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 H 2 O 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.