title: Hydrodynamic and longitudinal impedance analysis of cerebrospinal fluid dynamics at the craniovertebral junction in type I Chiari malformation.
abstract: Elevated or reduced velocity of cerebrospinal fluid (CSF) at the craniovertebral junction (CVJ) has been associated with type I Chiari malformation (CMI). Thus, quantification of hydrodynamic parameters that describe the CSF dynamics could help assess disease severity and surgical outcome. In this study, we describe the methodology to quantify CSF hydrodynamic parameters near the CVJ and upper cervical spine utilizing subject-specific computational fluid dynamics (CFD) simulations based on in vivo MRI measurements of flow and geometry. Hydrodynamic parameters were computed for a healthy subject and two CMI patients both pre- and post-decompression surgery to determine the differences between cases. For the first time, we present the methods to quantify longitudinal impedance (LI) to CSF motion, a subject-specific hydrodynamic parameter that may have value to help quantify the CSF flow blockage severity in CMI. In addition, the following hydrodynamic parameters were quantified for each case: maximum velocity in systole and diastole, Reynolds and Womersley number, and peak pressure drop during the CSF cardiac flow cycle. The following geometric parameters were quantified: cross-sectional area and hydraulic diameter of the spinal subarachnoid space (SAS). The mean values of the geometric parameters increased post-surgically for the CMI models, but remained smaller than the healthy volunteer. All hydrodynamic parameters, except pressure drop, decreased post-surgically for the CMI patients, but remained greater than in the healthy case. Peak pressure drop alterations were mixed. To our knowledge this study represents the first subject-specific CFD simulation of CMI decompression surgery and quantification of LI in the CSF space. Further study in a larger patient and control group is needed to determine if the presented geometric and/or hydrodynamic parameters are helpful for surgical planning.
authors.affiliation: Conquer Chiari Research Center, University of Akron, Ohio, United States of America ; Department of Mechanical Engineering, University of Akron, Ohio, United States of America.
authors.forename: Bryn A
authors.initials: BA
authors.lastname: Martin
authors.forename: Wojciech
authors.initials: W
authors.lastname: Kalata
authors.forename: Nicholas
authors.initials: N
authors.lastname: Shaffer
authors.forename: Paul
authors.initials: P
authors.lastname: Fischer
authors.forename: Mark
authors.initials: M
authors.lastname: Luciano
authors.forename: Francis
authors.initials: F
authors.lastname: Loth
mesh_terms: D001139:Arnold-Chiari Malformation / Q000378:metabolism* / Q000503:physiopathology; D002555:Cerebrospinal Fluid / Q000378:metabolism*; D002574:Cervical Vertebrae / Q000378:metabolism*; D017097:Electric Impedance; D057446:Hydrodynamics