Anencephaly: MRI findings and pathogenetic theories

A Devastating Diagnosis: Anencephaly With Unexpected Fetal Heartbeat

This case report describes a severe birth defect called anencephaly in a fetus at 18 weeks of pregnancy. Anencephaly occurs when the upper part of the baby's brain and skull do not form correctly. This condition is usually detected earlier in pregnancy, often in the first three months. However, this case was discovered at 18 weeks, highlighting the need for careful monitoring throughout pregnancy. The unique aspect of this case is that most pregnancies with anencephaly do not progress this far. This later diagnosis provides important information about the different ways the condition can develop. By studying cases like this, healthcare providers can improve prenatal care and potentially detect such defects earlier, even in the later stages of pregnancy. Overall, this report emphasizes the importance of continuous monitoring during pregnancy and offers insights that could lead to better diagnosis, care, and support for families facing similar situations.

Imaging of Congenital Malformations of the Brain

Brain formation is a continuous and complicated process that is historically categorized by the timing of development. The earliest disorders of dorsal induction occur in the first month of gestation and include anencephaly and cephalocele. Disorders of ventral induction occur during the second month of gestation and include the holoprosencephaly and septo-optic dysplasia spectrums. The third and longest timeframe include the disorders of neuronal migration and proliferation (gestational weeks eight-25) and include malformations of cortical development: lissencephaly, polymicrogyria, schizencephaly, gray matter heterotopia, and corpus callosal dysgenesis. This review will highlight the neuroimaging of these malformations.

Imaging of Congenital Malformations

PURPOSE OF REVIEW

Intracranial congenital malformations are anomalies of brain development caused by genetic and environmental influences. This article discusses common intracranial congenital malformations, presents the associated neuroimaging findings, and discusses how appropriate identification of intracranial anomalies can impact diagnosis and treatment.

RECENT FINDINGS

Advances in neuroimaging techniques and genetic research have led to a better understanding of the pathogenesis of many congenital malformations, adding insight into their clinical relevance and the intricate relationship between critical periods of development, genetic predisposition, and environmental insults. When one malformation is discovered, a high likelihood of more malformations exists. In some instances, the intracranial anomalies will lead to the diagnosis of a particular neurologic syndrome, which may, in turn, lead to modification of a plan of care.

SUMMARY

Knowledge of congenital malformations and their appearance on imaging sequences is essential to improve clinical outcomes and quality of life for patients.

Central nervous system injury in utero: selected entities

This report discusses the syndrome of amnionic bands, anencephaly, schizencephaly and hydranencephaly, four entities whose pathogenesis includes significant injury to the fetus in utero.

Characteristics of fetuses evaluated due to suspected anencephaly: a population-based cohort study in southern Brazil

CONTEXT AND OBJECTIVE

Anencephaly is considered to be the most common type of neural tube defect. Our aim was to assess the clinical and gestational features of a cohort of fetuses with suspected anencephaly.

DESIGN AND SETTING

Population-based retrospective cohort study in a referral hospital in southern Brazil.

METHODS

The sample consisted of fetuses referred due to suspected anencephaly, to the Fetal Medicine Service of Hospital Materno Infantil Presidente Vargas, between January 2005 and September 2013. Clinical, radiological, pathological and survival data were gathered.

RESULTS

Our sample was composed of 29 fetuses. The diagnosis of suspected anencephaly was made on average at 21.3 weeks of gestation. Seven fetuses had malformations that affected other organs, and these included oral clefts (n = 4) and congenital heart defects (n = 2). In 16 cases, there was termination of pregnancy (n = 12) or intrauterine death (n = 4). Regarding those who were born alive (n = 13), all of them died in the first week of life. After postnatal evaluation, the diagnosis of anencephaly was confirmed in 22 cases (75.9%). Other conditions included amniotic band disruption complex (6.9%), microhydranencephaly (6.9%), merocrania (3.4%) and holoprosencephaly (3.4%).

CONCLUSIONS

Different conditions involving the cranial vault may be confused with anencephaly, as seen in our sample. However, these conditions also seem to have a poor prognosis. It seems that folic acid supplementation is not being properly performed.

Anencephaly does not cause structural alterations in the fetal penis

INTRODUCTION

Anencephaly is the most severe neural tube defect in human fetuses. There is an increasing need for tissue replacement in chronic diseases and reconstructive surgeries. Fetal tissues have been used as a substitute for native organs.

AIM

The aim of this article was to compare the structure and morphology of the corpora cavernosa (CC) and spongiosum (SP) of penises from anencephalic and normal human fetuses.

MAIN OUTCOME MEASURES

The main outcome measures of this study were the proposition of a new model for biological studies and tissue transplantation.

METHODS

We studied 11 penises from normal human fetuses, aged 14-23 weeks postconception (WPC), and five penises from anencephalic fetuses, aged 18-22 WPC. The organs were removed and processed by routine histological and immunolabeling techniques. Analysis of connective tissue (Cot), smooth muscle (SMC), and elastic fiber (EF) were performed in sections. Data were expressed as area density (Ad) using digital processing and software. Means were statistically compared using the unpaired t-test and linear regression was performed. Statistical significance was considered if P<0.05.

RESULTS

The intracavernosal septum was present in all samples. We did not observe differences in the Ad of Cot and SMC in the penises of anencephalic fetuses when compared with normal ones. The simple linear regression suggested that during human development, there is a gradual increase in Cot (R(2)=+0.45) and a decrease of SMC (R(2)=-0.62) in the CC in both groups studied. Elastin was observed only in fetuses from 20th WPC.

CONCLUSIONS

There was no difference in the structure of the CC and corpus SP of anencephalic fetuses compared with normal ones. Elastin was documented from 20th WPC, which suggests the maintenance of erectile function. Histochemistry and immunolabeling suggested that penile shaft development is maintained and unaltered in anencephalic fetuses. Further studies should be performed to analyze anencephalic fetuses as a potential tissue-donating group and a model for biological studies.

Malformations of dorsal induction

Dorsal induction includes the formation and closure of neural tube, occurs during 3-5 weeks of gestation. Neurulation occurs in two phases, primary neurulation (formation of the neural plate and subsequently neural tube) and secondary neurulation (formation of distal cord and sacral and coccygeal segments). Failure of dorsal induction leads to anencephaly, exencephaly, cephaloceles, Chiari malformation and spinal dysraphism. In this article we discuss the relevant embryology, etiopathology and detail imaging appearances of these malformations.

Anencefalia numa perspectiva ética

Este artigo consta de uma revisão sumariada da anencefalia, um grave defeito embrionário do sistema nervoso central, sob o ponto de vista bioético, fundamentada em conhecimentos da embriologia e biologia celular modernas. Este tema tem sido alvo de debates acirrados em diversos setores da sociedade brasileira, visto que suscita grande interesse ao envolver a questão do abortamento, noções religiosas e de trazer à baila a questão dos direitos femininos, em face da possibilidade de se conceder à mulher a decisão de continuar ou não a gestar feto anencéfalo.