Brain Injury Biomechanics and Abusive Head Trauma

Contemporary biomechanical theory of traumatic brain injury has its foundation in Holbourn’s thesis on shear strain and Ommaya’s primate experimentation demonstrating the role of rotation in a variety of lesions including subdural hematoma(SDH)and diffuse axonal injury.Empirical human observations have since confirmed,for the most part,the early concepts.Ethical concerns regarding primate research,however,have prompted in vitro models,which in turn has led to challenges with respect to the correlation between in vitro observations and the clinical data.Despite these challenges,medicolegal proceedings may call upon biomechanical engineers to reconstruct complex injury scenarios and offer opinions on the scientific plausibility of clinical disease states,such as SDH,hemorrhagic retinopathy,and cerebral edema,associated with hypothetical or proffered action sequences during the course of an unwitnessed homicide.It is important to note,however,that in vitro models by their nature are low‑evidence quality studies that attempt to advance hypotheses but do not address cause and effect.As a whole,biomechanical models,as they pertain specifically to the brain and spine,are mathematically imprecise.Often,endpoints of limited relevance are relied upon(e.g.,skull fracture thresholds),which predictably overestimate the in vivo risk of significant injury.Given the increasing role of biomechanical engineering in the interpretation of fatal pediatric head trauma,a heightened awareness of the limitations warranted.

Is Rotational Trauma the Only Relevant Pathogenic Mechanism in Hemorrhagic Retinopathy of Shaken Baby Syndrome?

The pathogenesis of ocular hemorrhage in abusive head trauma/shaken baby syndrome(AHT/SBS)is complex.Whereas severe hemorrhagic retinopathy has a robust association with AHT/SBS,mild disease is less specific.We report the ocular and cerebral findings in an 8‑month‑old girl with spastic torticollis who presented following confessed,violent sagittal plane acceleration‑deceleration with impact.Autopsy revealed subdural hemorrhage over the convexities,ischemic brain injury,and preexisting polymicrogyria.Ocular examination showed extensive but unilateral retinal hemorrhage,extending broadly to the ora serrata,with perimacular retinal folds and retinoschisis.The retina of the right globe was entirely normal.The findings in this case,suggest that movement of the globe within the orbit with acceleration‑deceleration,in this case greater on one side due to torticollis,may be the primary factor for severe hemorrhagic retinopathy associated with AHT/SBS.The findings argue against putative global mechanisms,such as intracranial hypertension.

Homicidal Abuse of Young Children:A Historical Perspective

The past 50 years has seen a heightened awareness of abusive injury patterns and increased concern for the plight of children victimized by their caregivers.Murder of the young,however,has been embedded in society since the beginning of recorded time.Indeed,nature provides abundant examples of infanticide in lower animals,raising the question of whether exploitation,apathy,and violence toward children are on some level evolutionarily conserved.In human antiquity,selective killing of females,the illegitimate,and the malformed,killing by ritualistic sacrifice or to conserve resources was carried out with impunity.The middle ages and later saw a decline in these practices albeit limited.One hundred years into the industrial revolution,with harsh child labor in public view,legal remedies were sought to protect children but with little effect.The domestic abuse of children was not addressed until a pivotal 19^(th)-century case,in which the rights of animals were invoked to intervene on behalf of a child.In the 20th century,physicians began to look closely at anatomical findings;patterns due to trauma,especially inflicted trauma,began to emerge.“Battered child syndrome”was followed by“shaken baby syndrome”,the latter prompted by the recurrent findings of subdural hematoma,retinal hemorrhages,and brain injury with the absence of impact injuries and no plausible accidental or natural disease explanation.In the 21st century,high-quality studies and an emphasis on evidenced-based medicine substantiated the existence ofiiijury patterns resulting from homicidal violence.However,progress has been uneven.A case of child abuse that reached the US Supreme Court resulted in an ill-cited dissent that seems to have amplified an already toxic medicolegal environment,perhaps unjustifiably.The difficulties in balancing the welfare of society with that of caregivers in the aftermath of homicidal abuse will no doubt continue.