head injury and trauma Flashcards
which type of head injury is associated with lucid intervals?
extradural haematoma
what are primary head injuries?
- focal
- contusions (bruising)
- haematoma - can be extradural or subdural - diffuse
- diffuse axonal injury
which artery has most likely ruptured during a extradural haemorrhage?
middle meningeal artery
what are risk factors for subdural haematoma?
old age, alcoholism and anticoagulation.
what types of headaches do subarachnoid haemorrhages classically cause?
sudden occipital headache. Usually occurs spontaneously in the context of a ruptured cerebral aneurysm
why may you get pupillary dilation with a head injury?
– occulomotor 3rd nerve compression
- the eye may also look down and out
why might you get muscle weakness with a head injury?
– corticospinal tract compression
where is the middle meningeal artery found?
the pterion
what structures are responsible for subdural haematomomas?
bridging veins- these are vulnerable to rapid acceleration and deceleration
why do extradural haematomas cause a rapid rise in intracranial pressure?
build of blood trapped between the dura mater and skull.
dura mater is attached tightly to the sutures of the skull, so the blood can’t cross these sutures and is trapped with nowhere to go.
This means the intracranial pressure can increase rapidly.
where does blood collect in subdural haematoma?
blood collects between the dura mater (the outer layer of the meninges) and arachnoid mater, which is the middle layer of the meninges.
why is subdural haematoma more common in elderly and alcoholics?
because of brain atrophy the riding veins are stretched out and so are more vulnerable to rupture
why are the effects of subdural haematomas slow?
- veins rather than arteries bleed out slowly
- bleeding isn’t restricted by suture so it can spread out and pressure won’t build up
what is the equation for working out cerebral perfussion pressure?
CPP= mean arterial pressure- intracranial pressure
what is a subacute subdural heamatoma?
2 days- 2 weeks
What is an acute subdural heamatoma?
<2 days
what is a chronic subdural haematoma?
> 2 weeks
what is the most common cause of subarachnoid haemorrhage?
head trauma
which genetic factors can predispose an individual to a cerebral anneyurism?
- marfans
- elhers danklos syndrome
- polycystic kidney disease
lumbar puncture for spontaneous vs dramatic subarachnoid haemorrhage?
spontaneous:
- can do a lumbar puncture and it will show xanthocromia
traumatic:
- contraindicated due to increase intracranial pressure-> it may cause herniation
what are indications for head CT?
amnesia for >30 minutes prior to event
age >65
dangerous mechanism of injury
how does hydrocephalus appear on CT?
ventricular dilatation
what can diffuse axonal injury lead to?
- post traumatic coma lasting > 6hrs
which type of herniation is the most dangerous?
- tonsil herniation as this can push down on the brain stem
- this is a type of infratentorial herniation
