The influence of the relative timing of arterial and subarachnoid space pulse waves on spinal perivascular cerebrospinal fluid flow as a possible factor in syrinx development

Laboratory investigation

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The mechanisms of syringomyelia have long puzzled neurosurgeons and researchers alike due to difficulties in identifying the driving forces behind fluid flow into a syrinx, apparently against a pressure gradient between the spinal cord and the subarachnoid space (SAS). Recently, the synchronization between CSF flow and the cardiac cycle has been postulated to affect fluid flow in the spinal cord. This study aims to determine the effect of changes in the timing of SAS pressure on perivascular flow into the spinal cord.


This study uses a computational fluid dynamics model to investigate whether the relative timing of a spinal artery cardiovascular pulse wave and fluid pressure in the spinal SAS can influence CSF flow in the perivascular spaces.


The results show that the mass flow rate of CSF through a model periarterial space is strongly influenced by the relative timing of the arterial pulse wave and the SAS pressure.


These findings suggest that factors that might alter the timing of the pulse wave or the fluid flow in the SAS could potentially affect fluid flow into a syrinx.

Abbreviations used in this paper: CM = Chiari malformation; PVS = perivascular space; SAS = subarachnoid space.

Article Information

Address correspondence to: Lynne E. Bilston, Ph.D., Prince of Wales Medical Research Institute, University of New South Wales, Corner Barker and Easy Streets, Randwick, New South Wales 2031, Australia. email:

Please include this information when citing this paper: published online June 12, 2009; DOI: 10.3171/2009.5.JNS08945.

© AANS, except where prohibited by US copyright law.



  • View in gallery

    Schematic geometry of a PVS model. The top panel (A) shows the general location, and the 2 insets show the local area at the junction of the SAS and a penetrating artery and PVS that is modeled. The region in the lower circular inset corresponds to the model geometry as shown in B. The arrows in B represent the dimensions of various parts of the model. P = 0 represents pressure set to 0 in that location. PSAS(t) = time-varying pressure in the SAS. r = 75 μm indicates the radius of curvature of the pia mater where it attaches to the artery.

  • View in gallery

    Line graphs showing SAS pressure (upper) and arterial pulse wave (lower) over 1 second.

  • View in gallery

    Bar graph (upper) shows the mass flow rate through the PVS, depending on the relative timing of the arterial pulse wave and SAS pressure wave. The schematic illustration (lower) shows 2 scenarios with the peak SAS pressure wave arriving when arterial pressure is low (left), resulting in higher inflow (offset = ~ 0.5 seconds), and when arterial pressure is high (right), resulting in lower inflow (offset = ~ 0 seconds).


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