DIFFUSE AXONAL INJURY,CONCUSSION & CONTUSION

DIFFUSE AXONAL INJURY,CONCUSSION

1. Diffuse Axonal Injury & Concussion Dr.Nafeeya Department of Forensic Medicine & Toxicology

2. Overview Introduction Classification of TBI Causes Mechanism Grading Medicolegal importance

3. Introduction Severe craniocerebral traumas. Extensive lesion in white matter tracts spread over wide diffuse areas. Brainstem, corpus callosum , and cerebral hemispheres . 90 % never regain consciousness Survive - face significant impairs. This injury is extensive- diffuse rather than focal Widespread area of the brain rather than one specific location of the brain.

4. Classification of TBI Mild(concussion) Moderate Severe Closed head injury Penetrating head injury Focal -Contusion Diffuse -DAI Gcs-13-15 PTA-<1hr LOC-<30 min Severity Mechanism Location When an external force traumatically injury the brain.

5. Causes Of TBI Accidental falls Assaults RTA –head injury Child abuse Violent shaking of the baby Sports related injury Behavioural problems Cognitive impairement Physical disturbances

6. Mechanism Results in acceleration / deceleration injuries. Injury Sudden movement of head Compressive & tensile force (perpendicular to brain surface) Linear/rotational acceleration Brain-shearing force (parallel to brain surface)

7. Earliest mechanical theory Axonal damage Trauma – tear during mechanical stress Shear strain – axonal injury & rupture White matter junction & corpus callosum

8. Modern biochemical theory Stretching of axon during injury Disruption of axolemma Open up Na channels Voltage gated ca channel Inflow of ca into the axon Activated phospholipases & proteolytic enzymes Mitochondria, cytoskeleton damage Neuronal death

9. Grading of DAI

10. Histopathology Grossly – not much findings Significant findings - Bulb formation at the terminal end of axon (retraction balls) Tear in white matter Intraparenchymal haemorrhage Silver Impregnation technique & Immunoperoxidase methods

11. Intraparenchymal haemorrhage

12. Retraction balls

13. White matter tear

14. Cerebral Concussion Brain whipping around skull. Temporary loss of brain function Clinical syndrome- immediate and transient post- traumatic impairement of neural function –LOC, Vision.

15. Risk factors High contact sports Previous concussion

16. Initial Impact The brain swells ,the swelling puts pressure on the brain stem which controls breathing and basic life support Brain rebounds The force from the impact causes the brain to strike the inner surface of the skull Mechanism

17. Grading of concussion

18. Sequelae Secondary impact syndrome Post concussion syndrome Post traumatic epilepsy, headache & vertigo. Neuropsychological impairement.

19. Secondary impact syndrome When the brain swells rapidly shortly after a person suffers a second concussion before symptoms from an earlier concussion have subsided. Non- fatal Persistent muscle spasm Emotional instability, Hallucinations, Post-traumatic epilepsy, Mental disability, Paralysis, Coma, & Brain death.

20. Rowan's Law ( Concussion awareness resources ) 2018 makes it mandatory for sports organizations

21. Contusions of the brain A contusion is a bruise to the brain in which a small blood vessels leak into brain tissue. Coup Counter coup Intermediate Fracture Gliding Herniation

22. Mechanism Fixed head Accelerated Impact –motion Moving head Deceleration Motion – impact

23. Theories of Counter-Coup Positive pressure theory – Lindenberg Stage -1 -skull is accelerated .Brain lag behind due to inertia . Stage-2 -Creates negative pressure –leading skull surface. Creates positive pressure-trailing skull surface Stage-3 - no cushioning effect,countercoup lesion Negative pressure theory – Russel Skull –rest but brain continues to move. Negative pressure created-trailing skull surface. Produce –tensile stress Cavitation occurs,countercoup lesion

24. Rotational shear stress theory- Holbourn Inferior portion of temporal & frontal lobes

25. Medicolegal Importance Concealed trauma- cause death without any gross signs . Difference between concussion & drunkenness Face- warm,flushed pale Smell-present Absent Pupils –Mc Ewen’s sign Absent Breathing – fast Slow Memory –no amnesia Retrograde amnesia Behaviour –talkative Silent Blood & urine- positive Negative

26. Pediatric abusive head injury Repeated acceleration – deceleration forces. 30%- cause of death, 80%- permanent neurological damage Cinderella syndrome .

27. Boxers injury Chronic traumatic brain injury (CTBI) associated with boxing occurs in approximately 20% of professional boxers. Diffuse axonal injury ,cerebral edema also common. Subdural haemorrhage –death Punch -drunk syndrome

28. Reference Bardalae principles of forensic medicicne & toxicology. Anil Aggrawal textbook of forensic medicine and toxicology Narayana reddy text book of forensic medicin e and toxicology knights forensic pathology.