head injury Flashcards by Maria Keriakos

what is a non- missile head injury?

one where the dura mater remains intact. there may or may not be skull fracture

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what is a missile head injury?

one where there is penetration of the skull and dura mater

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what are the different types of distribution of lesions?

focal

diffuse

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what is primary damage?

damage due to the immediate biophysical forces of trauma

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what is secondary damage?

presents some time after the traumatic event 
eg 
- physiological response to trauma 
hypoxia/ischaemia 
infection

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what are the different cuases of focal damage after non-missile trauma?

scalp:
contusion
laceration

skull:
fracture

meninges:
haemorrhage
infection

brain: 
contusion
laceration 
haemorrhage 
infection

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what are the different types of diffuse brain lesions that can occur after non-missile trauma?

diffuse axonal injury
diffuse vascular injury
hypoxia-ischaemia
swelling

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what are the possible sequelae from skull fracture?

haematoma
infection
aerocele

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what type of fractures do flat surfaces cause?

linear fractures

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what type of fractures do angled or pointed objects cause?

localised fractures that are open or depressed

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what is an extradural haemorrhage usually associated with?

skull fracture

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what is the onset of an extradural haemorrhage like?

occurs slowly over several hours

usually a lucid interval - where a pt temporarily improves and then deteriorates again

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how does an extradural haematoma cause death?

brain displacement
raised intracranial pressure
herniation

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what is a subdural haematoma due to ?

tear in the bridging veins

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what are subdural haematomas sometimes surrounded by?

a membrane of granulation tissue

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what are the causes of subarachnoid haemmorhage?

contusions/lacerations
base of skull fracture
vertebral artery rupture or dissection
intraventricular haemorrhage

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when does superficial haemorrhage occur?

when there is severe contusion

when does deep haemorrhage occur?

when there is diffuse axonal injury

what is the predominant cause of infection in TBI?

skull fracture

what are the 2 different brain damage mechanisms leading to focal brain damage?

contact damage

acceleration or deceleration damage

what is contact damage?

damage at or just deep to the point of impact

What is acceleration or deceleration damage?

force causes differential movement of skull and brain
impact of inner surface of skull on underlying brain causes contusions
traction on bridging veins causes subdural haemorrhage
damages blood vessels and axons

What is a contusion?

superficial bruising of the brain

may lead to prolonged coma, focal signs and lasting damage

what does it mean if the contusion is described as ‘coup’?

the bruising is at the site of the impact

what does it mean if the contusion is contrecoup?

bruising of the brain is away from the site of impact

what is the progression of the macroscopic appearance of the brain in contusion?

haemorrhagic at first then brown/orange and soft after days-weeks then indented or cavitated after months or years

what is a laceration?

When contusion is sufficiently severe to tear the pia mater

what is diffuse axonal injury?

a type of diffuse lesion after non-missile trauma that results in widespread axonal damage it is usually due to acceleration and deceleration of the head

what is diffuse vascular injury?

Multiple petechial haemorrhages throughout brain | Usually result in near immediate death

what are the different mechanisms of brain swelling?

1. congestive brain swelling - due to vasodilation and increased in cerebral blood volume 2. vasogenic oedema - extravasation of oedema fluid from damaged blood vessels 3. cytotoxic oedema - a disruption in cellular metabolism impairs functioning of the sodium and potassium pump in the glial cell membrane, leading to cellular retention of sodium and water in neurones and glia

what are 2 causes of brain herniation?

bleeding | swelling of the brain

when does hypoxia-ischaemia occur?

pts who are hypoxic hypotension with BP <80 for 15mins increased intracranial pressure

describe the distribution of hypoxia-ischaemia

can be widespread or confined to vulnerable regions eg border zones between major cerebral vessels

what are the features of penetrating missile head injuries?

cause focal damage no loss of consciousness eg low velocity bullet

what are the complications of penetrating missile injuries?

high risk of infection | epilepsy

what are the features of perforating missile injuries?

missile enters and exits skull, passing through the brain eg high velocity bullet exit wound is worse than the entry wound damage produced by shock waves and cavitation

what is chronic traumatic encephalopathy?

Neurodegenerative condition usually seen 8-10 years after | due to repetitive mild TBI

What are the clinical features of chronic traumatic encephalopathy?

irritability, impulsivity, aggression, depression, memory loss dementia, gait and speech problems, Parkinsonism 1/3 are progressive may have MND-like symptoms

what are the pathological features of chronic traumatic encephalopathy?

• atrophy of the neocortex, hippocampus, diencephalon and mamillary bodies enlarged ventricles • also affects frontal, temporal cortex and limbic regions • tau positive neurofibrillary and astrocytic tangles

what are the 2 different types of spinal injury?

indirect (usually closed) | direct due to penetration by an external object eg a knife

what is the commonest place to have a spinal injury?

cervical