Cerebral Perfusion and Intracranial Pressure Flashcards
(34 cards)
what is vasogenic oedema?
when there is disruption of the blood brain barrier
what oedema is caused by membrane failure?
cytotoxic oedema influx of Ca creating cellular swelling
what are some secondary effects of raised ICP?
> herniation syndromes
> decreased cerebral perfusion
what is the munro kellie doctrine?
(brain + blood + CSF) volume = intracranial space. this must remain constant
in the adult brain how much of the cardiac output does the brain receive?
15%
what is the myogenic mechanism?
auto-regulation where vascular smooth muscle constricts in response to an increase in wall tension
what does a subfalcine herniation affect?
medial motor cortex
what may an uncal herniation affect?
> CN 3
ipsilateral corticospinal tracts
what sort of herniation would cause brain stem damage?
foramen magnum herniation
what management may a patient with raised ICP receive in ITU?
> 30 degree head position > no impediment of venous drainage > CO2 maintained below normal range > intermittent boluses of mannitol when ICP raised > fully sedated and paralysed
what surgical interventions can be carried out to reduced inter-cranial pressure?
> craniotomy and evacuation of clot
external ventricular drainage
decompressive craniectomy
list some common indications to perform a CT scan
> Head trauma > acute stroke > headache (sub arachnoid haemorrhage) > cancer > post surgical
what would indicate a MRI?
> demyelination > CNS tumours > suspected disc prolapse > TIA > epilepsy > paediatric neurology > headache > cancers
state some contraindications to perform a MRI
> cardiac pacemakers/cochlear implants
programmable shunts/insulin pumps (relative)
moveable metallic implants
for what can angiography be used?
diagnosis and treatment of vascular abnormalities: > aneurysm > arteriovenous malformation > carotidocavernous fistula > unstoppable epistaxis
define perfusion
the volume of blood passing through a defined volume of tissue per unit time
what are the units in CT perfusion?
ml blood/ 100g tissue/ min
name a disorder where there would be decreased perfusion
stroke
name a disorder where there would be increased cerebral perfusion
tumour: angiogenesis and a more aggressive tumour
what does PET scan map out?
glucose usage
where can increased metabolism be seen?
> tumour
inflammation
infection
in a CT is bone white?
yes
what type of MRI has white CSF?
T2
what colour is skull on an MRI?
black
