Idiopathic intracranial hypertension (IIH) - i.e. not produced by an expansile intracranial mass lesion - is often called "pseudotumor cerebri". Reported by Heinrich Quincke in 1893 and by Max Nonne in 1904, it was originally called "serous meningitis". It is most common in overweight women 20-50 years old. The clinical presentation usually includes headaches or visual problems.

» Reported causes include:
• Hypervitaminosis A
- by increasing interstitial water?
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• Dural sinus thrombosis/stenosis
- increasing intracranial venous pressure
- by deceasing CSF absorption
• Pregnancy
- increased venous pressure
• Obesity
- increased venous pressure

» The diagnostic criteria include:
• secondary features of increased pressure (e.g. papilledema)
• elevated CSF pressure (>250 mm H2O) by LP in lateral decubitus position
• normal cerebrospinal fluid chemistry and cells
• normal cerebral anatomy by CT/MR imaging

» LP Results in psedudotumor cerebri:
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» The physiology may be related to:
• cerebral brain interstitial edema
• hyperemic brain swelling - vasocongestion
• imbalance between CSF production and resorption
• venous hypertension
• dural sinus thrombosis or stenosis (including bilateral transverse sinus stenosis) - [PubMed] - LINK -

» Recent literature has demonstrated that the transverse sinus stenosis may be secondary to increased intracranial pressure - and can be reversed with CSF shunting alone - no vascular intervention. It may also recur when intracranial pressure rises [PubMed] - - LINK -
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» Thus, we have a classic "chicken and egg" problem: Is pseudo tumor caused by sinus stenosis or is it causing the stenosis?

» Hypervitaminosis A may cause IIH. This was described in arctic explorer who ate polar bear liver, as well as acne patients treated with retinoic acid.

» Patients with IIH may have elevation of both CSF and serum Vitamin A, w/o exogenous sources.
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• Treatment options
» Reduce

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