hydrocephalus

the lack of absorption, blockage of flow, or overproduction of the cerebral spinal fluid (CSF) that is found inside of the ventricles (fluid-filled areas) inside of the brain. This may result in a build-up of fluid, which may cause the pressure inside of the head to increase and the skull bones to expand to a larger-than-normal appearance. Fetal hydrocephalus is found by ultrasound during pregnancy and is often further visualized with magnetic resonance imaging (MRI).