Fluid dynamics in syringomyelia cavities: Effects of heart rate, CSF velocity, CSF velocity waveform and craniovertebral decompression

Abstract

Purpose How fluid moves during the cardiac cycle within a syrinx may affect its development. We measured syrinx fluid velocities before and after craniovertebral decompression in a patient and simulated syrinx fluid velocities for different heart rates, syrinx sizes and cerebrospinal fluid (CSF) flow velocities in a model of syringomyelia. Materials and methods With phase-contrast magnetic resonance we measured CSF and syrinx fluid velocities in a Chiari patient before and after craniovertebral decompression. With an idealized two-dimensional model of the subarachnoid space (SAS), cord and syrinx, we simulated fluid movement in the SAS and syrinx with the Navier-Stokes equations for different heart rates, inlet velocities and syrinx diameters. Results In the patient, fluid oscillated in the syrinx at 200 to 210 cycles per minute before and after craniovertebral decompression. Velocities peaked at 3.6 and 2.0 cm per second respectively in the SAS and the syrinx before surgery and at 2.7 and 1.5 cm per second after surgery. In the model, syrinx velocity varied between 0.91 and 12.70 cm per second. Increasing CSF inlet velocities from 1.56 to 4.69 cm per second increased peak syrinx fluid velocities in the syrinx by 151% to 299% for the three cycle rates. Increasing cycle rates from 60 to 120 cpm increased peak syrinx velocities by 160% to 312% for the three inlet velocities. Peak velocities changed inconsistently with syrinx size. Conclusions CSF velocity, heart rate and syrinx diameter affect syrinx fluid velocities, but not the frequency of syrinx fluid oscillation. Craniovertebral decompression decreases both CSF and syrinx fluid velocities.

The “Valva Cerebri”: Morphometry, Topographic Anatomy and Histology of the Rhomboid Membrane at the Craniocervical Junction

“…The CSF's physiological pulsatile flow is the result of a complex interaction between the cardiac cycle, intracranial capillary volumetric changes, and breathing related strongly to the head's venous outflow, posture, and even intraabdominal pressure. Several invasive, noninvasive radiological, and computational modeling studies have examined the exact pattern of CSF flow, physiological pressure changes (Williams, 1981;Haughton et al, 2003;Hentschel et al, 2010;Bunck et al, 2011;Bhadelia et al, 2013;Jacobsson et al, 2018), and pathological conditions, such as hydrocephalus, Chiari I malformation, syringomyelia, posterior fossa tumors, and cervical spinal stenosis (Hofmann et al, 2000;Lee et al, 2000;Haughton et al, 2003;Arriada and Sotelo, 2004;Iskandar et al, 2004;Yildiz et al, 2006;Bunck et al, 2012;Zhan et al, 2013;Mukherjee et al, 2014;Qvarlander et al, 2017;Gholampour and Taher, 2018;Jacobsson et al, 2018;Vinje et al, 2018). In their magnetic resonance 4D flow measurement study of healthy volunteers, Bunck et al (2011) found that under normal conditions, CSF velocities were the highest in the mid-to-low cervical regions and the lowest in the region of the foramen magnum.…”

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Physics-informed neural networks for solving nonlinear diffusivity and Biot’s equations

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