Biomechanics of acute subdural hematoma in the subhuman primate and man
Acute subdural hematoma (ASDH) is a common type of head injury which often occurs from the rupture of parasagittal bridging veins located along the cortical surface of the brain. Primate experiments have shown that ASDH can occur from sagittal plane, angular acceleration of the head. However, the level of mechanical force needed to produce ASDH in the human remains unclear. The goal of this dissertation was to use results from physical modeling studies, numerical simulations, and isolated tissue testing to develop an ASDH tolerance level for the subhuman primate and man. Physical models of the skull/brain structure were used to measure the change in superior margin deformation which occurred when specific model parameters (skull/surrogate brain adhesion, partitioning membranes, mechanical impedance of the foramen magnum, loading direction, and skull size) were modified. A numerical model was developed which simulated the physical model experiments and accounted for the mechanical properties of the parasagittal bridging veins. The brain was modeled as a cylinder of viscoelastic material surrounded by an elastic shell simulating the parasagittal bridging veins. It was found that the system behaved as an elastic material at low excitation frequencies, while at higher frequencies the majority of strain was located across the simulated bridging veins. Isolated tissue tests were conducted to determine a structural failure criteria for perfused parasagittal bridging veins tested from three age groups. The ultimate failure properties of the veins were found to be strain rate independent, and did not significantly (p =.05) depend upon either the perfusion pressure used during testing ($\Delta$P = 0, 10, 30 cm H$\sb2$O) or the age group (3-9 yr. old, 27-47 yr. old., $>$62 yr. old) tested. The results from these three previous studies were used to develop an ASDH tolerance level for the primate. The tolerance level for the subhuman primate, when compared to results from previous animal studies, was found to slightly underestimate to conditions needed to produce ASDH in the subhuman primate. The tolerance level for the man, developed from numerical simulation results and bridging vein tests, was compared to data collected in human volunteer and cadaver tests. ^
Meaney, David Francis, "Biomechanics of acute subdural hematoma in the subhuman primate and man" (1991). Dissertations available from ProQuest. AAI9125717.