PSEUDOTUMOR 

Etiology: unknown, but there are many theories: 
- Venous sinus obstruction/stenosis, leading to back pressure in CSF -- however there's an unclear chicken-and-egg problem here, because increase in ICP will lead to compression of venous sinuses. There have been some small studies that LP's lead to decompression of venous sinuses, also some small studies demonstrating resolution of pseudotumor symptoms with sinus stents
- Microthrombi occlusion of arachnoid granulations
- Vitamin A toxicity - reducing absorption of CSF - some reports of associations between retinols and pseduotumor
- Increased intraabdominal/intrathoracic pressure leading to reduced drainage of venous blood and thus of CSF - helps to explain the obesity connection, but not necessarily the gender discrepancy, or why there isn't necessarily an association between pseduotumor and pregnancy
- Some theories about increased CSF production - however lesions that make more csf (like cpp) tend to cause hydrocephalus

Clinical presentation
- Headaches - typically severe (disproportionately so) and may present in any location with any quality- may resemble migraines or tension type HA, nor not.
- Visual loss (from papilledema) - typically long-standing, insidious onset, although a small % of people will have malignant/rapidly progressive papilledema that decompensates quickly. Typically people will lose visual fields before they lose visual acuity.
- Pulsatile tinnitus "rushing of water or wind"
- Transient visual events - vision loss, flashes, diplopia, etc.
- Typically obese women of childbearing age (20-40) - so much so that some people are reluctant to diagnose pseudotumor in people over the age of 40.
- On exam - papilledema, 6th nerve palsy, visual field cuts. Pearl -- in someone with bad enough papilledema to cause significant visual loss, you should have a 6th nerve deficit. If you don't, suspect another etiology - like optic neuritis. Papilledema can be u/l or b/l.

Workup 
- MRI to r/o secondary cause of increased intracranial pressure, like mass effect from tumor or bleed, - MRV to r/o venous sinus thrombosis
- LP to look at OP
- Measurement of systemic BP- malignant HTN can lead to optic neuropathy that resembles

Treatment
- First line - weight loss
- First line - diamox - side effects: kidney stones, metallic taste in mouth; diamox makes you lose weight, going off of it can cause it to come back. Mildly contraindicated in pregnancy.
- Second line drugs - topamax, lasix (doesn't really work)
- For severe papilledema leading to vision loss - optic sheath fenestration
- Surgical shunts - VP or LP. LP shunts obstruct like crazy, VP shunts do slightly better, but its controversial how well either works.
- Venous sinus stents - must get diagnostic angio first and have evidence of sinus stenosis; small case series seem to show good outcomes, but this is still a new and controversial procedure.

Outcomes
- It's an unfortunate reality that for most patients, the headaches do not get significantly better no matter what you do - all the medications, gastric bypass, shunts, etc. Thus don't go around shunting everyone because you probably won't help them, especially if they don't have papilledema
- People with evidence of papilledema on exam are the most likely to benefit from invasive treatment.