Monday, September 6, 2010

Under Pressure

Greetings followers and friends. Sorry this hasn't been updated in a week, but I've either been sick (can't seem to shake the cough from my chicken pox and have been running a fever off and on) or busy working on my present for the wedding I'm going to later this month. Anyways, on to the blog.

September is Intracranial Hypertension awareness month, and so I though it was appropriate to talk about Idiopathic Intracranial Hypertension (IIH) today. Most people have never heard of IIH, and honestly I could have gone the rest of my life without hearing about it either. IIH is a "rare" neurological disease / disorder which effects 1 in 100,000 people with no known overall cause and no known cure. There may be things that can "trigger" IIH, including drugs (such as tetracycline, lithium, Vitamin A-derived oral acne medications, and steroids, especially during withdrawal), growth hormone treatments, excessive ingestion of Vitamin A, sleep apnea and certain systemic diseases such as lupus, leukemia, kidney failure (uremia), meningitis, dural venous sinus thrombosis, and Lyme Disease, but people can get it from no known cause at all. Previously it was thought that only overweight women between 20 and 45 could get this disease, but more recently it has been found that anyone can get it, and I am familiar with men, children, and "skinny" people with this disease. 

An old name for IIH is Pseudotumor cerebri (PTC), or "false brain tumor." While PTC is no longer considered an accurate name for IIH because it is too "mild", personally I feel it expresses very well what it feels like to have IIH, because it is exactly like having a brain tumor - headaches, dizziness, hearing loss, visual problems that can evolve into eventual blindness, neurological deficits - and, let's face it, people understand a whole lot better when you say you have a brain tumor than when you list your disease as some long word that no one (including most doctors) have never even heard of.

So what is IIH? The best technical definition can be found on the only research organization studying IIH in the world, the Intracranial Hypertension Research Foundation (IHRF):

"Intracranial hypertension literally means that the pressure of cerebrospinal fluid (CSF) within the skull is too high. “Intracranial” means “within the skull.” “Hypertension” means “high fluid pressure.” To understand how this happens, it’s helpful to look at the basic anatomy of the brain and skull, as well as the process in which cerebrospinal fluid is created and absorbed.

Cerebrospinal fluid is one of three major components inside the skull; the other two are the blood supply (the arteries and veins known as the vasculature) that the brain requires to function and the brain itself. Under normal circumstances, these components work together in a delicate balance. A pressure and volume relationship exists between CSF, the brain and the vasculature. But since the skull is made of bone and cannot expand, an increase in the volume of any one component is at the expense of the other two components. For example, if the brain swells and becomes enlarged, it simultaneously compresses blood vessels, causing the sub-arachnoid space to fill with more spinal fluid. This results in an increase in intracranial pressure (i.e. cerebrospinal fluid pressure), as well as a decrease in blood flow.

CSF has several important functions. It cushions the brain within the skull, transports nutrients to brain tissue and carries waste away. CSF is produced at a site within the brain called the choroid plexus, which generates about 400-500 ml. (one pint) of the fluid each day or approximately 0.3 cc per minute. (The total volume of CSF in the skull at any given time is around 140 ml. That means the body produces, absorbs and replenishes the total volume of CSF about 3-4 times daily.)

Click to Enlarge

Schematic Drawing of Cerebrospinal Fluid Circulation.

Elevated CSF pressure is transmitted around the brain and along the optic nerve (sub-arachnoid space) producing papilledema.

Cerebrospinal fluid flows from the choroid plexus through the brain’s four, interconnecting ventricles before finally entering the sub-arachnoid space, which surrounds the brain and spinal cord. The fluid then flows over the brain and spinal cord and is eventually absorbed into the venous blood system through tiny, one-way channels called arachnoid granulations or villi. 

When this continuous cycle of CSF production, circulation and absorption functions normally, it regulates the volume of CSF in the skull and the fluid pressure remains at a constant level. In other words, the CSF production rate remains equal to the CSF absorption rate. 

But when the body cannot effectively absorb or drain CSF, intracranial pressure increases within the fixed space of the skull. And since the brain and the vasculature can only be compressed so far, intracranial pressure must rise. Intracranial hypertension in adults is generally defined as intracranial pressure that reaches 250mmH2O or above."

That's a great technical description of the disease, but I have a better definition of it: IIH is a pain in the ass. Or the head, more accurately.

I don't know how I got IIH, I've been on Lithium and steroids, I've had meningitis twice and Lyme Disease once, and I have another disease that can contribute to it: Poly-cystic Ovary Syndrome (PCOS). As far as I can tell though, my trigger was my last bout of meningitis which I suffered exactly a year ago. I never got better from my meningitis; several months, three LPs (spinal taps), and two blood patches (to stop leaking after the spinal taps) later, my right ear kept ringing, I still felt tired, I was taking Excedrin Migraine like candy, and the slightest movement left me very dizzy. I'd had dizzy spells before (ironically enough, when I was on lithium I used to get dizzy, have strange tingling going up and down my spine, and lose my peripheral vision fairly often), so it was nothing for me to drive very dizzy, but I felt so sick that I knew it wasn't a good idea to drive to work through the heavy snow that marked the last few days of January here in Tennessee. Finally, on the 1st of February, my neck started seizing up and I knew something was very wrong. I drove myself to my GP, and his nurse practitioner did some neurological tests (which I failed miserably), decided I had meningitis again and sent me back to the ER.

For some reason, the anesthesiologist who did my LP decided to test my spinal pressure for the first time, and I knew something was very wrong when he let out a whistle and told me that my pressure was one of the highest he had ever seen, 380mmH2O, or 38 (later on I found out that for IIH that wasn't as bad as it could be, one of my IH friends routinely hits 55). The funniest thing was, after he did the tap and drained me down to a "normal" pressure, I felt much better. My dizziness went away, my head stopped hurting, and the buzzing in my ear got quieter. That's when they broke it to me: I had IIH.

Like most people, I had no idea what IIH was, so when I was done with my few days' rest to make sure I didn't leak again (thankfully I didn't this time), I logged onto the internet to find out what I could. It all made so much sense: this was everything I had been going through for months. If only everything was so simple as that research.

Like I said, most doctors don't have any idea what IIH is. After I was put on the first of the three medicines that I've been on so far, the swelling in my optic nerves went down, but I still felt so sick that I ended up having to change neurologists because the first one I was going to told me that everything was in my head (some of the problems that were "in my head" ended up with me getting surgery because I ended up having nerve damage in my arm that had to be reversed, but hey, I didn't have any idea what I was talking about). I like my new neurologist, but he keeps insisting that even though I'm still having terrible headaches, my ear can't shut up, I'm horribly dizzy at times, and my vision either gets spotty or cloudy, that I can't still have IIH because when he looks in my eyes he can't see any swollen optic nerves (although that doesn't mean much to me, as I went to an eye doctor literally a week before I was diagnosed, and he never saw my swollen optic nerves because the way my eyes are shaped you can only see them when my pupils are dilated).

So this is my life right now, I can't work, I can't bend over without getting dizzy, and all the needles shoved in my back have caused nerve damage and muscle damage, which means I'm constantly in pain. Then, a couple of weeks ago I was at the neurologist when I got really dizzy and almost past out in the bathroom, and he decided the pressure on my brain is effecting my heart...

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