Influence of Cerebral Vascular Factors on Brain-relative Stiffness

Abstract

Dynamic intracranial pressure measurements epidurally¹ yield typical pressure response curves. The subarachnoid CSF compartment and subpial region are identified at two distinct inflection points. Beyond the subpial inflection point (surface brain pressure), the curve rises sharply [1]. Its slope resembles an elastic response and primarily represents the brain’s resistance to deformation under moderate compression. The calculated slope (dP/dd) is then brain-relative stiffness. It is relative rather than absolute stiffness² because the entire force supported by the brain is not measured by the transducer head. However, pressure and displacement are known values at all times and the transducer surface area is fixed; therefore, the concept of stiffness in this case may be broadened by substituting pressure × area for the force (F).