Perivascular pathways of CSF flow through the spinal cord

Syringomyelia is a condition that is characterized by fluid containing cavities within the spinal cord. It is believed that the formation of syringomyelia is linked to the imbalance in the inflow and outflow of CSF in the spinal cord. Previous studies indicate that the perivascular spaces play an important role in the fluid outflow pathways in the spinal cord. In a study of the fluid flow pathways in the brain, it was demonstrated that the fluid inflow pathways are via periarteriolar spaces and outflow is from perivenular spaces. We know these pathways exist in the brain parenchyma, however, we do not know if the same fluid outflow pathways exist in the spinal cord. The aim of this study was to investigate the CSF outflow pathways and fluid flow from the gray matter in a normal spinal cord. To achieve this we first optimized a method which allowed movement of CSF to be followed from the spinal cord parenchyma. A fluorescent tracer (Ovalbumin Alexa Fluor 647) was injected into the gray matter of the spinal cord in Sprague-Dawley rats. Immunohistochemistry was performed using Rat endothelial cell antibody and smooth muscle actin to differentiate between all the blood vessels. This study showed that this technique can be used reliably to assess the outflow pathways in the spinal cord. Contrary to previous reports of the outflow pathways in the brain, the preliminary in the spinal cord suggested that the tracer was found to label all the blood vessels in the gray matter of the spinal cord. This indicated that the outflow in the spinal cord occurred along perivenular and periarteriolar spaces and the capillaries, into the vasculature. Further work with a larger cohort is required to gain a better understanding of the outflow pathways in the spinal cord.