Application of Sequential Changes of Dural Thickness and Biomechanical Parameters in Postmortem Interval Estimation / 法医学杂志

ABSTRACT

Objective To study the relations of the dural thickness and the biomechanical parameters with postmortem interval （PMI） of human cadavers, and to explore the feasibility of the two indexes used for PMI estimation. Methods Dural samples were collected at different postmortem intervals of 6 h, 12 h, 18 h, 24 h, 30 h, 36 h, 48 h, 60 h, 72 h, 84 h and 96 h, then fabricated into 4.0 cm×1.0 cm A and B test specimens. The thickness of the A test specimen was measured, and the biomechanical parameters, such as ultimate load, maximum force deformation, tensile strength, elastic modulus and fracture force, were measured. The regression equations of thickness, biomechanical parameters and PMI were fitted respectively, and the difference between the predicted value and actual measured value of PMI was verified by the verification group. The B test specimen was fixed with 10% neutral formaldehyde solution, then tissue sections were prepared to observe its morphological changes. Results From 6 h to 96 h after death, the dural thickness decreased gradually, the collagen fibers gradually changed from clear arrangement to mutual fusion, and the number of nuclei decreased gradually. The dural thickness, ultimate load, tensile strength, elastic modulus and fracture force decreased sequentially, among which the dural thickness, ultimate load, elastic modulus and fracture force had a correlation with PMI （P<0.05）. In the return test, the difference between the predicted value and actual measured value of PMI in the verification group had no statistical significance （P>0.05）. Conclusion The dural thickness, ultimate load, elastic modulus and fracture force change sequentially from 6 h to 96 h after death. The regression equation established by the relationship between the changes and PMI can be used for PMI estimation.