Head Injury Flashcards
How would you classify head injury
Type of injury
Distribution of lesions
Time course of damage following the traumatic event
Examples of type of injury (which is more common)
Non-missile (more common)
Missile head injury
What is meant by missile head injury
Head injury in which there is penetration of skull or brain
Examples of distribution of lesions
Focal
Diffuse brain lesions
Categories of time course of damage following the traumatic event
Primary
Secondary
What is meant by Primary time course of damage following the traumatic event
Due to immediate biophysical forces of trauma
What is meant by Secondary time course of damage following the traumatic event
Presenting some time after the traumatic event:
- Physiological responses to trauma
- Effects of hypoxia/ischaemia
- infection
What is non-missile
Blunt head trauma
Focal damage after non-missile trauma
Scalp
Skull (fracture)
Meninges
Brain
Focal damage to scalp after non-missile trauma
contusions
lacerations
Focal damage to meninges after non-missile trauma
Haemorrhage
Infection
Focal damage to brain after non-missile trauma
Contusions (bruise)
Lacerations
Haemorrhage
Infection
Diffuse brain lesions as result of non-missile trauma
Diffuse axonal injury
Diffuse vascular injury
Hypoxia-ischaemia
Swelling
What can result from skull fracture (implies considerable force)
Increased risk of haematoma, infection and aerocele
What can cause skull fracture
Angled or pointed objects cause localized fractures that are often open or depressed
Flat surfaces cause linear fractures
Can extend to skull base
Examples of haemorrhage (focal lesion)
Extradural haematoma
Subdural haematoma
Traumatic subarachnoid haematoma
Cerebral and cerebellar haemorrhage
Cause of superficial and deep cerebral/cerebellar haemorrhage
Superficial - due to severe contusion
Deep - related to diffuse axonal injury
Describe extradural haemorrhage
~15% of fatal head injurys (~10% of severe ones) Occur slowly over hours Causes death by brain displacement Raised intracranial pressure Herniation
Describe subdural haematoma
Usually due to tears in bridging veins (cross subdural space form superior surface of brain to mid-sagittal sinus
Can occur slowly
Usually surrounded by ‘membrane’ of granulation tissue
Causes of traumatic subarachnoid haemorrhage
Contusions/lacerations
Base of skull # (tear vessels)
Vertebral artery rupture/dissection
Intraventricular haemorrhage
Main cause of infection in brain
Skull fracture
Focal brain damage mechanisms
Contact damage (at or just deep to the point of impact) Acceleration or deceleration damage (force to head causes differential movement of skull and brain or get differential movement of brain tissue)
What can result from differential movement of brain tissue
Shearing, traction and compressive stresses
Damages blood vessels and axons
What can result from differential movement of skull and brain (as result of force to head)
Impact of inner surface of skull on underlying brain causes contusion
Traction on bridging veins causes subdural haemorrhage
What are contusions
Superficial bruises of the brain
What is difference between coup and contre coup contusions
coup = at site of impact
contre coup = away from site of impact
Describe how contusions change over time
At first - haemorrhagic
Then become brown/orange and soft (days weeks)
Then indented or cavitated (after months or years)
When do lacerations happen
When contusion is sufficiently severe to tear the pia mater
Example diffuse lesions
Diffuse axonal injury
Diffuse vascular injury
Swelling
Hypoxia-ischaemia
Pathophysiology of chronic traumatic encephalopathy
Atrophy:
-neocortex, hippocampus, diencephalon & mamillary bodies
Enlarged ventricles with fenustrated cavuum septum
Tau-positive neurofibrillary and astrocytic tangles:
-Frontal and temporal cortex and limbic regions
-Especially around depths of sulci and limbic regions
What % of chronic traumatic encephalopathy is TDP-43 pathology
~85%
