Warren N. Hardy

Recent firsts in cadaveric impact biomechanics research

High‐speed biplane x‐ray and neutral density targets were used to examine brain displacement and deformation, as well as aortic motion and deformation within the mediastinum, during impact. Thirty‐five impacts using eight human cadaver head and neck specimens and eight impacts of the intact cadaver thorax are summarized. During impact, local brain tissue tends to keep its position and shape with respect to the inertial frame, resulting in relative motion between the brain and skull and deformation of the brain. The local brain motions tend to follow looping patterns. Similar patterns are observed for impact in different planes, with some degree of posterior–anterior and right–left symmetry. Clinically relevant damage to the aorta was observed in seven of the thorax tests. The presence of atherosclerosis was demonstrated to promote tearing. The isthmus of the aorta moved dorsocranially during frontal impact and submarining loading modes. The aortic isthmus moved medially and anteriorly during impact to the left side. Clin. Anat. 24:294–308, 2011.

Evaluation of Impact-Induced Traumatic Brain Injury in the Göttingen Minipig Using Two Input Modes

Objectives: Two novel injury devices were used to characterize impact-induced traumatic brain injury (TBI). One imparts pure translation, and the other produces combined translation and rotation. The objective of this study was to evaluate the neuropathology associated with two injury devices using proton magnetic resonance spectroscopy (1H-MRS) to quantify metabolic changes and immunohistochemistry (IHC) to evaluate axonal damage in the corpus callosum. Methods: Young adult female Göttingen minipigs were exposed to impact-induced TBI with either the translation-input injury device or the combined-input injury device (n = 11/group). Sham animals were treated identically except for the injury event (n = 3). The minipigs underwent 1H-MRS scans prior to injury (baseline), approximately 1 h after injury, and 24 h post injury, at which point the brains were extracted for IHC. Metabolites of interest include glutamate (Glu), glutamine (Gln), N-acetylaspartate (NAA), N-acetylaspartylglutamate (NAAG), and γ-aminobutyric acid (GABA). Repeated measures analysis of variance with a least significant difference post hoc test were used to compare the three time points. IHC was performed on paraffin-embedded sections of the corpus callosum with light and heavy neurofilament antibodies. Stained pixel percentages were compared between shams and 24-h survival animals. Results: For the translation-input group (27.5–70.1 g), 16 significant metabolite differences were found. Three of these include a significant increase in Gln, both 1 h and 24 h postinjury, and an increase in GABA 24 h after injury. For the combined-input group (40.1–95.9 g; 1,014.5–3,814.9 rad/s2; 7.2–10.8 rad/s), 20 significant metabolite differences were found. Three of these include a significant increase in Glu, an increase in the ratio Glu/Gln, and an increase in the ratio Glu/NAAG 24 h after injury. The IHC analysis revealed significant increases in light and heavy neurofilament for both groups 24 h after injury. Conclusions: Only five metabolite differences were similar between the input modes, most of which are related to inflammation or myelin disruption. The observed metabolite differences indicate important dissimilarities. For the translation-input group, an increase in Gln and GABA suggests a response in the GABA shunt system. For the combined-input group, an increase in Glu, Glu/Gln, and Glu/NAAG suggests glutamate excitotoxicity. Importantly, both of these input modes lead to similar light and heavy neurofilament damage, which indicates axonal disruption. Identifying neuropathological changes that are unique to different injury mechanisms is critical in defining the complexity of TBI and can lead to improved prevention strategies and the development of effective drug therapies.

CHILD ATD RECONSTRUCTION OF A FATAL PEDIATRIC FALL

The current head Injury Assessment Reference Values (IARVs) for the child dummies are based in part on scaling adult and animal data and on reconstructions of real world accident scenarios. Reconstruction of well-documented accident scenarios provides critical data in the evaluation of proposed IARV values, but relatively few accidents are sufficiently documented to allow for accurate reconstructions. This reconstruction of a well documented fatal-fall involving a 23-month old child supplies additional data for IARV assessment. The videotaped fatal-fall resulted in a frontal head impact onto a carpet-covered cement floor. The child suffered an acute right temporal parietal subdural hematoma without skull fracture. The fall dynamics were reconstructed in the laboratory and the head linear and angular accelerations were quantified using the CRABI-18 Anthropomorphic Test Device (ATD). Peak linear acceleration was 125 ± 7 g (range 114–139), HIC15 was 335 ± 115 (Range 257–616), peak angular velocity was 57± 16 (Range 26–74), and peak angular acceleration was 32 ± 12 krad/s2 (Range 15–56). The results of the CRABI-18 fatal fall reconstruction were consistent with the linear and rotational tolerances reported in the literature. This study investigates the usefulness of the CRABI-18 anthropomorphic testing device in forensic investigations of child head injury and aids in the evaluation of proposed IARVs for head injury.Copyright