On the Study of the Brain Movement and Cerebrospinal Fluid Flow within Porous Subarachnoid Space under Translational Impacts

Traumatic brain injury remains a major global health issue. A key knowledge gap in concussion research is the overlooked role of transient cerebrospinal fluid (CSF) flow in the porous subarachnoid space (SAS). To address this, we developed a simplified mathematical model to study CSF pressurization in the porous arachnoid trabeculae (AT) and its impact on brain motion during translational head impacts. The model represents the head as an inner solid (brain), an outer rigid shell (skull), and a thin porous fluid gap (SAS). CSF flow is modeled as porous squeezing (coup) and expanding (contrecoup) flows, with Darcy's law governing lateral flow. Results show the porous AT network significantly dampens brain motion and pressure variations compared to a SAS without AT, especially under high-frequency, periodic impacts. This dampening stems from the AT's low permeability, which resists fluid movement and stabilizes pressure, reducing brain displacement. Our findings advance understanding of CSF dynamics and offer insights for brain injury prevention.