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Neurology > Raised ICP and Hydrocephalus > Flashcards

Raised ICP and Hydrocephalus Flashcards

1
Q

what 3 intracranial components make up the monroe-kellie doctrine?

A

brain
blood
CSF

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2
Q

what does the monroe-kellie doctrine say about the 3 intracranial components and their relationship to ICP?

A

all 3 components have pressure exerted on them

if pressure exerted in any of the 3 increase or if a 4th component introduced (tumour, bleed etc) then this can raise ICP

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3
Q

what physiological functions can increase ICP?

A

coughing / sneezing
going to toilet
(can also be elicited by valsalva maneouvers)

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4
Q

what is normal ICP at rest?

A

7-15mmHg

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5
Q

ICP can be negative - true or false?

A

true - if patient is in vertical position or under general anaesthetic

also often negative in babies

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6
Q

how do we immediately compensate for acute rise in ICP?

A

CSF pushed out of foramen magnum

decreased blood volume to the brain

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7
Q

roughly how much CSF is made per day?

A

around 1 pint

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8
Q

how is the cerebral perfusion pressure calculated?

A

mean arterial blood pressure (MAP) - ICP = CPP

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9
Q

cerebral perfusion pressure is the same as cerebral blood flow - true or false?

A

false
CPP = net pressure gradient causing cerebral blood flow to brain
(narrow limit as too little blood means ischaemia and too much raises ICP)

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10
Q

cushings triad is the opposite of a shock response from the body - what symptoms are experienced?

A

hypertension
bradycardia
irregular breathing

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11
Q

what is meant by the term “autoregulation” of cerebral blood flow?

A

means that cerebral blood flow remains constant over a variety of blood pressures

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12
Q

when would autoregulation of cerebral blood flow be lost?

A

post brain injury

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13
Q

how can ICP be decreased by patient themselves?

A

hyperventilation - decreases CO2 which decreases BP which causes vasoconstriction of blood vessels in body which decreases cerebral blood flow which decreases ICP

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14
Q

what non-CSF related causes are there for raised ICP?

A

mass - tumour, infarct
brain swelling - ischaemia, encephalopathy
increased central venous pressure - venous sinus thrombosis, heart failure

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15
Q

what problems with CSF flow can lead to raised ICP?

A

obstruction - masses (colloid cyst, tumour at midbrain), chiari (cerebellar tonsils herniate through foramen magnum)

increased production (choroid plexus papilloma)

decreased absorption (subarachnoid haemorrhage, after meningitis)

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16
Q

what are the early signs of a raised ICP?

A

decreased conscious level
headache
pupil dysfunction / change in vision
nausea and vomiting (due to midbrain distortion)

17
Q

what late signs present in raised ICP?

A 
coma 
fixed dilated pupil 
hemiplegia 
cushings triad 
hyperthermia 
increased urinary output
18
Q

what are the aims of intervention in raised ICP?

A

maintain cerebral perfusion pressure

prevent ischaemia

19
Q

how should blood flow to head be promoted through intervention?

A

ensure head in midline / neutral position
loosen any collars / jewellery
put head of bed between 30-45 degrees to maximise blood flow

20
Q

how should spikes in ICP be avoided through intervention?

A

decrease any environmental stimuli that could cause patient to gag/cough/sneeze etc

21
Q

why is it important to intervene when patients GCS can still be at 15?

A

rapid decompensation of brain after prolonged period of compensating

if any suspicion patient is about to decompensate, then they require surgery before herniation of brain

22
Q

what medicinal treatments can be used in raised ICP?

A

diuretics (mannitol, hypetonic saline, furosemide)

barbiturate coma (phenobarbitone used to subdue all but basic brain functions)

anti-epileptic drugs sometimes used

23
Q

what is the difference between a communicating and non-communicating hydrocephalus?

A

communicating = all ventricles dilated

non communicating = not all ventricles dilated (depends on point of obstruction - usually between 3rd or 4th ventricle causing triventricular enlargement)

24
Q

what is meant by the buzzword “sun-setting” eyes?

A

compression of midbrain in hydrocephalus causes problems moving eyes upwards

25
Q

how do infants with hydrocephalus usually look in western world?

A

flat and broad face (not usually the very large forehead)

26
Q

who normally gets normal pressure hydrocephalus and why?

A

elderly - idiopathic

27
Q

what is in the hakims triad of normal pressure hydrocephalus?

A

abnormal gait (wide based shuffle)
urinary incontinence
dementia (usually mild)

28
Q

what are other differentials of normal pressure hydrocephalus?

A 
other forms of dementia 
cervical myelopathy 
all urinary problems 
parkinsons 
depression
29
Q

why are dilated ventricles in the context of brain atrophy not considered to be hydrocephalus?

A

ventricles are dilating relative to the loss of brain tissue, not because of increased amount of CSF = ventriculomegaly

30
Q

how should normal pressure hydrocephalus be investigated?

A

lumbar puncture (see if taking off 30mls of CSF makes any difference to symptoms)

lumbar drain test (72 hours of draining CSF)

lumbar infusion study

31
Q

what should you complete before and after a lumbar train test to check if it has made difference to patient?

A

MMSE or other cognitive test
get up and go test

lumbar drain test should improve these, especially gait

32
Q

how is hydrocephalus treated?

A

ventriculoperitoneal shunt

33
Q

ventricles dilate in idiopathic intracranial hypertension - true or false?

A

false - no dilation of ventricles, if they are dilated it is not IIH

34
Q

who usually gets IIH?

A

women of childbearing age (hormones)

often overweight western population

35
Q

what are the usual presenting signs and symptoms of IIH?

A

headache (worse above eyes, patient doesnt want to look upwards)
double vision/blurring/field defects/papilloedema
pulsatile tinnitus
radiculopathy of arms if pressure reaches cervical spinal cord

36
Q

what treatments are recommended for IIH?

A

weight loss
bariatric surgery
carbonic anhydrase inhibitors (acetazolomide, topiramate)
diuretics
shunt
interventional radiology to stent stenotic veins

37
Q

what investigations are used in IIH?

A

LP - pressure can be grossly enlarged (45-50mmHg)

CT/MRI of head

CTV to check for venous stenosis

fundoscopy / ophthalmology review

Neurology (32 decks)

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