O.027 Comparison of intraparenchymal and CSF pulse waves

Abstract

Background: The ICP pulse wave is getting more and more attention in research on traumatic brain injury and hydrocephalus. This study aims to investigate the measurability of the ICP pulse wave via lumbar space. Methods: Ten patients with confirmed communicating CSF-systems were included in the study. ICP was measured in the parenchyma above the frontal right ventricle, and CSF pressure (LP) was measured via the lumbar space. Pressure was manipulated by CSF infusion from baseline (mean = 19 mm Hg) to a maximum excess pressure (mean = 45 mm Hg). The amplitude of the ICP wave was analysed using Matlab and SPSS. Results: The mean difference between the intracranial and lumbar amplitude was 0.55 mm Hg (SD=1.48) [range: -2.3 to +3.6] (p<0.05). Analyse of each pressure level showed that the amplitude difference was only significant at baseline (0.91 mm Hg (SD= 1.68)[range: -0.35 to +2.90], pressure range 10 to 23 mm Hg). A general linear model revealed that amplitude difference was significantly affected by factors related to the individual patients. Conclusion:. At baseline pressures there was a systematic difference between the ICP and LP amplitude which could be relevant if INPH patients are selected for surgery based on pulse amplitude. At higher pressure levels the pressure pattern tended to be more equalised in the craniospinal system. Furthermore, there seems to be a patient specific difference in amplitude as well which could be due to differences between sensors or have physiological reasons.