Medical Monday: Aqueductal Stenosis

It's that time again: Medical Monday! I blog each Monday about a different condition Connor has and then post a link to it on the side bar as I go. This way people can get a better idea of what Connor deals with on a daily basis and his family and friends can understand what I'm saying when I call and spout ridiculously long medical terms.

DISCLAIMER: I would like to emphasize for those people who stumble upon this blog that I'm not a doctor, and I have no medical experience other than the approximately 900 doctor's appointments I've been to in the past two years. I just know about these things in relation to how they apply to Connor and not anyone else's child, so if you want accurate info on this sort of thing, please please please ask your doctor or go to the medical library instead of looking it up on the Internet. The library is your friend.

Today's topic is aqueductal stenosis.

So in addition to your brain having that thick skull for protection, it's got this neat protection system to cushion it from damage-- kind of like a miniature Zorb ball. Basically, it produces a fluid, called cerebrospinal fluid (CSF), and the brain then "floats" in this fluid inside the skull, providing a buffer against damage-- in other words, preventing your brain from rattling around like a BB in a tin can.

CSF also brings nutrients to the brain and takes waste products away from it. The brain is constantly producing it-- around 500 ml a day, or a little less than 17 ounces. That's a lot of fluid, and it won't all fit in your skull. Instead, it constantly drains out a channel inside your brain and down into your spinal cord.

CSF is produced towards the center of your brain, in an area called the choroid plexus. It then flows into the third ventricle, from there down a little channel into the fourth ventricle, and then it has two channels that allow it to flow around the outside of the brain. Finally the fluid flows down the spinal cord. Here's a handy video to show what this looks like.

Now, the little passage way between the third and fourth ventricle is called the aqueduct of Sylvius, a name that sounds like it should refer to some river in Italy. This passageway is already a little bit narrow. In Connor's case, his passageway is stenotic-- too narrow. This could potentially cause him problems, because it's more likely to become blocked by swelling or a blood clot.

What happens if the aqueduct of Sylvius is blocked? Remember, all of the CSF is being produced near the third ventricle, and it is then flowing down the aqueduct and into all the other regions of the brain. Well, if the aqueduct is blocked, the brain continues to produce CSF, but it has nowhere to go. The third ventricle and the lateral ventricle above it fill up, and then the pressure begins to push the brain matter that forms the walls of the ventricle out. The problem is that the brain is surrounded by the skull, which isn't going to do a whole lot of stretching and giving. It can grow a little bit, but not enough. The brain ends up squeezed against the walls of the skull, and if the pressure isn't relieved quickly, you end up with, to use a technical term, mushed brain. This is not good.

So what can doctors do for aqueductal stenosis? Well, right now they don't have to do anything; Connor's intracranial pressure is normal-- in other words, he is not currently experiencing any brain mushing-- and so he's not having any problems with draining his CSF right now. If it were to become a problem in the future, then the doctors could install a shunt. This is basically a little pipe that would be inserted into his third ventricle and then down into his spine to drain the excess fluid off.

Right now, however, Connor isn't experiencing any issues from his aqueductal stenosis, and we're keeping our fingers crossed that it will stay that way. He has a neurologist who follows him, and once a year or so he has an MRI or a CT scan to see how things look in there. Other than that, it hasn't affected him in any way.

Here's some information about CSF and aqueductal stenosis:

The Neuroscience on the Web Series: The Meninges and Cerebrospinal Fluid

UCLA Neurosurgery: Aqueductal Stenosis

~Jess