Papilloedema

Question 1

Meaning of swollen optic discs?

Answer 1

Disc swelling secondary to ANY cause

Question 2

Definition of papilloedema?

Answer 2

Specific term for swollen optic discs due to raised intracranial pressure

Question 3

What does bilateral optic disc swelling indicate?

Answer 3

All patients with bilateral optic disc swelling should be suspected of having raised ICP due to a space occupying lesion (SOL), until proven otherwise

Not all swollen discs are caused by SOLs

Question 4

Why is it important to detect papilloedema?

Answer 4

Raised ICP is a medical emergency and thus should be detected on ophthalmoscopy

Question 5

Examination of CN II involves?

Answer 5

Visual acuity

Pupil exam

Visual field assessment

Colour vision

Question 6

Why does papilloedema occur due to raised ICP?

Answer 6

Optic nerve is an extension of the brain (with its meningeal sheaths)

Question 7

Pathophysiology of papilloedema?

Answer 7

Sub-arachnoid space around the optic nerve continuous with the sub-arachnoid space surrounding the brain

When ICP increases, this is transmitted to the sub-arachnoid space and then to the optic nerve, causing interruption of axoplasmic flow and venous congestion

Result is swollen discs

Question 8

Contributions to the ICP?

Answer 8

1. Brain
2. Blood
3. CSF

Question 9

What is the Monro-Kellie hypothesis?

Answer 9

Contributions to the ICP must remain constant; if there is an increase in 1 variable, this causes a decrease in one/both variable

Initially, when intracranial volume increases, ICP remains constant (compensatory mechanisms); eventually, as volume rises, ICP will also rise

Question 10

How can raised ICP cause fatalities?

Answer 10

Adult cranial vault is rigid and cannot expand with increased ICP

Brain is squeezed through the foramen magnum, the brainstem is compressed and the patient stops breathing; leads to death

Question 11

How is the cerebral blood flow maintained?

Answer 11

Brain requires a constant flow of blood over a range of pressures, as it is intolerant of hypo/hyperperfusion

This is called AUTO-REGULATION

Question 12

Why do the optic disc well in malignant hypertension?

Answer 12

May be due to a failure of ONH auto-regulation, resulting in ischaemia

OR

It could be a hypertension-related increase in the ICP; if this is case, it causes true papilloedema

Question 13

Ix for malignant hypertension?

Answer 13

BP

Always check BP with swollen optic discs

Question 14

Functions of CSF?

Answer 14

1. Maintains stable extracellular environment for the brain
2. Buoyancy
3. Provides mechanical protection
4. Waste removal
5. Nutrition

Question 15

Production of CSF?

Answer 15

Produced by the choroid plexus in all the ventricles; majority is produced in the lateral ventricles

Question 16

What is the choroid plexus?

Answer 16

A network of capillaries that filters blood to form CSF

Question 17

How can CSF be assoc. with a rise in ICP?

Answer 17

1. Obstruction to CSF circulation
2. Over-production of CSF
3. Inadequate absorption of CSF (at the arachnoid granulations)

Question 18

Ix for CSF issues assoc. with raised ICP?

Answer 18

Lumbar puncture

Question 19

What is idiopathic intracranial hypertension?

Answer 19

Unclear aetiology but the raised ICP may be due to:

Obstruction of CSF circulation - may be caused by stenosis of transverse cerebral sinuses OR be increased abdominal pressure (obese patients)

Impaired CSF production - may be vitamin-A related OR due to microemboli in the sagittal sinus (blocks CSF absorption)

Question 20

Consequences of chronic disc swelling?

Answer 20

Disc swelling can subside, with the disc becoming atrophic and pale

Loss of visual function occurs and blindness may result