Tuesday, December 20, 2011

Pseudotumor Cerebri

Pseudotumor Cerebri (False-tumor cerebri in other words) is also known as Benign Intracranial Hypertension.
I think “Benign” is a tricky name for this disorder, because if you don’t do anything about it, or even if you do, it can cause quite painful and sometime disabling headaches that impair your daily activities, can need neurosurgery to fix sometimes, and can be associated with vision loss, all of which are not that “benign” to me. That being said… that does make it more “benign” than the same symptoms being caused by a real brain tumor (again, since there is no tumor; it just mimics it some ways, the headache way).
Well, we aren't 100% sure, but the running theory is that there is "decreased absorption of CSF (cerebral spinal fluid) across the arachnoid granulations into the dural venous sinuses." What that means in English is that as the watery fluid that bathes your brain and spinal cord gets "old" it filters back through and into the veins in your head and into your bloodstream as more "fresh" fluid is made in your head. In this case, the fluid doesn't get recycles/filtered, but your brain doesn't know that, so it keeps making more, and suddenly you're not getting rid of the old fluid to make room for the new fluid being made, so the pressure goes up inside the skull "box" of your head. But WHY this suddenly happens is unknown, and WHY it is most often related to obesity or young women is unknown as well.
So that’s possibly what actually causes the condition at the level of anatomy.
So, again, WHY do you actually get this problem? The most common cause by far is “just because.” Really. We have a fancy word for it in medicine: Idiopathic.
But really, the exact cause of why you got this and not your neighbor is just not known.
BUT it can be because you have something else which causes pseudotumor cerebri as a symptom, such as certain types of anemia, lupus, vitamin A deficiency or overdose, recent steroid start or stop, and a bunch of medications (birth control pills, cyclosporine, isotretinoin, minocycline, nalidixic acid, nitrofurantoin, phenytoin, sulf meds, tamoxifen, tetracycline). There are also so some more exotic causes which I’ll mention here for completeness but which are either obvious or just very remote in chance (Pregnancy, Menstruation, Addison’s disease, Chronic Kidney Failure,  Cushing’s disease, Hypoparathyroidism).
Sometimes the symptoms can be less-than-precise, making it difficult to differentiate from other causes of headache. No one reads the textbook before they start to have their symptoms, so we often have to figure out just how closely they resemble the “usual” symptoms and complete our work up and treatment plan from there.
USUAL symptoms:
Headache worse in the morning (32% of patients) or headache worse when lying down flat, laughing, sneezing, coughing, bending over to pick something up, a bowel movement/constipation (essentially anything that raises the pressure in you head)
Nausea (32 %)
Visual changes in half of patients (usually bright or dark spots, or sudden waxing/waning vision loss in one or both eyes) or double vision in 29 %
Symptoms I don’t always hear:
Ringing/Buzzing/Swishing in the ears, sometime constant, sometime pulsing with your heartbeat
Interestingly, patients usually do not complain of visual field cuts, even if they have quite large areas of loss of vision, and some are even in disbelief when I relay to them the extent of vision loss they truly have. In fact, I think it’s intriguing enough to devote an education entry just to blind spots (under Topics), so that should be coming if not already on the site.

On my exam, you are more likely than other patients to be a woman, larger, younger, have papilledema (swelling of the optic disc at the back of your eye), have some double vision when you look to the far right or left, and have some sort of cut in your visual fields. But you may only have some of these things.
How do I diagnose you more officially with this disorder?
-I will often get a few possible labs to rule out other contributing causes. These are the most common ones I may pick from: Hemoglobin, hematocrit, MCV, iron, ferritin, calcium, TSH, ESR, ANA, a pregnancy test.
-Lumbar puncture (Please look under my separate Topic for that if you’d like; I have a whole entry devoted to “spinal tap”). This tap looks at the initial pressure with which the fluid comes out of your spinal column to see if that tells me it’s too high (like an overinflated tire  would tell me if I used one of those pressure-things buried in everyone’s glove box). The actual fluid itself should look normal under the microscope.
-Eye exam by a physician of the eye (ophthalmologist) to look for visual field cuts.
-MRI or CT to look for small ventricles… or large ventricles if there really is a blockage of flow somewhere… but these studies are usually NOT helpful other than to rule out some other cause for your symptoms (like a real tumor, which actually is helpful to rule out in its own way.)
-Seeing how you respond to treatment. Sometimes all of the above is ambiguous or your history is just too classic, in which case, we may try treatment and see how you respond. But you never want to try treatment with medications that potentially have their own concerning side effects unless it’s really needed.
-Stop all medications which could be causing it.

-Rarely, it will just go away on its own after some short period of time, and minimal treatment with medications
-Diamox (acetazolamide) at dose of 250mg twice a day, up to 4000mg a day, depending on the person and what they need or can tolerate.
-Topamax (topiramate) is less helpful but can be added if there is a dose limit of the above medication due to side effects or it doesn’t work well enough by itself. Its dose is anywhere from 25mg total a day to 400mg a day.
-Prednisone…. This IS actually a treatment, but I cringe to mention it because its side effects' list usually does not make it worth trying in the long run. And the most annoying side effect of this medication is weight gain.
-Salt restriction helps a touch.

Which leads me to my next treatment, the most important in fact:
I know, it’s not PC to tell your patient very directly that they need to lose weight, and really mean it in the most direct way, and not let your patient pass that off as you the physician doing what you feel obligated to mention in passing because you care about their overall health. But really, treatment number one, two, and three for this specific diagnosis should be a weight loss scheme. This is actually the hardest thing to recommend because I realize that modern society’s fast-paced life, work and family expectation, and fast food options don’t allow for this entirely or at least make it very hard. And it’s so much more wonderful to hope that a medication can make everything better without doing what modern society does not allow you, the patient, the time to do easily. But really, weight loss IS THE KEY. Medications are really just to keep symptoms at bay while you lose weight.

But, if you can’t lose weight, and the medications don't help, there’s always neurosurgery. …
because the headache pain is usually too much without it then, and even if you could tolerate it, you don’t want to continue to lose your vision irreversibly.

One of my neurosurgery colleagues will happily place a shunt from your spinal column or brain into your abdomen to drain some extra fluid off your brain, relieving the pressure that causes the headache and crimps down on the optic nerves damaging them. Now, this tube can clot up sometimes, cause its own type of headache if it drains too well, cause pain radiating into your legs if it pinches a nerve in your back… and is of course a tube inserted into your brain or low back. Too me, it makes medications and a diligent diet with neighborhood blocks less daunting by comparison.
There are other surgeries which can be done as well, such as a small hole cut into your temporal bone to relieve pressure. Or sometimes holes can be poked in the sheaths that surround your optic nerves to relieve the pressure on them, but hopefully that sounds as concerningly un-fun as it is, and I haven’t yet had to send a patient off for these latter two procedures.