Intracranial Pressure and Hydrocephalus Flashcards Preview

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Flashcards in Intracranial Pressure and Hydrocephalus Deck (28)
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what is intracranial pressure

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


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


what is normal ICP

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


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


what is the formula for cerebral perfusion pressure



what does a CPP below 20 usually mean



what is cushings response/ triad

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


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


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)


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


what are the early signs of raised ICP

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


what are the later signs of raised ICP

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


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


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


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


what is sunsetting eyes

unable to rise eyes due to high ICP


what type of hydrocephalus is caused by aqueductal stenosis



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


what are the symptoms of normal pressure hydrocephalus

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


what are the differentials for normal pressure hydrocephalus

dementia, cervical myelopathy, urinary problems, parkinsons, depression


what investigations and treatment for normal pressure hydrocephalus

LP, lumbar drain test, lumbar infusion studies

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


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


is there ventricular dilatation in IIH

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


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


what are the theories of causes of IIH

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


what is the treatment for IIH

weight loss,
possible bariatric surgery,
carbonanhydrase inhibitors (acetazolamide, topiramate),
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)


what differential for IIH

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


what investigations for IIH

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