Transcerebral Mantle Pressure in Normal Pressure Hydrocephalus

Abstract

Four patients with normal pressure hydrocephalus underwent constant infusion manometry during general anesthesia to determine their cerebrospinal fluid (CSF) absorption capacity. Before and during lumbar saline infusion, intraventricular (ICP_V), subdural (ICP_SD), and lumbar sac pressures were monitored continuously. The ICP_Vrose progressively in all four without equilibration of saline infusion and CSF absorption. A pressure gradient between the ventricle and the subdural space (ICP_V> ICP_SD), barely evident before infusion, increased as ICP_Vrose in three of the four. Two additional patients without ventricular dilation, failed to show a pressure gradient across the cerebral mantle within the measured ICP_Vrange (10 to 30 mm Hg). A pressure gradient across the cerebral mantle may contribute to ventricular dilation in normal pressure hydrocephalus.