Postnatal in-vivo MRI findings in anencephaly

Aims: Anencephaly represents the most severe form of neural tube defects. It is characterized by open defect in the calvaria and skin, partial or total absence of the cerebral structures, and abnormal development of the skull base. Anencephaly is uniformly lethal and live born infants die within hours or days of birth. Therefore, postnatal MRI findings in anencepahly are exceptional. We aim to extend the neuroimaging spectrum of this malformation and point out the findings in the posterior fossa.

Case report: We report the MRI findings of an anencephalic infant who survived for 10 weeks. A brain MRI study performed at the request of the parents showed absence of the cranial vault, all the supratentorial structures (including the pituitary gland), and cerebellum. A brainstem primordium without pontine prominence was present. The brainstem was surrounded by the area cerebrovasculosa. The inner ear apparatus was present bilaterally but dysmorphic. Both eyes were contained in small orbits, the optic nerves were hypoplastic. Two small lateral pseudo-meningoceles were seen along the superior cervical spinal cord extending into the adjacent neuroforamina. No other malformations outside of the CNS were noted.

Conclusion: Our case confirms the pathologically reported findings in the CNS. Particularly, bilateral malformations of the inner ear apparatus organs and hypoplasia of the optic nerves had been reported in another anencephalic patient with postnatal MRI. The absence of pontine prominence in an anencephalic infant without cerebellar tissue confirms the observation that absent pontine prominence is found in children with prenatal, not postnatal loss of cerebellar tissue.