Good luck. I've had multiple doctors tell me that the spinal tap can be "inconclusive". It's pretty clear at this point I have MS. Anyway, here if you apply for disability they send you to a doctor recommended by the state to verify. I don't know what they do in reading spinal taps. I still have yet to have one and can't really walk and sleep 14 hours a day with a multitude of other issues.
There's an entire section on the MS World website that deals with disability and another for test results.