Hydranencephaly is a rare brain malformation where the brain hemispheres are largely absent.
Pathology
Instead of functional nerve tissue, large fluid-filled cavities are found. In hydranencephaly, the meninges and the skull bone are intact and this condition is associated with a normal head shape[^1].
Variations
If only one half of the brain is affected, it is referred to as hemihydranencephaly.