TBI : Mechanism + Pathology Flashcards
How does DW-MRI work?
Allows estimation of the amount of water diffusion in a number of directions at each point in an image to allow quantification of the degree of white matter disruption
What kind of effects does primary injury in TBI have?
Focal and diffuse effects
Focal injuries result from….
An object striking the head or the brain striking the inside of the skull
Focal injuries produce ….
Skull Fractures
Haematomas
- extradural
- subdural
- haematomas within the brain parenchyma
Neuropathology of TBI
Variable multifocal and diffuse neuropathology
What do typical patterns of neuropathology in TBI arise from? (and who found this)
Acceleration-deceleration forces that scrape the soft brain tissue across the bony floor of the anterior and middle fossa of the skull (Bigler, 2007)
Medial frontal surfaces are compressed against the dorsal bone and collide with the cerebral falx.
What disrupts medial regions?
Immediate contusions and Wallerian degeneration
Where is pathology typically concentrated?
Ventrolateral, medial and orbital frontal lobes and the ventromedial temporal lobes.
What can we see in the neuropathology in extreme cases?
Mechanical stress at the time of impact results in axonal shearing
How is axonal transport damaged?
Although axons usually remain intact, damage commonly occurs to the axolemma around the nodes of Ranvier, as well as to neurofilament subunits, which disrupts axonal transport.
How is secondary damage produced?
Processes triggered by the initial injury, such as ischaemia, raised intracranial pressure, infection, inflammation and neurodegeneration.
What can DAI tell us about secondary damages?
DAI is an important determinant of persistent cognitive impairment caused by secondary damages
