Direct numerical simulation of transitional hydrodynamics of the cerebrospinal fluid in Chiari I malformation: The role of cranio‐vertebral junction

Abstract

Obstruction to the cerebrospinal fluid (CSF) outflow caused by the herniation of cerebellar tonsils as a result of Chiari malformation type I leads to altered CSF hydrodynamics. This contribution explores the minutest characteristics of the CSF hydrodynamics in cervical subarachnoid space (SAS) of a healthy subject and 2 Chiari patients by performing highly resolved direct numerical simulation. The lattice Boltzmann method is used for the simulations because of its scalability on modern supercomputers that allow us to simulate up to approximately 10 cells while resolving the Kolmogorov microscales. The results depict that whereas the complex CSF flow remains largely laminar in the SAS of a healthy subject, constriction of the cranio-vertebral junction in Chiari I patients causes manifold fluctuations in the hydrodynamics of the CSF. These fluctuations resemble a flow that is in a transitional regime rather than laminar or fully developed turbulence. The fluctuations confine near the cranio-vertebral junction and are triggered due to the tonsillar herniation, which perturbs the flow as a result of altered anatomy of the SAS.

Computational Investigation of Cerebrospinal Fluid Dynamics in the Posterior Cranial Fossa and Cervical Subarachnoid Space in Patients with Chiari I Malformation

“…The differential pressure varied by less than 1% between the two meshes for all three subjects. In an accompanying study [ 16 ] we have resolved the flow in full detail, i.e., performed a direct numerical simulation and demonstrated that cell sizes down to 0,01 mm was needed to resolve the flow. Such high resolution was not possible with the computational methods used in this study.…”

“…The peak velocities computed at systolic flow in P2 were high and the assumption of laminar flow may be questionable as also suggested in a recent study by members of our group [ 8 ]. Indeed, in a companion study where direct numerical simulations using the Lattice-Boltzman it was found transitional flow in P2 [ 16 ]. The observed vortices resulted in synchronous bidirectional flow throughout the flow cycle and not only at the time of flow reversal as recently reported [ 14 ].…”

Efficacy of the FDA nozzle benchmark and the lattice Boltzmann method for the analysis of biomedical flows in transitional regime

“…The lattice Boltzmann method (LBM), which is an alternative and relatively new technique for the numerical solution of Navier-Stokes equations (NSE), has been extensively used in the past decade by fluid dynamics researchers, and it has found particular interest in the biomedical community [2,13,29,33] as it can represent complex anatomical geometries with ease and can enable simulations on massively parallel computing architectures [13]. Recent works [12,13] applied and validated LBM for complex transitional flows in anatomical geometries and found the method efficient and valid for such flow regimes. Despite pressing needs, however, no extensive effort to the author's knowledge has been made to evaluate its efficacy in the aforesaid FDA nozzle benchmark.…”

“…White and Chong [32] did apply LBM to the FDA nozzle benchmark but only for the laminar case and their study was more oriented towards exploring the suitability of different lattice types. The previous works of transitional flow computations using LBM [12,13] were also for moderate Reynolds numbers.…”

Intrathecal catheter implantation decreases cerebrospinal fluid dynamics in cynomolgus monkeys

“…Chaotic CSF velocity or pressure fluctuations are not expected to occur before or after catheter placement. However, it is possible that disease states that result in strongly elevated CSF flow velocities (jets) could result in turbulence (26). Inertial effects are expected to dominate the SAS CSF flow field for normal physiological flow rates, frequencies and CSF fluid properties.…”