RESUMO PALAVRAS-CHAVEHidrocefalia. Classificação. ; internal and external; high pressure and normal pressure; acute, subacute and chronic; symptomatic and asymptomatic; communicant and noncommunicant; mono/bi/tri/tetraventricular; ex vacuo ABSTRACT Acute essential hydrocephalus Objective: To discuss the acute hydrocephalus and the necessity of identifying its subtypes to provide more subsidies for understanding and management of the patients in this condition. Background: Hydrocephalus is a disturbance in the CSF dynamics in which there is an expansion of CSF brain compartment especially of ventricular system. It becomes evident by literature revision that there is an extensive classification based on various parameters. Therefore, it is possible to determine many categories of hydrocephalus: congenital and acquired; obstructive and by overproduction of CSF KEY WORDSHydrocephalus. Classification.