Non-accidental head injury in children: gathering the evidence

[Shaken baby syndrome: which lesions in imaging ?]

Non-accidental brain trauma (also called shaken baby syndrome) represent the main cause for morbidity and mortality in the context of child abuse. It often occur in young infants aged less than 8months. The shaking leading to brain injuries are very violent and sometimes associated with a final impact. Intracranial injuries may be isolated without skeletal trauma or bruising. In any suspicion of such a diagnosis, emergency hospitalization is indicated. Brain CT, easy to perform in emergency, is the diagnostic key. It discloses diffuse subdural hematomas in typical sites as vertex, interhemispheric space and tentorium. There is no clear background of trauma and the related story is changing over time. The 3D analysis of the skull looks for signs of recent impact as a fracture that is sometimes complex and/or a soft tissue swelling of the scalp. Intraparenchymal injuries (contusions, tearing, and overall anoxic ischemic injuries) are better analyzed with MRI. The prognosis depends on their extent. Ophtalmologic examination is systematically performed looking for retinal hemorrhages (around one third of cases) which may be very subtle. Bruising is a major diagnostic sign, but inconstantly present. A precise datation of skeletal and/or brain injuries is not possible with imaging and the only indication of use is to establish the presence of "age different lesions". This indicates repeated trauma and thereby a high risk of recurrence.

Increased incidence of nonaccidental head trauma in infants associated with the economic recession

OBJECT

Nonaccidental head trauma (NAHT) is a major cause of death in infants. During the current economic recession, the authors noticed an anecdotal increase in infants with NAHT without an increase in the overall number of infants admitted with traumatic injuries. An analysis was performed to determine whether there was an association between economic recession and NAHT.

METHODS

With Institutional Review Board approval, the trauma database was searched for NAHT in infants 0-2 years old during nonrecession (December 2001 to November 2007) and recession (December 2007 to June 2010) periods. Incidence is reported as infants with NAHT per month summarized over time periods. Continuous variables were compared using Mann-Whitney U-tests, and proportions were compared using the Fisher exact test.

RESULTS

Six hundred thirty-nine infant traumas were observed during the study time period. From the nonrecession to the recession period, there was an 8.2% reduction in all traumas (458 in 72 months [6.4 /month] vs 181 in 31 months [5.8/month]) and a 3.5% reduction in accidental head traumas (142 in 72 months [2.0/month] vs 59 in 31 months [1.9/month]). Nonaccidental head trauma accounted for 14.6% of all traumas (93/639). The median patient age was 4.0 months and 52% were boys. There were no significant differences in the representative counties of referral or demographics between nonrecession and recession populations (all p > 0.05). The monthly incidence rates of NAHT doubled from nonrecession to recession periods (50 in 72 months [0.7/month] vs 43 in 31 months [1.4/month]; p = 0.01). During this recession, at least 1 NAHT was reported in 68% of the months compared with 44% of the months during the nonrecession period (p = 0.03). The severity of NAHTs also increased, with a greater proportion of deaths (11.6% vs 4%, respectively; p = 0.16) and severe brain injury (Glasgow Coma Scale score ≤ 8: 19.5% vs 4%, respectively; p = 0.06) during the recession.

CONCLUSIONS

In the context of an overall reduction in head trauma, the significant increase in the incidence of NAHT appears coincident with economic recession. Although the cause is likely multifactorial, a full analysis of the basis of this increase is beyond the scope of this study. This study highlights the need to protect vulnerable infants during challenging economic times.

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.

Abusive head trauma: judicial admissions highlight violent and repetitive shaking

OBJECTIVE

Confessions are uncommon in abusive head trauma (AHT) cases, and there is debate over whether shaking alone can cause the injuries characteristic of AHT. The objective of this article is to correlate legal statements by perpetrators with medical documentation to offer insights into the mechanism of injury.

METHODS

In this retrospective observational study we examined forensic evidence from 112 cases referred for AHT over a 7-year period. We compared 29 cases in which a perpetrator confessed to violence toward the child with 83 cases in which there was no confession. Inclusion criteria were subdural hematoma (SDH) on computed tomography and perpetrator admission of a causal relationship between the violence inflicted and the child's symptoms. Groups were compared by using Student's t test for age and Fisher's exact test for gender, death, fractures, retinal hemorrhages, ecchymoses, symptoms, and SDH patterns. All medical records from birth to diagnosis, imaging studies, and written investigation reports were reviewed.

RESULTS

All confessions came from forensic investigations. There was no statistically significant difference between the 2 groups for any of the variables studied. Shaking was described as extremely violent (100%) and was repeated (55%) from 2 to 30 times (mean: 10) because it stopped the infant's crying (62.5%). Impact was uncommon (24%). No correlation was found between repeated shaking and SDH densities.

CONCLUSIONS

This unique forensic case series confirms the violence of shaking. The high frequency of habitual AHT is a strong argument for reporting suspected cases to judicial authorities and helps to explain the difficulty in dating the injuries.

How to explore and report children with suspected non-accidental trauma

Child abuse is a controversial problem of special concern. Recent reports have focused on the broad variability of reporting to child protection services. Radiologists play a key role in the early diagnosis and imaging of suspected inflicted injury. Imaging must be performed and then interpreted with rigour.The aims of this review are: To review the recent recommended guidelines for imaging in cases of suspicion of abuse. These include a highly detailed complete skeletal survey with centered views, whilst brain CT and/or MRI are mandatory in children younger than 2 years. The use of abdominal imaging is debatable if the child has no symptoms. All siblings younger than 2 years should be assessed in the same way while the diagnosis of abuse is investigated. Body MRI is an interesting modality that remains a "work-in-progress". To highlight that dating of both brain and skeletal injuries is imprecise. The main point is, however, to determine if the pattern is of "age-different" lesions. This not only provides a strong argument for the diagnosis of abuse, but also indicates repetitive violence with a high risk for further injury and death. To remember that the medical perspective is to protect the child. Thus, radiologists must communicate clearly the suspicion of abuse and the degree of certainty to clinicians to aid reporting or hospitalization.

Natural history of traumatic meningeal bleeding in infants: semiquantitative analysis of serial CT scans in corroborated cases

BACKGROUND

The natural history of posttraumatic meningeal bleeding in infants is poorly documented, and the differences between inflicted head injury (IHI) and accidental trauma (AT) are debated. Autopsy findings have suggested that anoxia also plays a role in bleeding; however, these findings may not reflect what occurs in live trauma patients.

PURPOSE

We studied the natural history of traumatic meningeal bleeding in infants using serial computed tomography (CT) scans in corroborated IHI and AT.

MATERIALS AND METHODS

From our prospective series, we selected corroborated cases (confessed IHI or AT having occurred in public), who underwent at least three CT scans in the acute phase. We performed a semiquantitative analysis of meningeal bleeding using a four-tier scale (absent, faint, frank, and thick) derived from the Fisher grading for aneurysmal bleeding in four regions of interest (convexity, falx cerebri, sagittal sinus, and tentorium cerebelli).

RESULTS

We studied 20 cases: ten IHI and ten AT. Bleeding was maximal at the convexity initially, then increased along the falx and sagittal sinus, and then along the tentorium. Decrease and disappearance of blood was variable according to the site and the initial quantity of blood. We found no difference between IHI and AT.

CONCLUSION

Our findings suggest that the primary site of meningeal bleeding in infantile head trauma is the convexity of the brain; blood cells then migrate toward the midline following the flow of cerebrospinal fluid circulation and inferiorly following gravity. The pattern of bleeding in traumatic cases appears similar in IHI and AT but different from anoxic lesions.

Violence is not necessary to produce subdural and retinal haemorrhage: a reply to Puntet al

In this article we reply to the recent critique by Punt et al. in Pediatric Rehabilitation. Our hypothesis about the pathogenesis of intracranial bleeding in infants has three important implications. First, in the case of an infant with a swollen brain, subdural and retinal haemorrhage but no objective evidence of trauma, the findings by themselves are not certain evidence of abuse; second, violence is not necessary to produce subdural and retinal haemorrhage; and lastly, non-traumatic events producing apnoea with a catastrophic rise in intracranial pressure could produce a clinical picture identical to that seen in trauma.

Shaken baby syndrome: the quest for evidence

Shaken baby syndrome (SBS), characterized by the triad of subdural haemorrhage, retinal haemorrhage, and encephalopathy, was initially based on the hypothesis that shaking causes tearing of bridging veins and bilateral subdural bleeding. It remains controversial. New evidence since SBS was first defined three decades ago needs to be reviewed. Neuropathology shows that most cases do not have traumatic axonal injury, but hypoxic-ischaemic injury and brain swelling. This may allow a lucid interval, which traumatic axonal injury will not. Further, the thin subdural haemorrhages in SBS are unlike the thick unilateral space-occupying clots of trauma. They may not originate from traumatic rupture of bridging veins but from vessels injured by hypoxia and haemodynamic disturbances, as originally proposed by Cushing in 1905. Biomechanical studies have repeatedly failed to show that shaking alone can generate the triad in the absence of significant neck injury. Impact is needed and, indeed, seems to be the cause of the majority of cases of so-called SBS. Birth-related subdural bleeds are much more frequent than previously thought and their potential to cause chronic subdural collections and mimic SBS remains to be established.

Inflicted head injury in infants

There is scant neuropathological information in the child abuse literature; even the best reviews include assumptions based on the findings of a few inadequate early studies. Our recent series of 53 fatal cases (Brain 124 (2001) 1290, 1299 [1,2]) demonstrated age-related patterns of brain injury and showed the substrate of severe encephalopathy in the infants to be hypoxic brain damage, not diffuse traumatic axonal injury ('DAI'), as had previously been thought. About one-third had craniocervical injuries, particularly in the brain stem, suggestive of stretch injury to the neuraxis. Our interpretation was that this finding implied a mechanism of injury--brain stem damage from stretch injury to the neck with resultant apnoea--that could account for the clinical scenario in many cases, and for which violence would not necessarily be required. Since publishing this study we have turned our attention to the subgroup of infants who die without objective signs of injury, such as skull fracture or impact, whose carers are accused of abuse, usually, "violent shaking", on the pathologic findings alone. Given the striking discrepancy that there often is in such cases between the relatively trivial findings in the brain and the accusations of violence, we have been looking at the pathogenesis of the typical intracranial bleeding. A histologic study of dura from 50 paediatric autopsies, none of whom had suffered a head injury, has led us to propose that the subdural and retinal bleeding in such cases may well have a physiological aetiology, rather than being caused directly by trauma.

Why do histology on retinal haemorrhages in suspected non-accidental injury?

The detailed documentation of ocular pathology has become an important component in the autopsy investigation of suspected cases of non-accidental injury in infants and young children. Careful histological examination of retinal haemorrhages is of critical importance, but there remains debate about the significance of some findings. This issue has been thrown into sharper relief by recent neuropathological studies questioning the mechanisms of some CNS findings. To discuss the importance of histological findings in the retina and their potential significance and specificity, we have invited contributions from authors in the USA and UK.

Apnoea and brain swelling in non-accidental head injury

AIMS

(1) To identify whether infants and young children admitted to hospital with subdural haematomas (SDH) secondary to non-accidental head injury (NAHI), suffer from apnoea leading to radiological evidence of hypoxic ischaemic brain damage, and whether this is related to a poor prognosis; and (2) to determine what degree of trauma is associated with NAHI.

METHODS

Retrospective case series (1992-98) with case control analysis of 65 children under 2 years old, with an SDH secondary to NAHI. Outcome measures were presenting symptoms, associated injuries and apnoea at presentation, brain swelling or hypoxic ischaemic changes on neuroimaging, and clinical outcome (KOSCHI).

RESULTS

Twenty two children had a history of apnoea at presentation to hospital. Apnoea was significantly associated with hypoxic ischaemic brain damage. Severe symptoms at presentation, apnoea, and diffuse brain swelling/hypoxic ischaemic damage were significantly associated with a poor prognosis. Eighty five per cent of cases had associated injuries consistent with a diagnosis of non-accidental injury.

CONCLUSIONS

Coma at presentation, apnoea, and diffuse brain swelling or hypoxic ischaemia all predict a poor outcome in an infant who has suffered from SDH after NAHI. There is evidence of associated violence in the majority of infants with NAHI. At this point in time we do not know the minimum forces necessary to cause NAHI. It is clear however that it is never acceptable to shake a baby.