Hydranencephalyis a rare malformation of the brain system. It is characterized by the absence of bilateral cerebral hemispheres which are replaced by cerebrospinal fluid. The word Hydranencephaly is a fusion of hydrocephalus and anencephaly. Hydranencephaly often occurs as an isolated defect without other associated malformations. Nearly all cases are sporadic. Hydraencephaly occurs in less than 1 in 10,000 births and is characterized by near-total or total absence of the cerebral cortex and basal ganglia [1]. Hydranencephaly was first described by Cruveilhier in 1835. There are various hypotheses about the cause and pathogenesis of the disease. Infarction, leukomalacia, and diffuse hypoxic ischemic brain necrosis, infection (toxoplasmosis, cytomegalovirus, herpes simplex infections (HSV) are mostly blamed [2]. Here, we report the case of a male neonate with hydranencephaly confirmed by magnetic resonance angiography (MRA).

A 5day-old male infant born to a 22-year-old primiparous mother at the gestational age of 36 weeks via vaginal delivery. Maternal history was unremarkable. No known teratogenic or infectious exposures were documented during pregnancy. Family history is unremarkable, and there was no consanguinity. Apgar score was 7 at 1 minute and 8 at 5 minutes.

At presentation head circumference was 30cm (25^th percentile) with craniofacial disproportion, his birth body weight was 1900g (25^th percentile), and his body length was 45cm (10^th percentile), Pupils were equal in size, primitive reflexes like suckling and grasp were intact. He had normal tone on the limbs. Soon after the birth, he was noted to have feeding difficulties and hypotonia.

No seizure activity was noted in the neonatal period. Brain ultrasonography showed absence of bilateral cerebral hemispheres but intact cerebellar vermis. Subsequent brain magnetic resonance imaging revealed nearly total parenchymal loss of the entire fore brain with brain tissue replaced by cerebrospinal fluid, except for small right inferior medial temporal lobes, small bilateral medial occipital lobes, and small thalami, suggesting hydranencephaly.

Figure 1: MRI Brain (axial and sagittal) plan study revealed near absence of both cerebral hemispheres.

Routine laboratory examinations, including coagulation assessment, electrocardiogram, and renal ultrasound, were normal, and toxoplasmosis, rubella, cytomegalovirus, and herpes simplex titers were negative. The electroencephalogram (EEG) showed remarkable easy memory with an essentially silent record from left sided leads; right-sided leads showed diffuse mild-moderates lowing but no epileptic form activity. Regressive enlargement of the skull made oral feeding with the head tilted up difficult. Thus, feeding via nasogastric tube was begun.

Hydranencephalyis a rare congenital anomally characterized by loss of cerebral hemispheres and a cranial cavity filled with cerebrospinal fluid. It is one of the recognized forms of intracranial malformations associated with intrauterine fetal demise of one of twins in monochorionic twin gestation [3]. Various aetiologies have been proposed this include bilateral occlusion of the internal carotid arteries that leads to necrosis and haemorrhage of the developing brain [4,5] leukomalacia, diffuse hypoxic-ischemic brain necrosis, infections congenital toxoplasmosis, cytomegalovirus, and herpes simplex infections [6,7].

Several pathogeneses have been proposed recently for this condition. Fetal encephalitis caused by certain viral infections may be a possible origin of hydranencephaly. A study from Israel found that Akabane virus (AKAV) and Aino virus (AINV) could cause teratogenic malformations when they infected immunologically naive pregnant ruminants [8]. Diagnosis of hydranencephaly can be made in utero using ultrasonography or magnetic resonance imaging while, CT scan and MRI are important diagnostic tools postnatally [3,9].

Differential diagnoses of hydranencephaly include bilateral extra cerebral collection of fluid in the skull, severe open lips chizencephaly and extreme Hydrocephalus [7].These can be differentiated from hydranencephaly by using an EEG as extreme Hydrocephalus will show evidence of cortical activity while hydranencephaly will not and, will give a flat is electric recording [11]. Surgery is considered unnecessary as majority of infants with hydranencephaly will die within the first year of life [11,12].

However, survival up to first decade of life has been reported in literature [13]. Children with hemi hydranencephaly can lead a normal life however, complete hydranencephaly is not compatible with a prolonged life after birth, with the vast majority of live births dying prior to one year of age. Termination of pregnancy is usually considered justifiable due to this reason [8].

Hydranencephalyis a severe brain condition characterized by complete or almost complete absence of cerebral cortex with preservation of meninges, basal ganglia, pons, medulla, cerebellum, and falx. Bilateral occlusion of the internal carotid arteries mostly in the supraclinoid level in utero is a potential etiology. Ultrasound is the modality of choice for the diagnosis of Hydranencephaly in pre and postnatal period. Differential diagnosis are alobarholoprosencepaly, aqueductal stenosis and open–lipschizencephaly. Fetal MRI can be used to confirm diagnosis. Termination is offered because prognosis is dismal. If pregnancy progresses, monitoring of labor and neonatal resuscitation may be withheld.

Written informed consent was obtained from the patient for publication of this case report.

Disclosure

This clinical case was written based on clinical observation without any funding.

Conflicts of Interest

There are no conflicts of interest between the authors and between the authors and the patient.

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