Raised intracranial pressure (ICP) and space occupying lesions (SOL)

Question 1

What is the net pressure gradient causing cerebral blood flow to the brain called?

Answer 1

Cerebral perfusion pressure (CPP)

Question 2

What is the equation involving CPP, ICP, and mean arterial pressure?

Answer 2

CPP = MAP - ICP

Question 3

Name 2 causes of a raised ICP

Answer 3

• Idiopathic intracranial hypertension
• Traumatic head injuries
• Infection
• Meningitis
• Tumours
• Hydrocephalus

Question 4

Name 2 features of a raised ICP

Answer 4

• Headache
• Vomiting
• Reduced levels of consciousness
• Papilloedema
• Cushing’s triad

Question 5

What are the 3 components of Cushing’s triad?

Answer 5

• Bradycardia
• Widened pulse pressure
• Irregular breathing

Question 6

Papilloedema
1) What is papilloedema?
2) Is is usually unilateral or bilateral?
3) Name a feature on fundoscopy that may be seen in papilloedema

Answer 6

1) Optic disc swelling that is caused by increased intracranial pressure
2) Bilateral
3) Venous engorgement, blurring of the optic disc margin, elevation of optic disc, loss of the optic cup

Question 7

Name 2 aspects of the management of raised ICP

Answer 7

• Investigate + treat the underlying cause
• Head elevation to 30º
• IV mannitol may be used as an osmotic diuretic
• Controlled hyperventilation (to reduce PaCO2 which reduces ICP)
• Removal of CSF

Question 8

Name 2 features of a SOL

Answer 8

• Headache worse on waking, lying down or coughing/straining
• Nausea and vomiting in the morning
• Cranial nerve palsies (esp. CN VI)
• Cushing’s triad
• Papilloedema
• Seizures
• Drowsiness

Question 9

What are the 4 major causes of SOL?

Answer 9

• Tumours
• Vascular lesions i.e. chronic subdural haematoma
• Infective processes i.e. cerebral abscesses
• Granulomata i.e. tuberculoma

Question 10

1) In trauma, how would you test if a fluid is CSF or not?
2) What is the gold standard?

Answer 10

1) Glucose
2) Beta 2 transferrin