study limitations include small sample size, which was due to abrupt cessation of extramural funding as the ZIKV epidemic waned.

CONCLUSION

ZIKV-exposed infants exhibited smaller volumes in the amygdala, a brain region primarily involved in emotional and behavioral processing. This brain MRI finding may lead to poorer behavioral outcomes and warrants long-term monitoring of pediatric cases of infants with gestational exposure to Zika virus as well as other neurotropic viruses.

Electromyography in Congenital Zika Syndrome

INTRODUCTION

Congenital Zika virus syndrome is a distinct pattern of birth defects in fetuses infected by the Zika virus. It presents a broad clinical spectrum that includes occurrences of microcephaly, hypertonia, dysphagia, hyperexcitability, seizures, and arthrogryposis. Imaging findings show neuronal migration disorders.

METHODOLOGY

Case reports have suggested that arthrogryposis has a neurogenic cause. We analyzed needle electromyography and nerve conduction examinations on 77 patients aged 2-24 months presenting highly probable congenital Zika virus syndrome, with or without arthrogryposis.

RESULTS

All those with arthrogryposis presented with chronic muscle denervation in the electromyography examination. Similarly, children with single or reversible joint abnormalities at birth showed the same findings. Denervation in the paravertebral musculature was found in all of the children with diaphragmatic paralysis or thoracic deformities.

CONCLUSIONS

We propose that congenital contractures associated with congenital Zika virus syndrome are caused by the malformation of upper and lower motor neurons during embryogenesis.

Diagnostic workup in children with arthrogryposis: description of practices from a single reference centre, comparison with literature and suggestion of recommendations

INTRODUCTION

Arthrogryposis multiplex congenita (AMC) refers to a clinical presentation of congenital contractures involving two or more body areas. More than 400 distinct conditions may lead to AMC, making the aetiological diagnosis challenging. The objective of this work was to set up evidence-based recommendations for the diagnosis of AMC by taking advantage of both data from our nation-wide cohort of children with AMC and from the literature.

MATERIAL AND METHODS

We conducted a retrospective single-centre observational study. Patients had been evaluated at least once at a paediatric age in the AMC clinic of Grenoble University Hospital between 2007 and 2019. After gathering data about their diagnostic procedure, a literature review was performed for each paraclinical investigation to discuss their relevance.

RESULTS

One hundred and twenty-five patients were included, 43% had Amyoplasia, 27% had distal arthrogryposis and 30% had other forms. A definitive aetiological diagnosis was available for 66% of cases. We recommend a two-time diagnostic process: first, non-invasive investigations that aim at classifying patients into one of the three groups, and second, selected investigations targeting a subset of patients.

CONCLUSION

The aetiological management for patients with AMC remains arduous. This process will be facilitated by the increasing use of next-generation sequencing combined with detailed phenotyping. Invasive investigations should be avoided because of their limited yield.

Zika virus congenital microcephaly severity classification and the association of severity with neuropsychomotor development

BACKGROUND

Zika virus infection during pregnancy is linked to birth defects, most notably microcephaly, which is associated with neurodevelopmental delays.

OBJECTIVE

The goals of the study were to propose a method for severity classification of congenital microcephaly based on neuroradiologic findings of MRI scans, and to investigate the association of severity with neuropsychomotor developmental scores. We also propose a semi-automated method for MRI-based severity classification of microcephaly.

MATERIALS AND METHODS

We conducted a cross-sectional investigation of 42 infants born with congenital Zika infection. Bayley Scales of Infant and Toddler Development III (Bayley-III) developmental evaluations and MRI scans were carried out at ages 13-39 months (mean: 24.8 months; standard deviation [SD]: 5.8 months). The severity score was generated based on neuroradiologist evaluations of brain malformations. Next, we established a distribution of Zika virus-microcephaly severity score including mild, moderate and severe and investigated the association of severity with neuropsychomotor developmental scores. Finally, we propose a simplified semi-automated procedure for estimating the severity score based only on volumetric measures.

RESULTS

The results showed a correlation of r=0.89 (P<0.001) between the Zika virus-microcephaly severity score and the semi-automated method. The trimester of infection did not correlate with the semi-automated method. Neuropsychomotor development correlated with the severity classification based on the radiologic readings and semi-automated method; the more severe the imaging scores, the lower the neuropsychomotor developmental scores.

CONCLUSION

These severity classification methods can be used to evaluate severity of microcephaly and possible association with developmental consequences. The semi-automated methods thus provide an alternative for predicting severity of microcephaly based on only one MRI sequence.

Host genetic diversity drives variable central nervous system lesion distribution in chronic phase of Theiler's Murine Encephalomyelitis Virus (TMEV) infection

Host genetic background is a significant driver of the variability in neurological responses to viral infection. Here, we leverage the genetically diverse Collaborative Cross (CC) mouse resource to better understand how chronic infection by Theiler's Murine Encephalomyelitis Virus (TMEV) elicits diverse clinical and morphologic changes in the central nervous system (CNS). We characterized the TMEV-induced clinical phenotype responses, and associated lesion distributions in the CNS, in six CC mouse strains over a 90 day infection period. We observed varying degrees of motor impairment in these strains, as measured by delayed righting reflex, paresis, paralysis, seizures, limb clasping, ruffling, and encephalitis phenotypes. All strains developed neuroparenchymal necrosis and mineralization in the brain, primarily localized to the hippocampal regions. Two of the six strains presented with axonal degeneration with myelin loss of the nerve roots in the lumbar spinal cord. Moreover, we statistically correlated lesion distribution with overall frequencies of clinical phenotypes and phenotype progression to better understand how and where TMEV targets the CNS, based on genetic background. Specifically, we assessed lesion distribution in relation to the clinical progression of these phenotypes from early to late TMEV disease, finding significant relationships between progression and lesion distribution. Finally, we identified quantitative trait loci associated with frequency of lesions in a particular brain region, revealing several loci of interest for future study: lysosomal trafficking regulator (Lyst) and nidogen 1 (Nid1). Together, these results indicate that the genetic background influences the type and severity of clinical phenotypes, phenotypic resilience to TMEV, and the lesion distribution across strains.

Congenital Infections of the Nervous System

PURPOSE OF REVIEW

This article provides an overview of congenital infections affecting the central nervous system (CNS), discussing the epidemiology, clinical features, diagnostic tools, and preventive and treatment measures for a variety of pathogens with the potential to infect the developing fetal brain.

RECENT FINDINGS

Contrary to popular belief, many congenital CNS infections are preventable and treatable. Treatment options exist for congenital cytomegalovirus, human immunodeficiency virus (HIV), herpes simplex virus, toxoplasmosis, and syphilis, although the efficacy of these treatments and the populations that may benefit from treatment are variable. Zika virus has recently emerged as a pathogen affecting the fetal brain, and new data suggest that the pathogenesis of Zika virus involves direct infection of neuronal progenitor cells leading to destruction of CNS tissue. The incidence of congenital syphilis has been increasing in the United States over the past decade as a direct result of new syphilis cases among adults and poor access to adequate maternal health care.

SUMMARY

Congenital CNS infections often result in significant neurologic morbidity in pediatric patients. Therefore, early identification of maternal illness and implementation of preventive measures are important in improving developmental outcomes and quality of life.

Is the ZIKV Congenital Syndrome and Microcephaly Due to Syndemism with Latent Virus Coinfection?

The emergence of the Zika virus (ZIKV) mirrors its evolutionary nature and, thus, its ability to grow in diversity or complexity (i.e., related to genome, host response, environment changes, tropism, and pathogenicity), leading to it recently joining the circle of closed congenital pathogens. The causal relation of ZIKV to microcephaly is still a much-debated issue. The identification of outbreak foci being in certain endemic urban areas characterized by a high-density population emphasizes that mixed infections might spearhead the recent appearance of a wide range of diseases that were initially attributed to ZIKV. Globally, such coinfections may have both positive and negative effects on viral replication, tropism, host response, and the viral genome. In other words, the possibility of coinfection may necessitate revisiting what is considered to be known regarding the pathogenesis and epidemiology of ZIKV diseases. ZIKV viral coinfections are already being reported with other arboviruses (e.g., chikungunya virus (CHIKV) and dengue virus (DENV)) as well as congenital pathogens (e.g., human immunodeficiency virus (HIV) and cytomegalovirus (HCMV)). However, descriptions of human latent viruses and their impacts on ZIKV disease outcomes in hosts are currently lacking. This review proposes to select some interesting human latent viruses (i.e., herpes simplex virus 2 (HSV-2), Epstein-Barr virus (EBV), human herpesvirus 6 (HHV-6), human parvovirus B19 (B19V), and human papillomavirus (HPV)), whose virological features and co-exposition with ZIKV may provide evidence of the syndemism process, shedding some light on the emergence of the ZIKV-induced global congenital syndrome in South America.

The Neurobiology of Zika Virus: New Models, New Challenges

The Zika virus (ZIKV) attracted attention due to one striking characteristic: the ability to cross the placental barrier and infect the fetus, possibly causing severe neurodevelopmental disruptions included in the Congenital Zika Syndrome (CZS). Few years after the epidemic, the CZS incidence has begun to decline. However, how ZIKV causes a diversity of outcomes is far from being understood. This is probably driven by a chain of complex events that relies on the interaction between ZIKV and environmental and physiological variables. In this review, we address open questions that might lead to an ill-defined diagnosis of CZS. This inaccuracy underestimates a large spectrum of apparent normocephalic cases that remain underdiagnosed, comprising several subtle brain abnormalities frequently masked by a normal head circumference. Therefore, new models using neuroimaging and artificial intelligence are needed to improve our understanding of the neurobiology of ZIKV and its true impact in neurodevelopment.

Congenital Zika Virus Infection: a Review with Emphasis on the Spectrum of Brain Abnormalities

Purpose of Review

In 2016, the World Health Organization declared the Zika virus (ZIKV) outbreak a Public Health Emergency of International Concern following a cluster of associated neurological disorders and neonatal malformations. Our aim is to review the clinical and neuroimaging findings seen in congenital Zika syndrome.

Recent Findings

ZIKV injures neural progenitor cells in the hippocampus, a brain region important for learning, memory, cognition, and emotion/stress response. Positron emission tomography has revealed global neuroinflammation in ZIKV infection in animal models.

Summary

Congenital Zika syndrome is associated with a spectrum of brain abnormalities, including microcephaly, parenchymal calcifications, malformations of cortical development and defective neuronal migration, corpus callosum abnormalities, ventriculomegaly, and brainstem and cerebellar abnormalities.

Fetal Neuroimaging Update

OBJECTIVES

To review the current imaging techniques available for the evaluation of the fetal brain.

FINDINGS

Ultrasound remains the initial screening modality with routine scanning typically performed at 18-20 weeks gestation. When a central nervous system (CNS) abnormality is noted by ultrasound, MRI is increasingly being used to further clarify findings. Fetal MRI has the unique ability to provide high detailed anatomical information of the entire human fetus with high contrast resolution. This technique has grown due to the development of rapid single shot image acquisition sequences, improvement of motion correction strategies and optimizing shimming techniques.

CONCLUSIONS

The assessment of fetal CNS anomalies continues to improve. Advanced MRI techniques have allowed for further delineation of CNS anomalies and have become a cornerstone in the assessment of fetal brain well-being. Those interpreting fetal studies need to be familiar with the strengths and limitations of each exam and be sensitive to the impact discussing findings can have regarding perinatal care and delivery planning. Collaboration with neurologists, neurosurgeons, geneticists, counselors, and maternal fetal specialists are key in providing the best care to the families we treat.

Outcomes of Congenital Zika Virus Infection During an Outbreak in Valle del Cauca, Colombia

BACKGROUND

Despite increasing information in the literature regarding congenital Zika infection, gaps remain in our knowledge of its clinical manifestations.

METHODS

We did a prospective observational study of exposed fetuses and infants whose mothers developed symptomatic and confirmed Zika infection during pregnancy in Valle del Cauca, Colombia. We performed neurological, ophthalmologic and audiologic evaluations, and classified outcomes as possibly or uncertainly related to Zika. Frequencies of outcomes were compared according to the trimester of pregnancy when infection occurred.

RESULTS

We evaluated 171 products of gestation including 17 pregnancy losses and 154 patients evaluated postnatally. Ninety (52.6%) pregnancies presented an adverse outcome, 36% possibly related with Zika and the remaining 64% of uncertain relation. Infection in the first trimester had the highest frequencies of adverse outcomes possibly related with Zika compared with the second and third trimesters (39% vs. 12.5% vs. 12%) with risk ratios of adverse outcomes possibly related to Zika in pregnancies infected in the first versus second or third trimester of 3.1 (95% CI: 2.4-4.1) and 3.3 (95% CI: 2.5-4.2), respectively. The frequencies of pregnancy loss and microcephaly were 9.4% and 4.5%, respectively. Auditory and ophthalmic abnormalities possibly related with Zika were present in 3% and 6% of the patients evaluated, respectively.

CONCLUSIONS

We observed a high frequency of gestational and neonatal complications in pregnant women who acquired Zika infection, especially in early pregnancy, resulting in a broad spectrum of clinical manifestations. Preventive measures are urgently needed to reduce the clinical burden during future Zika outbreaks.

Arrest of Fetal Brain Development in ALG11-Congenital Disorder of Glycosylation

BACKGROUND

Arrest of fetal brain development and the fetal brain disruption sequence describe a severe phenotype involving microcephaly, occipital bone prominence, and scalp rugae. Congenital disorders of glycosylation are a heterogeneous group of inherited disorders involved in glycoprotein and glycolipid biosynthesis, which can cause microcephaly and severe neurodevelopmental disability.

METHODS

We report an example of fetal microcephaly diagnosed at 36 weeks' gestation with a history of normal fetal biometry at 20 weeks' gestation. Postnatal genetic testing was performed.

RESULTS

Fetal magnetic resonance imaging at 36 weeks' gestational age showed severe cortical thinning with a simplified gyral pattern for gestational age, ventriculomegaly, and agenesis of the corpus callosum. The fetal skull had a posterior shelf at the level of the lambdoid suture, characteristic of fetal brain disruption sequence. Postnatal brain magnetic resonance imaging found no brain growth during the interval from the fetal to postnatal study. The infant was found to have biallelic pathologic mutations in ALG11.

CONCLUSIONS

Arrest of fetal brain development, with image findings consistent with fetal brain disruption sequence, is a previously unreported phenotype of congenital microcephaly in ALG11-congenital disorder of glycosylation. ALG11-congenital disorder of glycosylation should be considered in the differential diagnosis of this rare form of congenital microcephaly.

Virus-triggered spinal cord demyelination is followed by a peripheral neuropathy resembling features of Guillain-Barré Syndrome

Theiler’s murine encephalomyelitis virus (TMEV)-induces a demyelinating disease in the spinal cord (SC) of susceptible but not in resistant (B6) mouse strains. The aim of the present study was to induce SC demyelination and a peripheral neuropathy in resistant mice by switching the infection site from cerebrum to SC. B6 mice were intraspinally inoculated with TMEV. Infected mice showed clinical signs starting at 7 days post infection (dpi). Histopathology revealed a mononuclear myelitis, centred on the injection site at 3 dpi with subsequent antero- and retrograde spread, accompanied by demyelination and axonal damage within the SC. Virus protein was detected in the SC at all time points. SC inflammation decreased until the end of the investigation period (28 dpi). Concurrent with the amelioration of SC inflammation, the emergence of a peripheral neuropathy, characterized by axonal damage, demyelination and macrophage infiltration, contributing to persistent clinical sings, was observed. Intraspinal TMEV infection of resistant mice induced inflammation, demyelination and delayed viral clearance in the spinal cord and more interestingly, subsequent, virus-triggered inflammation and degeneration within the PN associated with dramatic and progressive clinical signs. The lesions observed in the PN resemble important features of Guillain-Barré syndrome, especially of acute motor/motor-sensory axonal forms.

Baicalein and baicalin as Zika virus inhibitors

At present, there is no effective antiviral agent for Zika virus (ZIKV), an arbovirus that is known for its teratogenic effects on newborns. Baicalein and baicalin were found to be capable of downregulating ZIKV replication up to 10 hours postinfection, while prophylactic effects were evident in pre-treated cells. Baicalein exhibited its highest potency during intracellular ZIKV replication, whereas baicalin was most effective against virus entry. Our in silico interaction assays predicted that both compounds exhibited the strongest binding affinities towards ZIKV NS5, while the virus envelope glycoprotein was the least likely target protein. These findings serve as a crucial platform for further in-depth studies to decipher the underlying anti-ZIKV mechanism(s) of each compound.

Adverse outcomes of pregnancy-associated Zika virus infection

The spread of Zika virus to the Americas was accompanied by surge in the number of infants with CNS abnormalities leading to a declaration of a health emergency by the WHO. This was accompanied by significant responses from governmental health agencies in the United States and Europe that resulted in significant new information described in the natural history of this perinatal infection in a very short period of time. Although much has been learned about Zika virus infection during pregnancy, limitations of current diagnostics and the challenges for accurate serologic diagnosis of acute Zika virus infection has restricted our understanding of the natural history of this perinatal infection to infants born to women with clinical disease during pregnancy and to Zika exposed infants with obvious clinical stigmata of disease. Thus, the spectrum of disease in infants exposed to Zika virus during pregnancy remains to be defined. In contrast, observations in informative animal models of Zika virus infections have provided rational pathways for vaccine development and existing antiviral drug development programs for other flaviviruses have resulted in accelerated development for potential antiviral therapies. This brief review will highlight some of the current concepts of the natural history of Zika virus during pregnancy.