Brain Injury Flashcards
Primary TBI: Axonal Injury
Diffuse Axonal Injury (DAI)
Vulnurable:
- viscoelastic therefore brittle response
- very aligned in tracts thus highly susceptible to damage from tract-oriented strains
Unrestricted head movement post-impact:
- rotational acceleration
- tissue deformation creates axonal tension
- depends on plane of head injury
Rapid tensile stretch of axons:
- damaged cytoskeleton > plastic deformation > undulation + misalignment > mechanical damage to sodium channels > sodium influx > axonal swelling and sodium triggers Ca+ channels > Ca+ triggers proteolysis > damages cytoskeleton further = secondary axotomy
Primary TBI: Vascular Injury (types)
- epidural haematoma
- subdural haematoma
- subarachnoid haematoma
- intraventricular haemorrhage
Epidural Haematoma
- temporal bone/skull fracture ruptures middle meningeal artery
- pressure from bleed separates dura + bone
- dura contains blood –> biconvex shape
- expansion limited by tight adhesion of dura to skull
- early surgical evacuation = good prognosis
Subdural Haematoma
- violent shaking of head severs bridging veins
- deceleration injury
- crescent-shaped (doesn’t cross falx or tentorium)
- mass effect is midline shift
- burr hole drainage
Subarachnoid Haematoma
- haemorrhagic stroke/arterial aneurysm bleed
- cerebral vessels bleed into subarachnoid space
- blood mixes with CSF
- superficial contusions + vessels break
- vasospasm may cause focal ischaemia
Intraventricular Haemorrhage
- damage to vessels lining ventricles
- haemorrhage of small arterioles/capillaries in brain parenchyma
Types of Primary TBI
- axonal injury
- vascular injury
- contusion
- lacerations
Glasgow Coma Scale
1-4 for eye response, 1-5 for verbal, 1-6 for motor.
Mild (13-15), moderate (9-12), severe (<9)
MILD:
- loss of consciousness < 30mins
- post-traumatic amnesia < 24hrs
- no macroscopic damage
Secondary TBI
- Focal, multifocal, or diffuse
- Ischaemic –> hypoxic damage
- Brain swelling
- Inc. intracranial pressure
- Neuroinflammation
- Infection
- Oedema
Stroke: Ischaemic
- most common
- sudden blockage of flow to CNS
- transient ischaemic attacks –> clot moves and symptoms dissipate
Arterial occlusion via: - thrombus = blood clot
- embolus = piece of plaque/thrombus travels and blocks downstream artery
Stroke: Intracerebral Haemorrhage (ICH)
Main cause: hypertension
Most in basal ganglia + thalamus
Cell toxicity from mechanical forces + chemical toxicity
Perihaematomal oedema
Stroke: Subarachnoid Haemorrhage (SAH)
Cause: rupture of intracranial aneurysm
- Early brain injury
- transient global ischaemia
- toxic effects of blood in subarachnoid space - Delayed cerebral ischaema (1/3 patients 3-14 days)
- Systemic response
- increased sympathetic
- angiotensin system activated
- inflammatory cytokines
Incidence vs Mortality of Strokes
Incidence:
ischaemic > ICH > SAH
Mortality:
SAH > ICH > ischaemic
