In this study, we tested the hypothesis that fluid velocities within syringes in the spinal cord related to syringomyelia can be explained by fluid-structure interaction (FSI), and that spinal cord movements alter cerebrospinal fluid (CSF) dynamics in the subarachnoid space (SAS). We formulate the coupled fluid-structure interaction problem with an Arbitrary-Lagrangian-Eulerian formulation based on Eulerian coordinates in a moving domain. Our implementation is based on the FEniCS software. The model is then used to investigate FSI effects of syringomyelia in idealized geometries of the spinal cord and SAS.

Our results indicate that FSI in a model of a healthy subject yields results quantitatively and qualitatively similar to computational fluid dynamics. In contrast, in the presence of a syrinx, FSI predicts greater displacements of the cord, and a nonlinear pressure distribution is introduced in the CSF along the cord. With a sinusoidally pulsating flow of CSF in the SAS, an opposing sinusoidal flow is seen within the syrinx. With CSF pulsation closer to the natural environment in the SAS, higher frequencies of oscillatory fluid flow are observed within the syrinx.