Syringomyelia can be caused by multiple different things. In my case, we believe it is being caused abnormal tension on my cord. Here is my understanding of why we are treating syringomyelia--which effects much of my spinal cord--by simply snipping the filum at the bottom (pasted from recent email):
Children born with obvious spina bifida are well known in
medicine, and treated young. However, tethered cord is not
a black-or-white condition. Children with borderline
("occult") spina bifida (a.k.a. occult tethered cord) are
sometimes treated by experts like Dr. W. Adults who
have grown up with spina bifida occulta (me) may not have
serious symptoms until mid age--when more cord damage has
accumulated. Most of these adults are diagnosed with
chronic pain syndromes like fibromyalgia or if they have
syringomyelia (SM) on an MRI, "idiopathic" SM. Most slowly
deteriorate without help, because adult-onset tethered cord
is not widely understood. This is changing (see research links
on lower right of my blog).
Dr. X takes advantage of the gap between vertebra to
minimize bone removal in the lumbar spine; he/she doesn't do a
full laminectomy. She only needs about an 8mm cut of the
dura (spinal sac). She says the procedure takes her about
half an hour. She has done thousands of the procedures
with very few complications. She considers my case
straight-forward, and expects I would have relief of some pain and
numbness. She reports that %90+ of patients like me have
neurologic improvement after detethering. I told her I'm
not getting my hopes up, but I'd be happy just to stabilize
my condition.
As I said in that email, my main hope is just to stabilze my condition, so I don't keep getting worse. There is a little permanent damage to my spinal cord, so I probably won't be back to the old crazy-endurance-sports me. About six months to a year after surgery, I should have a good idea of how it worked.