This paper on "The Effects of Brain-Skull Interface on Intracranial Responses and Traumatic Subdural Hematoma During Frontal Head Impact" was presented at the NAFEMS World Congress on The Evolution of Product Simulation From Established Methods to Virtual Testing & Prototyping - 24-28 April 2001, The Grand Hotel, Lake Como, Italy.

Abstract

The effects of brain-skull interface during frontal head impact were studied by modeling the influences of the cerebral-spinal-fluid (CSF) layer on intracranial responses using finite element techniques. The aims of the study were to better understand the roles that the CSF plays during head impact and the mechanisms of traumatic subdural hematoma.
A previously published three-dimensional finite element human head model was used in this study. The CSF layer of the human head model simulates the subarachnoid space and it was modeled by varying its thickness from the baseline value to form two models: model I and model II. In model I, the thickness of the CSF layer was increased from its baseline value of 1 mm to 2.3 mm and in model II to 3.6 mm. Due to these increases, the volume of the CSF layer was increased from its baseline value of 90,000 mm³ to 150,000 mm³ for model I and to 226,000 mm³ for model II; the CSF to brain volume ratio was increased from its baseline value of 0.074 to 0.14 for model I and to 0.21 for model II.
The head models were impacted by a cylinder in the forehead resulting in the same impact forces for the baseline model and model I and model II. Pressures at the coup and contrecoup for the CSF and brain, principal stresses at coup and contrecoup for the skull were measured and compared. It was shown that the CSF does influence the dynamic response of the head to impacts: as the thickness or volume of the CSF increased, coup pressures of the CSF were decreased moderately and contrecoup pressures (magnitudes) were increased dramatically; coup pressures of the brain were changed slightly and contrecoup pressures (magnitudes) were increased moderately; principal stresses of the skull were not changed at the coup but were increased dramatically at the contrecoup. It was also shown that high negative pressure (great than 200 kPa) was generated in the vertex along the superior sagittal sinus, where the parasagittal bridging veins are located. In general, negative (tension) pressures of the CSF and the brain were increased as CSF volume or CSF to brain volume ratio was increased.
It is concluded that the CSF layer plays a significant role in head traumatic impact and that high negative (tension) pressures generated along the superior sagittal sinus may be responsible for parasagittal bridging veins rupture and hence can cause traumatic subdural hematoma mostly associated with contact phenomena.