Tuesday, October 25, 2011

Idiopathic Intercranial Hypertension; neither pseudo nor benign...

Doug, sorry I had so few answers for you in the ED. Had to go hit the books after we had that patient!

This isn't a comprehensive article on IIH, nor is it an efficient outline of the critical information for the boards, life, or pimping. It's just a list of 5 things that took me somewhat by surprise, that I had never learned, or that I swear I had learned as the opposite.

1. "Transient visual obscurations" - The predominant visual disturbance isn't a nice, clean visual field cut. Instead, over 70% of patients have really brief episodes (< 1 minute) of loss of acuity, provoked by standing, sitting, light, Valsalva, or extra-ocular movements. Yeah, you'll get field loss on perimetry, but the TVOs are what patients will actually complain of.

2. Sparkles - They can also get flashes, or photopsias, as well as the TVOs.They are described as "white or less commonly coloured small flashes, flickering lights, stars twinkling, or flashes in the periphery of the visual field
Simulation available

3. Patients with IIH also report an odd kind of noise inside their heads. It's termed "pulsatile tinnitus," but it only infrequently seems to be a high-pitched tone. More often, it's described as '"a rushing river', a waterfall or a buzzing, whistling or blowing sound."

4. You get imaging to r/o something else, like a not-so-pseudo tumor or a sinus venous thrombosis. It's not used to diagnose IIH. However, one finding that would be consistent with IIH would be small ventricles or an empty sella,  according to some.
Flattened ventricles.

5. Perhaps the imaging study that we should be using more often is our ultrasound. Up until this month, the world's literature for using ultrasound to detect papilledema was limited to this study by Michael Stone (Download). While the case provided an example of using an optic nerve sheath diameter of >5 mm  to make a diagnosis of increased ICP, it also demonstrated sonographic papilledema.
3mm posterior to the retina, check for OSD  > 5 mm.
Also note optic disc elevation.


But now there are 2 new publications that provide more evidence that we should be dropping our old clinical skills (polished as they may be...) in favor of using newer technology!
1880 Loring opthalmoscope. Not new.
The first article is an abstract that was just published in the October issue of Annals of Emergency Medicine, the ACEP Research Forum 2011 supplement, and is entitled "Point-of-Care Ocular Sonography to Detect Optic Disc Swelling." (Download pdf)

The authors compared EP-performed ultrasound exams of the optic disc with those of an neuro-ophthalmologist, as well as optical coherence tomography.
Optic disc swelling as seen on OCT
For the study,  2 EPs hung out in a neuro-optho clinic, and did ocular US on a number of patients. They later compared their results with the specialist, who also had access to the OCT images and results. After 20 patients, they found they had "excellent correlation" between the OCT and height of the disc seen on ultrasound.
Another example of an elevated optic disc (small arrow)
Another article, still in-press at the American Journal of Emergency Medicine (by Daulaire et al.) (Download pdf), reviews a series of 3 headache patients who had apparent optic disc elevation on bedside US. The US results were considered confirmed, in each respective case, through a finding of elevated CSF pressure, an exam of the fundus by the ophthalmology service, and an MRI. There's a review of the technique, as well as of the scant literature.


So, the next time you have that odd headache patient, ask them about TVOs and photopsias, and put a probe on their eyes!

3 comments:

  1. Great post, Brooks. And excellent blog. I will forever ask my patients with headache and visual changes if they see "sparkles, you know, like a Lite-Brite"!
    --brock

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  2. By turning the light on the ophthalmascope to dim, you can usually maintain a pupil diameter sufficient to see the disk. I saw blurry margins in my patient with the opening pressure of 34. More telling were the angles the blood vessels made at the base of the little mountain that was her optic disk. Imagine a picture of the base of a cone in 2D projection.

    I should have done US though!!!

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