Transcript 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 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 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 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 Types of Head Injuries • Focal injuries – Epidural hematomas – Subdural hematomas – Subarachnoid hemorrhages – Contusions – Parenchymal hemorrhages • Diffuse injuries – Axonal • Traumatic – Concussion • Vascular – Vascular 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 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 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 noncompressive • May be associated with skull fracture • May be present in open or closed head injury Subdural Hematoma • Commonly occur in – Falls 72% – Assaults – MVA: 24% – Child abuse – Sports 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 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 Diffuse Axonal Injury • First recognized as an essential component of posttraumatic 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 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 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 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 accelerationdeceleration 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 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 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 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