Loss of the Cerebrum
Hydranencephaly is a birth defect in which the cerebral hemispheres are absent and replaced by cerebrospinal fluid.
The brainstem usually remains. Babies with this condition have a very poor prognosis. In hydrocephalus
, cerebrospinal fluid is increased in the ventricles of the brain. The brain is intact, however. It is usually treated by a surgical shunt to drain the excess fluid.