Adult-onset hydrocephalus can be acquired from other pathologies, congenital with a late onset, or idiopathic. Subarachnoid hemorrhage, normal-pressure hydrocephalus, tumors, and aqueductal stenosis are the most frequent causes, and clinical presentation may be acute or chronic. The pathophysiology of the more chronic form involves hypoxia and blood vessel changes. The treatment of adult hydrocephalus is dependent on its setting and may involve ventroposterior or ventroanterior shunting or endoscopic procedures.