Intracranial Pressure and Hydrocephalus Flashcards Preview

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Flashcards in Intracranial Pressure and Hydrocephalus Deck (28):
1

what is intracranial pressure

pressure exerted by the cranium on the brain tissue, CSF and intracranial circulating blood volume

2

what is the monroe- kellie- doctrine

three components of intracranial pressure (brain tissue, CSF and circulating intracranial blood), have pressure exerted on them, if you increase the volume of any of these components you will increase in the intracranial pressure

3

what is normal ICP

7-15mmHg
can be negative when in vertical position
higher than 15/16 probably abnormal

4

what are the compensatory mechanisms for an expanding mass

immediate- decrease in CSF volume by moving out of FM, decrease in blood by squeezing sinuses
delayed- decrease in ECF

5

what is the formula for cerebral perfusion pressure

MAP - ICP = CPP

6

what does a CPP below 20 usually mean

coma

7

what is cushings response/ triad

response to increased ICP
opposite of shock result:
-increased BP
-irregular breathing
-bradycardia

8

what are the theories of autoregulation of cerebral blood flow

pressure- vessel constriction/ dilatation
-metabolic- arterioles dilate in response to CO2/ lactic acid etc

CO2 is a potent dilator:
-increase CO2/ increased BP = vasodilation
-decreased CO2/ decreased BP= vasoconstriction

9

what are the common causes of raised ICP

mass effects- distort surrounding brain
brain swelling (ischaemia, anoxia, metabolic, acute liver failure, encephalopathy, IIH, hypercarbia) - decreased cerebral perfusion but minimal tissue shift
increase in central venous pressure (venous sinus thrombosis, HF, obstruction of jugular veins)
problems with CSF flow (obstruction - masses, chiari syndrome), (increased production- choroid plexus papilloma), (decreased absorption- communicating hydrocephalus = SAH, meningitis, malignant meningeal disease)

10

what is chiari syndrome

a structural defect in the cerebellum, characterized by a downward displacement of one or both cerebellar tonsils through the foramen magnum

11

what are the early signs of raised ICP

decreased consciousness, HA, pupillary dysfunction +/- papilloedema, changes in vision, N&V

12

what are the later signs of raised ICP

coma, fixed dilates pupils, hemiplegia, bradycardia -> cushings triad, hyperthermia, increased urinary output

13

what is the intervention for raised ICP

goals= maintain CPP, prevent ischaemia and brain compression

-maintain head in midline to facilitate blood flow
-loosen tube ties, collars, jewellery etc
-head oh bed 30-45 degrees elevation
-avoid gagging/ coughing etc
-decrease environmental stimuli
-treat hyperthermia
-maintain fluid balance and normal electrolytes (watch urine output)
-maintain normocarbia (short term can hyperventilate patient to decrease CO2

14

what medical management exists for raised ICP

diuretics (mannitol, hypertonic saline, furosemide, urea)
barbiturate coma (later down the line, subdues the brain)
antiepileptics (prevent energy expendature that seizure would cause)
surgical decompression
other surgery- mass removal (abscesses have to removed within 24hrs) CSF diversion

15

what are the types of hydrocephalus

communicating (the dilatation of CSF is throughout the entire ventricular system)
non communicating (obstruction occurs before the CSF floes out into the sagittal sinus, commonly at cerebral aqueduct)

can be congenital (aqueduct stenosis, choroid cyst, malformations, intraventricular haemorrhage)
or acquired

16

what is sunsetting eyes

unable to rise eyes due to high ICP

17

what type of hydrocephalus is caused by aqueductal stenosis

obstructive

18

what is normal pressure hydrocephalus

idiopathic disease of the eldery
get large ventricles (ventricular megaly) due to a smaller brain- will have large slyvian fissures
possibly due to decreased brain elasticity

19

what are the symptoms of normal pressure hydrocephalus

hakims triad- abnormal (wide based, shuffling gate), urinary incontinence (frontal dysfunction, loos inhibition), dementia

20

what are the differentials for normal pressure hydrocephalus

dementia, cervical myelopathy, urinary problems, parkinsons, depression

21

what investigations and treatment for normal pressure hydrocephalus

LP, lumbar drain test, lumbar infusion studies

Tx= VP shunt, median-low or low pressure valve

22

what is idiopathic intracranial hypertension and who gets it

raised ICP of unknown cause- must investigate fully, is a diagnosis of exclusion

mainly overweight women of child bearing age
mostly western civilisations

23

is there ventricular dilatation in IIH

no- if they have this then not IIH, will be hydrocephalus due to another cause

24

what are the symptoms of IIH

HA (v severe), double vision, visual blurring, tinnitus (usually pulsatile), radicular pain, papilloedema -> 25% have severe/ permanent visual loss

25

what are the theories of causes of IIH

CSF imbalance, hormonal (oestrogen), venous pressure (transverse/ sigmoid sinus stenosis)

26

what is the treatment for IIH

weight loss,
possible bariatric surgery,
carbonanhydrase inhibitors (acetazolamide, topiramate),
diuretics,
CSF diversion (LP or VP shunt),
interventional radiology (intracranial venous sinus plasty, intracranial venous sinus stenting),
ONSF (optic nerve sheath fenestration- purely to save vision, decreases pressure on nerves)

27

what differential for IIH

any other type of HA
any other reason for ICP
cervical radiculopahty

28

what investigations for IIH

LP
CT/ MR head
CTV/ MRV (look at veins and for stenosis)
fundoscopy +/ ophthalmology review