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 Injuries • Accidental falls • Assaults • RTA –90 % • Child abuse • Violent shaking of the baby • Sports related injury •Behavioural problems •Cognitive impairement •Physical disturbances Commotio cerebri
- 6. Mechanism • Results in acceleration / deceleration injuries. • Injury Sudden movement of head Compressive & tensile force (perpendicular to brain surface) Linear/rotati onal 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
- 11. 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 GFAP S100 IDH 1 ATRX
- 15. Cerebral Concussion • Brain whipping around skull. • Temporary loss of brain function • Clinical syndrome- immediate and transient post- traumatic impairement of neural function – LOC, amnesia etc .
- 17. 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
- 19. Sequelae • Secondary impact syndrome • Post concussion syndrome • Post traumatic epilepsy, headache & vertigo. • Neuropsychological impairement.
- 20. 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.
- 21. Rowan's Law • (Concussion awareness resources) • 2018 makes it mandatory for sports organizations •
- 23. • Concealed trauma- cause death without any gross signs . Pediatric abusive head injury • Repeated acceleration – deceleration forces. • 30%- cause of death, 80%- permanent neurological damage .
- 24. • 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
- 25. Reference • Bardalae principlesof forensicmedicicne& toxicology. • Anil Aggrawal textbookof forensicmedicineandtoxicology • Narayanareddy textbookof forensicmedicine andtoxicology • knights forensicpathology.
Editor's Notes
- #14: Naturally occurring protein clump together to form plaques that collect between neurons and disrupt cell function.
- #16: Transient electrophysiological dysfunction of reticular activation system in upper midbrain .
- #17: Acceleration & deceleration of the head .This causes shearing or stretching of the nerve fibre & axonal damage. Coronal head motion .Physiological dysfunction.Recover completely.