What is it that you think is supposed to show up on the LP?? What is your doctor telling you would be positive or negative?
A LP is only used to show Obands- which are indicative of autoimmune disorders...and as Jayhawk stated, only 85% of people with MS even show those Obands. Im negative for them, but have a positive MS dx (and over 50 lesions to back it up).
MRIs, on the other hand, can change from week to week. What was too small one week to show up, can show up the following week. Thats why they are usually repeated every 6 months. Make sure they are using contrast as well, as contrast will show smaller lesions which might be missed without it.
The other reason a LP is given, is infections, especially PML or Meningitis show up in spinal fluid....this test is often run to RULE OUT infections which might present such as MS. Basically if nothing shows up, its still more indicative that MS is the answer, if you have the other supporting evidence (lesions, symtoms). Keep in mind, MS is only diagnosed when everything else is ruled out. and therefore, negative LP results can actually mean a dx of MS!
I wish you well. MS is controllable- its not the worst dx to get! We are all living proof that its manageable and that life does goes on....let us know what you find out!
RRMS- dx 05