From what I've heard, it depends on who did your CT myelogram. When mine was done, my surgeon insisted on my having it done at his hospital, by his expert. He did not want me doing it anywhere else. I think it's kind of like the time everybody thought I had a muscle cancer, and when I got to the sarcoma specialists finally, they weren't interested in seeing anyone's MRIs, only the ones they did at their hospital, that were read by specialists in sarcomas.
Generally, the CT myelogram should be far more accurate than the MRI for revealing the nature of nerve impingement. The impingement I have was visible on both types of images. The doctor who did my CT myelogram showed the the picture on the monitor, and it was obviously clearer than the MRI for showing the nerves...was your MRI with or without contrast? That could make a difference, too.
You can have a narrowing of the space the individual nerves pass out of, without having stenosis, which as I understand it is the narrowing of the spinal canal where the spinal cord itself travels. But if the guy doing your myelogram said he didn't see anything that would cause nerve impingement, he certainly ought to have seen it if it was there. Unless it takes an eye practiced in reading myelograms of scoliosis patients, and maybe it does.
Stephanie, age 53
Diagnosed age 8
Milwaukee brace 9 years, no further treatment, symptom free and clueless until my 40s that curves could progress.
Thoracolumbar curve 39 degrees at age 17
X-rays in Dec. 2010 and January 2011 at 58 degrees thoracic, 70 degrees thoracolumbar
Expect eventually to need long fusion to Pelvis.
Surgeon Dr. Michael S. O'Brien, Baylor's Southwest Scoliosis Center, Dallas TX
Bilateral laminectomies at L3 to L4, L4 to L5 and L5 to S1 on April 4, 2012