Date of Award
Spring 2008
Document Type
Dissertation - Restricted
Degree Name
Doctor of Philosophy (PhD)
Department
Biomedical Engineering
First Advisor
Pintar, Frank A.
Second Advisor
Gennarelli, Thomas A.
Third Advisor
Ropella, Kristina M.
Abstract
Diffuse brain injury (DBI) is a frequent occurrence in motor vehicle collisions, falls, assaults, and sports-related activities. Recent epidemiologic data has estimated that nearly 1.5 million new cases occur annually in the United States. This high rate of incidence identifies a need to design more robust protective measures to prevent and mitigate DBI. The foundation of injury prevention is tolerance thresholds which correlate kinematic and kinetic measures with injury severity. However, the only currently accepted metric dedicated to brain injury tolerance is not injury specific, and is incapable of predicting DBI occurrence. Although other DBI-specific thresholds have been proposed, their accuracy remains suspect. Furthermore, the relative importance of various loading parameters to DBI sequelae remains undefined. To address these issues, this study focused on determining primary kinematic determinants of DBI occurrence and severity that are critical to development of new tolerance thresholds. Chapter I introduces the mechanical and pathological characteristics unique to DBI. In addition, a brief overview of the experimental approaches that were critical to the understanding of DBI is provided, followed by the scope and specific aims of the current research. Chapter II involves a review of pathological mechanisms, and previous experimental and analytical models dedicated to investigating DBI. Since experimentation will involve brain injury in rats, Chapter Ill provides an anatomical synopsis of the rat head. Chapter IV consists of a retrospective analysis that describes the physiologic factors and loading conditions critical to DBI through the development of preliminary tolerance thresholds. Based on this analysis, Chapters V and VI detail the design and implementation of a novel experimental rat model, and describe the severity induced through functional and pathological results. Further experimentation described in Chapter VII, introduces graded loading levels and measures functional, behavioral, and pathological outcomes to determine primary kinematic correlates of severity .. Chapters VIII and IX develop a finite element model of the rat head to quantify the tissue-level response to graded loading kinematics. Finally, conclusions, summary, and future considerations are provided in Chapter X.