June 2014 Updates on Syrinx Research Projects, Dr. Marcus Stoodley

It is a pleasure to provide an update on the progress we have been making with our syringomyelia research work:

1. Paper accepted for publication in Journal of Biomechanics (published) “Effects of fluid structure interaction in a three dimensional model of the spinal subarachnoid space.” http://www.jbiomech.com/article/S0021-9290(14)00248-6/abstract This paper examines the effect of interactions between the spinal cord and the surrounding cerebrospinal fluid (CSF) in the normal situation and when there is narrowing of the fluid space around the cord. We showed that spinal cord movement is increased in the setting of stenosis, but that this appears to have a small effect on CSF flow and pressure. The structural interactions between the CSF and the spinal cord are not likely to be a major contributor to syrinx formation.
2. Role of Potassium channels in syringomyelia A certain type of potassium channel (Kir4.1) is linked to aquaporin 4 and is a major channel for controlling fluid content in cells in the brain and spinal cord. We examined this channel in our experimental model of post-traumatic syringomyelia. There is a reduction of Kir4.1 in the spinal cord around syrinx cavities. A decrease in potassium clearance may result in an influx of water from the vasculature into the spinal cord and may therefore play a role in the development of posttraumatic syringomyelia. A manuscript from this work is in an advanced state of preparation, with submission expected in July or August.
3. Accuracy of MRI in measuring syrinx size in animal models Experiments performed to study syrinx formation or to assess the effects of various interventions (such as aquaporin-modulating medications) rely heavily on the ability to measure syrinx size. Traditionally this is done using tissue harvested from experimental animals. This makes it difficult to assess the changes that occur over time, requiring the use of large numbers of animals. Ideally, MRI could be used to re-image the same animal at different time points, thus obtaining more accurate information and requiring the use of fewer animals. Unfortunately, the accuracy of MRI in measuring cysts has not been tested. We have recently completed a study demonstrating a very high correlation between cyst size on MRI and cyst size measured in harvested tissue, thus supporting the use of MRI for future studies (Figure 1). Submission of this manuscript is expected in August.
4. Quantitative assessment of fluid flow into normal rat spinal cord and the effect of thecal sac constriction. This study is to demonstrate our new technique of studying CSF flow in the subarachnoid space and in perivascular spaces in the same animal in a way that can be measured (Figure 2). This will be extremely valuable in our future studies of CSF flow in syringomyelia. A manuscript is expected to be submitted in August or September.

Marcus Stoodley PhD,FRACS Professor of Neurosurgery