Raised ICP

Question 1

List 8 different causes of raised ICP

Answer 1

Idiopathic intracranial HTN
CNS inflammation, infection, abscess
SOL: haemorrhage, aneurysm, tumour
Elevated venous pressures, e.g. HF
Increased CSF
Metabolic disturbance: hyponatraemia, hepatic encephalopathy
Epilepsy/ seizures

Question 2

What symptoms are experienced in raised ICP?

Answer 2

Headache: worse when waking, coughing or moving head
Altered mental state: drowsiness to coma
Lethargy, irritability, slow decision making + abnormal social behaviour.
Blurred vision/ diplopia
Vomiting

Question 3

What signs may be seen in raised ICP?

Answer 3

Cushing’s triad: irregular RR, widening pulse pressure + bradycardia
Reduced levels of consciousness
Papilledema
Psychiatric changes

Question 4

What investigations should be performed for raised ICP?

Answer 4

CT/ MRI: to determine any underlying lesion.
Check + monitor blood glucose, renal function, electrolytes + osmolality.

Question 5

What happens when ICP reaches a certain point?

Answer 5

The high BP causes reflex bradycardia + brainstem compromise resulting in irregular RR
(Cushing triad: bradycardia, HTN + irregular RR)

Question 6

Which drug is used in patients with raised ICP secondary to traumatic brain injury to reduce pressure and increase diuresis?

Answer 6

IV Mannitol

Question 7

Which drug is used in patients with raised ICP secondary to vasogenic oedema from CNS infections/ neoplasms?

Answer 7

IV Dexamethasone

Question 8

Describe the pathophysiology of raised ICP

Answer 8

Cerebral perfusion pressure = MAP - ICP

Pressure gradient causing cerebral blood flow to the brain

Question 9

What monitoring techniques can be used for raised ICP?

Answer 9

Invasive ICP monitoring
Catheter placed into lateral ventricles to monitor pressure
May also be used to take collect CSF samples + also to drain small amounts of CSF to reduce the pressure
A cut-off of > 20 mmHg is often used to determine if further Tx is needed to reduce the ICP

Question 10

Describe management of raised ICP

Answer 10

Head elevation to 30º
IV mannitol (osmotic diuretic)
Controlled hyperventilation
Removal of CSF

Question 11

What is controlled hyperventilation?

Answer 11

Aim is to reduce pCO2 → vasoconstriction of 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

Question 12

Give 3 techniques to remove CSF

Answer 12

Drain from intraventricular monitor
Repeated lumbar puncture (e.g. idiopathic intracranial hypertension)
Ventriculoperitoneal shunt (for hydrocephalus)