How do you evaluate asymptomatic patients referred for benign intracranial hypertension?
"Benign intracranial hypertension" is not really the preferred term for pseudotumor cerebri or idiopathic intracranial hypertension (IIH) anymore, as the phenomenon can lead to permanent vision loss and thus cannot be considered truly benign.
Having said that, if the patient has no symptoms (no blurred vision, no headache, no pulsatile tinnitus, no transient visual obscurations) but was referred for a workup for IIH, then I have to assume that he/she was referred because someone noticed incidental "papilledema" on fundus examination (maybe by an optometrist on routine eye examination) or perhaps a brain MRI report incidentally noted an empty sella when obtained for a different indication.
My first step would usually be to examine the patient. I would want to look for any evidence of visual dysfunction (even in the absence of symptoms). Optic neuropathies from many etiologies can cause swelling of the optic nerve, usually with a significant effect on visual acuity, visual fields and color vision (as in optic neuritis or ischemic optic neuropathy). Even if central vision is normal, visual field testing would be very important, looking for enlargement of the blind spot/visual field constriction, which can occur with papilledema.
Of course, the optic discs should also be evaluated, as sometimes congenital optic disc elevation or pseudopapilledema (from optic disc drusen, for example) or even myelinated retinal nerve fibers can be mistaken for a pathological process. Frequently I have been asked to evaluate asymptomatic patients with "empty sella syndrome" and found them to have normal vision and completely normal optic discs.
After all that, if the optic discs actually are swollen, and I have ruled out an optic neuropathy, then the evaluation of possible asymptomatic papilledema should be the same as for possible symptomatic papilledema: brain imaging and lumbar puncture.
I agree with @Dr. First Last.
It is very important to recognize that the individual with headache or with brain imaging findings that could suggest raised intracranial pressure is not at risk for vision loss in the absence of papilledema. Therefore, anyone who is suspected of having "idiopathic intracranial hypertension" should be examined by a neuro-ophthalmologist prior to commencement of invasive therapies (lumbar puncture, etc) or referral to a neurosurgeon.
There are many other possible causes of the swollen appearance of the optic discs besides papilledema (raised ICP) including pseudopapilledema and compressive or inflammatory entities.
Many referrals for "idiopathic intracranial hypertension" are based on the patients' description of headaches, the patient being overweight, or the brain imaging with findings such as empty sella, etc. In many (perhaps most) of these cases, careful history and examination will uncover an alternate cause of headaches.
References
Unless the patient has already seen ophthalmology and been diagnosed with papilledema, my first step would be to request that evaluation. Then if positive, I would proceed with MRI and if no contraindication, proceed with spinal tap for opening pressure. One interesting case I had turned out to have transverse sinus stenosis and is being evaluated for TS stent.