Three-dimensional sonography of prenatal skull base development

A methodological review of fetal neurosonographic studies: New directions in assessment of neurodevelopmental risk for mental health problems

Most mental disorders are now considered to have neurodevelopmental origins, with a growing body of research pointing to neural alterations that predate birth. However, lack of established methods for reliable investigation of fetal brain development has limited research into early neural vulnerability. Using a systematic approach and quantitative evaluation of study methodology, we review neurosonographic studies of fetal brain structure with objective quality measures. A total of 81 studies were identified. High quality studies were identified for measurement of the corpus callosum, cerebellum, vermis, ventricles and frontal cortex, with reference ranges provided to facilitate future clinical research. Fewer and lower quality studies were available for subcortical structures, prompting a need for further research to create reliable reference ranges. Development and adoption of reference ranges for fetal brain structures should facilitate future research in neurosonographic evaluation of fetal brain development and lead to a better understanding of neurodevelopmental risk and resilience processes for mental disorders.

Variation of the slope of the tentorium during childhood

BACKGROUND AND PURPOSE

Neural structures in the posterior fossa grow at different rates during development. While there are computationally intensive approaches to analyze growth of the cerebellum and brainstem, there is a paucity of information about summary measures of normal posterior fossa development suitable for real-time clinical use. The present study investigates changes in the trajectory of the tentorium as measured by the occipital and tentorial angles at different stages of development.

METHODS

A retrospective study was conducted drawing from a Boston Children's Hospital database of over 1500 magnetic resonance imaging (MRI) studies. The imaging study population included fetuses older than 20 gestational weeks and children between the ages of 0 and 10 years. Two parameters were measured for all subjects: (1) the tentorial angle (the angle between the tentorium and a line from the internal occipital protuberance to the tuberculum sellae) and (2) the occipital angle (the angle between the tentorium and a line from the internal occipital protuberance to the opisthion). Descriptive statistics were used to analyze the study cohort.

RESULTS

We reviewed 1510 brain MRI studies, and 367 studies met the inclusion criteria (125 fetal and 242 postnatal studies). During fetal development, the inclination of the tentorium showed an ascending course, while it plateaus after birth.

CONCLUSIONS

During the second and third trimesters, the tentorial and occipital angles steadily increase reflecting the dynamic growth of the posterior fossa structures. Postnatally, the tentorial angle decreases and the tentorium slopes downward and plateaus, possibly due to stabilization of posterior fossa development and ongoing growth of the cerebrum. Together, these findings suggest that the tentorial angle can serve as an imaging biomarker of posterior fossa development during the second half of fetal life.

Imaging the Cell and Molecular Dynamics of Craniofacial Development: Challenges and New Opportunities in Imaging Developmental Tissue Patterning

The development of the vertebrate head requires cell-cell and tissue-tissue interactions between derivatives of the three germ layers to coordinate morphogenetic movements in four dimensions (4D: x, y, z, t). The high spatial and temporal resolution offered by optical microscopy has made it the main imaging modularity for capturing the molecular and cellular dynamics of developmental processes. In this chapter, we highlight the challenges and new opportunities provided by emerging technologies that enable dynamic, high-information-content imaging of craniofacial development. We discuss the challenges of varying spatial and temporal scales encountered from the biological and technological perspectives. We identify molecular and fluorescence imaging technology that can provide solutions to some of the challenges. Application of the techniques described within this chapter combined with considerations of the biological and technical challenges will aid in formulating the best image-based studies to extend our understanding of the genetic and environmental influences underlying craniofacial anomalies.

Prenatal Identification of Pierre Robin Sequence: A Review of the Literature and Look towards the Future

Fetal ultrasonography is an important tool used to prenatally diagnose many craniofacial conditions. Pierre Robin sequence (PRS) is a rare congenital deformation characterized by micrognathia, glossoptosis, and airway obstruction. PRS can present as a perinatal emergency when the retropositioned tongue obstructs the airway leading to respiratory compromise. More predictable and reliable diagnostic studies could help the treating medical team as well as families prepare for these early airway emergencies. The medical literature was reviewed for different techniques used to prenatally diagnose PRS radiologically. We have reviewed these techniques and suggested a possible diagnostic pathway to consistently identify patients with PRS prenatally.

Fetopathological aspects of holoprosencephaly

Holoprosencephaly (HPE) is a congenital central nervous system malformation estimated to occur in 1/250 conceptuses and 1/10,000 live births. While the severe forms, which are incompatible with life, are easier to detect in the prenatal period, the milder forms can remain unrecognised. As this can have serious consequences for the pregnancy and malformation carriers it is of crucial importance to find ways of timely detection of this pathological condition. The present study AIMED at finding an association of holoprosencephaly with facial dysmorphia and anomalies of visceral organs that would alert the physician to be very careful in making the prenatal diagnosis, which may require termination of pregnancy by medical indications.

MATERIAL AND METHODS

The study included 15 fetuses diagnosed with holoprosencephaly out of 2095 cases analysed post-mortem in the Fetopathology Clinic at the Centre for Maternity and Neonatology in the town of Tunisia over a period of 3 years (Oct. 2006 - Oct. 2009). The fetuses were analysed macro- and microscopically.

RESULTS

All forms of holoprosencephaly include elements of facial dysmorphism with the facial phenotypes of cyclopia, cebocephaly and ethmocephaly. It can be associated with specific internal organs anomalies, the hydrocephaly being the most common anomaly of the central nervous system. Our study suggested that holoprosencephaly can be correlated with craniofacial anomalies affecting the midfacial and medium craniovisceral structures.

CONCLUSION

The anatomical variations of HPE and the phenotypic facial correlations require a systematic and targeted study of central nervous system.

Prenatal Assessment of the Antero-Posterior Jaw Relationship in Human Fetuses: From Anatomical to Ultrasound Cephalometric Analysis

Objectives

We wished to develop an ultrasound cephalometric analysis, particularly of the antero-posterior jaw relationship, to increase the accuracy of prenatal diagnosis of retrognathism during the routine midterm test.

Methods

Anatomical cephalometric analysis was performed in 18 formalin-fixed human fetuses (between 16 and 39 gestational weeks), and ultrasound cephalometry was prospectively carried out in 52 pregnant women (21 to 25 gestational weeks). The same landmarks were used in the anatomical and ultrasound median sagittal planes for comparison. Four cephalometric angles were measured relative to the anterior cranial base: alveolar projection of the maxilla and the mandible, chin projection, and facial angle. The antero-posterior jaw discrepancy was calculated.

Results

The projection of the maxilla was similar in the two cephalometric analyses (IC [–3.39, 0.23]), whereas the values of the projection of the mandible were lower in the ultrasound sample. The slope of the regression line of the antero-posterior jaw discrepancy on fetuses' age did not show significant differences (IC [–0.05, 1.54]) between anatomical and ultrasound cephalometry, although a difference of 3.23° ± 0.78° (IC [1.69, 4.77]) was observed. Despite this variability, the projections of mandible and chin were well determined by the projection of the maxilla both in the anatomical and ultrasound sample.

Conclusions

Cephalometric analysis by prenatal sonography can be performed to study the antero-posterior jaw relationship. We think that this procedure could be useful to improve prenatal diagnosis of retrognathism in high-risk pregnancies. Further studies should address the reproducibility and accuracy of such analysis.

Fetal micrognathia: objective assessment and associated anomalies on prenatal sonogram

OBJECTIVE

To determine the accuracy and characteristics of prenatally detected fetal micrognathia.

METHODS

A retrospective analysis of all pregnancies with the suspicion of fetal micrognathia was performed. The affected fetuses were reassessed by estimation of the inferior facial angle (IFA) and the frontal nasomental angle on stored gray scale images to objectively establish the diagnosis.

RESULTS

Of the 28.935 ultrasounds (USs) reviewed, 58 cases were eligible and 4 were excluded because of inconclusive data. The mean values for IFA and frontal nasomental angle were 44.8° and 123.3°, respectively. In 33 cases, the pregnancy was terminated. Four fetuses died sub partu or immediately after birth, five were stillborn. Invasive testing in 40/54 cases revealed aneuploidies in 35%. Associated anomalies comprised musculoskeletal disorders (43%) and non-skeletal anomalies (15%). Less than one fifth (9/54) were alive beyond postnatal period. Four fetuses had an isolated micrognathia, one of which was found to have a cleft palate postnatally.

CONCLUSION

The diagnosis of micrognathia has a crucial impact on both prenatal and postnatal outcomes of affected individuals due to its association with additional abnormalities. A detailed sonographic survey using objective criteria for defining micrognathia is mandatory. Once the diagnosis is confirmed, an intensive interdisciplinary counseling of the parents is needed.

Nomograms of the axial transverse diameter of the fetal foramen magnum between 14 and 40 weeks' gestation

OBJECTIVE

The purpose of this study was to create reference range nomograms of the axial transverse diameter of the fetal foramen magnum (TDFM) between 14 and 40 weeks' gestation.

METHODS

This cross-sectional study included pregnant patients between 14 and 41 weeks' gestation. Inclusion criteria consisted of well-established dates (confirmed by early sonography) and nonanomalous singleton fetuses with intact amniotic membranes. Sonographic measurements included biparietal diameter, head circumference, abdominal circumference, femur length, humerus length, transcerebellar diameter, and sonographically estimated fetal weight. Values of the TDFM were each calculated as the mean of 3 separate measurements. The 5th, 50th, and 95th percentiles were estimated at each week of gestational age (GA) by least squares regression for the mean and SD of the TDFM as functions of GA. R(2) and associated P values for the relationships between the TDFM and other biometric measurements were calculated.

RESULTS

The study included 602 consecutive patients meeting the inclusion criteria. The mean maternal age +/- SD was 27.5 +/- 6.4 years; median gravidity, 3 (range, 1-12); and median parity, 1 (range, 0-7). The mean TDFM was 13.5 +/- 3.7 mm. The reference curve formulas for the mean and SD of the TDFM (mm) were TDFM = -12.58 + GA/0.5616 - GA(2)/24.9 + GA(3)/2430.7, and SD(TDFM) = 1.05 - GA/19.4 + GA(2)/588.8. The TDFM correlated significantly and strongly with biparietal diameter, head circumference, abdominal circumference, humerus length, femur length, transcerebellar diameter, and estimated fetal weight (all R(2) >or= 0.90; all P < .0001).

CONCLUSIONS

We present reference range nomograms of the TDFM between 14 and 40 weeks' gestation.