Analysis of Intracranial Pressure Signals Using the Spectral Turbulence

Abstract

Hydrocephalus includes a range of conditions characterized by clinical symptoms, enlarged ventricles and disorders in cerebrospinal fluid (CSF) circulation. Infusion tests can be used to analyze CSF dynamics in patients with hydrocephalus. In infusion tests, intracranial pressure (ICP) is artificially raised, while the resulting ICP is measured in order to detect CSF circulation alterations. In this study, we analyzed 77 ICP signals recorded during infusion tests using the spectral turbulence (ST). Each signal was divided into four artifact-free epochs. The mean ST,, and the standard deviation of ST, SD[ST], were calculated for each epoch. Statistically significant differences were found between the basal phase of the infusion test and the remaining phases using and SD[ST] (p<1.7·10-3, Bonferroni-corrected Wilcoxon tests). Furthermore, we found significantly higher and significantly lower SD[ST] values in the plateau phase than in the basal phase. These findings suggest that the increase in ICP induced by infusion studies is associated with a significant loss of irregularity and variability of the spectral content of ICP signals. In conclusion, spectral analysis of ICP signals could be useful for understanding CSF dynamics in hydrocephalus. © Springer International Publishing Switzerland 2014.