Hydranencephaly in a Neonate: A Literature Review
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0028-3886.279698
Source of Support: None, Conflict of Interest: None
We report a case of hydranencephaly (HE) on an hour old female neonate born to an HIV positive mother at a gestational age of 38 weeks to 30-year-old para 2 mother through cesarean section for congenital hydrocephalus detected during antenatal ultrasound imaging. The mother was tested positive for HIV before pregnancy and had been on highly active antiretroviral therapy (HAART) using Atripla with good viral suppression and CD4+ count. The outcome of the delivery was a female neonate with Apgar score of 8/10, 9/10, and 10/10 at first, fifth, and tenth min, respectively. The birth weight was 3040 gm, head circumference 39 cm, and length of 53 cm. The mother was tested negative for syphilis using the VDRL test. There was no history of congenital malformation or dysmorphism in the other sibling and mother has no previous miscarriage of pregnancy or chronic medical conditions such as hypertension, diabetes mellitus, or connective tissue diseases. The mother has denied a history of travel outside Botswana.
On examination, the newborn had macrocephaly which was above 97th percentile on head circumference for age CDC curve. Nevertheless, the baby appeared active, pink in color, and with no respiratory distress. We did not identify obvious dysmorphic features upon general examination. On central nervous system (CNS) examination, we observed the baby moving all limbs. The neonate had increased tone in all extremities and sustained ankle clonus. The Moro reflex was symmetrical and brisk with good sucking and grasp reflexes. On the calvarium, we noted a wide anterior fontanel which was flat and soft with absence of occipital bone prominence. Examination of other organ systems were unremarkable. Brain computed tomography (CT) showed complete replacement of the cerebral hemispheres with fluid and no visible cortical plate or hemispheric white matter [Figure 1]. The neonate was started on acetazolamide and discharged while awaiting further management at the neurosurgery unit.
HE is a rare, mostly isolated abnormality, which is reported to affect about 1 out 5000 continuing pregnancies. It is one of the most severe forms of bilateral cerebral cortical anomaly. In this condition, the cerebral hemispheres are completely or almost completely missing. In their place, there is a membranous tissue filled with cerebrospinal fluid, glial tissue, and ependyma.
Patients with HE typically have a markedly reduced life expectancy, either being stillborn or dying within a few weeks or months after birth. Although prolonged survival has rarely been reported, specific neuroimaging or neuropathologic details that permit either confirmation of the diagnosis or ascertainment of a putative pathophysiologic feature to account for the prolonged survival are often lacking.,
Furthermore, HE is a term of gross description that includes a group of disorders that vary widely in their presumable time of onset, mechanisms of pathogenesis, regions of involvement of the CNS, and anatomic organization of the brain remnant. Although remnants of nonfunctioning cortex can be present, the hallmark is the extensive reduction in brain matter that has been replaced with cerebrospinal fluid. Facial features are uniformly normal, which distinguishes HE from other major CNS anomalies.
Despite the increasing evidence from ultrasonography, computed tomography (CT), magnetic resonance imaging (MRI), and histopathologic and clinical data; several aspects of HE remain controversial in terms of pathogenesis, time of onset, the spectrum of phenotypic presentation, and prognosis.
The pathogenesis of HE is still unknown, however most researchers support the hypothesis that the brain damage in HE is related to early internal carotid artery involvement, as demonstrated by angiographic and autopsy observation, in which internal carotid artery anomalies, both aplastic and hypoplastic, are reported and by the anatomic distribution of the anomaly in HE, which follows the internal carotid artery supply., Moreover, HE was associated with bilateral internal carotid artery occlusion, congenital infection such as TORCH syndrome, Treponema palladium, equine virus, and extensive hemorrhagic infarction following either germinal matrix hemorrhage or intraventricular hemorrhage which cannot be overlooked.
Regarding the gross pathologic study, the extensive replacement of brain matter with cerebrospinal fluid and the preservation of diencephalic/posterior cranial fossa structures are the hallmarks of HE. However, many reports demonstrated the frequent persistence of occipital, temporal, or frontal cerebral remnants., There is usually preservation of the deeper structures such as the cerebellum, midbrain, thalami, and basal ganglia. The diagnosis may initially be overlooked because of normal appearance and behavior at birth, since brainstem functions are preserved as observed in our patient.
The case we identified with HE can be overlooked as they appear to have normal vital signs and smooth postnatal course because of preservation of midbrain structures, it is important to have imaging of the brain for newborns with macrocephaly to identify such kind of extensive brain lesion which has management and prognostic impact.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient has given her consent for her child's images and other clinical information to be reported in the journal. The mother understand that the child's names and initials will not be published, and due efforts will be made to conceal her identity, but anonymity cannot be guaranteed.
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