Increased Intracranial Pressure

Question 1

What is the Normal ICP

(intracranial pressure)?

Answer 1

• 7-15 mm Hg*
• -in supine adult-*

Question 2

What is ICP

Answer 2

• Intracranial pressure;*
• pressure exerted by CSF on the brain tissue

Question 3

What happens if ICP increases above

20-25mm Hg

Answer 3

• signs of ↑ICP: headache (worst in the morning) -nausea/vomiting,
• neurological abnormalities -altered consciousness
• papilledema (optic disc swelling) -seizures
• possible brain herniation:
• subtentorial herniation – CN III affected ->pupil dilates (on side of herniation)
• tonsillar herniation = brainstem herniates through foramen magnum ->death
• Cushing phenomenon = ↓HR (Bradycardia < 60bpm), ↑SBP, irregular breathing

Question 4

What are the causes of ICP?

Answer 4

- causes:

tumour, hydrocephalus, subarachnoid haemorrhage, meningitis,
idiopathic intracranial hypertension (in this case, try to exclude venous thrombosis first!)

Question 5

ICP Tests and diagnosis:

Answer 5

• CT, MRI:

loss of sulci, finger-like oedema

Question 6

Treatment for ICP

Answer 6

- Tx:

diuretics (Acetazolamide, Furosemide, Mannitol) + steroids

_{<strong><em>Mannitol </em></strong>works primarily by increasing plasma osmotic pressure, leading to brain dehydration and a decrease in ICP, with consequent improvement in cerebral perfusion.}

Question 7

Define

Cushing phenomenon

Answer 7

The Cushing reflex (vasopressor response, Cushing reaction, Cushing effect, and Cushing phenomenon)

physiological nervous system response to acute elevations of intracranial pressure (ICP) resulting in Cushing’s triad of widened pulse pressure (increasing systolic, decreasing diastolic), bradycardia, and irregular respirations.