Nonaccidental head injury in infants--the "shaken-baby syndrome"

Excitatory amino acid concentrations in ventricular cerebrospinal fluid after severe traumatic brain injury in infants and children: the role of child abuse

BACKGROUND

Excitotoxicity is an important mechanism in secondary neuronal injury after traumatic brain injury (TBI). Excitatory amino acids (EAAs) are increased in cerebrospinal fluid (CSF) in adults after TBI; however, studies in pediatric head trauma are lacking. We hypothesized that CSF glutamate, aspartate, and glycine would be increased after TBI in children and that these increases would be associated with age, child abuse, poor outcome, and cerebral ischemia.

METHODS

EAAs were measured in 66 CSF samples from 18 children after severe TBI. Control samples were obtained from 19 children who received lumbar punctures to rule out meningitis.

RESULTS

Peak and mean CSF glycine and peak CSF glutamate levels were increased versus control values. Subgroups of patients with TBI were compared by using univariate regression analysis. Massive increases in CSF glutamate were found in children <4 years old and in child abuse victims. Increased CSF glutamate and glycine were associated with poor outcome. A trend toward an association between high glutamate concentration and ischemic blood flow was observed.

CONCLUSIONS

CSF EAAs are increased in infants and children with severe TBI. Young age and child abuse were associated with extremely high CSF glutamate concentrations after TBI. A possible role for excitotoxicity after pediatric TBI is supported.

[Infant diseases of neurologic origin]

Whenever abnormalities are found during the neurological examination of an infant who presented an apparent life-threatening event, traumatic or metabolic etiologies must be searched for in priority. Indeed, these etiologies require emergency diagnosis and treatment due to the major risk of recurrence, and consequent worsening of the neurological and functional prognosis or death.

A theoretical model of benign external hydrocephalus that predicts a predisposition towards extra-axial hemorrhage after minor head trauma

INTRODUCTION

There is controversy over whether there exists a predisposition towards bleeding into the subdural space in infants with benign external hydrocephalus (BEH) or other enlargement of the extra-axial space (e.g. subdural hygroma). The presumed etiology implicates shear forces in over-stretching the extra-axial blood vessels. We have created a model of the intracranial space that approximates certain aspects of BEH. Using this model, we predict situations where children with BEH will bleed into the extra-axial space when normal infants will not.

METHODS

The cranial model consists of two spheres representing the brain and the skull. The distance between them represents the width of the extra-axial space. The spheres are concentric (with interspheric distance equal to N) in the normal condition and nonconcentric in BEH. In BEH, the distance between the two spheres varies from N to Q (0 < N </= Q) over a 906 M </= Q, with the translation orthogonal to the vector of N and parallel to that of M or vice versa), then the final length V(f) of a vein V is V(f) = (N(2) + M)(1/2), and the stretch ratio V(f)/V(i) is: V(f)/V(i) = (N(2) + M(2))(1/2)/N.S(i), with S(i) the slack factor, where i represents either n for normal or b for BEH and M = N in the normal condition.

RESULTS

Given an equivalent capacity of veins to resist stretch injury (based on the proportion of change in length), for brain translations after a low-impact head injury, stretch ratios for BEH veins range from 1.677 to 3.436, whereas in the normal condition they range from 1.061 to 1.179. Therefore, for an increase in subarachnoid space from 3 (normal) to 6 mm (BEH), brain translocation in BEH will stretch veins beyond an average breaking point when the translation for the normal condition will not.

CONCLUSIONS

Mathematical modeling of the cranial vault produces a relationship between venous stretch and the width of the extra-axial space. These equations predict an increased frequency of venous stretch injury in the situation of widened extra-axial space. Such venous injury is consistent with forces generated by minor trauma. This relationship, as predicted by our model, could underlie a predisposition towards extra-axial bleeding after minor head trauma in infants with BEH.

Increases in bcl-2 protein in cerebrospinal fluid and evidence for programmed cell death in infants and children after severe traumatic brain injury

OBJECTIVES

To determine whether bcl-2, a protein that inhibits apoptosis, would be increased in cerebrospinal fluid (CSF) in infants and children after traumatic brain injury (TBI) and to examine the association of bcl-2 concentration with clinical variables.

STUDY DESIGN

Bcl-2 was measured in CSF from 23 children (aged 2 months-16 years) with severe TBI and from 19 children without TBI or meningitis (control subjects) by enzyme-linked immunosorbent assay. CSF oligonucleosome concentration was also determined as a marker of DNA degradation. Brain samples from 2 patients undergoing emergent decompressive craniectomies were analyzed for bcl-2 with Western blot and for DNA fragmentation with TUNEL (terminal deoxynucleotidyl-transferase mediated biotin-dUTP nick-end labeling).

RESULTS

CSF bcl-2 concentrations were increased in patients with TBI versus control subjects (P =.01). Bcl-2 was increased in patients with TBI who survived versus those who died (P =.02). CSF oligonucleosome concentration tended to be increased after TBI (P =.07) and was not associated with bcl-2. Brain tissue samples showed an increase in bcl-2 in patients with TBI versus adult brain bank control samples and evidence of DNA fragmentation within cells with apoptotic morphology.

CONCLUSIONS

Bcl-2 may participate in the regulation of cell death after TBI in infants and children. The increase in bcl-2 seen in patients who survived is consistent with a protective role for this anti-apoptotic protein after TBI.

Child maltreatment related injuries: incidence, hospital charges, and correlates of hospitalization

OBJECTIVE

This study was undertaken to determine the incidence, hospital charges, and correlates associated with inpatient treatment of child maltreatment related injuries.

METHODS

The data were based on the 1995 Pennsylvania Hospital Discharge Data which included all Pennsylvania acute care hospitals that reported child maltreatment discharges. Per capita hospital discharge rates were computed for children discharged with child maltreatment related injuries according to selected variables. Odds ratios for child maltreatment related injury hospitalizations were also computed.

RESULTS

A total of 348 maltreated injured children ages 0-19 years were discharged from Pennsylvania hospitals in 1995, representing an incidence rate of 10.8 per 100,000 persons. The total hospital charges for child maltreatment related injury discharges amounted to over $5.4 million, of which Medicaid alone paid for 45%. Compared to a random sample of non-maltreated injured children (n = 1052), maltreated injured children were found to be significantly younger, more likely to be females, and more likely to be Black. Child maltreatment related injury hospitalizations were more likely to be urgent and via physician referral or transfer from other health care facility. Maltreated injured children were three times as likely to die as other children.

CONCLUSIONS

These findings indicate that injury from child maltreatment is a major cause of hospitalization of young children 5 years and younger and represents a significant cost to publicly financed health care. While hospital discharge data can be used for population-based surveillance of child maltreatment related trauma, there is need for improvement in the surveillance of these injuries.

Biochemical, cellular, and molecular mechanisms in the evolution of secondary damage after severe traumatic brain injury in infants and children: Lessons learned from the bedside

OBJECTIVE: To present a state-of-the-art review of mechanisms of secondary injury in the evolution of damage after severe traumatic brain injury in infants and children. DATA SOURCES: We reviewed 152 peer-reviewed publications, 15 abstracts and proceedings, and other material relevant to the study of biochemical, cellular, and molecular mechanisms of damage in traumatic brain injury. Clinical studies of severe traumatic brain injury in infants and children were the focus, but reports in experimental models in immature animals were also considered. Results from both clinical studies in adults and models of traumatic brain injury in adult animals were presented for comparison. DATA SYNTHESIS: Categories of mechanisms defined were those associated with ischemia, excitotoxicity, energy failure, and resultant cell death cascades; secondary cerebral swelling; axonal injury; and inflammation and regeneration. CONCLUSIONS: A constellation of mediators of secondary damage, endogenous neuroprotection, repair, and regeneration are set into motion in the brain after severe traumatic injury. The quantitative contribution of each mediator to outcome, the interplay between these mediators, and the integration of these mechanistic findings with novel imaging methods, bedside physiology, outcome assessment, and therapeutic intervention remain an important target for future research.

Optic nerve damage in shaken baby syndrome: detection by beta-amyloid precursor protein immunohistochemistry

BACKGROUND

Rapid acceleration-deceleration of an infant's head during intentional shaking should in theory exert stretch or shear forces upon the optic nerves sufficient to cause axonal injury. beta-Amyloid precursor protein (beta-APP) immunohistochemistry recently has been shown to be a highly effective method for identifying diffuse axonal injury in the brains of infants with shaken baby syndrome. In this study, we investigated the utility of beta-APP in identifying optic nerve damage in infants who have sustained fatal whiplash shaking.

MATERIALS AND METHODS

beta-Amyloid precursor protein immunohistochemistry was performed on formalin-fixed, paraffin-embedded sections of eyes (including optic disc and distal optic nerve) from infants less than 1 year of age with shaken baby syndrome (5 cases), combined shaken baby syndrome/blunt head trauma (3 cases), and "pure" blunt head trauma (1 case). Nontraumatic control cases included infants who died of suffocation (1 case), sudden infant death syndrome (1 case), and positional asphyxia (1 case) and an enucleation from a child with a retinoblastoma (1 case). Matched hematoxylin-eosin-and neurofilament-stained sections were used for comparison.

RESULTS

Three of the 5 shaken baby cases and all 3 combined shaken baby/blunt head trauma cases had optic nerve axonal injury identified by the presence of strongly beta-APP-immunoreactive beaded or swollen axonal segments. Axonal injury could not be detected in the corresponding hematoxylin-eosin-or neurofilament-stained sections. Optic nerve axonal injury was not seen in the case involving pure blunt head trauma or in the nontraumatic control cases.

CONCLUSIONS

Optic nerve axonal injury is a prominent feature of intentional fatal whiplash head trauma in infants less than 1 year of age. beta-Amyloid protein precursor immunohistochemistry appears to be the most effective method for demonstrating axonal damage in the optic nerve.

Minor head injury in the pediatric patient

Minor head injury is a common occurrence in children of all ages; however, controversy exists regarding the management of these children. Reports of neurologically intact children with intracranial injuries have caused many to recommend cautious management, while the infrequency of serious intracranial injuries after minor head trauma have prompted others to be less conservative. Based on recent literature reports, strategies for the management of children with minor head trauma are presented.

Monitoring and management of the paediatric neurosurgical patient

Head injury remains the most common cause of death in children, and tumours of the central nervous system are the most common solid tumour encountered. There is little class 1 evidence on which to base the monitoring and management of the paediatric patient with these conditions, management strategies commonly being extrapolated from those in use for adults. However, the clinical outcome for these conditions appears to be improving, with evidence suggesting that this improvement is being achieved by the management of these children in specialist centres.

An unresponsive infant in the emergency room

The physician must be aware of the computed tomography appearance of an acute-hyperacute subdural hematoma in child abuse and not mistake it for chronic subdural hematoma with "spontaneous" rebleeding. As always, the imaging findings must be correlated with the clinical findings. Clinical and imaging findings of injury out of proportion to the history, and injuries of different ages are the key indicators to the possibility of child abuse, particularly when encountered in a young infant.

Emergency department evaluation of child abuse

Child abuse has been documented in various forms since the beginning of recorded history. This article reviews the legal aspects of reporting child abuse, the epidemiology of child abuse, various physical manifestations of child abuse, and effective treatment procedures. It is only with the appropriate interventions that physicians can begin to make an impact on the future of abused children.

The role of cranial MRI in identifying patients suffering from child abuse and presenting with unexplained neurological findings

OBJECTIVE

The aim of this study was to demonstrate the usefulness of cerebral MRI to detect possible child abuse in children with unexplained neurologic findings.

METHOD

Between 1990 and 1997, 208 children were referred for suspected physical child abuse to the Child Protection Clinic of Ste-Justine Hospital, a tertiary care pediatric hospital. Among them, 39 children presented initially with neurological findings. For 27 of them, the CT Scan results prompted the diagnosis of child abuse. However, in 12 children, even if a CT-Scan was performed, the diagnosis and/or the mechanisms of the neurologic distress remained obscure. Investigation was completed with MRI study in those 12 cases.

RESULTS

MRI findings were diagnostic for physical abuse in eight cases. A diagnosis of child abuse was made in two more cases by a combination of MRI and skeletal survey findings. In one case, MRI was suggestive but the diagnosis of child abuse could not be confirmed. One case was misinterpreted as normal.

CONCLUSIONS

MRI is the test of choice to rule out child abuse when faced with a child presenting unexplained neurologic signs lasting for few days. The fact that MRI can better differentiate collections of different ages makes this imaging test particularly useful in identifying cases of child abuse. These results, however, always have to be integrated in a well conducted multidisciplinary clinical approach.

A piglet model for evaluation of cerebral blood flow and brain oxidative metabolism during gradual cerebral perfusion pressure decrease

A piglet model was developed to study the effect of epidural volume expansion on cerebral perfusion pressure (CPP) by stepwise elevating intracranial pressure (ICP). Mean arterial blood pressure (ABP) was strictly maintained using an extracorporeal ABP controller. Two-week-old piglets (n = 10) were studied by surgically placing an epidural balloon over the right parietal region and gradually increasing the inflation to increase ICP to 25, 35 and 45 mm Hg, maintaining each pressure level for 30 min. Regional cerebral blood flow was measured using the colored microsphere technique, and cerebral oxygen delivery and cerebral metabolic rate of oxygen were calculated at baseline conditions and after reaching ICP levels of 25, 35 and 45 mm Hg. The results showed that this model of epidural volume expansion reproducibly reduces CPP to 70, 50 and 33% of baseline CPP values with elevation of ICP, and that the physiological variables remained stable throughout each increase in ICP. We conclude that the model simulates the effects of an acute intracranial focal mass expansion and is well suited for the evaluation of different therapeutical strategies for increased ICP in newborns and infants.