Analysis of intracranial pressure signals recorded during infusion studies using the spectral entropy

Hydrocephalus includes a range of disorders characterized by clinical symptoms, abnormal brain imaging and altered cerebrospinal fluid (CSF) dynamics. Infusion tests can be used to study CSF circulation in patients with hydrocephalus. In them, intracranial pressure (ICP) is deliberately raised and CSF circulation disorders evaluated through measurements of the resulting ICP. In this study, we analyzed 77 ICP signals recorded during infusion tests using the spectral entropy (SE). Each signal was divided into four artifact-free epochs. The mean SE, <;SE>, and the standard deviation of SE, SD[SE], were calculated for each epoch. Statistically significant differences were found between phases of the infusion test using <;SE> and SD[SE] (p<;1.7·10^-3, Bonferroni-corrected Wilcoxon tests). Furthermore, we found significantly lower <;SE> and SD[SE] values in the plateau phase than in the basal phase. These findings suggest that the increase in ICP during infusion studies is associated with a significant decrease in irregularity and variability of the spectral content of ICP signals, measured in terms of SE. We conclude that the spectral analysis of ICP signals could be useful for understanding CSF dynamics in hydrocephalus.