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
SYNONYMS
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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
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
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 accelerationdeceleration 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
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
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
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
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.
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
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
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