hi tm, people can have white matter hyperintensities for a variety of reasons. when i was getting diagnosed they were looking for at least 9 i think?, and particularly in a formation known as dawson's fingers (check and.. check). some people never have any noticeable problems and on autopsy their brains are full of lesions. they just don't seem to have anything to do with a person's level of disability. at least not using current systems of assessment. spinal lesions on the other hand... you can definitely feel the effects of those! there are quite a few people out there who suffer neurological symptoms without having any of the 'checklist' stuff that results in an ms dx. sometimes ppl have to wait years before they finally develop a visible sign that lets the docs say 'aha'!
as for the tap, that is inconceivable that they did not test for igg or oligoclonal banding. i really don't get it. don't know what's up with the RBC thing!