Sonographic findings in septo-optic dysplasia in the fetus and newborn infant

Pediatric outcome of children with the prenatal diagnosis of isolated septal agenesis

BACKGROUND

Isolated Septal Agenesis (SA) is a rare disease with clinical outcomes (especially neurological outcomes) that are unknown. The purpose of this study was to evaluate the clinical outcome of these children.

METHODS

We conducted a retrospective multicenter study of 17 children with an isolated SA or SA combined with a moderate ventricular dilatation (VD) that was diagnosed antenatally and confirmed by a magnetic resonance imaging (MRI) performed in the antenatal period.

RESULTS

Of the 17 children, 14 had normal neurological examinations, 2 had language development delay and visuo-spatial dyspraxia, and 3 of the 17 children had behavioral problems. Eight children had neuropsychological evaluations, and the results were normal in six cases. There were 3 cases of septo-optic dysplasia (SOD) diagnosed postnatally, which highlighted the difficulties in assessing the optic tract and hypothalamic-pituitary region in antenatal imaging. Language delay and behavioral disorders were the main abnormalities at follow-up.

CONCLUSION

The discovery of an isolated SA reveals the difficulties of prenatal diagnosis to correlate the neurological and functional prognosis to morphological findings. The prognosis seemed to be good. It appears necessary to improve the diagnostic performance of fetal brain imaging and to follow-up these children prospectively to assess their long-term cognitive-behavioral outcomes.

Prenatal diagnosis of septal agenesis with normal pituitary function

Septal agenesis is a rare brain malformation that is characterized by partial or complete absence of the septum pellucidum, either isolated or associated with other brain anomalies. We report a case presenting with septal agenesis and normal optic chiasm and pituitary function in a fetus at 19 weeks of gestation.

Septo-optic dysplasia complex: a heterogeneous malformation syndrome

Septo-optic dysplasia is defined by a variable combination of dysgenesis of midline brain structures including optic nerve hypoplasia and hypothalamic-pituitary dysfunction often associated with a wide variety of brain malformations of cortical development. Multiple congenital anomalies have been reported only sporadically. Despite recent demonstration of the possible pathogenic role of HESX1/Hesx1 gene (a homeobox gene important for development of prosencephalon), the etiology of most cases of septo-optic dysplasia still remains unclear. This report describes eight children (4 males, 4 females; age 2 to 17 years) with septo-optic dysplasia who manifested dysmorphic features (involving not only the midline facial structures) and a spectrum of additional clinical and imaging features including autism, facial hemangioma, and holoprosencephaly. Full mutational screening for the HESX1 gene in seven of eight children was negative. Based on the extreme variability of the clinical and imaging phenotypes hereby observed, on literature review, and on septo-optic dysplasia animal models, this study confirmed that the phenotypic heterogeneity in septo-optic dysplasia is high. We suggest that: (1) dysmorphic features are more frequent than previously thought--they may represent a relevant part of the phenotype; (2) septo-optic dysplasia should be recategorized as an heterogeneous malformation syndrome (septo-optic dysplasia complex) (encompassing multiple brain, endocrine, and systemic anomalies) rather than a single precisely defined entity.

Difficult early sonographic diagnosis of absence of the fetal septum pellucidum

Standard sonographic views of the brain obtained along the axial planes at mid-gestation failed to identify absence of the septum pellucidum in two consecutive fetuses. It was presumably the close proximity of the walls of the lateral ventricles that generated an artifact resembling a normal cavum septi pellucidi. In one of these fetuses, septo-optic dysplasia was confirmed by magnetic resonance demonstration of hypoplastic optic tracts. In the other fetus, isolated absence of the septum pellucidum was the final diagnosis. Standard axial scans are unreliable in predicting absence of the septum pellucidum in the mid-trimester fetus when the lateral ventricles are normal in size.

Differential diagnosis in fetuses with absent septum pellucidum

OBJECTIVE

To elucidate the characteristic morphological features that may help in the prenatal differential diagnosis of absent septum pellucidum as demonstrated by ultrasound.

METHODS

Twenty-six fetuses were referred to the fetal neurology clinic due to mild to severe ventriculomegaly and a connection between the lateral ventricles. The following ultrasonographic features were evaluated: place and extent of the ventricular communication, non-cleavage of the hemispheres and deep gray nuclei, callosal anomalies, position of the choroid plexus, and other central nervous system and facial or body anomalies. A flowchart was created in order to facilitate the final diagnosis.

RESULTS

The presence of non-cleavage and/or characteristic facial anomalies prompted the diagnosis of holoprosencephaly (HPE) in 14 fetuses, including two fetuses with the middle interhemispheric variant. Ten fetuses were diagnosed as having hydrocephalus based on the lack of the same features and the observation that the communication between the lateral ventricles was at the level of the third ventricle with almost normal anterior and posterior segments. In two fetuses the diagnosis of septo-optic dysplasia vs. isolated agenesis of the cavum septi pellucidi was contemplated.

CONCLUSIONS

The use of the proposed flowchart enabled differentiation between hydrocephalus and HPE. The communication between the ventricles in hydrocephalic fetuses may be due to a disruption of the septum pellucidum or to a pathological enlargement of the foramen of Monro. Published by John Wiley & Sons, Ltd.

Prenatal diagnosis of absence of the septum pellucidum associated with septo-optic dysplasia

Septo-optic dysplasia (SOD; De Morsier syndrome) is a rare congenital disorder characterized by the absence of the septum pellucidum (SP), hypoplasia of the optic chiasma and nerves, and various types of hypothalamic-pituitary dysfunction. We report on two fetuses with absence of the SP diagnosed by ultrasound examination at 29 and 30 gestational weeks. In the first case the diagnosis of SOD was suspected in utero and confirmed postnatally; to the best of our knowledge this is the first report of the prenatal diagnosis of SOD. In the second case absence of the SP appeared to be isolated and no visual or endocrine impairment were detected after birth.

Septo-optic dysplasia with digital anomalies?a recurrent pattern syndrome

A distinct form of septo-optic dysplasia (SOD) comprises limb malformations in addition to the characteristic CNS and ocular abnormalities. To date, there have been 4 reports, citing 5 affected patients with this combined phenotype. We now add a further case and present neuroradiological images of the CNS findings in this condition. The striking consistency of the limb malformations and their overlap with the Streeter's band phenotype is emphasized.

Transabdominal sonography of the cavum septum pellucidum in normal fetuses in the second and third trimesters of pregnancy

OBJECTIVES

To assess the visualization rate and size of the cavum septum pellucidum (CSP) by transabdominal sonography in normal fetuses throughout pregnancy.

METHODS

The CSP was prospectively researched and measured using an axial transventricular plane in 286 consecutive uncomplicated singleton pregnancies between 15 and 41 weeks of gestation.

RESULTS

The CSP was seen in 40% of cases at 15 weeks, 82% at 16-17 weeks, 100% at 18-37 weeks and 79% at 38-41 weeks. Compared to biparietal diameter (BPD), the visualization rate was 33% between 31 and 32 mm, 45% between 33 and 34 mm, 84% between 35 and 43 mm, 100% between 44 and 88 mm and 86% between 89 and 99 mm. Mean CSP width was 5.3 +/- 1.7 mm (range 2-9 mm). The CSP width increased with gestational age and BPD but with a slight decrease around term.

CONCLUSIONS

In normal fetuses the CSP should always be visualized between 18 and 37 weeks, or with a BPD of 44-88 mm. Failure to observe the CSP in this interval, or possibly the presence of a large CSP, may indicate abnormal cerebral development and warrant further investigation. Conversely, absence of the CSP prior to 18 weeks, or later than 37 weeks, is a normal finding.

Absence of the septum pellucidum and related disorders

We present an illustration of the spectrum of intracranial abnormalities associated with absence of the septum pellucidum to better define and illustrate this disorder. CT and 1.5 Tesla MRI examinations of fifteen patients with absence of the septum pellucidum were meticulously analyzed and correlated with clinical and laboratory studies. The findings were compiled and categorized based upon the presence and type of associated radiologic abnormalities. Absence of the septum pellucidum may occur as an isolated abnormality (n = 3). In most patients (n = 12), associated complex developmental abnormalities are present which include heterotopias, hypoplastic falx, ventricular clefts, encephalocele, small pituitary gland, small optic nerves and chiasm, and corpus callosal dysgenesis. Inferior pointing and a squared-off appearance of the frontal horns are frequently noted. These, or other, more severe ventricular configuration deformities are present in all patients. We have portrayed the complete range of findings associated with absence of the septum pellucidum using an illustrative approach to clarify the different patterns of radiologic abnormalities which may be seen with this complex entity.