A Coupled Simulation of Spinal Cord Blood Flow and Cerebrospinal Fluid Motion in the Spinal Subarachnoid Space Based on In Vivo Measurements

A preliminary coupled 1-D model of the systemic arterial tree and cerebrospinal fluid (CSF) system was constructed. The systemic tree model includes arteries greater than 2 mm in diameter and a simplified spinal cord vasculature. Coupling of the arterial tree and CSF system is accomplished by a transfer function based on in vivo cerebral blood flow (CBF) and CSF pulsation measurements in 17 young healthy adults. A 1-D tube model of the CSF in the spinal subarachnoid space (SSS) is formed based on in vivo measurements and used to determine flow and pressure along the SSS. The pressure and flow results in the CSF and systemic arterial tree are qualitatively and quantitatively similar to in vivo measurements in healthy subjects. The relative arrival time of blood pulsations in the spinal cord and CSF in the SSS is impacted by CSF system compliance and geometry. With low CSF system compliance the CSF pulsations arrive around the spinal cord before arterial pulsations and vice versa. Overall, the preliminary results support that geometric and mechanical properties of the CSF and cardiovascular system have an important impact on the flow and pressure environment and accent the importance to obtain in vivo measurements to improve modeling capabilities.