Cerebro-spinal Flow Pattern in the Cervical Subarachnoid Space of Healthy Volunteers: Influence of the Spinal Cord morphology

IntroductionThe cerebrospinal fluid is a fundamental part of the central nervous system. The objective of this study is to assess the variations in the CSF flow pattern associated with change in the morphology of the subarachnoidal space of the cervical canal of healthy humans by developing a Computational Fluid Dynamics model. Methods3D T2-space MRI sequence images of the cervical spine were used to segment 11 cervical subarachnoid space. Model validation (time-step, mesh size, size and number of boundary layers, influences of parted inflow and inflow continuous velocity) was performed a 40-year-old patient-specific model. Simulations were performed using CFD approach simulating transient flow (Sparlart-Almaras turbulence model) with a mesh size of 0.6, 6 boundary layers of 0.05 mm, a time step of 20 ms simulated on 15 cycles. Distributions of components velocity and WSS were respectively analyzed within the subrachachnoidal space (intervertebral et intravertebral levels) and on dura and pia maters. ResultsMean values of CSF velocity ranges between 0.07 and 0.17 m.s-1 and 0.1 and 0.3 m.s-1 for maximum values. Maximum Wall Shear Stress values vary between 0.1 and 0.5 Pa with higher value at the middle of the cervical spine on pia mater and at the lower part of the cervical spine on dura mater. Intra and inter-individual variations of the Wall Shear Stress were found to differ between individuals and significant correlation was found with compression ratio (r=0.76) and lower correlation with occupation ratio and cross section area of the spinal cord. ConclusionThis study is a first to present WSS and velocity distribution in the subarachnoidal canal of 11 individuals and to described the relationship between with subarachnoid canal morphology highlighting the influence of the shape of the spinal cord within the canal on the CSF flow pattern.