Case report: Idiopathic Intracranial Hypertension

The other day I saw a patient for a routine eye test. He was a 31 year old Caucasian male with no particular complaints (my favourite sort of patient – the no complaints part that is, not the 31yo Caucasian male).  I had last seen him two years ago for a regular check, and so I went through all my regular interview questions – any recent issues with sore, dry, itchy eyes, any problems with persistent/new headaches, episodes of double vision? No, no, no, and no. Any medications or medical conditions you’re being followed for? Only infliximab, a medication for autoimmune stomach problems, started eight months ago.

Went through refraction as per usual, very low hyperopic prescription, got him to 6/4.5 in each eye.

Anterior eye exam under the slit lamp was next, and it looked fairly normal except for some very early, very faint arcus in the peripheral corneas of both eyes – potentially indicative of elevated cholesterol and not usual for a 31 year old.

Following that was an undilated retinal examination – normal maculae, but the optic nerves looked a bit raised and a bit fluffy around the edges. Intraocular pressures were at RE 20.5 and LE 19mmHg, which are considered normal values. I took some retinal photos:

TA LE 2017
The right retinal photo taken at this consult in 2017
TA RE 2017
Left eye, 2017

For optoms and optom students, you’ll be able to see straight away what the problem is in these pictures. For those who have never seen the inside of someone’s eyeballs before, here are pictures of the same patient’s retinas when I saw him previously in 2015:

TA RE 2013
Right eye, 2015

 

TA LE 2013
Left eye, 2015

You can see the optic nerves, the little round disc where all the blood vessels emanate from, are blurred around the edges in the 2017 photos with a condition called papilloedema, but have a much cleaner, clearer margin in the 2015 photos.

What do you think is a possible differential diagnosis? (hintIt’s the title of this postunhint).

I sent this patient to the emergency department at the public Eye and Ear hospital. Unfortunately not much correspondence comes out of that place back to the referring optometrist, so I made one phone call the following day to find out what happened, and was told that brain imaging had come back clear for any masses or lesions, and he was booked in for a lumbar puncture the following week. They suspected idiopathic intracranial hypertension (IIHT) but I’ve not heard any more since.

What was interesting was that this wasn’t the typical presentation for IIHT. Usually these patients are overweight pre-menopausal women complaining of headaches, transient losses of vision, blurred vision, or diplopia (double vision). This guy was maybe a tiny bit pudgy but definitely not what I’d class as overweight, he wasn’t a woman, and not pre-menopausal or any-menopausal as far as I knew. He also denied any issues with his vision, and it took a bit more persistent questioning about headaches before he had a real think about it and decided that maybe he did actually have some headaches over the last several months, and yes it did seem a little worse when he lay down.

papilloedema
I saw this 21yo male for an eye test after the chiropractor had failed to fix his headaches for the last month. This is an example of papilloedema but unfortunately the cause of this was a brain tumour, not an idiopathic case.

IIHT, also known as pseudotumour cerebri or benign intracranial hypertension, occurs when the pressure inside the skull (intracranial) is elevated (hypertension) due to an imbalance of cerebrospinal fluid production vs drainage but for no particularly good reason (idiopathic). Other causes of papilloedema must be excluded before one can decide the situation is idiopathic, and a quick Google search has found a handy way of remembering these:

MOVIES: mass lesions/meningitis – obstructive hydrocephalus – venous obstructive diseases – infection – essential hypertension – secondary causes of pseudotumour symptoms

U DEVILS: uraemia – drugs – endocrine disorders – vitamin A excess – iron deficiency anaemia – last menses – sleep apnoea/steroid withdrawal.

Credit to http://www.ophthnotes.com/causes-of-papilledema/, ignore the unfortunate fact that they spelled “mnemonic” as “pneumonic” (not the same).

IIHT is a diagnosis in the presence of raised intracranial pressure as determined by a spinal tap and measuring the opening pressure of the cerebrospinal fluid, and in the absence of any MOVIES or U DEVILs. It is typically addressed by asking the patient to lose weight as shedding 5-10% of total body weight can be enough to relieve the problem; in some cases diuretic medication may be required to reduce cerebrospinal fluid production and relieve the intracranial pressure. IIHT isn’t known to be a fatal condition in itself (though the associated obesity can be) but if untreated it can cause permanent vision loss as the optic nerve is compressed by the intracranial pressure. In rare occasions surgical optic nerve sheath fenestration is warranted to relieve this pressure.

In conclusion, lessons learnt:

  • textbook presentations belong in textbooks only
  • sometimes patients don’t tell the truth, the whole truth, or nothing but the truth
  • even if nothing feels wrong with your eyes or vision doesn’t mean nothing is wrong; it’s important to keep up with your regular optometrist visits
  • Both the letters M and P are silent when followed by an N, but still doesn’t make mnemonic and pneumonic the same thing
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