Shaken baby syndrome: re-examination of diffuse axonal injury as cause of death

Difficulties Encountered by Forensic Pathologists in Proving Abusive Head Trauma in Children: A Case Report

Shaken baby syndrome (SBS) or abusive head trauma (AHT) is one of the most common causes of death or serious neurological injury resulting from child abuse. AHT is defined as injury to the skull or intracranial contents of an infant or child younger than five years due to intentional abrupt impact and/or violent shaking. It is characterized by acute encephalopathy with subdural and retinal hemorrhages. We present a case of AHT that does not show the typical clinical triad. We describe one case of a pediatric patient addressed for forensic autopsy and where suspicion of AHT has arisen. The injury mechanism involved in the production of this syndrome and its clinical manifestation are sources of debate in forensic medicine. Thus, forensic pathologists must analyze all findings to determine SBS/AHT.

Tödliche Hirnmassenblutung infolge Vitamin-K-Mangels bei einem 9 Wochen alten Säugling

Intrakranielle Blutungen sind im Säuglingsalter seltene, aber lebensbedrohende Ereignisse. Neben Gefäßmissbildungen, Stoffwechseldefekten sowie Störungen der Blutgerinnung kommen v. a. nichtakzidentielle Traumata, Schütteltrauma in Betracht. Die klinische Diagnostik umfasst hinsichtlich der Blutungsgenese neben Sonographie und MRT als apparatives Verfahren auch eine Fundoskopie sowie laborchemische Analysen, insbesondere der Gerinnungsparameter. Für die Blutgerinnung ist das fettlösliche Vitamin K essenziell: Frühe, klassische und späte Vitamin-K-Mangel-Blutungen werden dabei unterschieden. Um ein gehäuftes Wiederauftreten von Vitamin-K-Mangel-Blutungen bei Neugeborenen und jungen Säuglingen zu verhindern, bedarf es einer hinreichenden Aufklärung der Eltern. Eine Verweigerung der Prophylaxe scheint Folge einer weltanschaulich begründeten Ablehnung der Schulmedizin und ein zunehmendes Phänomen in wohlhabenden Industrieländern zu sein.

The pathology and aetiology of subcortical clefts in infants

In infants, traumatic surface contusions of the brain are rare but subcortical clefts or cysts, variously labelled "contusional tears", "contusional clefts", "cortical tears" or "parenchymal lacerations" have been ascribed to trauma, and are even said to be characteristic of shaking and abuse. We describe the pathology of subcortical clefts or haemorrhages in seven infants. In none were the axonal swellings characteristic of traumatic axonal injury seen in relation to the clefts. Subpial bleeding was associated with clefts in all the cases of recent onset. We hypothesize that subcortical clefts are not due to direct mechanical forces of trauma but are part of a secondary cascade caused by impaired venous drainage which may or may not follow trauma. The finding of subcortical and subpial haemorrhages should prompt a search for CVT. We consider the term "contusion" is not accurate and is misleading.

The Big Black Brain: Subdural Hemorrhage with Hemispheric Swelling and Low Attenuation

The term "Big Black Brain" was first coined in 1993 to describe cases of abusive head trauma associated with subdural hematoma(s), brain swelling, and uni- or bilateral hypo-density involving the entire supratentorial compartment on CT scan imaging. This constellation of findings was invariably followed by extensive cerebral parenchymal destruction and a dismal neurological outcome or death. We describe two such cases and review the pathophysiology and differential diagnosis of this entity.

Seizure Severity Is Correlated With Severity of Hypoxic-Ischemic Injury in Abusive Head Trauma

BACKGROUND

The objective of this study was to characterize hypoxic-ischemic injury and seizures in abusive head trauma.

METHODS

We studied 58 children with moderate or severe traumatic brain injury due to abusive head trauma. Continuous electroencephalograms and magnetic resonance images were scored.

RESULTS

Electrographic seizures (51.2%) and hypoxic-ischemic injury (77.4%) were common in our cohort. Younger age was associated with electrographic seizures (no seizures: median age 13.5 months, interquartile range five to 25 months, versus seizures: 4.5 months, interquartile range 3 to 9.5 months; P = 0.001). Severity of hypoxic-ischemic injury was also associated with seizures (no seizures: median injury score 1.0, interquartile range 0 to 3, versus seizures: 4.5, interquartile range 3 to 8; P = 0.01), but traumatic injury severity was not associated with seizures (no seizures: mean injury score 3.78 ± 1.68 versus seizures: mean injury score 3.83 ± 0.95, P = 0.89). There was a correlation between hypoxic-ischemic injury severity and seizure burden when controlling for patient age (r_s=0.61, P < 0.001). The ratio of restricted diffusion volume to total brain volume (restricted diffusion ratio) was smaller on magnetic resonance imaging done early (median restricted diffusion ratio 0.03, interquartile range 0 to 0.23 on magnetic resonance imaging done within two days versus median restricted diffusion ratio 0.13, interquartile range 0.01 to 0.43 on magnetic resonance imaging done after two days, P = 0.03).

CONCLUSIONS

Electrographic seizures are common in children with moderate to severe traumatic brain injury from abusive head trauma, and therefore children with suspected abusive head trauma should be monitored with continuous electroencephalogram. Severity of hypoxic-ischemic brain injury is correlated with severity of seizures, and evidence of hypoxic-ischemic injury on magnetic resonance imaging may evolve over time. Therefore children with a high seizure burden should be reimaged to evaluate for evolving hypoxic-ischemic injury.

A Conceptual Overview of Axonopathy in Infants and Children with Allegedly Inflicted Head Trauma

Fatal, allegedly inflicted pediatric head trauma remains a controversial topic in forensic pathology. Recommendations for systematic neuropathologic evaluation of the brains of supposedly injured infants and children usually include the assessment of long white matter tracts in search of axonopathy - specifically, diffuse axonal injury. The ability to recognize, document, and interpret injuries to axons has significant academic and medicolegal implications. For example, more than two decades of inconsistent nosology have resulted in confusion about the definition of diffuse axonal injury between various medical disciplines including radiology, neurosurgery, pediatrics, neuropathology, and forensic pathology. Furthermore, in the pediatric setting, acceptance that "pure" shaking can cause axonal shearing in infants and young children is not widespread. Additionally, controversy abounds whether or not axonal trauma can be identified within regions of white matter ischemia - a debate with very significant implications. Immunohistochemistry is often used not only to document axonal injury, but also to estimate the time since injury. As a result, the estimated post-injury interval may then be used by law enforcement officers and prosecutors to narrow "exclusive opportunity" and thus, identify potential suspects. Fundamental to these highly complicated and controversial topics is a philosophical understanding of the diffuse axonal injury spectrum disorders.

Infants dying suddenly and unexpectedly share demographic features with infants who die with retinal and dural bleeding: a review of neural mechanisms

The cause of death in infants who die suddenly and unexpectedly (sudden unexpected death in infancy [SUDI]) remains a diagnostic challenge. Some infants have identified diseases (explained SUDI); those without explanation are called sudden infant death syndrome (SIDS). Demographic data indicate subgroups among SUDI and SIDS cases, such as unsafe sleeping and apparent life-threatening events. Infants dying suddenly with retinal and dural bleeding are often classified as abused, but in many there is no evidence of trauma. Demographic features suggest that they may represent a further subgroup of SUDI. This review examines the neuropathological hypotheses to explain SIDS and highlights the interaction of infant oxygen-conserving reflexes with the brainstem networks considered responsible for SIDS. We consider sex- and age-specific vulnerabilities related to dural bleeding and how sensitization of the dural innervation by bleeding may influence these reflexes, potentially leading to collapse or even death after otherwise trivial insults.

Shaken Baby Syndrome: a review

Shaken Baby Syndrome occurs in infants as a result of the brain pushing against the skull due to severe acceleration-deceleration forces. Symptoms of Shaken Baby Syndrome include subdural, subarachnoid, and retinal hemorrhages. MRI and ocular examinations are used to determine the extent of mental and visual damage and β-amyloid precursor protein immunohistochemical staining is used to detect axonal injuries. Surgeries such as Subdural hemorrhage (SDH) evacuation surgery and the Burr hole craniotomy are used to treat Shaken Baby Syndrome; however, the prognosis is poor in many cases. Because of the severity of Shaken Baby Syndrome and its traumatic and sometimes fatal effects, it is important to educate new parents, nurses, and doctors on the syndrome in order to prevent incidents.

Mechanics of the brain: perspectives, challenges, and opportunities

The human brain is the continuous subject of extensive investigation aimed at understanding its behavior and function. Despite a clear evidence that mechanical factors play an important role in regulating brain activity, current research efforts focus mainly on the biochemical or electrophysiological activity of the brain. Here, we show that classical mechanical concepts including deformations, stretch, strain, strain rate, pressure, and stress play a crucial role in modulating both brain form and brain function. This opinion piece synthesizes expertise in applied mathematics, solid and fluid mechanics, biomechanics, experimentation, material sciences, neuropathology, and neurosurgery to address today’s open questions at the forefront of neuromechanics. We critically review the current literature and discuss challenges related to neurodevelopment, cerebral edema, lissencephaly, polymicrogyria, hydrocephaly, craniectomy, spinal cord injury, tumor growth, traumatic brain injury, and shaken baby syndrome. The multi-disciplinary analysis of these various phenomena and pathologies presents new opportunities and suggests that mechanical modeling is a central tool to bridge the scales by synthesizing information from the molecular via the cellular and tissue all the way to the organ level.

Child abuse - some aspects for neurosurgeons

Neurosurgeons are mainly concerned with child abuse in cases of severe cranio-cerebral trauma. Aim of the present paper is to highlight the clinical picture and symptoms in cases of child abuse and our multidisciplinary approach to reveal a solid diagnosis. The detection of child abuse requires a high index of suspicion, especially in cases of subtle injuries. Besides reporting to the appropriate agencies primary goals are to terminate suspected abuse and to prevent further harm to the child. All this requires a confirmed diagnosis.

The "Shaken Baby" syndrome: pathology and mechanisms

The "Shaken Baby" syndrome (SBS) is the subject of intense controversy; the diagnosis has in the past depended on the triad of subdural haemorrhage (SDH), retinal haemorrhage and encephalopathy. While there is no doubt that infants do suffer abusive injury at the hands of their carers and that impact can cause catastrophic intracranial damage, research has repeatedly undermined the hypothesis that shaking per se can cause this triad. The term non-accidental head injury has therefore been widely adopted. This review will focus on the pathology and mechanisms of the three physiologically associated findings which constitute the "triad" and are seen in infants suffering from a wide range of non-traumatic as well as traumatic conditions. "Sub" dural bleeding in fact originates within the deep layers of the dura. The potential sources of SDH include: the bridging veins, small vessels within the dura itself, a granulating haemorrhagic membrane and ruptured intracranial aneurysm. Most neuropathologists do not routinely examine eyes, but the significance of this second arm of the triad in the diagnosis of Shaken Baby syndrome is such that it merits consideration in the context of this review. While retinal haemorrhage can be seen clinically, dural and subarachnoid optic nerve sheath haemorrhage is usually seen exclusively by the pathologist and only rarely described by the neuroradiologist. The term encephalopathy is used loosely in the context of SBS. It may encompass anything from vomiting, irritability, feeding difficulties or floppiness to seizures, apnoea and fulminant brain swelling. The spectrum of brain pathology associated with retinal and subdural bleeding from a variety of causes is described. The most important cerebral pathology is swelling and hypoxic-ischaemic injury. Mechanical shearing injury is rare and contusions, the hallmark of adult traumatic brain damage, are vanishingly rare in infants under 1 year of age. Clefts and haemorrhages in the immediate subcortical white matter have been assumed to be due to trauma but factors specific to this age group offer other explanations. Finally, examples of the most common causes of the triad encountered in clinical diagnostic and forensic practice are briefly annotated.

Shaken Infants Die of Neck Trauma, Not of Brain Trauma

Shaken baby syndrome (SBS) is routinely diagnosed on the basis of a classic triad of autopsy findings, namely retinal hemorrhage, subdural hemorrhage, and anoxic encephalopathy. However, ongoing controversy exists regarding the specificity and potential causes of these signs, and hence their reliability as de facto markers of SBS, or of non-accidental head injury, where no external signs of trauma are evident.

We investigated the deaths of 35 infants and young children, which fell into two broad groups: those with suspected hyperflexion/extension neck injuries, and those without. At autopsy, the entire cervical spinal column (spinal cord, vertebrae, intervertebral discs, neurovascular structures and adjacent soft tissues) was removed, formalin-fixed, decalcified, dissected, and microscopically evaluated.

Of the 12 cases in which hyperflexion/extension was either suspected or confirmed, all had evidence of either bilateral or unilateral hemorrhages within or surrounding the C3, C4, and/or C5 cervical spinal nerve roots.

We provide evidence that hyperflexion/extension forces as experienced by shaken and impacted infants and young children lead to injury of the cervical spinal nerve roots that innervate the diaphragm, with resulting asphyxia and hypoxic brain injury. Therefore, we propose that trauma to the third through fifth cervical spinal nerve roots induced by hyperflexion/extension of the neck is the cause of the anoxic encephalopathy of the classic SBS triad, and is therefore not only a more specific indicator of hyperflexion/extension injury than subdural hemorrhage alone, but is the mechanism of injury in these cases.

Spinal nerve root β-APP staining in infants is not a reliable indicator of trauma

This preliminary communication describes seven babies with β-amyloid precursor protein (βAPP) positive axonal swellings in nerve roots at multiple levels of the spinal cord. All seven babies died of natural causes. Two died in utero providing evidence for nerve root injury in the absence of trauma, two died within one day of birth and the possibility of birth related injury has to be considered. Three babies were over one month of age and had no history or pathological evidence of trauma. These findings show that if axonal injury is carefully sought in every infant death, not just in babies where trauma is suspected, it will be found in a proportion of babies dying from natural diseases. While spinal nerve root axonal injury in infants may suggest trauma, it is not, in itself, diagnostic of trauma.

Multicystic encephalomalacia as an end-stage finding in abusive head trauma

Abusive head trauma (AHT) is one of the most severe forms of physical child abuse. If a child initially survives severe AHT the neurological outcome can be poor. In recent years several children were seen who developed multicystic encephalomalacia (MCE) after documented severe AHT. A search of the Netherlands Forensic Institute database in The Hague was performed. Inclusion criteria were cases of AHT between 1999 and 2010 where the child was under the age of 1 year old at the time of trauma. Trauma mechanism and radiological information were collected. Five children, three boys and two girls (mean age 57 days, range 8–142 days) who developed cystic encephalomalacia after inflicted traumatic brain injury were included. Survival ranged from 27 to 993 days. In all cases judicial autopsy was performed. All cases came before court and in each case child abuse was considered to be proven. In two cases the perpetrator confessed, during police interrogation, to shaking of the child only. Although a known serious outcome, this is one of the few reports on MCE as a result of AHT. In all cases the diagnosis was confirmed at autopsy.

Update on child maltreatment

PURPOSE OF REVIEW

The authors explore the literature published in the past year addressing child maltreatment issues, including sexual abuse, physical child abuse, inflicted head trauma, and child abuse prevention.

RECENT FINDINGS

The body of knowledge about child abuse and its mimics continues to expand. Evident in this year's literature is the challenge which the diagnosis of child abuse creates for clinicians. Although further strides are being made toward universal education of providers, it is clear that there is still a reluctance to report abuse to child welfare agencies. The legal repercussions of diagnosing abuse can be extensive, and there has been a proliferation of medical defense experts who disagree with the commonly accepted tenets of abusive injury and who are vocal in the literature.

SUMMARY

It remains the responsibility of pediatric providers to consider child maltreatment in the differential diagnosis of any unexplained injury or medical problem. Several studies document the high rate of spanking, slapping or shaking children, and primary care clinicians may be the first professionals in a position to begin the evaluation for possible child maltreatment. Despite the natural hesitancy to diagnose abuse, clinicians have an ethical and moral obligation to address this issue both in their practice and in their communities. The short-term and long-term costs to individuals who experience family violence have been well demonstrated and include not only emotional repercussions, but also chronic health conditions, which result in significant cost to society.