Biparietal diameter-to-crown-rump length disproportion in first-trimester fetuses with holoprosencephaly

Insights into neurosonographic indicators for prenatal diagnosis of fetal neurological anomalies and cortical development: A systematic review of the literature

BACKGROUND

Congenital defects of the central nervous system are the second cause of disability in childhood, representing up to 20 % of structural malformations diagnosed prenatally. The accurate prenatal diagnosis of fetal neurological anomalies and the assessment of cortical development are critical for early intervention and improved long-term outcomes. Neurosonography plays a vital role in this process, providing detailed insights into the structural and functional development of the fetal brain. This systematic review aims to synthesize current knowledge on neurosonographic indicators for prenatal diagnosis, with a special focus on cortical development and its impact in cases of fetal growth defects.

MATERIAL AND METHODS

We conducted a comprehensive search for primary literature in PubMed database were searched for English and Spanish-language, peer-reviewed literature published in the last 15 years. Additional articles were identified by scrutinizing others search platforms (Cochrane Library, UpToDate). Inclusion criteria were single pregnancy and no known feto-maternal pathologies at the beginning of the study.

RESULTS

Of the 361 published abstracts identified, 35 met criteria for inclusion. The review highlighted the importance of detailed neurosonographic assessments, including the evaluation of cerebral fissures such as the Sylvian fissure, parieto-occipital fissure, and calcarine fissure. Targeted ultrasound techniques were found to provide comprehensive insights comparable to fetal magnetic resonance imaging. We underscored the significant impact of intrauterine growth restriction on cortical development, with early intervention being crucial. Genetic and congenital infection screenings were emphasized as essential components of prenatal assessment.

CONCLUSION

The assessment of fetal brain maturation patterns according to gestational age allows us to rule out a delay in cortical development. The heterogeneity of methods and evaluable parameters in fetal neurodevelopment makes it necessary to standardize the evaluation of the main structures of interest both for screening and for the diagnosis of cortical development anomalies, even with the aim of trying to improve upgrade prognostic advice.

Basic sonographic examination of the fetal brain at 11-13 weeks' gestation: Rationale for a simple and reliable four-step technique

The widespread incorporation of first-trimester scanning between 11 and 13 weeks' gestation has shifted from the screening of chromosomal abnormalities, mainly by measuring nuchal translucency thickness and visualization of the nasal bone, to a more detailed study of the fetal anatomy leading to early detection of several structural congenital anomalies. This goal can be improved by the routine and focused sonographic assessment of specific anatomic planes and the identification of distinctive landmarks that can help disclosing a particular, non-evident condition. In this article we present the basis for a basic, early examination of the fetal brain during screening using a four-step technique, which can be readily incorporated during the first-trimester scan. The technique includes the focused visualization of the cranial contour, choroid plexuses of the lateral ventricles and midline, aqueduct of Sylvius, brainstem, fourth ventricle, and the choroid plexus of the fourth ventricle. The rationale for this approach is presented and discussed.

First Trimester Ultrasound Detection of Fetal Central Nervous System Anomalies

OBJECTIVE

To evaluate the potential of the first-trimester ultrasound (US) features for the detection of central nervous system (CNS) anomalies. Methods/Methodology: This is a prospective one-center three-year study. Unselected singleton pregnant women were examined using an extended first-trimester anomaly scan (FTAS) that included the CNS assessment: the calvaria shape, the septum (falx cerebri), the aspect of the lateral ventricles, the presence of the third ventricle and aqueduct of Sylvius (AS) and the posterior brain morphometry: the fourth ventricle, namely intracranial translucency (IT), brain stem/brain stem-occipital bone ratio (BS/BSOB) and cisterna magna (CM). The spine and underlying skin were also evaluated. The cases were also followed during the second and third trimesters of pregnancy and at delivery. FTAS efficiency to detect major CNS abnormalities was calculated.

RESULTS

We detected 17 cases with CNS major abnormalities in a population of 1943 first-trimester (FT) fetuses, including spina bifida with myelomeningocele, exencephaly-anencephaly, holoprosencephaly, hydrocephaly, cephalocele and Dandy-Walker malformation. The CNS features in the abnormal group are presented. In the second trimester (ST), we further diagnosed cases of corpus callosum agenesis, cerebellar hypoplasia, vein of Galen aneurysm and fetal infection features (ventriculomegaly, intraventricular bands, intraventricular cyst and hyperechoic foci), all declared normal at the FTAS. During the third trimester (TT) scan we identified a massive fetal cerebral haemorrhage absent at previous investigations. We report a detection rate of 72.7% of fetal brain anomalies in the FT using the proposed CNS parameters. The sensitivity of the examination protocol was 72.7%, and the specificity was 100%.

CONCLUSION

A detailed FT CNS scan is feasible and efficient. The majority of cases of major CNS abnormalities can be detected early in pregnancy. The visualization rates of the CNS parameters in the FT are great with short, if any, additional investigation time. FT cerebral disorders such as haemorrhage or infections were missed in the FT even when an extended evaluation protocol was used.

Surveillance guidelines for children with trisomy 13

Trisomy 13 is one of the three most common aneuploidy syndromes in live-born infants. It is associated with mortality rates as high as 90% within the first year of life, in large part, due to the high prevalence of severe congenital abnormalities that increase mortality and morbidity. However, life-saving and life-prolonging medical interventions are being performed at a higher rate for these infants, resulting in increased rates of survival. Although cardiac complications have been well described in infants with trisomy 13, these patients also experience other complications such as respiratory, neurological, genitourinary, abdominal, otolaryngologic, and orthopedic complications that can impact their quality of life. The goal of this review is to present a comprehensive description of complications in children with trisomy 13 to aid in the development of monitoring and treatment guidelines for the increasing number of providers who will be caring for these patients throughout their lives. Where the evidence is available, this review presents screening recommendations to allow for more rapid detection and documentation of these complications.

Fetal and neonatal neurogenetics

Disorders of the developing nervous system may be of genetic origin, comprising congenital malformations of spine and brain as well as metabolic or vascular disorders that affect normal brain development. Acquired causes include congenital infections, hypoxic-ischemic or traumatic brain injury, and a number of rare neoplasms. This chapter focuses on the clinical presentation and workup of neurogenetic disorders presenting in the fetal or neonatal period. After a summary of the most frequent clinical presentations, clues from history taking and clinical examination are illustrated with short case reports. This is followed by a discussion of the different tools available for the workup of neurogenetic disorders, including the various genetic techniques with their advantages and disadvantages. The implications of a molecular genetic diagnosis for the patient and family are addressed in the section on counseling. The chapter concludes with a proposed workflow that may help the clinician when confronted with a potential neurogenetic disorder in the fetal or neonatal period.

Sonographic detection of central nervous system defects in the first trimester of pregnancy

The fetal central nervous system can already be examined in the first trimester of pregnancy. Acrania, alobar holoprosencephaly, cephaloceles, and spina bifida can confidently be diagnosed at that stage and should actively be looked for in every fetus undergoing first-trimester ultrasound. For some other conditions, such as vermian anomalies and agenesis of the corpus callosum, markers have been identified, but the diagnosis can only be confirmed in the second trimester of gestation. For these conditions, data on sensitivity and more importantly specificity and false positives are lacking, and one should therefore be aware not to falsely reassure or scare expecting parents based on first-trimester findings. This review summarizes the current knowledge of first-trimester neurosonography in the normal and abnormal fetus and gives an overview of which diseases can be diagnosed.