Figure 7.

Sensitivity analysis of ventricular pressure level (a) and mechanical brain tissue stiffness (b) uncovers the impact on ependymal wall stretches. A ten-fold increase in referential ventricular pressure leads to cell stretch of up to 1.56 and cell compression as low as 0.71. In comparison, a four-fold increase in tissue stiffness reduces peak cell stretches by a factor 0.97 and a four-times lower shear modulus leads to a 1.07-fold increase in peak cell stretch. (All values are relative to tissue stiffness reported in the “Methods” section). Ventricular pressure is highly heterogeneous across subjects⁷⁶. As discussed in the next section, ventricular pressure appears to be the critical parameter in the etiology of ependymal cell fatigue.