Raised intracranial pressure

Question 1

Pathophysiology

Answer 1

Normal ICP is 7-15 mmHg in adults in supine position

Cerebral perfusion pressure is net pressure gradient causing cerebral blood flow to brain

Question 2

Causes

Answer 2

IIH

Traumatic head injuries

Infection (meningitis)

Tumours

Hydrocephalus

Question 3

Features

Answer 3

Headache

Vomiting

Reduced level of consciousness

Cushing’s triad

Question 4

Cushing’s triad

Answer 4

Widening pulse pressure

Bradycardia

Irregular breathing

Question 5

Investigations

Answer 5

CT/MRI key to investigate underlying cause

Question 6

Monitoring

Answer 6

Invasive ICP

Catheter placed into lateral ventricles of brain to monitor pressure

May also be used to collect CSF sample and drain small amounts of CSF to reduce pressure

Question 7

Management

Answer 7

Investigate and treat underlying cause

Head elevation to 30’

IV mannitol

Controlled hyperventilation

Removal of CSF

Question 8

Controlled hyperventilation

Answer 8

Aim to reduce pCO2 –> vasoconstruction of the cerebral arteries –> reduce ICP

Leads to rapid, temporary lowering if ICP

Caution needed as may reduce blood flow to already ischaemic parts of the brain

Question 9

Techniques for removal of CSF

Answer 9

Drain from intraventricular monitor

Repeated LP

Ventriculoperitoneal shunt (for hydrocephalus)