Idiopathic intracranial hypertension

Question 1

What is IIH?

Answer 1

a syndrome of raised ICP in the absence of an intracranial mass lesion or hydroephalus

Question 2

What is the risk of idiopathic intracranial hypertension?

Answer 2

can cause permanent visual loss due to optic nerve damage (but rarely life-threatening)

Question 3

In which demographic group is IIH particularly common?

Answer 3

Obese women of child-bearing age (17-45 years)

Question 4

What is the female:male ratio affected by IIH?

Answer 4

4:1

Question 5

What are 4 key symptoms of IIH?

Answer 5

1. Constant, but variable, headaches
2. Visual disturbance: diplopia, transient visual obscurations, scotoma
3. Nausea
4. Sixth nerve palsy may be present

Question 6

What key features do not occur in the presentation of IIH?

Answer 6

focal neurology, including epilepsy

Question 7

What is the key feature on examination that almost invariably occrs in IIH?

Answer 7

fundoscopy shows papilloedma

Question 8

What are 4 associations of IIH?

Answer 8

1. Obesity or recent weight gain
2. Drugs (tetracycline, isotretinoin and etretinate, nalidixic acid, nitrofurantoin, lithium)
3. COCP
4. Steroid withdrawal

Question 9

What are 3 types of visual disturbance in the presentation of IIH?

Answer 9

1. Diplopia
2. Transient visual obscurations
3. Scotoma

Question 10

What are 6 types of drugs which are associated with IIH?

Answer 10

1. Tetracycline
2. Isotretinoin
3. Etretinate
4. Nalidixic acid
5. Nitrofurantoin
6. Lithium

Question 11

What are 2 key types of investigations which should be performed in suspected IIH?

Answer 11

1. CT or MRI head with venography - to rule out venous sinus thrombosis
2. Lumbar puncture - will show elevated CSF pressure

Question 12

Why should CT or MRI head with venography be performed in IIH?

Answer 12

to rule out venous sinus thrombosis

Question 13

What will lumbar puncture shown in IIH?

Answer 13

elevated CSF pressure

Question 14

How can the result of pressure on lumbar puncture be interpreted to rule in or out IIH?

Answer 14

• >30cm unequivocally high
• 20-30cm H₂O is intermediate

Question 15

What position must be used for the lumbar puncture in suspected IIH, and why?

Answer 15

lateral position - not sat upright as this would increase CSF pressure

Question 16

What are 5 aspects of treatment of IIH?

Answer 16

1. Losing weight
2. Identifying other causative factors such as drugs
3. Acetazolamide (maintenance dose 500mg bd)
4. Surgical shunting (lumboperitoneal shunt)
5. Surgical optic nerve sheath decompression and fenetration may be done

Question 17

What is the maintenance dose of acetazolamide to treat IIH?

Answer 17

500mg bd

Question 18

What type of surgical shunting is used for IIH?

Answer 18

lumboperitoneal shunt (LPS)

Question 19

What is the role for lumbar punctures as therapeutic interventions for IIH?

Answer 19

repeated LPs no longer a favoured approach

Question 20

What are 2 alternative names for idiopathic intracranial hypertension (IIH)?

Answer 20

1. Pseudotumour cerebri
2. Benign intracranial hypertension (formerly)

Question 21

What are 4 risk factors for IIH?

Answer 21

1. Obesity
2. Female sex
3. Pregnancy
4. Drugs: COCP, steroids, tetracyclines, vitamin A, lithium

Question 22

What is another type of drug which can sometimes be used to treat IIH and what effects does it have?

Answer 22

topiramate: for headache + added benefit of causing weight loss in most patients

Question 23

Why might surgical optic nerve sheath decompression and fenetration be performed?

Answer 23

to prevent damage to the optic nerve