230
V. Kurtcuoglu et al.
made the first animal-specific numerical model of wave propagation for a Cavalier
King Charles Spaniel [103] – a dog species that often develops syringomyelia – and
found that repetitive stressing of the spinal cord could initiate cyst development.
Cheng et al. conducted the first 3D fluid-structure-interaction (FSI) simulation of
the upper spinal SAS with spinal stenosis [106]. Further models were developed to
elucidate the influence of the relative timing of arterial and CSF pressure waves on
perivascular transport of fluid into syrinxes (see Sect. 9.3.3).
9.3.2.3 Chiari Malformation
Chiari malformation is a craniospinal disorder characterized by protrusion of the
cerebellar tonsils out of the cranial cavity into the spinal SAS. This protrusion results
in partial blockage of fluid movement between cranial and spinal CSF spaces. The
exact mechanism of pathogenesis remains unclear. Thus, as a potential indicator of
disease state or surgical effectiveness, researchers have applied CFD to predict the
pressure and fluid velocities within the region of CSF restriction.
In 2009, Roldan et al. [109] completed the first subject-specific CFD simulation
of Chiari malformation and predicted anterolateral flow jets located around the
spinal cord near the point of tonsillar obstruction to CSF flow. Linge et al.
conducted parametric investigations with varying degrees of tonsillar obstruction at
the foramen magnum [10, 110]. Rutkowska et al. [34], Yiallourou et al. [78], Clarke
et al. [80] and Martin et al. [111] compared CFD-predicted parameters of CSF
dynamics in Chiari patients versus controls and found CSF velocities to be elevated
in patients. These velocities tended to decrease following surgical treatment.
Martin et al. proposed the use of longitudinal impedance [111] as a new
parameter to quantify unsteady resistance to CSF flow at the craniocervical junction.
Longitudinal impedance was found by Shaffer et al. to be elevated in Chiari patients
compared to controls and to decrease following surgical treatment [112], indicating
a potentially clinical relevant use of CFD for modelling CSF dynamics in Chiari.
Longitudinal impedance tended to increase with tonsillar descent into the spine. In
2017, Jain et al. completed a DNS study of CSF flow using the lattice Boltzmann
method [35], observing high velocities in the spinal SAS of Chiari I patients and
predicting the presence of transitional flow near the region of stenosis (Figs. 9.4
and 9.5). Pahlavian et al. conducted the first CFD study of Chiari malformation that
included patient-specific pulsatile motion of the cerebellar tonsils [113]. Results
from that study indicated that pulsatile motion of the tonsils can greatly affect
CSF velocities. Subsequently, Pahlavian et al. applied displacement-encoded MR
imaging to quantify regional displacement and strain within the brain [43]. In
combination, these studies support the application of CFD in the quantification of
Chiari malformation disease states. However, the most appropriate model boundary
conditions for Chiari malformation have yet to be established.
V. Kurtcuoglu et al.
made the first animal-specific numerical model of wave propagation for a Cavalier
King Charles Spaniel [103] – a dog species that often develops syringomyelia – and
found that repetitive stressing of the spinal cord could initiate cyst development.
Cheng et al. conducted the first 3D fluid-structure-interaction (FSI) simulation of
the upper spinal SAS with spinal stenosis [106]. Further models were developed to
elucidate the influence of the relative timing of arterial and CSF pressure waves on
perivascular transport of fluid into syrinxes (see Sect. 9.3.3).
9.3.2.3 Chiari Malformation
Chiari malformation is a craniospinal disorder characterized by protrusion of the
cerebellar tonsils out of the cranial cavity into the spinal SAS. This protrusion results
in partial blockage of fluid movement between cranial and spinal CSF spaces. The
exact mechanism of pathogenesis remains unclear. Thus, as a potential indicator of
disease state or surgical effectiveness, researchers have applied CFD to predict the
pressure and fluid velocities within the region of CSF restriction.
In 2009, Roldan et al. [109] completed the first subject-specific CFD simulation
of Chiari malformation and predicted anterolateral flow jets located around the
spinal cord near the point of tonsillar obstruction to CSF flow. Linge et al.
conducted parametric investigations with varying degrees of tonsillar obstruction at
the foramen magnum [10, 110]. Rutkowska et al. [34], Yiallourou et al. [78], Clarke
et al. [80] and Martin et al. [111] compared CFD-predicted parameters of CSF
dynamics in Chiari patients versus controls and found CSF velocities to be elevated
in patients. These velocities tended to decrease following surgical treatment.
Martin et al. proposed the use of longitudinal impedance [111] as a new
parameter to quantify unsteady resistance to CSF flow at the craniocervical junction.
Longitudinal impedance was found by Shaffer et al. to be elevated in Chiari patients
compared to controls and to decrease following surgical treatment [112], indicating
a potentially clinical relevant use of CFD for modelling CSF dynamics in Chiari.
Longitudinal impedance tended to increase with tonsillar descent into the spine. In
2017, Jain et al. completed a DNS study of CSF flow using the lattice Boltzmann
method [35], observing high velocities in the spinal SAS of Chiari I patients and
predicting the presence of transitional flow near the region of stenosis (Figs. 9.4
and 9.5). Pahlavian et al. conducted the first CFD study of Chiari malformation that
included patient-specific pulsatile motion of the cerebellar tonsils [113]. Results
from that study indicated that pulsatile motion of the tonsils can greatly affect
CSF velocities. Subsequently, Pahlavian et al. applied displacement-encoded MR
imaging to quantify regional displacement and strain within the brain [43]. In
combination, these studies support the application of CFD in the quantification of
Chiari malformation disease states. However, the most appropriate model boundary
conditions for Chiari malformation have yet to be established.