Neuroimaging in non-accidental head injury: if, when, why and how

Acute Subdural Hematoma in Infants with Abusive Head Trauma: A Literature Review

The number of cases with child abuse is increasing in Japan, and abusive head trauma (AHT) is a major cause of death in abused children. Child abuse has been recognized by the late 19th century, and widely accepted as battered child syndrome in the middle of the 20th century. As terms, there had been considerable mechanistic controversies between shaken-baby and -impact syndrome until the beginning of the 21st century. In recent years, AHT has been utilized as a less mechanistic term. Most of the characteristics of AHT in Japan have been similar to those in the United States as follows: infant is the most common victim, acute subdural hematoma (SDH) is the most common intracranial lesion, and retinal hemorrhage is often complicated. On the other hand, several characteristics have been different as follows: mother is the most common perpetrators, impact is a more common mechanism of trauma than shaking, and external trauma is more common reflecting the existence of impact. Since AHT as well as child abuse is a social pathological phenomenon influenced by victims, perpetrators, socioeconomic circumstances, and so on, various aspects of AHT as well as child abuse can be changed with times. Actually, a recent paper suggests such changes in infants with acute SDH due to AHT. In this review article, AHT, abusive infantile acute SDH in particular, are reviewed from the aspect of neurosurgical perspectives, including its mechanisms of trauma, biomechanics, clinical features, management, and prognosis, to update the trend in Japan.

Recent progress and future issues in the management of abusive head trauma

Head trauma is the leading cause of death in child abuse cases and one of the important issues in the care of abused children. Since the Child Abuse Prevention Law was enforced in 2000 in Japan, various measures have been taken to prevent child abuse over the following decade. Accordingly, medical research on abusive head trauma (AHT) has advanced, leading to significant progress in the medical diagnosis of AHT. This progress has been brought about by (1) the widespread establishment of child protection teams (CPTs) at core hospitals, (2) the progress in neuroradiological imaging and ophthalmoscopic technologies, and (3) the introduction of postmortem imaging. However, the pathological condition of patients with AHT, particularly that of the diffuse brain swelling type, still remains poorly understood. As a result, no clear treatment strategies for AHT have been developed and no treatment outcomes have been improved to date. The development of new treatment strategies for AHT and the construction of a comprehensive database that supports clinical studies are required in the future.

Characterization of microstructural injury: a novel approach in infant abusive head trauma-initial experience

Abusive head trauma (AHT) is the leading cause of morbidity and mortality among abused children, yet the neuroanatomical underpinnings of AHT outcome is incompletely understood. The aim of this study was to characterize white matter (WM) abnormalities in infants with AHT using diffusion tensor imaging (DTI) and determine which microstructural abnormalities are associated with poor outcome. Retrospective DTI data from 17 infants (>3 months) with a diagnosis of AHT and a comparison cohort of 34 term infants of similar post-conceptual age (PCA) were compared using a voxel-based DTI analysis of cerebral WM. AHT cases were dichotomously classified into mild/moderate versus severe outcome. Clinical variables and conventional imaging findings were also analyzed in relation to outcome. Outcomes were classified in accordance with the Pediatric Cerebral Performance Category Score (PCPCS). Reduced axial diffusivity (AD) was shown in widespread WM regions in the AHT infants compared with controls as well as in the AHT severe outcome group compared with the AHT mild/moderate outcome group. Reduced mean diffusivity (MD) was also associated with severe outcome. Radial diffusivity (RD), conventional magnetic resonance findings, brain metric measurements, and clinical/laboratory variables (with the exception of Glascow Coma Scale) did not differ among AHT outcome groups. Findings support the unique role of DTI techniques, beyond conventional imaging, in the evaluation of microstructural WM injury of AHT. Reduced AD (likely reflecting axonal damage) and MD were associated with poor clinical outcome. DTI abnormalities may uniquely reflect AHT patterns of axonal injury that are not characterized by conventional imaging, which may have both therapeutic and prognostic implications.

ACR Appropriateness Criteria(®) on suspected physical abuse-child

The appropriate imaging for pediatric patients being evaluated for suspected physical abuse depends on the age of the child, the presence of neurologic signs and symptoms, evidence of thoracic or abdominopelvic injuries, and whether the injuries are discrepant with the clinical history. The clinical presentations reviewed consider these factors and provide evidence-based consensus recommendations by the ACR Appropriateness Criteria(®) Expert Panel on Pediatric Imaging.

Imaging of nonaccidental injury and the mimics: issues and controversies in the era of evidence-based medicine

Because of the controversy involving the determination of child abuse, or nonaccidental injury (NAI), radiologists must be familiar with the issues, literature, and principles of evidence-based medicine to understand the role of imaging. Children with suspected NAI must receive protective evaluation along with a timely and complete clinical and imaging work-up. Imaging findings cannot stand alone and must be correlated with clinical findings, laboratory testing, and pathologic and forensic examinations. Only the child protection investigation may provide the basis for inflicted injury in the context of supportive clinical, imaging, biomechanical, or pathology findings.

Advanced neuroimaging in children with nonaccidental trauma

Physical abuse associated with nonaccidental trauma (NAT) affects approximately 144,000 children per year in the USA and, frequently, these injuries affect the developing brain. Most infants with suspected NAT are initially evaluated by skull X-rays and computed tomography to determine whether fractures are present, the severity of the acute injury and the need for urgent neurosurgical intervention. Increasingly, magnetic resonance imaging (MRI) is conducted as it provides additional diagnostic and prognostic information about the extent and nature of the injury. In this review, we examine 4 MRI techniques as they apply to children who present acutely after NAT. Susceptibility-weighted imaging is a 3-D high-resolution MRI technique that is more sensitive than conventional imaging in detecting hemorrhagic lesions that are often associated with diffuse axonal injury (DAI). Magnetic resonance spectroscopy acquires metabolite information reflecting neuronal integrity and function from multiple brain regions and provides a sensitive, noninvasive assessment of neurochemical alterations that offers early prognostic information regarding outcome. Diffusion-weighted imaging (DWI) is based on differences in the diffusion of water molecules within the brain and has been shown to be very sensitive in the early detection of ischemic injury. It is now being used to study the direct effects of traumatic injury as well as those due to secondary ischemia. Diffusion tensor imaging is a form of DWI and allows better evaluation of white matter fiber tracts by taking advantage of the intrinsic directionality (anisotropy) of water diffusion in the human brain. It has been shown to be useful in identifying white matter abnormalities after DAI when conventional imaging appears normal. Although these imaging methods have been studied primarily in adults and children with accidental traumatic brain injury, it is clear that they have the potential to provide additional value in the imaging and clinical evaluation of children with NAT.

Shaken baby syndrome: a common variant of non-accidental head injury in infants

BACKGROUND

Recent cases of child abuse reported in the media have underlined the importance of unambiguous diagnosis and appropriate action. Failure to recognize abuse may have severe consequences. Abuse of infants often leaves few external signs of injury and therefore merits special diligence, especially in the case of non-accidental head injury, which has high morbidity and mortality.

METHODS

Selective literature review including an overview over national and international recommendations.

RESULTS

Shaken baby syndrome is a common manifestation of non-accidental head injury in infancy. In Germany, there are an estimated 100 to 200 cases annually. The characteristic findings are diffuse encephalopathy and subdural and retinal hemorrhage in the absence of an adequate explanation. The mortality can be as high as 30%, and up to 70% of survivors suffer long-term impairment. Assessment of suspected child abuse requires meticulous documentation in order to preserve evidence as well as radiological, ophthalmological, laboratory, and forensic investigations.

CONCLUSIONS

The correct diagnosis of shaken baby syndrome requires understanding of the underlying pathophysiology. Assessment of suspected child abuse necessitates painstaking clinical examination with careful documentation of the findings. A multidisciplinary approach is indicated. Continuation, expansion, and evaluation of existing preventive measures in Germany is required.

Controversies in non-accidental head injury in infants

Non-accidental head injury in infants is not uncommon and is associated with significant morbidity and mortality. It is therefore important to identify it at the earliest opportunity so that appropriate intervention can be made which protects the child from further harm. The whole topic is controversial and the aim of this paper, in question and answer format, is to review some of the more controversial areas to give an overview of the neuroimaging features of this condition. The author has drawn on his clinical and medicolegal experience of these cases, and the review is based upon questions commonly encountered in Court.