Hydranencephaly
Background
Hydranencephaly is a condition that usually arises in mid/late pregnancy when a major reduction of blood supply to the brain results in loss of most of both cerebral hemispheres. The more primitive parts of the brain (brain stem, thalamus and cerebellum) are preserved so that usually the vital functions of breathing, heart function and temperature regulation are possible. The head mainly contains fluid-filled cavities with occasional small islands of the cerebral cortex remaining, particularly at the back of the head. A related condition of multiple cavities with more surviving brain is referred to as multicystic encephalomalacia.