This study was conducted to determine whether local arterial pulsations are sufficient to cause cerebrospinal fluid (CSF) flow along perivascular spaces (PVS) within the spinal cord. A theoretical model of the perivascular space surrounding a "typical" small artery was analysed using computational fluid dynamics. Systolic pulsations were modelled as travelling waves on the arterial wall. The effects of wave geometry and variable pressure conditions on fluid flow were investigated. Arterial pulsations induce fluid movement in the PVS in the direction of arterial wave travel. Perivascular flow continues even in the presence of adverse pressure gradients of a few kilopascals. Flow rates are greater with increasing pulse wave velocities and arterial deformation, as both an absolute amplitude and as a proportion of the PVS. The model suggests that arterial pulsations are sufficient to cause fluid flow in the perivascular space even against modest adverse pressure gradients. Local increases in flow in this perivascular pumping mechanism or reduction in outflow may be important in the etiology of syringomyelia.

The treatment of patients with cerebrospinal fluid (CSF) pathway disorders (including hydrocephalus, syringomyelia, and arachnoid cysts), requires an understanding of CSF pathways and the cerebral water system. Although outcome with these disorders has improved, only limited treatment options remain available. Ongoing research has continued to improve our understanding of the cerebral water circulation and is starting to provide insight into the pathogenesis and potential treatment options of this common group of disorders. This article reviews current concepts of CSF function and pathways, following the journey of CSF from conception to absorption.

✓ The impetus for the enlargement of syringes is unknown. The authors hypothesize that there is a flow of cerebrospinal fluid (CSF) from perivascular spaces into the central canal and that the flow is driven by arterial pulsations. Using horse-radish peroxidase as a tracer, the CSF flow was studied in normal sheep, in sheep with damped arterial pulsations, and in sheep with lowered spinal subarachnoid pressure. The CSF flow from perivascular spaces into the central canal was demonstrated in the normal sheep, and two patterns of flow were identified: 1) from perivascular spaces in the central gray matter; and 2) from perivascular spaces in the ventral white commissure. Flow into the central canal was also observed in the sheep with lowered spinal subarachnoid pressure, but not in those with reduced arterial pulse pressure. This study provides evidence that CSF flow from perivascular spaces into the central canal is dependent on arterial pulsations. Arterial pulsation—driven CSF flow may be the impetus for the expansion of syringes.

Object: 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. Methods: 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. Results: 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. Conclusions: 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.