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NEUROLOGY > Raised ICP and Hydrocephalus > Flashcards

Raised ICP and Hydrocephalus Flashcards

1
Q

Define ICP.

A
  • pressure exerted by the cranium onto the -
    brain tissue,
  • CSF
    -intracranial circulating blood volume
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2
Q

What is the usual pressure intracranially?

A
  • at rest; approx 7-15 mmHg in adults

- in yound children (3-7 mmHg)

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3
Q

When can ICP be negative?

A
  • positioned VERTICALLY
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4
Q

What does the Monro-Kellie Doctrine suggest when in a compensated state?

A
  • ICP will be normal

- compensatory mechanisms can accomodate small volume changes

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5
Q

What occurs in large volume changes according to the M-K d?

A
  • compensatory mechanisms will become exhausted
    –> significant incr. to intracranial pressure
    and potential herniation
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6
Q

What immediate compensatory mechanisms occurs= for expanding masses?

A
  • decr. CSF volume by moving it out of the foramen magnum

- decr. in BLOOD volume by squeezing sinuses

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7
Q

What delayed compensatory mechanisms occur for expanding intracranial masses>

A
  • decr. in extracellular fluid
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8
Q

How much CSF produced in a day ?

A
  • 500ml secreted in 24hr
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9
Q

What produces CSF?

A
  • choroid plexus (in the LATERAL ventricles)
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10
Q

What is the course of CSF flow in the CNS?

A

> ventricular system> subarachnoid space (Maendia and Luschka)> venous system (arachnoid granulations_

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11
Q

What occurs with obstruction in CSF flow?

A

–> hydrocephalus and raised ICP

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12
Q

How to calculate Cerebral perfusion pressure?

A

MAP- ICP = CPP

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13
Q

What is main determinant of CPP?

A

ICP

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14
Q

How to calculate cerebral blood flow

A

(CBF)= cerebral perfusion pressure/ cerebral vasc. resistance

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15
Q

What is the normal range of CBF?

A

50-150mmHg: maintained by autoreg.

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16
Q

What occurs with pressure autoreg?

A
  • arterioles DILATE or CONSTRICT in resp. to BP/ ICP
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17
Q

What occurs wirh metabolic autoreg.?

A
  • arterioles DILATE in resp/ to chems like to Lactic acid and CO2
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18
Q

What is CO2?

A
  • a potent DILATOR

- —incr. CO2/ incr. BP= vasodilation !

19
Q

What are causes of incr. ICP?

A
  1. Mass effect (tumor/infarct/ contusions/ hematoma/abscess) > distorts surrounding brain
  2. Brain swelling
  3. Incr. central venous pressure
20
Q

What could cause brain swelling?

A

ischemia/anoxia, acute liver failure, encephalopathy, IIH. hypercarbia

21
Q

What causes incr. central venous pressure?

A
  • venous sinus thrombosis
  • heart failure
  • obstuct. of Jugular veins
22
Q

What causes problems in CSF flow?

A
  1. obstruction (masses or Chiari $)
  2. Incr. prodn (choroid plexus papilloma)
  3. Decr. absorption
23
Q

What causes decr. absorption of CSF?

A
  • SAH
  • Meningitis
  • Malignant meningeal disease
24
Q

What is meant by communicating hydrocephalus?

A
  • something disrupting CSF absorption `
25
Q

What are the early signs of raised ICP?

A
  1. reduc. level of consciousness
  2. headache
  3. Pupillary dysfxn +/- papilloedema
  4. changes in vision
  5. N.V
26
Q

Later signs of raised ICP?

A
  1. coma
  2. FIXED, DILATED pupils
  3. HEMIPLEGIA
  4. bradycardia (CUshing’s Triad)
  5. Hyperthermia
  6. incr. Urinary output
27
Q

What are the goals when managing raised ICP?

A
  • GOALS: maintain CPP and prevent ischemia and brain compression
28
Q

What does raised ICP management involve?

A
  • maintain head in MIDLINE (helps blood flow)
  • HoB (30-45 degrees elevation)
  • avoid gagging, coughing
  • decr. env. stimuli
  • treat hyperthermia
  • maintain fluid balance and NORMAL electrolytes
  • maintain normocarbia
29
Q

How to medically manage raised ICP?

A
  • use diuretics (Mannitol, hypertonic saline, furosemide, urea)
  • barbiturate coma (induced coma)
  • anti-epileptics
  • surgical decompression
30
Q

What are other surgical treatments for raised ICP?

A
  • remove MASS lesions

- CSF diversions

31
Q

What causes hydrocephalus?

A
  1. obstrucion in CSF flow
  2. Incr. Prodn (Choroid plexus papilloma)
  3. Decr. Absorption (communicating)
32
Q

What is seen on imaging with Obstructive hydrocephalus?

A

with Aqueductal stenosis

  • SMALL/normal 4th ventricle
  • rounded 3rd ventricle
  • enlarged FRONTAL horns
  • —-temporal tip dilation
33
Q

What is seen on imaging for communicating hydrocephalus?

A
  • rounded 3rd
  • enlarged 4th V
  • lateral ventricles
  • sulcal effacement
34
Q

Where is normal pressure hydrocephalus seen?

A
  • in the OLD
  • PD
  • ALL urinary problems
  • depression
  • forms of dementia
35
Q

How does normal pr. hydrocephalus present as?

A

HAKIM’s Triad

= abnormal gait+ urinary incontinence+ dementia

36
Q

What ivx can be done for normal pr. hydrocephalus?

A
  • LP
  • Lumbar Drain test
  • Lumbar infusion studies
37
Q

What rx if done for normal pr. Hydrocephalus ?

A
  • VP shunt (ventriculoperitoneal shunt)

- medium-low or low-pressure valve

38
Q

what is idiopathic intracranial hypertension?

A
  • raised ICP of UNKNOWN cause

- —no ventricular dilation

39
Q

How does IIH present ?

A
  • blindness
  • severe headache
  • speech impairment
  • visual disturbance, - -loss of balance – tinnitus
  • N.V.
  • blackouts
  • confusion
40
Q

in whom is IIH commonly seen in?

A
  • women of child-bearing age
  • western countries
  • OVERWGT
41
Q

What vision problems may people with IIH present with?

A
  • blind spots
  • poor peripheral vision
  • short episodes of blindness (may even be permanent)
  • double vision
42
Q

List causes of raised ICP?

A
  1. CSF imbalance
  2. Hormonal - estrogen
  3. Venous pressure (transverse/ sigmoid stenosis)
43
Q

Invx for raised icp>

A
  • ct/ MRI of head
  • CTV (CT cerebral venography)
  • fundoscopy
  • LP
44
Q

What is the rx of raised icp?

A

wgt loss
bariatric surgery
-carboanhydrase inhibitors (acetazolamide/ topiramate)
- diuretics
- Interventional radiology (intracranial venous sinus plasty and stent )
-ONSF (optic nerve sheath fenestration)

NEUROLOGY (36 decks)

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