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Neurology > ICP > Flashcards

Flashcards in ICP Deck (30)
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1
Q

kellie Monroe doctrine?

A

3 components contributing to ICP

  • brain tissue
  • CSF
  • intracranial circulating volume
2
Q

normal ICP?

A

7-15 mmHg at rest

can be negative in vertical position

3
Q

immediate compensation for raised ICP?

A

decrease CSF volume by moving it out of FM

decrease blood volume by squeezing sinuses

4
Q

delayed compensation?

A

///

5
Q

cerebral perfusion pressure (CPP) is equal to what?

A

MAP - ICP

6
Q

CPP in hypotension?

A

low

7
Q

cushings response?

A

opposite to shock response

- BP increases to compensate for lower ICP

8
Q

cerebral blood flow equals what?

A

cerebral perfusion pressure / cerebrovascular resistance

9
Q

in a healthy brain, cerebral blood flow is constant over wide range of pressure, what happens in abnormal brain?

A

cant autoregulate

blood flow varies

10
Q

types of autoregulation of CBF?

A
pressure autoregulation (dilation/constriction in response to BP)
metabolic autoregulation (dilation in response to chemicals - lactic acid, CO2 etc)
CO2 is a potent dilator (increased CO2 = dilation vice versa)
11
Q

causes of raised ICP?

A
mass effect (tumour, infarct, abscess, haematoma etc)
brain swelling (encephalopathy, ischaemia, liver failure, IIH, hypercarbia)
- decreased CPP but don't really cause any brain tissue shift/herniation
increased central venous pressure (venous sinus thrombosis, heart failure, jugular vein obstruction)
problems with CSF flow
12
Q

what can cause CSF flow problems?

A
obstruction (0bstructive/non-communicative)
- masses
- chiari syndrome
increased CSF production (choroid plexus tumour)
decreased absorption (communicating)
- SAH
- meningitis
- malignant meningeal disease
13
Q

early signs of raised ICP?

A
reduced conscious level
headache
pupillary dysfunction +/- papilloedema
changes in vision
nausea and vomiting
14
Q

later signs of raised ICP?

A
coma
fixed, dilated pupils
hemiplegia
bradycardia > cushings triad
hyperthermia
increased urine output (compensates for raised ICP via changing BP)
15
Q

interventions for raised ICP?

A

maintain head in midline to facilitate blood flow
loosen tube ties, collars etc to maximise venous return
HoB 30-45 degrees elevation
avoid gagging, coughing etc which could increase ICP
decrease environmental stimuli which could increase ICP
treat hyperthermia
maintain fluid balance and normal electrolytes
maintain normocarbia

16
Q

point of decompensation?

A

point where brain cant compensate for volume of mass (hydrocephalus, bleed etc) any longer and ICP suddenly and rapidly increases, quickly causing damage and herniation etc

17
Q

medical management of raised ICP?

A
diuretics
- mannitol, hypertonic saline, furosemide, urea)
barbiturate coma (late down line)
antiepileptics
surgical decompression
- remove mass lesion
- CSF diversion (drain, shunt etc)
- hemicraniectomy
18
Q

communicating vs non-communicating?

A

communicating
- dilation of CSF throughout all ventricles in the brain
- meningitis, post subarachnoid haemorrhage
- all ventricles enlarged on imaging
non-communicating/obstructive
- obstruction occurs before CSF flows out into spinal spaces
- usually between 3rd and 4th ventricles
- stenosis, tumours etc

19
Q

VP shunt?

A

between ventricles and peritoneum

20
Q

features of normal pressure hydrocephalus?

A
disease of elderly
hakims triad
- abnormal gait
- urinary incontinence
- dementia
21
Q

differential diagnoses of normal pressure hydrocephalus?

A
other dementias
cervical myelopathy
urinary problems
parkinsons
depression
22
Q

features on imaging of NPH?

A

enlarged ventricles
wide sulci
normal brain at top (pressure pushes brain up to top)
90 degree angle between lateral ventricles

23
Q

how is NPH investigated?

A

LP
lumbar drain test
lumbar infusion studies

24
Q

how is NPH managed?

A

VP shunt using medium-low or low pressure valve

- can be better to use a variable valve

25
Q

features of IIH?

A

raised ICP of no known cause
never have ventricular dilation
normal imaging

26
Q

who usuall gets IIH?

A

women of child bearing age
mainly western civilisations
overweight

27
Q

signs and symptoms of IIH?

A
headache
diplopia
visual blurring
visual field defects progressing to tunnel vision
tinnitus
radicular pain
papilloedema
- 25% of people end up with severe/permanent visual loss
28
Q

how is IIH managed?

A

weight loss
- potentially bariatric surgery
CA inhibitors (acetazolamide, topiramate)
diuretics
CSF diversion
interventional radiology (venous sinus plasty/stenting)
ONSF

29
Q

IIH differentials?

A

any other headache
cervical radiculopathy
any other reason for ICP

30
Q

investigations in IIH?

A

LP
CT/MRI head
CTV/MRV
fundoscopy +/-ophthalmology review