When my Neurosurgeon (NS) diagnosed me with Syringomyelia (SM) he took the time to tell me a little story about how this tube in my spinal cord got it's name. Looking back it was one of those precious moments with a good Doctor. Since then I've read several versions of the story and this is how the basic plot runs:
Once upon a time, an extremely long time ago, there was a beautiful Greek nymph named Syrinx. She had a wonderful voice and sang all the time. The God Pan was in love with her, but alas, she did not return his affections. She took to avoiding him and hiding, and one day she turned herself into a river reed to avoid his pursuit. This angered Pan greatly, so he cut down the reeds and bound them into the first Pan Flute. Of course this killed the nymph Syrinx, so her love was lost forever, but her voice was not.
Debussy has written a flute solo with this title and I don't think I have heard it yet, but one day I would like to. Syrinx is considered a "flute legend" and the origin of the Pan Flute. The word is also the root word for "syringe", and for a similar reason "syringomyelia". While "syringe" has a soft g, syringomyelia has a hard one "sigh-ring-go-my-ale-yah". Yep, it's a mouthful.
What is syringomyelia?
When we are children the spinal cord is still growing and that means that it needs a good flow of nutrients and it needs waste carried away in slightly higher quantities than it does once we stop growing. So in addition to having spinal fluid flow along the outside of the spinal cord, it also has a central canal which is very narrow and acts kind of like a "back alley" inside the cord, where the milkman leaves his jars by the door and the trash truck picks up the waste. It was designed for minimal traffic. They are normal, so they cause no symptoms. Once the spinal cord stops growing this very narrow central canal collapses and you should no longer be able to see it on an MRI, but sometimes it remains with a width of about .3mm. That's a "retained central spinal canal". .3mm is too narrow to be seen on a normal sized MRI. You have to blow the pictures of your spine up 3 times normal size to make that canal appear 1mm wide, so you can see it.
Syringomyelia is when spinal fluid forms a tube (like the reed in the myth) in the center of the spinal cord where this "back alley" used to be, and it damages the cord from the inside out, causing weird neurological sensations, odd reflexes, dysfunction, and pain, including central cord pain which can be extremely severe and very difficult to treat.
A point I try to make to people who say (often in tears) that their doctor says they have an "asymptomatic" 1 or 2mm "retained central spinal canal" is that 1mm is 3 times the width that central canal ever was when they were children. It is carrying 3 times as much fluid traffic as it was designed to carry. It was a narrow unused back alley. Now it's a surface street. It only increases from there. The average spinal cord is only 10 mm wide, so 1mm is taking up 10% of the width. You do the math. So perhaps the symptoms with a very narrow syrinx are conservative, but they are not non-existent. The patient's experience should be valued.
Several things can cause a syrinx. Mine probably started with a horseback riding accident in my teens. My NS thinks that perhaps my spinal cord got nicked and since I only had xrays, nobody saw it. I feel extremely fortunate that the injury was so mild that it wasn't obvious, but I do remember my back really ached a lot in school afterwards. I'd had xrays. I knew none of the vertebra were broken or fractured and I assumed if I had a cord injury I would be paralysed, right? So I must be fine. That's not always the case. Paralysation is dramatic so it gets our attention, while the incomplete injuries or "nicks" as my Neurosurgeon called it in my case, can cause problems that are not so obvious and get overlooked for years. In my case it took a second "twisting" cord injury to make the problem obvious enough to warrant a serious investigation into the symptoms. So the accident with the dogs made a pre-existing syrinx worse. I had problems before but the doctors would say it was a pinched nerve, or a sprained neck, or tendinitis. It had to get worse before the symptoms became obviously neurological in origin.
Spinal cord inflammation is very different than inflammation in other parts of the body. It takes many more weeks to resolve, and for some reason some of the spine-specific-inflammation-chemistry is actually destructive to the spinal cord and nobody knows yet what purpose that serves. So I have this nicked cord as a teen, and that area of the cord was inflamed as a result, and this blocks the proper flow of spinal fluid, which has the pressure of the heart beat behind it. Like a kink in a hose, the pressure will build until it finds a weak spot and it tries to break through. In my case it somehow went through my spinal cord and put that old central canal back into use, only this time it's not just a slow back alley, it's a surface street or highway of spinal fluid and it was never intended to handle that much traffic. Fortunately, mine seems to be staying with street or highway traffic, and has so far refrained from becoming a wider Interstate.
There is a lot of argument, even among Neurosurgeons, about Syringomyelia and symptoms. As somebody who personally endures it and has read up on it, I believe it creates symptoms in 2 ways. One is that as the syrinx progresses and starts widening, the fluid flow erodes neurons in the center part of the spinal cord and that creates one set of symptoms which are permanent. Even if the syrinx collapses those symptoms will always remain. I believe the 2nd set of symptoms are from the pressure that the syrinx puts on the exterior part of the cord from the inside out, possibly pushing the outside edge of the cord against vertebra and nerve roots between the vertebra, causing weird neurological feeling like tingling and numbness, and later dysfunction, and as the central cord erosion damage at those levels progresses the dysfunction becomes permanent. But as long as the symptoms are only due to inflammation pressure on cord neurons they are fully reversible. I believe that is why many syringomyelia patients experience so many neurological symptoms that come and go, often relatively quickly. And Doctors are correct in saying "No these symptoms are not due to syringomyelia damage", but they are incorrect in excusing the symptoms altogether. They are due to syringomyelia pressure, which in my opinion, may actually be more important because it can tell you what area may get damaged next if inflammation is not kept under control with medication and limitation on certain activities related to that region of the spinal cord.
Another big question is how the fluid gets in the syrinx in the first place. Syrinx vary in length and width from one person to the next, and there is no obvious hole in the cord where fluid moves in or out. My theory is that in some cases, or many, a genetic variation which causes connective tissue disorders (and they are notoriously common in Chiari patients, which represent roughly 80% of all syringomyelia) causes the protective tissue around the spinal cord to be less dense or more porous, so when pressure is present spinal fluid pushes it's way through the weakest tissue...the cord...instead of being forced around it. I've pondered what kind of evolutionary advantage this predisposition to syringomyelia might give humans? I believe that it might actually allow some people like myself to retain near normal function after a mild or incomplete spinal cord injury that might otherwise be catastrophic. For example, perhaps the gene that allowed my spinal fluid pressure to be released into my spinal cord rather than forcing it around the cord, prevented a spinal fluid leak, which would've been potentially fatal through human history until recently when doctors with technology have learned to stop it. This would give me an advantage to pass on this gene, while my cord injured neighbor without it might die. I could be way off. It's just a thought.
No comments:
Post a Comment