Imaging of Traumatic Brain Injury Flashcards
Describe the basic pathophysiological mechanisms that lead to brain injury following trauma Understand basic principles of CT and MRI imaging Understand how neuroimaging is used to characterise TBI Understand how advanced MRI approaches can be used to study white matter damage
State 2 common areas for contusions, and why
Orbitofrontal cortex and temporal poles, because the skull is ridged at these locations
Name a classic consequence of orbitofrontal cortex injuries and why
Anosmia, due to shearing of the fibres involved in smell
Describe the appearance of an extradural haematoma on CT
A concave shape, bright white, with clearly defined margins
Describe the appearance of a subdural haematoma on CT
Acutely, bright white, but with a less concave shape and more irregular margins than extradurals. Chronic subdurals are dark and can be a similar shade to the brain
State 2 reasons why the incidence of subdural haematomas is increasing
Ageing population, increasing use of blood-thinning medication
Give 2 methods used to manage subdural haematomas
Burr holes and craniectomies
Describe diffuse axonal injury
The application of a large amount of force to the brain rips the long-distance axons
Why does the image on CT correlate poorly with TBI outcomes?
Diffuse axonal injuries is invisible on CT scans but has a huge functional impact on the patient
Which tract is the most vulnerable to diffuse axonal injury?
Corticospinal tract
Name an imaging modality used to visualise diffuse axonal injury
Diffusion tensor imaging on MRI - but this is rarely used clinically
Name a type of MRI routinely used in TBI
Susceptibility weighted imaging
Describe how susceptibility weighted imaging on MRI works, and what it is used to detect
Bleeding leaves minute iron deposits in the brain which can be picked up on MRI. This can be used to detect microbleeds and linear vascular injuries - the latter of which are usually associated with axonal injuries, so can be used as surrogate markers
Describe the typical distribution of microbleeds
Parafalcine distribution, due to strain on the corpus callosum
Where does tau accumulate in chronic traumatic encephalopathy?
The depths of the sulci
