Willowj - I think the spinal fluid is also tested for certain "diseases" present. I don't know here and imagine yours (US) much more comprehensive. Whatever they looked for they did not find in mine. Always felt that that was the stage (before years of ME cascading illhealth) something should have been found. At least the process was painless as they had bothered to look at spinal Xrays to guide them through. Are they looking for the right thing comes to mind - all the viruses known to infect the nervous system.