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Forensic Neuropathology: Blunt Force Trauma to the Brain - Part 1

This article provides an introduction to the forensic neuropathology of blunt force trauma to the brain, including common modalities, biomechanical loading, definitions of primary and secondary brain injury, and manifestations of blunt force trauma to the head.

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Forensic Neuropathology: Blunt Force Trauma to the Brain - Part 1

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  1. THE FORENSIC NEUROPATHOLOGY OF BLUNT FORCE TRAUMA OF THE BRAIN Part 1: An Introduction Bennet I. Omalu, M.D., M.P.H. Forensic Pathologist/ Neuropathologist

  2. SYNONYMS • Brain Trauma • Neuro-trauma • Traumatic Brain Injury [TBI] • Cranio-Cerebral Injury • Blunt Force Trauma of the Head • TBI causes 44% of traumatic deaths in the US Blunt force trauma of the brain can be induced by transference of Kinetic Energy [KE] to the brain by an un-yielding object or surface with a relatively broad surface area like a base ball bat or a floor

  3. OTHER COMMON MODALITIES OF BRAIN TRAUMA • Penetrating Force Trauma of the Head • E.g.: Stab or incised wounds • Gunshot/ Firearm Wounds of the Head • E.g.: Hand-guns, rifles, shot-guns etc • Asphyxiation [Diffuse Hypoxic-Ischemic Cerebral Injury] • E.g.: Hanging, smothering, Carbon Monoxide intoxication etc • Toxic Injuries e.g. mercury, arsenic, methotrexate • Blunt Force Trauma of the Head is the most prevalent cause of brain injuries

  4. BIO-MECHANICAL LOADING [BML] • Mechanism of transference of K.E. to the brain; three major types: • Impact Bio-Mechanical Loading • Transference of energy by direct impact of the head • E.g.: a fall from a height and impact of the head on a floor • E.g.: a base ball bat hitting the head in an assault • Inertial Bio-Mechanical Loading • Transference of energy to the head by acceleration-deceleration shearing forces without impact • E.g.: when a baby is shaken excessively • E.g.: sudden jerk of the head in the elderly without impact • Combined Impact-Inertial Bio-Mechanical Loading

  5. BIO-MECHANICAL LOADING [BML] • Angular or rotational acceleration-deceleration is more deleterious to the brain than linear acceleration-deceleration • There is a selective topographic vulnerability of the brain to modalities of bio-mechanical loading • E.g.: the splenium of the corpus callosum is most vulnerable to diffuse shearing of the brain • Impact BML is more likely to generate focal traumatic brain injury • Inertial BML is more likely to generate diffuse traumatic brain injury

  6. DEFINITIONS • Primary Brain Injury Direct and immediate consequence of trauma to the brain e.g. cerebral contusion • Secondary Brain Injury Indirect and delayed consequence of trauma to the brain e.g. cerebral edema, cerebral herniation • Closed Head Injury Brain injury with intact dura mater • Open Head Injury Brain injury with lacerated or disrupted dura mater Major complications: Streptococcal meningitis and dural fistula

  7. DEFINITIONS • Focal Traumatic Brain Injury Localized injury of the brain e.g. lobar cerebral contusion, subdural hemorrhage • Diffuse Traumatic Brain Injury Generalized injury to all regions of the brain e.g. diffuse shearing of the brain: Diffuse Traumatic Axonal Injury, Diffuse Hypoxic Injury • Brain Injury Grading: Glasgow Coma Scale Within 48 hours: Severe TBI: GCS 1–8 Moderate TBI: GCS 9–12 Mild TBI: GCS 13-15

  8. GLASGOW COMA SCALE Best Eye Response. (4) 1. No eye opening. 2. Eye opening to pain. 3. Eye opening to verbal command. 4. Eyes open spontaneously Best Verbal Response. (5) 1. No verbal response 2. Incomprehensible sounds. 3. Inappropriate words. 4. Confused 5. Orientated • Best Motor Response. (6) • 1. No motor response. • 2. Extension to pain. • 3. Flexion to pain. • 4. Withdrawal from pain. • 5. Localising pain. • 6. Obeys Commands. A minimum score of 3 A maximum score of 15 Teasdale G., Jennett B., LANCET (ii) 81-83, 1974.

  9. MILD TRAUMATIC BRAIN INJURY Physiological disruption of brain function due to trauma, as manifested by at least one of the following: 1. Any period of loss of consciousness 2. Any loss of memory for events immediately before or after the trauma 3. Any alteration in mental state at the time of the accident (e.g., feeling dazed, disoriented, or confused) 4. Focal neurological deficit(s) that may or may not be transient But where the severity of the injury does not exceed the following: a. Post-traumatic amnesia (PTA) not greater than 24 hours b. After 30 minutes, an initial Glasgow Coma Scale (GCS) of 13-15 c. Loss of consciousness of approximately 30 minutes or less

  10. MANIFESTATIONS OF BFT OF THE HEAD • Abrasions/ Contusions/ Lacerations of Scalp • Galeal Hemorrhages • Fractures of the skull • Intra-cranial hemorrhages • Cerebral contusions/ lacerations • Congestive brain swelling and cerebral edema • Hypoxic-ischemic brain injury • Traumatic axonal injury • Diffuse vascular injury • Cerebral fat embolism

  11. EPIDEMIOLOGY • 500,000 - 750,000 cases of CNS trauma per year in the U.S. • 10% are fatal • 30 - 50% are moderate/ severe • 5 - 10% result in residual deficits • 150/100,000 population have sequelae of CNS trauma • Leading cause of death in people under 45 years of age • Accounts for 1% of all deaths • Accounts for 30% of deaths from trauma • Accounts for 50% of deaths due to road traffic accidents

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