Raised ICP Flashcards
what is the normal values of ICP
5-15mmHg
what can be done to assess the value of the ICP
lumbar puncture
at what level is a lumbar puncture performed and why
L3/4 as the spinal cord has finished at L1 so less risk of damage
in raised ICP why would headaches be worse in the morning
- lying down increases the venous pressure in the head
- slower breathing increases CO2 levels causing vasodilation which also increases blood volume in the head
in raised ICP why does coughing make headaches worse
compression of the vena cava means that venous return to the heart is momentarily paused leading to an increase in blood volume in the head
what are the signs and symptoms of raised ICP
headache, vomiting, visual disturbance, depression of consciousness, abducens palsy
why do you get vomiting with raised ICP
due to ischaemia
why do you get visual disturbance in raised ICP
due to compression of the optic nerve
what would be seen in fundoscopy in raised ICP
papilloedema - swelling of the optic disc due to raised ICP
why do you experience depression of consciousness in raised ICP
due to ischaemia of the reticular formation
why do you get abducens palsy in raised ICP
abducens nerve runs close to the skull so is easily compressed causing lateral rectus damage
what is the management for hydrocephalus
shunts from the ventricles, down the neck to the peritoneum
what is cytotoxic cellular oedema
this is where compression of brain tissue causes a lack of oxygen. this means the Na/K/ATPase doesn’t work as well giving a build up of Na in cells so water also accumulates in cells eventually causing them to burst
what are the 3 types of herniation which may occur in raised ICP
subfalcine, uncal and temporal
what is a subfalcine herniation
when the cingulate gyrus moves underneath the fall cerebri
what is the most common type of herniation
subfalcine
what does uncal herniation result in
compression of the midbrain causing occulomotor damage, cerebral peduncle damage and decreased consciousness
what does temporal herniation result in
compression of medulla, brainstem - affects respiratory and cardiovascular centres
what is Cushing’s reflex
this is when there is herniation through foramen magnum which leads to bradycardia, high bp and low respiratory rate
what causes the low respiratory rate in Cushing’s reflex
ischaemia of the medulla as this is where the respiratory centre is
what re the causes of raised ICP
increased blood volume increased CSF cerebral oedema mass idiopathic
what can cause an increase in blood volume In the head
venous outflow obstruction
venous sinus thrombosis
what is hydrocephalous
accumulation of CSF due to an imbalance in production and removal of CSF
what is a communicating hydrocephalous
where the CSF can still flow between the ventricles. however, there is reduced absorption or increased production of CSF
what causes a communicating hydrocephalous
meningitis, subarachnoid haemorrhage and trauma
what is a non-communicating hydrocephalus
where CSF can move between ventricles due to blockage e.g. from a tumour
what is choroid plexus papilloma
where there is excessive secretion of CSF
is choroid plexus papilloma a communicating or non-communicating hydrocephalus
communicating
what can cause cerebral oedema
infarction. meningitis, encephalitis
what are most brain tumours
metasteses
where do mets in the brain usually come from
kidney, breast and lung
