|Year : 2019 | Volume
| Issue : 13 | Page : 35-37
Alobar holoprosencephaly in one of twin neonates
Bukunmi Michael Idowu
Department of Radiology, Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Osun State, Nigeria
|Date of Web Publication||19-Feb-2019|
Bukunmi Michael Idowu
Department of Radiology, Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Osun State
Source of Support: None, Conflict of Interest: None
Holoprosencephaly (HPE) is a congenital structural anomaly of the forebrain which is often diagnosed prenatally, usually in singleton pregnancies. This is a case of alobar HPE affecting one of 19-day-old twin neonates which was only detected postnatally. The other twin was unaffected. The anomaly was not diagnosed in utero because a prenatal sonogram was not performed. This case is presented to reemphasize the need for thorough routine prenatal/obstetrics sonography. After birth, transfontanelle ultrasonography is a useful imaging modality for diagnosing this debilitating cerebral structural anomaly, but definitive classification requires cross-sectional brain imaging with computed tomography or magnetic resonance imaging.
Keywords: Alobar holoprosencephaly, transfontanelle sonography, twin pregnancy
|How to cite this article:|
Idowu BM. Alobar holoprosencephaly in one of twin neonates. N Niger J Clin Res 2019;8:35-7
| Introduction|| |
Holoprosencephaly (HPE) results from complete or incomplete nonseparation of the prosencephalon (forebrain). There are four subtypes of HPE: alobar HPE, semilobar HPE, lobar HPE, and a middle interhemispheric fusion variant (MIHFV) (syntelencephaly). Alobar HPE is the severest form with complete nonseparation of the cerebral hemispheres, monoventricle, corpus callosal agenesis, absent interhemispheric fissure, and fusion of the thalami. In semilobar HPE, there is incomplete separation of the cerebral hemispheres (partially separated posteriorly but fused anteriorly). Lobar HPE is typified by cerebral hemispheric fusion at the frontal lobes, completely separated ventricles, foci of incomplete division of the cerebral cortex, and hypoplastic anterior falx. The posterior portion of the frontal lobe and the parietal lobes are unseparated in the MIHFV. The lobar HPE and MIHFV are the most prevalent types.
Alobar HPE occurs more frequently in singleton gestations than in twin pregnancies and often affects only one of the twin fetuses. HPE is reportedly most common in females than in males although other researchers reported an equal sex incidence.
| Case Report|| |
A 19-day old female neonate and the second of a set of unidentical twins (the first twin is male), was referred on account of facial deformity since birth, difficulty with breathing, and continuous fever which started a day after birth. There was difficulty with suckling with repeated episodes of coughing/choking while breastfeeding. There are no associated vomiting or diarrhea and no history of seizure since birth. She was delivered at term through spontaneous vertex delivery. Weight and APGAR score at birth were not known but were said to have cried only after active resuscitation and administration of hydrocortisone. The mother is a 32-year-old para 2+0(3 alive) woman who received antenatal care at a primary health center. Mother is not a known hypertensive or diabetic. The twin brother was in apparently normal state of health. There is no history of similar illness in the first child.
Examination revealed a pink neonate in respiratory distress (dyspneic). She was febrile with temperature of 38.8°C, not pale, acyanosed, not dehydrated. The anterior and posterior fontanelles were patent and normotensive. Head-and-neck findings include microcephaly with occipitofrontal circumference of 28 cm, hypotelorism, left microphthalmia, flattened nasal bridge with poorly developed nasal skin fold, bilateral complete cleft lip, and complete cleft palate. Subcostal chest recession was noted, she was tachypneic, and breath sounds were vesicular with widespread-transmitted sounds. Cardiovascular system and abdominal examinations were normal. The external genitalia was normal, and the anus was perforate. The extremities were well formed; no hair tuft or swelling on the back. There were no abnormal neonatal reflexes. The clinical assessment was aspiration pneumonitis with background cleft lip, cleft palate, and midline abnormalities.
Hematologic, blood chemistry, urinalysis parameters, as well as the random blood sugar were within normal limits. Blood culture yielded growth of Staphylococcus aureus sensitive to cefuroxime, cefixime, cephalexin, streptomycin, and erythromycin.
Transfontanelle ultrasound (USS) showed fused thalami [Figure 1], absent falx cerebri and interhemispheric fissure, and single ventricle (monoventricle). The third and fourth ventricles were not visualized. The midbrain and cerebellum appeared preserved.
|Figure 1: Transfontanelle sonogram (coronal view) showing a monoventricle (down arrow) and fused thalami (upward arrow), and thin mantle of the cerebral cortex (left arrow)|
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Cranial computerized tomography (CT) showed a large hypodense monoventricle, fused thalami, severe thinning of the cerebral cortex, as well as absent interhemispheric fissure, falx cerebri, septum pellucidum, and corpus callosum. The cerebellum and fourth ventricle were normal [Figure 2]a and [Figure 2]b.
|Figure 2: (a and b) Axial computerized tomography showing a large hypodense monoventricle, fused thalami, thinned-out cerebral cortical mantle, and absent interhemispheric fissure|
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The aspiration pneumonitis was successfully managed with cefuroxime and streptomycin while feeding through orogastric tube. The patient was discharged and was being seen on outpatient basis preparatory to repair of the cleft lip and palate. However, the parents requested to transfer her management elsewhere, so as to take advantage of extended family support there. The patient was seen last in the clinic at 4 months old.
| Discussion|| |
HPE is a spectrum of disorders. Alobar HPE is the most severe form with no separation of the cerebral hemispheres. There is usually a single ventricle (monoventricle/holoventricle), which may communicate with a dorsal cyst (expanded tela choroidea)., The cerebral sulcation/gyration is extremely poor. The corpus callosum and interhemispheric fissure are absent, and the thalami are unseparated/fused. However, alobar HPE with unfused thalami has also been reported.
The reported worldwide incidence of HPE is variable, estimated at 1–1.7 per 10,000–53,394 live births. Higher birth prevalence of HPE has been reported among Far East Asians and Filipinos. In Nigeria, Frank-Briggs and Alikor reported one case of HPE among 35,473 children over a period of 5 years. Erondu et al. also documented three cases in 10,440 (0.29 cases/1,000) prenatal sonograms over a 2-year period. The vast majority of previous case reports of this anomaly in Nigeria had been in singleton deliveries.,,,,,,,,,
Relatively fewer cases of alobar HPE have been reported in twin gestations.,, Most of the previous cases of twin affectation involved dizygotic twins. These twin patients are also presumed to be dizygotic on account of their different genders. Furthermore, cases involving twin pregnancies in which one of the twins are unaffected like the index case appear to be fewer.
HPE often results in miscarriage, preterm delivery, or stillbirth. However, those that survive usually present in infancy. HPE in this patient was not detected prenatally likely because prenatal sonogram was not performed in the rural area where the mother received antenatal care. However, the features of alobar HPE were well demonstrated on the postnatal transfontanelle ultrasound and cranial CT.
Although it has been observed that postnatal USS could be difficult and limited in cases of microcephaly with small fontanelles, such a challenge was not encountered in this patient. Cranial CT was only done to confirm the diagnosis, classify the anomaly, and exclude close imaging differentials such as semilobar HPE, severe hydrocephalus, and hydraencephaly. Only a few of the previous case reports documented postnatal transfontanelle sonographic findings.,
Mortality and morbidity in HPE are determined by the severity of the malformations. Among live births (i.e., HPE cases that are not stillborn and did not die in utero), those with the severe type (alobar variety and those with cyclopia, ethmocephaly, and cebocephaly) often die within 1 week of birth. Those with milder malformations survive beyond infancy. Life expectancy is the poorest among those with syndromal and alobar HPE. This patient had alobar HPE with midline defects and was still alive up to 4 months after birth. Prognosis is worse for those who have a coexistent cytogenetic abnormalities such as chromosomal trisomies, duplications, deletions, and ring arrangements. The 2-year survival rate is 2% and 30%–54% for those with and those without cytogenetic abnormalities, respectively. Cytogenetic studies could not be done in the index patient because the facilities were unavailable.
| Conclusion|| |
HPE may be suspected when clinical features such as orofacial deformity, small head, hypo-/hypertonia, and seizures are noted in a newborn. Imaging is necessary to confirm the diagnosis. Transfontanelle sonography is a reliable and accurate diagnostic method postnatally. The role of imaging is to diagnose and classify the disorder. Imaging also helps distinguish HPE from other brain disorders with similar imaging features (hydranencephaly, hydrocephalus, porencephalic cyst, arachnoid cyst, and Dandy–Walker malformation).
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.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]