Antenatally diagnosed alobar holoprosencephaly: A report of two cases

CR Srinivasa Babu; Inampudi Vineel; Arjun Prakash; Y Ravi Kumar

doi:10.4103/cjhr.cjhr_23_17

CASE REPORT

Year : 2017 | Volume : 4 | Issue : 4 | Page : 283-285

Antenatally diagnosed alobar holoprosencephaly: A report of two cases

CR Srinivasa Babu, Inampudi Vineel, Arjun Prakash, Y Ravi Kumar
Department of Radio-diagnosis, PES Institute of Medical Sciences and Research, Kuppam, Andhra Pradesh, India

Date of Web Publication

11-Oct-2017

Correspondence Address:
Inampudi Vineel
S/o I. Ramesh Babu, H/N 8-114, Nidamanuru, Vijayawada Rural, Krishna District - 522 104, Andhra Pradesh
India

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/cjhr.cjhr_23_17

Abstract

Holoprosencephaly is a complex developmental abnormality of the brain arising from the failure of cleavage of the prosencephalon. The condition termed “holoprosencephaly” includes cyclopia, cebocephaly, ethmocephaly, and median cleft. We present two cases of antenatally diagnosed alobar holoprosencephaly with multiple associations, which were confirmed after termination of pregnancy. One of them had a proboscis and a single midline eye. The other had multiple facial abnormalities such as hypotelorism, median cleft lip and palate, and preauricular skin tag.

Keywords: Cyclopia, holoprosencephaly, proboscis, ultrasound

How to cite this article:
Srinivasa Babu C R, Vineel I, Prakash A, Kumar Y R. Antenatally diagnosed alobar holoprosencephaly: A report of two cases. CHRISMED J Health Res 2017;4:283-5

How to cite this URL:
Srinivasa Babu C R, Vineel I, Prakash A, Kumar Y R. Antenatally diagnosed alobar holoprosencephaly: A report of two cases. CHRISMED J Health Res [serial online] 2017 [cited 2023 Mar 31];4:283-5. Available from: https://www.cjhr.org/text.asp?2017/4/4/283/216467

Introduction

Holoprosencephaly is a disorder caused by the absence or incomplete diverticulation and cleavage of the prosencephalon into the cerebral hemispheres and lateral ventricles. The incidence of holoprosencephaly is 1:250 during embryogenesis and 1:16,000 of all the births.^[1] Cyclopia has been reported to occur in 1:40,000 births and median cleft has been reported to occur at a rate of 1:16,000 births.^[2] Females are affected three times more than the males with a female:male ratio of 3:1.^[3]

Case Report

A 22-year-old primigravida with 7 months of amenorrhea presented to the radiology department for obstetric ultrasonography (USG) examination as a part of the routine antenatal checkup. There was no history of consanguinity. USG revealed single live intrauterine fetus corresponding to gestational age of 28 weeks 4 days. Bilateral lateral ventricles were enlarged and fused with centrally fused thalami and peripherally compressed cerebral parenchyma [Figure 1]. The falx cerebri, septum pellucidum, and corpus callosum were completely absent. The facial features were dysmorphic with centrally fused orbits forming single eye called the cyclops, and an external midline soft tissue projection was seen the proboscis [Figure 2]. The nose was not seen separately. The findings were better appreciated on three-dimensional images [Figure 2]a. The pregnancy was terminated, and antenatal findings were confirmed postnatally [Figure 2]b.

Figure 1: (a and b) Antenatal ultrasonography shows central large monoventricle with surrounding thin mantle of cerebral parenchyma and fused thalami. The falx cerebri, septum pellucidum, and corpus callosum are absent. An external midline soft tissue projection is seen-proboscis (green arrow)

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Figure 2: (a) Three-dimensional ultrasonography image clearly delineates the proboscis (green arrow) with extreme degree of hypotelorism leading to cyclops (red arrow). (b) Postnatal image confirms the presence of proboscis (green arrow) and cyclops (red arrow)

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Another 21-year-old gravida two, para one female with 6 months of amenorrhea presented to the department for a routine antenatal USG scan. Medical and family histories were unremarkable, with the previous child being born at term with no congenital anomaly. Her general physical examination was normal. A routine antenatal USG revealed a central large monoventricle with surrounding thin mantle of cerebral parenchyma [Figure 3]. The septum pellucidum, falx cerebri, and interhemispheric fissure were absent. Both the thalami were fused [Figure 3]. There was associated hypotelorism [Figure 4]a and [Figure 4]b, median cleft lip [Figure 4]a and [Figure 4]c, depressed nasal bridge, left preauricular skin tag [Figure 4]a, and gastroschisis with a portion of liver protruding out through the defect in the anterior abdominal wall [Figure 5]. Rest of the fetus was normal. The antenatal USG features were confirmed postpartum [Figure 5]b.

Figure 3: Antenatal ultrasonography axial section shows central large monoventricle with surrounding thin mantle of cerebral parenchyma with fused thalami. The septum pellucidum, falx cerebri, and interhemispheric fissure are absent

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Figure 4: (a and b) Antenatal ultrasonography shows extreme degree of hypotelorism, median cleft lip and left preauricular skin tag (red arrow). (c) Three-dimensional image better depicts the hypotelorism, median cleft lip, and depressed nasal bridge

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Figure 5: (a) Axial section at the level of abdomen shows gastroschisis with portion of liver protruding out through defect in anterior abdominal wall. (b) Postnatal images confirm presence of hypotelorism, median cleft lip (green arrow), depressed nasal bridge, and gastroschisis (red arrow)

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Discussion

Holoprosencephaly is a complex developmental abnormality of the brain arising from failure of cleavage of prosencephalon. Prosencephalon is the most rostral of the three primitive cerebral vesicles and gives rise to cerebral hemispheres and diencephalic structures (including neurohypophysis, thalami, third ventricle, and optic bulbs). This differentiation process is thought to be induced by prechordal mesenchyme interposed between roof of the mouth and prosencephalon. The same tissue is responsible for normal development of median facial structures (forehead, nose, interorbital structures, and upper lip).^[2] so any interference with the activity of prechordal mesenchyme would lead to defects in brain and face.

The most relevant classification of holoprosencephaly for antenatal diagnosis is that suggested by Demyer, which recognizes three types: alobar, semilobar, and lobar according to the degree of incomplete division of prosencephalic derivatives.^[2] According to the degree of failure of rotation, alobar holoprosencephaly is commonly subdivided into three types: pancake, cup, and ball varieties.^[2] The association between facial anomalies and holoprosencephaly has led to the well-known phrase, “the face predicts the brain.”^[4] The most severe of facial malformations associated with alobar holoprosencephaly are cyclopia, ethmocephaly, and cebocephaly. The others are hypotelorism, median cleft lip and palate, lateral cleft lip and palate and pyriform aperture stenosis. Semilobar and lobar types show milder facial anomalies. However, similar faces are occasionally seen in the absence of holoprosencephaly and presence of these facial features is not always diagnostic. Cyclopia is the most severe abnormality among the median cerebrofacial anomalies and mild hypotelorism with flat face being the least severe.

Holoprosencephaly is often associated with chromosomal abnormalities, primarily trisomy 13, trisomy 18, and trisomy 13/15.^[2] Alobar type shows no cleavage of prosencephalon with a large monoventricle surrounded by thinned out mantle with absent interhemispheric fissure, falx cerebri, corpus callosum, fornix, optic tract, neurohypophysis, and olfactory bulbs. The thalami are fused with absent third ventricle.^[5] Failure of inward rotation of primitive cerebral hemispheres prevents the thin membranous roof of the ventricular cavity from being enfolded within the brain. Because of increase in cerebrospinal fluid, the membrane may balloon out to form a cyst between cerebral convexity and calvarium (so-called dorsal cyst). There may be a complete absence of gyri with few shallow sulci. The single ventricle that persists shows a typical horseshoe shape when seen in coronal section. On the contrary, the posterior fossa contents which include cerebellum and brain stem are normal.

Ultrasound is most helpful in prenatal diagnosis of holoprosencephaly especially of alobar type and is the decisive modality for the management and follow-up of such cases so that the mother can opt for termination of pregnancy and doctor can decide for a vaginal delivery rather than caesarean section. It has already been emphasized previously about the association of hypotelorism and absent Falx for diagnosing holoprosencephaly.^[6] Infants with alobar form usually die within 1^st year of life.^[2]

When the diagnosis of alobar or semilobar holoprosencephaly is made before viability, the option of pregnancy termination with fetal karyotyping is indicated. When detected before 24 menstrual weeks, most women will elect to terminate pregnancy; when identified after 24 weeks, cephalocentesis may be a justifiable option.^[7]

The decision-making in lobar holoprosencephaly is difficult because data concerning outcome are not available.

Conclusion

Holoprosencephaly is a major malformation of the central nervous system that should be distinguished from other causes of fetal hydrocephalus. Awareness of the spectrum of sonographic findings seen with holoprosencephaly should improve the accuracy of prenatal diagnosis. Identification of concurrent facial and extracranial malformations can help predict chromosomal anomalies and subsequent fetal outcome. Because of recent advances in development and improvement of high-resolution USG, early diagnosis of congenital anomalies such as holoprosencephaly is now possible.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Acknowledgment

I, sincerely thank all my staff and co-residents for their cooperation during the workup of this case report.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

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