Pediatric Head Trauma

1. Pediatric Head Trauma Glenn D. Sandberg, M.D. Neuropathologist Harris County Institute of Forensic Sciences Presented by Jennifer L. Ross, M.D. Neuropathology Fellow The Methodist Hospital

2. Objectives • Review the epidemiology of pediatric head trauma • Provide an introduction to major subtypes of head injuries observed in pediatric head trauma • Show examples of typical head injuries • Discuss challenges specific to the investigation of fatal, non-accidental pediatric head trauma

3. Pediatric Head Trauma • 80% of all significant head injury under the age of 2 years is due to abuse • 75-80% of child abuse fatalities are due to head injury • Majority are infants <1 year • Percentage of deaths due to head trauma decreases with age as abdominal trauma becomes more prevalent

4. Sequelae of Head Injury • 7-30% of children with abusive head injuries die • 30-50% live, but have significant cognitive or neurological deficits • Mental retardation, learning disabilities, seizures, and blindness • 30% recover

5. Types of Head Injuries • Focal injuries • Epidural hematomas • Subdural hematomas • Subarachnoid hemorrhages • Contusions • Parenchymal hemorrhages • Diffuse injuries • Axonal • Traumatic • Concussion • Vascular • Vascular

7. Epidural Hematoma • Bleeding between skull and dura • Occurs in approximately 2% of head injury • 5-15% of fatal head injuries • Almost always associated with skull fracture • Usually thin squamous portion of temporal bone • May occur in children without fracture • Laceration of arteries or veins • Middle meningeal artery-up to 50% • Middle meningeal veins-30%

8. Epidural Hematoma • Clinical • Classical lucid interval sequence • Features: • Brief period of unconsciousness after injury • Conscious, lucid interval of variable duration • Coma • Occurs in 13-43% of EDH • Might be no more frequent in EDH than SDH

9. EPIDURAL HEMATOMA Trauma ‑> fracture & concussion Tearing/stripping of dura away from inner table Laceration of meningeal vessels Blood between naked bone and dura NORMAL arterial pressure continues to dissect

10. Epidural Hematoma • Blood cannot cross suture lines • Often causes significant mass effect • Acutely can tolerate up to 40 mL • Rarely survive if > 150 mL

11. Subdural Hematoma • Accumulation of blood between dura and brain • Blood free to diffuse throughout subdural space • Evident in ~95% of abusive head trauma • May be small (<5 ml), bilateral and non-compressive • May be associated with skull fracture • May be present in open or closed head injury

12. Subdural Hematoma • Commonly occur in • Falls • Assaults • MVA: 24% • Child abuse • Sports 72%

13. Subdural Hematoma • Result of torn bridging veins • Some are secondary to ruptured cortical arteries • Sudden, rapidly applied angular acceleration/deceleration of the moveable head • High strain stretches and snaps bridging veins • Span between cerebral hemispheres and superior sagittal sinus • Subdural portions have a thin, irregular collagenous wall • Subarachnoid portions are covered by arachnoid trabeculae

14. Subdural Hematoma • Characteristically form over the frontoparietal regions • Bilateral • Adults: 18.5% • Children: 76.7% • Posterior fossa • Rare: <1 % • Particularly rare in a neonate • Fracture to occiput present in 20-80% • Spinal cord • Rare; usually not compressive

15. Subdural Hematoma • Gross: • Loosely adherent dark red blood: 3-5 days. • Well-formed outer membrane: 1 week. • Well-formed inner membrane: 3-4 weeks.

18. Subdural Hematoma • Associated findings • 25% who undergo removal of acute subdural have underlying cerebral edema • >80% of these patients die • Ischemia • May be due to local compression of the microcirculation or effects of vasoactive substances released from the SDH • Excitotoxic neuronal injury

19. Subarachnoid Hemorrhage • Trauma most frequent cause • Associated with contusions and lacerations • Fatal traumatic SAH should be suspected in • Ear injuries • Parotid region injuries • Upper neck injuries

20. Contusion • “Bruise” of cerebral cortex • Focal type of brain injury occurring at the moment of impact • Caused primarily by the surface of the brain striking the skull or being impacted by it • Overlying dura usually remains intact • Injury patterns differ whether head is stationary or in motion at moment of impact • Freely mobile head motionless at impact • Coup injury • Freely mobile head accelerated in a fall prior to impact • Contrecoup injury

21. Contusion • Do not occur in infancy • Contusional tears • Tears at cortex-white matter junction • Occur before 6 months of age • Especially in frontal and temporal lobes • Not usually hemorrhagic

22. Contusion • Gliding • Head is in motion at the time of impact • Hematoma confined to the parasagittal white matter of the frontal lobes • Each hemisphere is firmly tethered to dura by arachnoid granulations • Subcortical white matter glides more than cortex • Deep basal ganglia hematomas and DAI often present • Forces sufficient to cause both axonal and vascular damage

23. Contusion • Fracture • Occur at site of fracture, related to displaced bone against cortex, may not be at site of impact

24. Contusion • Patients usually make good recovery • In absence of DAI • Remote contusion • Common incidental finding at autopsy • Cavitary lesion • Destruction involving full thickness of cortex • Hemosiderin deposition

25. Diffuse Primary Head Injuries • Diffuse injuries • Concussion • Diffuse axonal injury

26. Concussion • Temporary, reversible neurological deficit caused by trauma • Velocity r necessary • Consciousness can be retained in crush injury of fixed head • Results in immediate temporary loss of consciousness • Both retrograde and post-traumatic amnesia always accompanies concussion • Length of amnesia is indicative of severity of concussion

27. Diffuse Axonal Injury • First recognized as an essential component of post-traumatic dementia in 1956 by Strich • Caused by inertial forces • Angular or rotational acceleration • Produced by long acceleration loading • Common in MVA • Falls have shorter acceleration loading • Injury attributed to shear and tensile strains • Occurs at moment of injury • Do not experience lucid interval in severe cases • Most common cause of coma and severe disability in absence of intracranial hemorrhage

28. Diffuse Axonal Injury • Occurred in: • 34% of all fatal head injuries • 53% of deaths that occurred after at least 12 hour survival • For equivalent levels of angular acceleration • Lateral most severe • Sagittal best tolerated • Horizontal intermediate

29. Diffuse Axonal Injury • Low incidence of: • Surface contusions • Skull fracture • Intracranial hemorrhages • Increased ICP • Increased incidence of: • Gliding contusions • Deep intracerebral hematomas

30. Diffuse Axonal Injury • Location • Corpus callosum • Cerebral lobar white matter • Dorsolateral quadrant of rostral brainstem adjacent to the superior cerebellar peduncles • “Shearing injury triad”

33. Diffuse Axonal Injury • Primary axotomy • Rare • Secondary axotomy • Calcium hypothesis • Physical stretch of axon • Disrupts axons ability to regulate ions • Influx of Ca2+ , K +,& Cl – • Activation of neutral proteases • Disruption of axonal cytoarchitecture • Mechanical disruption • Neurofilament subunits disrupted • Axonal transport impaired

34. Axonal Spheroids • H&E • Need at least 18-24 hour survival • BAPP • Need at least 2-4 hour survival

36. Retinal Hemorrhages • 80% of inflicted head trauma • Multifocal • Involve multiple retinal layers • Extend to the ora serrata • Optic nerve sheath hemorrhage is frequent

37. Causes of Retinal Hemorrhages • Severe head injuries (not limited to abuse) • Birth trauma - 30% are resolved by 1 month • Bleeding disorders • Sepsis • Vasculopathies • Sudden changes in intracranial pressure • Terson’s syndrome • CPR – Rarely • Purtscher’s retinopathy-head or chest trauma

42. Pediatric Head Trauma • “Lucid interval” concept • Vast majority of children who sustain fatal head trauma show an immediate decrease in consciousness (i.e. no lucid interval) • An infant or young child who has sustained an ultimately fatal head injury is not likely to act normally • Has important implications in criminal investigation of cases of fatal inflicted blunt head trauma

43. Shaken Baby Syndrome (SBS) • Caffey, 1972 • Retinal, subdural, and/or subarachnoid hemorrhages caused by violent shaking • Whiplash action of head associated with weak neck muscles resulting in acceleration-deceleration injuries • Immature, partial membranous skull • Relatively large subarachnoid space • Soft, immature brain

44. Shaken Baby Syndrome (SBS) • Controversies • SBS injuries (retinal, subdural, subarachnoid hemorrhage) can also be seen in impact head injury • Impact site may not be recognized by treating physicians • Even if no impact site is identified at autopsy, the possibility of impact against a broad, superficially soft surface cannot be excluded • In addition, the specificity of retinal hemorrhages for abuse has been questioned • Conflicting research models

45. Shaken Baby Syndrome (SBS) • Diagnosis of SBS should not be made when evidence of direct impact is present • Most cases of fatal head injury have evidence of direct impact (facial or scalp contusions, skull fractures) • Even without identifiable impact site, impact cannot be ruled out • Therefore, SBS is rarely listed as a cause of death

46. Infant Death Investigation • Age, date of birth, birth weight, race, sex • Normal delivery vs C-section; any complications • Last known alive - by whom, date, time • Found dead - by whom, date, time • Place of death - crib, bed, floor • Position of infant when found - supine, prone • Resuscitation - method and by whom • Recent injuries/illnesses and medical history • Change in behavior or appearance; last time child was behaving “normally” • Prior infant deaths in the family

47. Investigative Challenges • Caregivers are often perpetrators • Reliable witness accounts are often lacking • Confessions may be unreliable • Determining mechanism of injury from autopsy findings alone may be impossible • Estimating age of injuries may be critical, but is unreliable and further complicated by medical treatment and hospital survival

48. Investigation – Red Flags • Reported history is inconsistent with physical findings • Injuries that occur during the course of normal daily activities (including playing and short falls) do not usually result in fatal injuries • Delay in seeking treatment • Prior history of child abuse in household