Intracranial Pressure and Hydrocephalus Flashcards Preview

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

what is intracranial pressure

A

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

2
Q

what is the monroe- kellie- doctrine

A

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
Q

what is normal ICP

A

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

4
Q

what are the compensatory mechanisms for an expanding mass

A

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

5
Q

what is the formula for cerebral perfusion pressure

A

MAP - ICP = CPP

6
Q

what does a CPP below 20 usually mean

A

coma

7
Q

what is cushings response/ triad

A
response to increased ICP 
opposite of shock result:
-increased BP
-irregular breathing 
-bradycardia
8
Q

what are the theories of autoregulation of cerebral blood flow

A

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
Q

what are the common causes of raised ICP

A
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
Q

what is chiari syndrome

A

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

11
Q

what are the early signs of raised ICP

A

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

12
Q

what are the later signs of raised ICP

A

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

13
Q

what is the intervention for raised ICP

A

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
Q

what medical management exists for raised ICP

A

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
Q

what are the types of hydrocephalus

A
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
Q

what is sunsetting eyes

A

unable to rise eyes due to high ICP

17
Q

what type of hydrocephalus is caused by aqueductal stenosis

A

obstructive

18
Q

what is normal pressure hydrocephalus

A

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
Q

what are the symptoms of normal pressure hydrocephalus

A

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

20
Q

what are the differentials for normal pressure hydrocephalus

A

dementia, cervical myelopathy, urinary problems, parkinsons, depression

21
Q

what investigations and treatment for normal pressure hydrocephalus

A

LP, lumbar drain test, lumbar infusion studies

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

22
Q

what is idiopathic intracranial hypertension and who gets it

A

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

mainly overweight women of child bearing age
mostly western civilisations

23
Q

is there ventricular dilatation in IIH

A

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

24
Q

what are the symptoms of IIH

A

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

25
Q

what are the theories of causes of IIH

A

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

26
Q

what is the treatment for IIH

A

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
Q

what differential for IIH

A

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

28
Q

what investigations for IIH

A

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