I don't know the exact statistics on no lesions of the cervical spine on imaging studies. In the proper clinical and historical setting, an abnormal MRI with positive oligoclonal bands is enough. My right side has been affected, limited use in right hand and require cane as my right foot drops when I walk and my stability is off. The criteria for diagnosing MS is changing but given a normal MRI and normal LP, your doctor probably wants some further support for the diagnosis.
Family history is highly suggestive.
My last MRI raised concern for ventriculitis or ependymitis. Could you please explain these terms in language that I can understand. I would suggest that the scan is re-read by a neuroradiologist. I have been experiencing pain behind my eye and have noticed that depth perception has been affected with slight blurring. It has been recommended to have a spinal tap, but at this time I do not feel it has come to that point.