Age dependence of cerebrospinal pressure-volume compensation in patients with hydrocephalus

Object. The dynamics of both drainage and storage capacity become altered d uring the sequential pathological processes that lead to hydrocephalus. Cer ebrospinal fluid (CSF) formation and drainage rate have been reported to be age dependent. The aim of this study was to investigate whether CSF compen satory parameters are dependent on age in patients who have symptoms of hyd rocephalus and apparently normal intracranial pressure (ICP). Methods. Forty-six patients who presented with ventriculomegaly, the clinic al symptoms of hydrocephalus, and normal ICPs underwent a computerized CSF infusion test. Parameters used to describe CSF compensation were calculated and correlated with the age of each patient. The mean ICPs were found to be independent of the age of the patient. Resis tance to CSF outflow (Rcsf), however, demonstrated a nonlinear increase wit h advancing age (r = -0.57; p < 0.0001) and was associated with a decrease in the CSF production rate, which also occurred with increasing age (r = 0. 49; p < 0.002). Both the pulse amplitude of the ICP waveform and the slope of the amplitude-ICP regression line increased significantly with advancing age (r = 0.39; p < 0.01 and r = 0.43, p < 0.004, respectively). The nonlin ear increase in the elastance coefficient indicated increasing brain stiffn ess, which acompanies older ages (r = -0.31; p < 0.04). Conclusions. In a study of patients with symptoms of hydrocephalus, but nor mal ICPs, the increase in Rcsf and decrease in CSF production were most pro nounced in patients who were older than 56 years of age. This relationship was more significant than previously suggested.