Hydrocephalus is a medical condition in which there is an unusual buildup of cerebrospinal fluid (CSF) in brain cavities known as ventricles. According to the National Institute of Nervous Disorders and Stroke (NINDS), the exact number of hydrocephalus is hard to determine because it strikes both children and adults. Hydrocephalus can be a congenital condition. However, it can also be acquired in cases of head trauma before, during, or birth.