This is my *opinion* from things that both you and Karlin said along with Ella's neurologist. I would quote them but there are on several different posts. One thing Karlin said is it is hard to get an idea from people on forums. It is one experience vs. another is so little to judge things on. I can say what I have heard (two cavaliers with great results) Riley and another one whose syrinx has seen to decline in size. This cavalier was part of his study. That is only two, yet weigh that against the two negative results Karlin knew about. You have been on this forum long enough and have been treating Blitz for SM to know the best for your situation. You know how he is reacting to medical management which also played in my decision.
Ella's neurologist said some of the same things as yours and Karlin. He said he wanted to see long term results before actually stating that it is worth it. He has done them before *I think* but it was offered as an addition to the surgery prior. He said is it worth the extra $1000, risk *he said it was *riskier*, recovery time, etc. he could not say without seeing reports from long term studies. As far as your neurologist saying it was a somewhat simple procedure, I dont know. However, I do know that Ella's neurologist said that there was more risk from drilling holes and placing screws.
Karlin said one thing Ella's neurologist was concerned about which was the long term results from the screws in the skull. Whatever Karlin said it was the same which I can't say right.
My personal decision was based on where I lived, the neurologist Ella saw and wanted to do her surgery, among other factors which varies by individual. If I lived in NY close to Dr. Marino and Dr. Dewey would my decision be different? Probably. I did not want something more complicated done by a neurologist (even though I was extremely happy with him) that did not have as much experience with this procedure.
In case others read this and are deciding on surgery, I will say this. (You have been treating Blitz with medical management so may differ with age, etc.) This is what I will say FWIW. You know Ella developed scar tissue. This was shown on her MRI in September 2010. You can see past threads or remember but I thought I would have to take drastic measures like a second surgery but due to other things (I waited). What I saw as declining fast started to become managed with changes in medication. I thought she had months but she could have had years. I'm not sure and will never know. However her neurologist said it could be a couple months she had, but that was not the case.
One last thing. I too find it strange the number of Cavaliers said to no longer need medication after surgery. You know this but thought I would point that out also.