Arterial pulsations drive flow in a hydraulic network model of the glymphatic system*

The glymphatic system is hypothesized to serve as a brain waste clearance system, where cerebrospinal fluid (CSF) flows through perivascular channels around arteries into brain tissue. Previous in vivo experiments have demonstrated that arterial pulsations drive net CSF flow. Additionally, arterial pulsation can exhibit locally enhanced or reduced amplitudes in response to stimuli or injury. However, the effect of local pulsations on brain-wide flows is poorly understood. In this study, we propose a hydraulic resistance network model to simulate fluid transport caused by arterial pulsations. These pulsations are modeled as local pressure sources that drive flow proportional to the conductance of each segment. Directional valves into brain tissue ensure net flow. We compare networks experiencing a variety of pulsation waveforms, including brain-wide vasomotion and regionally reduced or enhanced vasomotion to match previous experiments. We observe that the model can drive significant flow into brain tissue, particularly when combined with a previously calculated steady pressure in surface perivascular channels. This model can be used to explore trends in brain-wide CSF motion in response to local events that disrupt arterial pulsations, such as stroke or traumatic brain injury.