Neurotrauma: neuropathology Flashcards
Brain, Volume 136, Issue 1, January 2013, Pages 43–64,
https://doi-org.iclibezp1.cc.ic.ac.uk/10.1093/brain/aws307
- Chronic traumatic encephalopathy is a result of mild traumatic brain injury, often occuring in atheletes, military veterens, and those with head banging behaviours as a form of self injury
- It is a tauopathy, initally affecting the frontal neocortex, and then gradually becoming more widespread
- Axonal loss is found, and TAR DNA binding protein
The Second NINDS/NIBIB Consensus Meeting to Define Neuropathological Criteria for the Diagnosis of Chronic Traumatic Encephalopathy. doi: 10.1093/jnen/nlab001
Asked neroscientists to look at cases and make diagnoses. Came to the conclusion that a pathway is needed to help categorise CTE, as the McKee staging system is not adequate
Describe epidemiology of TBI
- Trauma single largest cause of death in people under 45
- 9 deaths from head injury per 100,000
- Account for 25% of all trauma deaths
- High morbidity:
19% vegetative or severely disabled
31% good recovery
List types of head injury
Missile
- Gunshot
Non-missile
- Acceleration/deceleration
rotation
- RTA, falls and assaults
May also be focal or diffuse
Describe skull fractures
- Can extend into the base of the skull
- May pass through middle ear or anterior cranial fossa, causing otorrhea or rhinorrhea
- Signs of basalscull fracture: battles sign (bruising just behind the mastoid process, raccoon eyes (periorbital haemorrhage or bruising)
- Risk of infection
Describe contusions
- Brain in collision with the skull
- Surface bruising
- If the pia mater is torn then it becomes a laceration
- Lateral surfaces of hemispheres, inferior surfaces of frontal and temporal lobes are most susceptible
- Coup or contrecoup (damage may occur directly under the site of impact [coup] or on the side opposite the impact [contrecoup])
Describe diffuse axonal injury
- Occurs at the moment of injury
- Shear and tensile forces affecting axons
- Commonest cause of coma when there is no bleed
- Midline structures particularly affects eg. corpus callosum, rostral brainstem and septum pellucidum
Describe DAI grading
On imaging:
- Grade 1: Parasagittal frontal, internal capsule, cerebellum
- Grade 2: As Grade 1 plus corpus callosum
- Grade 3: As Grade 2 plus dorsal brainstem
Describe pathogenesis of DAI
Primary axotomy
- Traumatic tear (activates calcium activated proteases)
- Cytoskeletal disruption
- Development of swelling, causing immediate disconnection
Secondary axotomy
- Traumatic tear (activates calcium activated proteases)
- Cytoskeletal disruption
- Neuron has increased sensitivity to excitotoxic or hypoxic damage
- Resuts in swelling and late disconnection
How is traumatic axonal injury identified
Immunostaining for amyloid precursor protein
List secondary damage in trauma
- Swelling (causes raised ICP,)
- Ischaemic brain damage
- Infection
- Raised ICP (midline shift, herniation)
Describe causes of brain swelling
- Vasodilatation and increased CBV (congestive)
- Blood vessel damage (vasogenic oedema)
- Increase water content of cells (cytotoxic cerebral oedema)
List types of herniation
- Sulfalcine herniation through the cingulate gyrus
- Uncal herniation due to raised pressure above the tentorium, pushing down towards the cerebellum
- Herniation of the cerebellar tonsil, protruding through the inferior part of the cerebellum
Describe mechanisms of cellular damage
- Calcium changes affecting membrane potentials. This causes enzyme modulation, which may activate apoptosis or necrosis
- Gene modulation can result in repair and recovery
