Negative intracranial pressure hydrocephalus in adults with shunts and its relationship to the production of subdural hematoma

Abstract

Subdural hematomas and effusions have been noted in at least 20% of adult patients treated with CSF shunts for normal pressure hydrocephalus. In a series of 39 cases the incidence of this complication is correlated with the low 41% improvement rate. The very low intracranial pressure achieved with conventional shunt systems is probably the most important factor causing subdural collections of blood or fluid. In a study of pre and post shunt CSF pressures in 25 patients it was found that in the erect position ventriculoatrial and ventriculoperitoneal shunt systems produced pressures averaging -238 and -251 mm H2O respectively. Although the new antisiphon valves produced much smaller decrements of CSF pressure with significant clinical improvement in some cases, these units did not always prevent subdural hematomas.