Intracranial Pressure

Question 1

What is the normal value for ICP?

Answer 1

5-15 mmHg

Question 2

Which three components exist in equilibrium in the skull?

Answer 2

Brain
CSF
Blood

Question 3

How does an increased ICP affect cerebral blood flow (CBF) and cerebral perfusion pressure (CPP)?

Answer 3

Decreases both CBF and CPP

Question 4

What are the clinical features of raised ICP?

Answer 4

Headache worse on waking, coughing, sneezing
Nausea and vomiting
Papilloedema
Drowsiness
Cushing's triad

Question 5

What is Cushing’s triad?

Answer 5

Increased BP
Decreased HR
Irregular, decreased RR

–> physiological response to raised ICP

Question 6

What is hydrocephalus?

Answer 6

Excessive accumulation of CSF –> enlargement of ventricles

Question 7

What are the type different types of hydrocephalus?

Answer 7

Communicating –> no obstruction of flow between ventricles and subarachnoid space

Non-communicating –> obstruction of CSF flow in ventricles

Question 8

What causes communicating hydrocephalus?

Answer 8

Problem with CSF absorption due to arachnoid granulations

Question 9

What causes non-communicating hydrocephalus?

Answer 9

Obstruction due to:

• tumour
• colloid cyst
• stenosis of aqueduct

Question 10

What are the causes of congenital hydrocephalus?

Answer 10

• usually due to aqueductal stenosis
• type 2 Arnold-Chiari malformations
• spina bifida

Question 11

Which imaging modality is best for hydrocephalus?

Answer 11

MRI

Question 12

What are the signs and symptoms of hydrocephalus?

Answer 12

Symptoms of raised ICP
Diplopia, impaired upgaze, 'setting sun' appearance
Dilated scalp veins
Increased head circumference
Incontinence
Gait abnormalities

Question 13

What is the management for hydrocephalus?

Answer 13

CSF diversion procedure

• -> VP shunt most common
• -> endoscopic 3rd ventriculotomy

Question 14

What is normal pressure hydrocephalus?

Answer 14

Build up of CSF due to impaired resorption at the arachnoid granulations or overproduction of CSF
BUT normal opening pressure on lumbar puncture

Question 15

What are the clinical features of normal pressure hydrocephalus?

Answer 15

Progresses gradually, triad of:

• apraxia of gait (shuffling)
• dementia (can be reversible)
• urinary incontinence (due to overactivity of detrusor)

Question 16

What would you see on MRI of a patient with normal pressure hydrocephalus?

Answer 16

Massively enlarged ventricles

Question 17

What is the treatment for normal pressure hydrocephalus?

Answer 17

VP shunt

Question 18

What are Chiari malformations?

Answer 18

congenital or acquired malformations of the hindbrain affecting structural relationships between cerebellum, medulla and upper cervical spinal cord

–> impaired CSF circulation through the foramen magnum

Question 19

What is idiopathic intracranial hypertension?

Answer 19

Raised ICP in the absence of any SOLs or hydrocephalus

Question 20

Which patients are more likely to get idiopathic intracranial hypertension?

Answer 20

Women

Obesity

Question 21

What would you see on CT or MRI of a patient with idiopathic intracranial hypertension?

Answer 21

Normal or reduced (slit-like) ventricles

Question 22

What are the lifestyle, medical and surgical management options for idiopathic intracranial hypertension?

Answer 22

Weight loss
Diuretics e.g. acetazolamide
CSF diversion with lumbo-peritoneal shunt