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NEUROLOGY > Intracranial Pressure and Hydrocephalus > Flashcards

Intracranial Pressure 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 intrcrania components and their relationship to ICP

A

All 3 components have pressure exerted on them

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

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3
Q

What physiological functions can increase ICP?

A

Coughing/sneezing
Going to the toilet
(can also be elicited by valsalva maneouvres)

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4
Q

What is a normal ICP at rest?

A

7-15mmHg

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5
Q

ICP can be negative. TRUE/FALSE?

A

TRUE - if patient is in vertical position OR if under general anaesthetic

Also very often negative in babies

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6
Q

How do we immediately compensate for an 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/FALSE?

A

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

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10
Q

Cushing’s 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 the patient themselves?

A

Hyperventilation

  • Decreases CO2
  • Decreases BP => causes vasoconstriction of blood vessels in body
  • Decreases cerebral blood flow
  • 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 a raised ICP?

A

Obstruction:

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

Increased production - e.g. 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
  • Cushing’s 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 the head be promoted through intervention?

A
  • ensure head is in midline/neutral position
  • loosen any collars/ jewellery that could impair blood flow
  • 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, hypertonic 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/4th ventricle => triventricular enlargement)
24
Q

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

A

Compression of the midbrain in hydrocephalus causes problems moving eyes upwards

25
Q

How do infants with hydrocephalus usually look in the western world?

A

Flat and Broad face

not usually the very large forehead

26
Q

Who usually gets Normal Pressure Hydrocephalus and why?

A

Elderly patients

Condition is idiopathic

27
Q

What is in Hakim’s triad of Normal Pressure Hydrocephalus?

A

Abnormal gait (wide based shuffle)
Urinary incontinence
Dementia (usually mild)

28
Q

What are the other differentials of Normal Pressure Hydrocephalus?

A
  • other form of dementia
  • cervical myelopathy
  • all urinary problems
  • Parkinson’s
  • 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 drain test to check it has made a difference to the patient?

A

MMSE or other cognitive test
Get up and GO test

  • Lumbar drain test should improve these tests, especially gait
32
Q

How is hydrocephalus treated?

A

Ventriculoperitoneal shunt

33
Q

Ventricles dilate in Idiopathic intracranial hypertension. TRUE/FALSE?

A

FALSE no dilatation of ventricles

=> if ventricles ARE dilated it is NOT IIH

34
Q

Who usually gets Idiopathic intracranial hypertension?

A

Women of child bearing age (hypothesis of condition being linked to hormones)
Often overweight
western population

35
Q

What are the usual presenting signs and symptoms of IIH?

A
  • Headache (worse above eyes, pt doesn’t 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 (if pregnant, giving birth counts)
  • 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 Head
CTV to check for venous stenosis
Fundoscopy/ Ophthalmology review

NEUROLOGY (29 decks)

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