Raised ICP

Question 1

What is the normal ICP in adults?

Answer 1

5-15 mmHg

Question 2

What is the normal ICP in children?

Answer 2

5-7 mmHg

Question 3

What is the value for a raised ICP?

Answer 3

> 20 mmHg

Question 4

What is the Monro-Kelly doctrine?

Answer 4

Any increase in the volume of one of the cranial constituents must be compensated by a decrease in the volume of another

Question 5

What are the broad causes of raised ICP?

Answer 5

Too much blood
Too much CSF
Too much brain
Something else in the skull

Question 6

What can cause too much blood?

Answer 6

Raised arterial pressure
Raised venous pressure

Haemorrhage

• Extradural
• subdural
• subarachnoid
• haemorrhagic stroke

Question 7

What can cause too much CSF?

Answer 7

Hydrocephalus

• congenital
• acquired

Question 8

What is congenital hydrocephalus?

Answer 8

Obstruction to CSF flow

• neural tube defects
• aqueductal stenosis

Question 9

How can congenital hydrocephalus be managed in an infant?

Answer 9

Fontanelle tapping

Question 10

How else can congenital hydrocephalus be managed?

Answer 10

External ventricular drain

Ventricular shunts

Question 11

What are advantages to an external ventricular drain?

Answer 11

Short-medium term drainage

Continuous pressure monitoring

Question 12

What are disadvantages to an external ventricular drain?

Answer 12

Direct pathway for bacteria into brain

Chamber must be at same height as ventricles

Question 13

What can cause too much brain?

Answer 13

Cerebral oedema

Question 14

What are the types of cerebral oedema?

Answer 14

Vasogenic
Cytotoxic
Osmotic
Interstitial

Question 15

What causes vasogenic cerebral oedema?

Answer 15

Breakdown of tight endothelial junctions at BBB

Question 16

What causes cytotoxic cerebral oedema?

Answer 16

Intracellular retention of sodium and water

Question 17

What causes osmotic cerebral oedema?

Answer 17

Higher osmolality in the brain compared to serum

Question 18

What causes interstitial cerebral oedema?

Answer 18

Rupture of BBB - CSF spreads to interstitial spaces

Question 19

What other things can cause raised ICP?

Answer 19

Tumour

Abscess

Question 20

How do you calculate cerebral perfusion pressure?

Answer 20

CPP = MAP - ICP

Question 21

What should CCP be normally?

Answer 21

70 mmHg

Question 22

What are the parts of cushings triad?

Answer 22

Raised MAP
Bradycardia
Irregular breathing

Question 23

What causes a raised MAP?

Answer 23

Raised ICP reduces CPP

Blood pressure increases to maintain cerebral prfusion

Question 24

What causes bradycardia?

Answer 24

Increased pressure detected by carotid body barorecptors - slows heart rate

Question 25

What causes irregular breathing?

Answer 25

Herniation of the brain stem

Question 26

What the types of brain herniation?

Answer 26

Tonsillar
Sub-falcine
Uncal
External

Question 27

What is tonsillar herniation?

Answer 27

Cerebellar tonsils and brain stem herniate into foramen magnum

Question 28

What is sub-falcine herniation?

Answer 28

Cerebrum under falx

Question 29

What is uncal herniation?

Answer 29

Uncus of temporal lobe herniates into brainstem

Question 30

What is external herniation?

Answer 30

Herniation through skull factor

Question 31

What are the early features of raised ICP?

Answer 31

Headache - worse in morning 
N+V
Drowsiness 
Difficulty concentrating 
Confusion 
Double vision - papilledema

Question 32

What is idiopathic intracranial hypertension?

Answer 32

Benign raise in intracranial pressure

Common in obese middle aged women
Improves with weight loss + BP control

Question 33

How is raised ICP managed?

Answer 33

Mannitol
3% hypertonic saline
External ventricular drain
Decompressive craniectomy

Question 34

How does mannitol help?

Answer 34

It is a sugar

• draws water out of brain
• diuretic effect