Prenatal diagnosis of agnathia-holoprosencephaly: three-dimensional imaging by helical computed tomography

Morphometric Development of the Mandible in Fetal Cadavers

PURPOSE

The aim of this study is to present reliable data by measuring the morphometric properties of the mandible in the fetal period.

METHODS

A study was performed on mandibles of 35 fetuses (18 male fetuses and 17 female fetuses), aged between 21 and 40 weeks of gestation. Fetuses were examined in 3 groups according to their developmental stages: 2nd trimester, 3rd trimester, and full-term. Morphometric measurements were performed for both the right and left sides of each mandible. The measurements of the mental foramen were performed using a digital caliper, and other measurements were performed using the ImageJ program. The data obtained were analyzed using the SPSS 20 for Windows program.

RESULTS

There was no significant gender difference for all parameters. When the parameters were compared by the trimesters, no significant difference was determined in the 2nd trimester - 3rd trimester, 3rd trimester-full-term, and second trimester - full-term comparisons of the angle of the mandible, and there was a significant difference in all other parameters (P < 0.05). According to the trimesters, all parameters, except the angle of the mandible, increased naturally with the development of the mandible. It was observed that the angle of the mandible decreased from the 2nd trimester to the 3rd trimester and increased from the 3rd trimester to the full term. When the right and left measurements were compared, no significant difference was found for all parameters in both general and trimester groups.

CONCLUSION

The present study includes fetal mandibular parameters that have not been reported elsewhere. It is thought that the obtained data will contribute to the determination of anomalies, pathologies, and variations.

Prenatal Diagnosis of Isolated Agnathia-Otocephaly: A Case Report and Review of the Literature

Agnathia is a rare disease characterized by the absence of a mandible. Few cases of prenatally diagnosed isolated agnathia have been reported. We present a case report and review of the literature of prenatally diagnosed agnathia. A 38-year-old woman (gravida 0, para 0) was referred to our hospital at 28 weeks and 3 days of gestation for fetal evaluation because of polyhydramnios and suspected facial anomalies. Three-dimensional ultrasonography and MRI indicated agnathia. Premature rupture of the membranes occurred before the parents could reach a decision on the postnatal treatment. We performed emergency cesarean section on the second day of the 33rd week of gestation. The neonate was deemed nonresuscitable and he died of airway obstruction shortly after birth. Because agnathia is associated with very poor prognosis, accurate prenatal diagnosis and detailed counseling should be promptly provided before unexpected delivery to the parents for the determination of postnatal treatment.

Severe micrognathia with 21 trisomy assessed prenatally by performing three-dimensional computed tomography

Severe micrognathia can lead to death shortly after birth without a proper resuscitation. However, it is difficult to develop an effective resuscitation strategy without a prenatal diagnosis of the severity of micrognathia. In the present case, we used fetal three-dimensional computed tomography (3D-CT) to assess the severity of micrognathia. Its images clearly demonstrated bony framework of mandible and suggested that mandibular hypoplasia was too severe to allow for oral intubation. We therefore decided that the ex utero intrapartum treatment (EXIT) procedure would be more appropriate to establish the airway at birth. The prenatal 3D-CT is useful to evaluate the mandibular anatomy in utero if the severity of the micrognathia is not confirmed by the ultrasound or magnetic resonance imaging (MRI).

Prenatal diagnosis of osteogenesis imperfecta type II by three-dimensional computed tomography: the current state of fetal computed tomography

We report a case of osteogenesis imperfecta (OI) (OMIM166210) type II, in which a prenatal diagnosis was made by three-dimensional computed tomography (3D-CT). Subsequent molecular analysis revealed a recurrent, heterozygous mutation in COL1A2. Fetal CT is a powerful tool for visualizing the fetal skeleton and can provide a definitive diagnosis of fetal skeletal dysplasias; however, whether or not its employment for prenatal diagnosis is warranted in terms of fetal radiation risks remains controversial, both medically and ethically. Based on our experience, we review the current state of fetal CT for the diagnosis of skeletal dysplasias, with a discussion of the relevant literature.

Suspected fetal skeletal malformations or bone diseases: how to explore

Skeletal dysplasias are a heterogeneous and complex group of conditions that affect bone growth and development and result in various anomalies in shape and size of the skeleton. Although US has proved reliable for the prenatal detection of skeletal abnormalities, the precise diagnosis of a dysplasia is often difficult to make before birth (especially in the absence of a familial history) due to their various phenotypic presentations, the variability in the time at which they manifest and often, the lack of precise molecular diagnosis. In addition to the accuracy of the antenatal diagnosis, it is very important to establish a prognosis. This is a clinically relevant issue as skeletal dysplasias may be associated with severe disability and may even be lethal. We will therefore describe the respective role of two-dimensional (2-D) US, three-dimensional (3-D) US and CT in the antenatal assessment of skeletal malformations.

Otocephaly: report of five new cases and a literature review

Otocephaly, characterized by mandibular hypoplasia or agnathia, ventromedial auricular malposition (melotia) and/or auricular fusion (synotia), and microstomia with oroglossal hypoplasia or aglossia, is an extremely rare anomalad, identified in less than 1 in 70,000 births. The malformation spectrum is essentially lethal, because of ventilatory problems, and represents a developmental field defect of blastogenesis primarily affecting thefirst branchial arch derivatives. Holoprosencephaly is the most commonly identified association, but skeletal, genitourinary, and cardiovascular anomalies, and situs inversus have been reported. Polyhydramnios may be the presenting feature, but prenatal diagnosis has been uncommon. We present five new cases of otocephaly, the largest published series to date, with comprehensive review of the literature and an update of research in the etiopathogenesis of this malformation complex. One of our cases had situs inversus, and two presented with unexplained polyhydramnios. Otocephaly, while quite rare, should be considered in the differential diagnosis of this gestational complication.

Determination of dimensions and angles of mandible in the fetal period

The aim of the present study was to determine the dimensions of the mandible during the fetal period, the relationship between the growth rates of the angle of the mandible and the dimensions of the mandible. Furthermore the angle of union of the two halves of the body of the mandible on the horizontal mandibular plane, which was not described elsewhere, is explored in this study. One hundred and sixty-one human fetuses (83 males and 78 females) without any cranio-facial or mandibular asymmetry, external pathology or anomaly and aged between 9 and 40 weeks of gestation were used in the study. Cases were stratified into four groups according to their developmental ages, that is, first trimester, second trimester, third trimester, and term fetuses. Cranio-facial parameters in addition to bi-condylar, bi-gonial, bi-mental tubercular, condyle-gonion, gonion-mental tubercle, condyle-mental tubercle, gonion-pogonion distances were measured. The degree of the angle of the mandible, angle of union of the two halves of the body of the mandible and sagittal length of the base of the mandible were calculated. The means of the parameters with respect to gestational weeks and groups were computed. While there were no sex differences in any of the parameters (P>0.05) there were very significant relationships between gestational age and parameters (P<0.001). The mean degree of the angle of the mandible during the fetal period was 122+/-8 degrees . The mean alpha angle of the base of the mandible was 65+/-8 degrees . None of these angles varied significantly throughout the fetal period. Height of the ramus of the mandible increased more than the length of the body of the mandible and bi-gonial distance in the first and second trimesters while in the third trimester and term period they increased at the same rate. Comparisons of groups for the ratio of the transverse to the sagittal lengths of the mandible revealed significant differences between first and second trimesters with term group (P<0.05). Accordingly, bi-gonial distance of the mandible increased more during the third trimester and term time than the first and second trimesters, compared with the sagittal length of the mandible. The morphometric features and architectural changes observed in the mandible do not totally occur during the fetal period but continue later in childhood and adulthood.

Prenatal Diagnosis of Hypochondroplasia: Three-Dimensional Multislice Computed Tomography Findings and Molecular Analysis

We report the first case of sporadic hypochondroplasia diagnosed in utero by computed tomography (CT) three-dimensional (3D) imaging and molecular analysis at 38 weeks' gestation. Prenatal sonographic examinations performed at 32 and 35 weeks' gestation revealed a rhizomelic shortness of the long bones (femur and humerus) with macrocephaly. Based on these findings, a nonlethal form of skeletal dysplasia was suspected and a multislice CT imaging with 3D reconstruction was performed depicting skeletal abnormalities which suggested hypochondroplasia. The prenatal diagnosis was confirmed by DNA mutation analysis of the fibroblast growth receptor 3 gene.

Airway management during an EXIT procedure for a fetus with dysgnathia complex

Nonsyndromal dysgnathia is a rare disorder with a probable genetic basis characterized by a hypoplastic or absent mandible (agnathia), microstomia, microglossia, and ear anomalies secondary to a defect in the ventral portion of the first branchial arch caused by defective neural crest migration or proliferation. Dysgnathic newborn infants often suffer fatal respiratory failure from airway obstruction. Nineteen children with isolated dysgnathia complex are described in the literature--six were stillborn, eight died shortly after birth, and only five survived infancy. All survivors required tracheostomy to maintain an airway. It is difficult to intubate the trachea of these children and early airway management planning is important. We report a neonate who presented with a prenatal ultrasound diagnosis of severe micrognathia, polyhydramnios and a family history of severe micrognathia. Airway management was achieved with fiberoptic intubation through a laryngeal mask airway (LMA) during an ex utero intrapartum treatment procedure. Fiberoptic intubation was hampered by copious amounts of amniotic fluid. This child and her sibling are the first two siblings with isolated dysgnathia complex to have survived infancy and provide further support for a genetic basis to this condition.

Prenatal diagnosis of fetal skeletal dysplasias by combining two-dimensional and three-dimensional ultrasound and intrauterine three-dimensional helical computer tomography

OBJECTIVE

To evaluate the contribution of new imaging techniques in the prenatal diagnosis of skeletal dysplasia.

METHODS

Between May and October 2003, a prospective study was conducted in a single referral center. Three-dimensional ultrasound (3D-US) and three-dimensional helical computer tomography (3D-HCT) were performed after two-dimensional ultrasound (2D-US) in six cases of skeletal dysplasia. Diagnostic accuracy and detailed findings with each of the three techniques were compared with postnatal radiological findings.

RESULTS

There were three cases of achondroplasia, two cases of osteogenesis imperfecta type II and one case of chondrodysplasia punctata. Termination of pregnancy was performed in five cases and one fetus with osteogenesis imperfecta type II was delivered at term by Cesarean section. 2D-US made the correct diagnosis in four cases. 3D-US and 3D-HCT achieved an accurate diagnosis in all six cases. 3D-HCT and 3D-US identified significantly more abnormalities than did 2D-US (3D-HCT: 94.3% (33/35); 3D-US: 77.1% (27/35); 2D-US: 51.4% (18/35); P < 0.01). The diagnosis was made between 27 and 36 weeks' gestation in all cases. The advantage of 3D-HCT over 3D-US was the possibility of imaging the entire fetus.

CONCLUSION

3D-US and 3D-HCT seem to be useful complementary methods to 2D-US, and may improve accuracy of the prenatal diagnosis of skeletal disorders. These new imaging technologies may have a role in the prenatal multidisciplinary approach to the diagnosis of skeletal dysplasias.

Prenatal sonographic diagnosis of isolated agnathia: a case report

Agnathia is a rare malformation characterized by the absence of the mandible, microstomia, aplasia or hypoplasia of the tongue, and low-set or medially fused ears. It occurs alone or in combination with a variety of malformations such as holoprosencephaly. All previous cases of the prenatal diagnosis of agnathia have been accompanied with fatal anomalies. We report here the first case of isolated agnathia, which was diagnosed by prenatal sonography at 32 weeks of gestation. In this case, prenatal sonographic examination showed the severe defect of the chin, small opening of the mouth and severe polyhydramnios. There was no sonographic evidence of holoprosencephaly or anomalies in other organ systems. The diagnosis was confirmed postnatally.