Raised ICP Flashcards
What are normal ranges of ICP in adults children and infants ?
what is a good rule of thumb for raised ICP ?
Adults= 5-15 mmHg
Children = 5-7mmHg
Term infants = 1.5 - 6 mmHg
if >20mmHg = raised
what is the Monro-kellie doctrine ?
Any increase in the volume of one of the intracranial
constituents (brain, blood or CSF) must be compensated by a decrease in the volume of the one of the others
what is the first components to decrease in IC mass ?
CSF and venous blood, since they are at the
lowest pressure
how do you work out CPP?
What is normal CCP , MAP and ICP
CPP = mean arterial pressure (MAP) – ICP
CPP >70 MMhG
MAP ~90mmHg
ICP ~10 mmHg
What happpens when CPP is <50 mmHg ?
cerebral blood flow cannot be
maintained as cerebral arterioles are maximally dilated
what can damage brain lead to ?
impair or even abolish cerebral
auto-regulation (Vaso contriction/ dilation)
what happens in Cushing triad/ reflex ?
Raised ICP -
Hypertension = Increase in MAP to maintain CPP
Bradycardia = Due to vagal activity via baroreceptors from increased MAP
Irregular breathing = compression of the brainstem leads to
damage to respiratory centres
what mights cause raised ICP from blood ?
too much in vessels -
Raised arterial pressure = Malignant hyperntsion
Raised venous = SVC obstruction
Haemorrhage- SA, SD, ED, Stroke and intraventricular
what are the cause of Hydrocephalus ?
too much CSF
What are the causes of congenital hydrocephalus ?
Obstructive - Neural tube defects, Aqueduct stenosis, part of other syndromes
Communicating- Increased CSF production , Decreased CSF absorption
what are the clinical signs of congenital hydrocephalus ?
Bulging head with head circumference increasing faster than expected Sunsetting eyes (due to direct compression of orbits as well as involvement of oculomotor nerve as it exits midbrain)
what is the management of congenital hydrocephalus ?
tapping fontanelle with needle
Medium term drainage can be achieved by external ventricular drain
(EVD)
what is the advantages / disadvantages of EVD?
allows - Short / medium term drainage , continuous pressure monitoring , used if shunt fails or contraindicated
cons - Infection pathway , chamber must be kept at same height as ventricles
inpatient monitoring - not long term
what is a Ventricular shunt ? what types can you get ?
one way valve tunelled under skin
tube is placed from the ventricular system
into the peritoneum (V-P) or
right atrium (V-A), VP more common
what are cons of VP shunts ?
Extra length of tubing is provided to allow growth before revision is required V-P shunts vulnerable to infection (e.g. if abdominal infection, can track back up to brain) or kinking Most s hunts will require revision
what are some acquired forms of hydrocephalus ?
Meningitis Trauma Haemorrhage (e.g. post subarachnoid haemorrhage) Tumours (e.g. compressing cerebral aqueduct)
What are the 4 types of cerebral oedema ?
Vasogenic -
Cytotoxic
Osmotic
Interstitial
what are each types pathologies (Cerebral oedema )?
v - Breakdown of tight junctions at BB due to vasoactive substances
C- damage to brian cels ia toxins
O- ECF becomes hypotonic due to SIADH or excessive H20 intake
I - Flow of CSF to due to rupture of BB from hydrocephalus trauma
what are alternative Causes of raised ICP?
Tumour
Cerebral abscess
Idiopathic
what is IIH ?
Symptoms ?
associations ?
Idiopathic intracranial hypertension - Aka benign intracranial hypertension
headache and visual
disturbance
Usually obese middle aged females
how is IIH diagnosed ?
what must you be careful of ?
management ?
raised opening pressure on an LP no signs of intracranial pathology before doing an LP in a patient with suspected raised ICP as this can precipitate brain herniation
weight loss and BP control
what are early symptoms of Raised ICP ?
Headache nausea and vomiting Difficulty concentrating or drowsiness - Daily life Confusion Double vision Focal nero signs Seizures - blackouts
what kind of headaches will a patient get in raised ICP ?
Constant
o Worse in the morning
o Worse on bending / straining
what specially will be wrong with vision ?
Problems with accommodation (early sign, pupillary dilatation a late sign) o Maybe effects on acuity o Visual field defects o Papilloedema
define tonsillar herination
Cerebellar tonsils herniate through foramen
magnum, compressing medulla
define subfalcine herination
Cingulate gyrus is pushed under the free edge of
the falx cerebri
Can compress anterior cerebral artery as it loops
over the corpus callosum
define uncal herination
symptoms ?
Uncus of temporal lobe herniates through tentorial
notch compressing adjacent midbrain
Can cause third nerve palsy and maybe even
contralateral hemiparesis (due to compression of
cerebral peduncle)
define central downward herniation
Medial temporal lobe / other midline structures
pushed down through tentorial notch
define external herniation
skull fracture or therapeutic
craniectomy
what are brain protective measures ?
airway and breathing control Circulation sedation, analgesia and paralysis Head up tilt - improve drainage Temperature - avoid high temps Anticonvuslants Nutritions and PPIs - increased Vagal activity
what are treatment options ?
Mannitol or hypertonic saline
o Osmotic diuresis
• Ventricular drainage
• Decompressive craniectomy as a last resort
