Noninvasive MRI assessment of intracranial compliance in idiopathic normal pressure hydrocephalus

Abstract

Purpose To assess the state and dynamics of the intracranial system in idiopathic normal‐pressure hydrocephalus (I‐NPH), we determined intracranial compliance using magnetic resonance imaging (MRI). Materials and Methods The intracranial compliance index (ICCI), which was defined as the ratio of the peak‐to‐peak intracranial volume change (ICVCp‐p) to the peak‐to‐peak cerebrospinal fluid (CSF) pressure gradient (PGp‐p) during the cardiac cycle, was obtained from the net transcranial blood and CSF flow measured with phase‐contrast (PC) cine MRI. ICCI was determined in patients with I‐NPH (N = 7), brain atrophy, or asymptomatic ventricular dilation (VD) (N = 6), and in healthy volunteers (control group; N = 11). The changes in ICCI indices were also analyzed after a CSF tap test (N = 2). Results The ICCI in the I‐NPH group was significantly lower than in the control and VD groups, whereas no difference was found between the control and VD groups. The ICVCp‐p was also lower than in the control and VD groups. However, no significant difference was found in the PGp‐p between groups. The ICCI increased after the tap test. Conclusion Intracranial compliance analysis with MRI makes it possible to noninvasively obtain more detailed information of intracranial biomechanics in the I‐NPH and to assist in the diagnosis of I‐NPH. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.

CSF dynamic analysis of a predictive pulsatility-based infusion test for normal pressure hydrocephalus

“…Corresponding information is collected during an infusion test when the CSF system is exposed to an external perturbation, which will lead to larger or smaller AMP increase depending on the compliance. Important knowledge gained from this study was that, if further clinical studies confirms the effectiveness of AMPmean to select NPH patients for shunt surgery, it supports the recent focus on the compliance and pulsatility aspect of CSF dynamics, rather than Rout, in research into the pathophysiology of NPH [9,19,23,27].…”

Bulk motion-independent analyses of water diffusion changes in the brain during the cardiac cycle

“…Furthermore, we measured volume loading of the cranium, i.e., the net intracranial volume change (ICVC) [14,15] with phase-contrast (PC) cine MRI during the cardiac cycle, and we calculated the phase difference among the main wave components of ADC, fractional anisotropy (FA), and ICVC by Fourier analysis.…”

Idiopathic Normal-Pressure Hydrocephalus: Temporal Changes in ADC during Cardiac Cycle

“…The CSF tap test is a particularly reliable examination, but it is invasive and has low sensitivity. It has been proposed that MR imaging CSF flow studies can be used to noninvasively obtain information about intracranial mechanical properties in INPH (eg, intracranial compliance) (2,(8)(9)(10)(11)(12). However, the diagnostic utility of this latter method is still not established.…”

“…Arterial inflow into the cranium induces venous and CSF outflow and displacement of the intracranial spinal cord during the cardiac cycle, resulting in pulsatile brain motion (12)(13)(14). Brain pulsation (ie, bulk motion) reportedly can give rise to artifactual phase dispersion and may lead to overestimation of the apparent diffusion coefficient (ADC) (15,16).…”

“…Furthermore, many studies (2,(8)(9)(10)(11)(12) have demonstrated reduced compliance in INPH. Bateman et al (25) reported that venous resistance is increased; that is, venous compliance is decreased as a consequence of the low intracranial compliance.…”