Hydranencephaly

Excerpt

Hydranencephaly is a rare congenital post-neurulation disorder that occurs during the second trimester characterized by the destruction of the cerebral hemispheres, which are replaced with a membranous sac filled with cerebrospinal fluid (CSF). The cranial cavity may have remnants of glial tissue and ependyma, especially along the falx and close to the diencephalon. The cranial vault and meninges are intact. It is most commonly caused by a vascular insult involving the anterior circulation. Midbrain structures such as the basal ganglia, brainstem, and posterior fossa structures are present. Patients at birth can appear normal with intact primitive reflexes. With time, they can present with macrocrania due to increased CSF pressure or less commonly with microcephaly. Diagnosis can be made in-utero with ultrasonography. Treatment is usually supportive, although in some cases with hydrocephalus, shunting of the CSF may be considered.