CSF Flow in Chiari I and SyringomyeliaFrom the perspective of Computational Fluid DynamicsKaren H. Støverud, K.-A. Mardal, V. Haughton, H.P. Langtangen

Bologna, Oct. 6, 2010

This presentation aims to describe how abnormal CSF flow can affect the spinal cord

1) Oscillatory CSF flow• Measurements• Simulations

2) Consequences of abnormal CSF flow on the spinal cord• Simulations

Why do Chiari patients develop syringomyelia?

CSF flow varies throughout the cardiac cycle, in relation with changing pressure gradients

Systole Diastole

The goal of PCMR is to identify patients that will benefit from surgery

Minor abnormalities

Major abnormalities

Limits:‒ Inaccurate

velocities‒ Low temporal

resolution

Today, computational models are used throughout all industries

…but to a little extent in medicine…

To gain a better insight of cyclic CSF flow and pressures, computational models are powerful tools.

MRI + Computer Models = Optimal Treatment

CSF flow in the subarachnoid space simulated by a computational model:

Complex flow:• Jets• Bidirectional flow• Greater flow anterior than posterior

• Variation along the spinal axis

Linge et al. 2010

Magnitude of flow varies both in the axial and sagittal plane

Geometries Velocity profiles

Roldan et al. 2009

Greater pressure gradients have been observed in Chiari patients than in normals

Steeper pressure gradient in regions of narrowed SAS

Roldan et al. 2009

Simulations of CSF flow have been validated by the means of PC MRI

Shah et al. 2009

Computer models have improved the understanding of CSF flow and pressure in the subarachnoid space

CSF flow is characterized by:1) Jets 2) Bidirectional flow3) Greater flow anterior than posterior

to the cord.4) Pressure gradient

Models• 3D• Velocity• Pressure

PCMR • 2D• Velocity

Investigating the effects of abnormal pressure gradients on the spinal cord tissue Spinal cord tissue as a poro-elastic medium:

We created an idealized model of the spinal cord and prescribed the pressure in the surrounding CSF

Fluid enters the spinal cord in regions of high pressure and leaves in regions of low pressure

Fluid accumulate in the spinal cord when a central canal with high permeability is added

The spinal cord contracts where the pressure is high and expands where the pressure is low

Blue: Tissue contracts

Orange: Tissue expands presyrinx develops

In conclusion, computational models may increase our understanding of CSF flow and syrinx formation

• Volume (3D) display of velocity and pressure• Greater spatial and temporal resolution• Demonstrates increased jets and bidirectional flow in Chiari

• Demonstrates steeper pressure gradients in Chiari• Including the central canal fluid accumulate in the spinal cord

• Predicts presyrinx state