Acrania-Exencephaly-Anencephaly Sequence. [Neuroradiology] [US]

Mom was a 36 year old with active meth abuse, homelessness, and scant prenatal care.

Prenatal ultrasound at 36 weeks shows a highly deformed fetal brain with large fluid-filled spaces that might represent cysts or hydrocephalus. The brain contours are lobulated and irregular due to absence of an overlying skull.

She was recommended for pregnancy termination but no-showed to that procedure. She then presented 3 weeks later, at 39 weeks, in labor. The baby was delivered spontaneously. The baby had absent skull above the level of the ears. The brain was large and could be seen through a membranous sac. The baby passed away one day later.

Acrania is the absence of a skull. Exencephaly is the condition where a brain (which may have otherwise been normal) is not covered by the skull in the prenatal setting. Due to the exposure of brain tissue to amniotic fluid, which is toxic to brain, exencephaly will invariably lead to anencephaly, which is the absence of all/most of the brain.