Idiopathic Intracranial Hypertension

(the diagnosis formerly known as pseudotumor cerebri)

  • Presentation = acute, subacute, chronic headache with associated blurry vision or visual loss, papilledema, pulsatile tinnitus (“whooshing sound in ears”), abducens nerve palsy, nausea, vomiting
  • Patients typically young obese women
  • ** Meds to know causing pseudotumor = vitamin A, oral contraceptives, glucocorticoids
  • ** Brain MRI = empty sella, slit like ventricles
  • ** Will have normal brain imaging with elevated CSF pressure
  • Tx = weight reduction, acetazolamide
    • Medical measure fail or visual field defects are progressive –> shunting or optic nerve sheath fenestration
    • Acetazolamide MOA = inhibits choroid plexus carbonic anhydrase –> decrease CSF production and intracranial hypertension

Dandy criteria for dx of IIH:

  1. signs/symptoms of ICP
  2. no other neuro abnormality or impaired consciousness
  3. normal CSF
  4. neuroimaging showing no etiology
  5. no other cause of intracranial hypertension apparent

Podcast on Idiopathic intracranial hypertension

From Free Emergency Talks

32 yr old woman presents to the ED with one week history of diplopia (with images side by side), right facial numbness and tingling, and two weeks of headache. The first things I notice about the patient is that she is unhappy about me turning on the light, and her left eye is deviated to the midline. She can move the eye though (non-paralytic palsy), and the double vision resolves with closing one eye. She also was not kidding about the left side of her face being numb, as she can’t feel me poking with a sharp point from a broken tongue depressor. She can’t recall any recent trauma, has had no surgeries or medical problems. The rest of the exam doesn’t give more information, and her vital signs are within normal limits. I left the room to go ponder and talk to the resident.

I thought back to silly neuroanatomy test questions and imagine some obscure tumor location that would be causing her problems. A sixth cranial nerve palsy, all three branches of the trigeminal affected. The resident is not so amused about recalling with me the paths of these nerves. He asks what I saw on the fundoscopic exam. Ummmm well…I didn’t do one. The look on his face said that I needed to go back and do it.

PAPILLEDEMA! The crucial piece of the puzzle.

The first thing that comes to mind when I think of papilledema is hypertension, but also increased cranial pressure (ICP) from other sources and problems within the eye can cause it.

ICP would explain why the fifth and sixth cranial nerves were being affected, and of course explain the headache too. So now we needed to find out what is causing the ICP. MRI is the preferred test, and contrast enhances sensitivity for subtle masses. Also, a post-contrast MR venography is helpful to visualize the dural sinuses.

[note: if you are thinking about doing a lumbar puncture to look for meningitis or bleed, and the patient has ICP, think again. You could cause uncal herniation, compression of the brainstem, and that is never good]

In the absence of pathological findings on the MRI (masses, reason for increased CSF production, obstructive hydrocephalus, clots, etc), you have yourself a diagnosis of Idiopathic Intracranial Hypertension (IIH), or pseudotumor cerebri.

The problem with IIH is that it can lead to permanent vision loss. Treatment is aimed at preventing vision loss and alleviating symptoms. Now you can do your lumbar puncture! Of course, opening pressure will be increased (over 250 mm H2O), but otherwise normal. Draining some fluid should improve symptoms, but it only helps in the short-term as CSF reforms within 6 hours.

Medical treatment includes carbonic anhydrase inhibitors, which are believed to reduce the rate of CSF production. Loop diuretics can also be used. Losing weight may help, and also has other obvious benefits. When patients have problems despite medical therapy, surgical shunting is indicated. A shunt is made that drains CSF from the ventricles or spine to the peritoneum. Patients with this diagnosis need to follow-up with neurology and ophthalmology.

The etiology of IIH is unknown. There some theories, and some implicated medications: growth hormone, tetracyclines, hypervitaminosis A, lithium, and nitrofurantoin.

It most commonly occurs in obese women ages 15-44. Incidence is 1-2 per 100,000.

Usual presenting complaints: Headache (92%), transient visual problems (72%), intracranial noises like rushing water or wind (60%), photopsia (perceived flashes of light) (44%), diplopia (38%), or sustained visual loss (26%)

Exam: papilledema (don’t leave out the dreaded optho exam in headache patients), visual field loss, sixth nerve palsy.

Labs and Imaging. MRI w/ contrast and MRVenography (or CT if unavailable or contraindicated), then LP

Dandy criteria for dx of IIH:

1. signs/symptoms of ICP

2. no other neuro abnormality or impaired consciousness

3. normal CSF

4. neuroimaging showing no etiology

5. no other cause of intracranial hypertension apparent

Treatment: therapeutic LP, carbonic anhydrase inhibitors, weight loss, CSF shunting.

Resources:

Humphries RL, Stone C. Chapter 20. Headache. In: Humphries RL, Stone C, eds. CURRENT Diagnosis & Treatment Emergency Medicine. 7th ed. New York: McGraw-Hill; 2011. http://www.accessemergencymedicine.com/content.aspx?aID=55749542. Accessed October 2, 2012.

Lee AG, Wall M. Idiopathic intracranial hypertension. In: UpToDate, PB (Ed)

Compiled by:Kristin Bianchi

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