What is "hydranencephaly"

alt. A condition where the brain's cerebral hemispheres are absent, replaced by sacs filled with cerebrospinal fluid. n. A condition where the brain's cerebral hemispheres are absent, replaced by sacs filled with cerebrospinal fluid.

Hydranencephaly or hydrancephaly is a condition in which the brain's cerebral hemispheres are absent to varying degrees and the remaining cranial cavity is filled with cerebrospinal fluid.

Hydranencephaly (or hydrancephaly) is a type of cephalic disorder. These disorders are congenital conditions that derive from either damage to, or abnormal development of, the fetal nervous system in the earliest stages of development in utero. Cephalic is the medical term for “head” or “head end of body.” These conditions do not have any definitive identifiable cause factor; instead generally attributed to a variety of hereditary or genetic conditions, but also by environmental factors such as maternal infection, pharmaceutical intake, or even exposure to high levels of radiation.

This should not be confused with hydrocephalus, which is an accumulation of cerebrospinal fluid in the ventricles of the brain.

In hemihydranencephaly, only half of the cranial cavity is filled with fluid.