I know we have covered this before, and I really should spend more time on the National MS Society site, but this is a quote from the NMSS Sourcebook on MRI's. It says everything so much more succinctly than I do when I'm "winging it."
Because MRI is particularly useful in detecting central nervous system demyelination, it is a powerful tool in helping to establish the diagnosis of MS. It should be remembered, however, that approximately 5% of patients with clinically definite MS do not show lesions on MRI, and the absence of demyelination on MRI does not rule out MS. Also, since many lesions seen on MRI may be in so-called "silent" areas of the brain, it is not always possible to make a specific correlation between what is seen on the MRI scan and the patient's clinical signs and symptoms. In addition, with advancing age (probably over age 50), there are often small areas seen on MRI in healthy people that resemble MS but are actually related to the aging process, and are of no clinical significance."
Guys, not to restate the obvious but this is 1 out of every 20!!! I'll keep looking, but even my MS Neuro, whom I consider very smart, felt that MS was ruled out by normal MRI's. I need to understand whether the 5% got diagnosed because they presented so classically - maybe with Optic Neuritis, more than one clear attack, a very positive LP, and a tatoo on their forehead that says, "I have MS!"