[Csf ex vacuo (author's transl)]

CSF ex vacuo is a proposed designation for abnormal collection of CSF replacing brain tissue which has been lost by trauma, infection, hemorrhage etc., or which has not been developed e.g. in aplasia of the temporal lobe. Such collections are known as arachnoid, leptomeningeal or porencephalic cysts. Under certain, however unsufficiently understood, conditions CSF ex vacuo may develop expansive tendencies, most obvious in growing fracture of the skull vault or base. In unexplained recurrent meningitis the presence of a frontobasal CSF collection should be looked for.