Raised ICP

Question 1

Pathos

Answer 1

normal ICP is 7-15 mmHg in adults in the supine position

cerebral perfusion pressure (CPP) is the net pressure gradient causing cerebral blood flow to the brain

CPP = mean arterial pressure - ICP

[MAP = DP + 1/3(SP – DP) or MAP = DP + 1/3(PP)]

Question 2

Causes

Answer 2

idiopathic intracranial hypertension
traumatic head injuries
infection
- meningitis
tumours
hydrocephalus

Question 3

Features

Answer 3

headache
vomiting
reduced levels of consciousness
papilloedema
Cushing’s triad
- widening pulse pressure
- bradycardia
- irregular breathing

Question 4

Invx

Answer 4

neuroimaging (CT/MRI) is key to investigate the underlying cause
invasive ICP monitoring

Question 5

Mx

Answer 5

1. Underlying cause treatment
2. head elevation to 30º
3. IV mannitol may be used as an osmotic diuretic
4. controlled hyperventilation
   - aim is to reduce pCO2 → vasoconstriction of the cerebral arteries → reduced ICP
   - leads to rapid, temporary lowering of ICP. However, caution needed as may reduce blood flow to already ischaemic parts of the brain
5. removal of CSF, different techniques include:
   - drain from intraventricular monitor (see above)
   - repeated lumbar puncture (e.g. idiopathic intracranial hypertension)
   - ventriculoperitoneal shunt (for hydrocephalus)