Neuropathology of Traumatic Brain Injury Flashcards
Identify the key neuropathological features of focal and diffuse TBI Observe the differences between primary and secondary trauma damage List the molecular and cellular pathways implicated in TBI
What percentage of trauma deaths are due to TBI?
25%
What percentage of TBI patients make a good recovery?
31%
Name at least 3 types of non-missile head trauma
Acceleration/deceleration, rotation, falls, assaults
Describe the relationship between GCS score and TBI severity
GCS 13+ = mild injury, 9-12 = moderate injury, 8- = severe injury
Describe a verbal GCS score of 3
Utters words, but they are inappropriate
Describe a motor GCS score of 3
Abnormal flexion to pain - decorticate response
Describe a motor GCS score of 2
Extension to pain - decerebrate response
Describe an eye GCS of 2
Opens eyes to pain
State at least 3 factors influencing the outcome from TBI
Age and brain atrophy, drugs (e.g. warfarin), nutrition, pre-existing disease, psychosocial status, genetic makeup
Name at least 4 types of secondary injury
Ischaemia, raised ICP, seixures, oedema, infection, fever, hyperglycaemia
Why do seizures occur in TBI?
Cytotoxic glutamate activity
Name the 2 types of oedema in TBI
Vasogenic and cytotoxic
State 5 factors involved in secondary injury
Mediators, calcium ions, receptor dysfunction, free radicals, inflammation
Name at least 4 primary injuries in non-missile TBI
Scalp laceration, skull fracture, cerebral contusion, cerebral laceration (breach of pia & meninges into brain parenchyma), intracranial haemorrhage, diffuse axonal injury
In fatal non-missile head injuries, how many patients have surface contusions?
95%
Describe the difference between diffuse axonal injury and traumatic axonal injury
Diffuse axonal injury is a clinical and radiological phenomenon used to determine prognosis; traumatic axonal injury is the pathological phenomenon seen in tissue after the event
State the 3 most common secondary injuries in fatal non-missile head injury
Raised ICP, ischaemic brain damage, brain swelling (oedema)
What is Battle’s sign?
A bruise behind the ear that indicates a skull fracture
What are raccoon eyes?
Periorbital haemorrhages which indicate a skull fracture
Why are fissure fractures affecting the middle ear or anterior cranial fossa important?
They can cause CSF leakage and otorrhoea or rhinorrhoea, which increases infection risk
Describe the difference between cerebral contusions and cerebral lacerations
Cerebral contusions are where the brain collides with the skull, producing a bruise on the brain surface. Cerebral lacerations are when this is severe enough to tear the pia mater
State the most common sites for cerebral contusions
Lateral surfaces of the hemispheres and interior surfaces of the frontal and temporal lobes
What causes diffuse axonal injury?
Shear and tensile forces affecting the axons
Which structures are most commonly affected by diffuse axonal injury?
Midline structures - corpus callosum, rostral brainstem, septum pallucidum - due to the rotational nature of many traumas
Describe the grading of diffuse axonal injury
1) Fibres affected in the parasagittal frontal lobe, internal capsule, and cerebellum
2) Fibres also affected in the corpus callosum
3) Fibres also affected in the dorsal brainstem
Name a method of immunostaining for traumatic axonal injury
Immunostaining for amyloid precursor protein
Describe the process of damage in primary axotomy
Disturbed calcium homeostasis activates calcium-dependent processes, especially calpain, leading to cytoskeletal disruption with disconnection and the development of swelling
Why can repeated injury - e.g. in boxing - lead to axotomy?
The repair after initial axotomy is imperfect, leading to greater susceptibility to damage
Name the types of intracranial haematoma
Extradural, subdural, subarachnoid, intracerebral, burst lobe
Name the 3 types of brain swelling
Congestive, vasogenic, cytotoxic
What causes cytotoxic brain swelling?
The increased water content of cells and cell lysis
What causes congestive brain swelling?
Vasodilation and increased cerebral blood volume
Name the 3 main brain herniation sites
Subfalcine, transtentorial, transforaminal
Describe subfalcine herniation
A major space-occupying lesion above the tentorium causes the cingulate cortex just above the corpus callosum to herniate
Describe transtentorial herniation
Supratentorial pressure cause the medial temporal lobe to herniate, shutting down cardiorespiratory centres
Describe transformaminal herniation
The cerebellar tonsil herniates through the foramen magnum
What is chronic traumatic encephalopathy?
A tauopathy at the base of the sulci as a result of multiple TBIs
How can chronic traumatic encephalopathy be differentiated from AD?
Prominent astrocytic tau tangles in CTE - AD is a purely neuronal tauopathy
State some behavioural symptoms of CTE
irritability, aggression, substance abude
State some cognitive symptoms of CTE
Memory impairments, executive dysfunction, dementia
State some mood symptoms of CTE
Depression, anxiety, suicidal ideation
State some motor symptoms of CTE
Dysarthria, ataxia, parkinsonism
What is ageing-related tau astrogliopathy?
The deposition of tau in astrocytes with age
