Glenn D. Sandberg, M.D.Neuropathologist

Harris County Institute of Forensic Sciences

Presented by Jennifer L. Ross, M.D.Neuropathology FellowThe Methodist Hospital

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

• 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

Pediatric Head Trauma

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

• Focal injuries– Epidural hematomas– Subdural hematomas– Subarachnoid hemorrhages– Contusions– Parenchymal hemorrhages

• Diffuse injuries– Axonal• Traumatic– Concussion

• Vascular– Vascular

Types of Head Injuries

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%

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

EPIDURAL HEMATOMATrauma > fracture & ‑

concussionTearing/stripping of dura away

from inner tableLaceration of meningeal

vesselsBlood between naked bone

and duraNORMAL arterial pressure

continues to dissect

Epidural Hematoma

• Blood cannot cross suture lines– Often causes significant

mass effect

• Acutely can tolerate up to 40 mL– Rarely survive if > 150 mL

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

Subdural Hematoma

• Commonly occur in– Falls – Assaults– MVA: 24%– Child abuse– Sports

72%

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

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

Subdural Hematoma

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

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

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

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

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

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

Contusion

• Fracture– Occur at site of fracture,

related to displaced bone against cortex, may not be at site of impact

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

Diffuse Primary Head Injuries

• Diffuse injuries– Concussion– Diffuse axonal injury

Concussion• Temporary, reversible neurological deficit

caused by trauma– Velocity 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

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

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

Diffuse Axonal Injury• Low incidence of:– Surface contusions– Skull fracture– Intracranial hemorrhages– Increased ICP

• Increased incidence of:– Gliding contusions– Deep intracerebral hematomas

Diffuse Axonal Injury• Location– Corpus callosum– Cerebral lobar white matter– Dorsolateral quadrant of rostral brainstem

adjacent to the superior cerebellar peduncles– “Shearing injury triad”

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

Axonal Spheroids

• H&E– Need at least 18-24 hour survival

• BAPP – Need at least 2-4 hour survival

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

• 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

Causes of Retinal Hemorrhages

• “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

Pediatric Head Trauma

• 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

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

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

Shaken Baby Syndrome (SBS)

• 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

Infant Death Investigation

• 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

Investigative Challenges

• 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

Investigation – Red Flags