I had an MRI after my sudden CFS onset in 1995. It showed a lesion of some type in the very center of my cerebellum. The MRI was repeated with gadolinium contrast and the lesion proved not to be cancerous and the neurologist concluded it was merely a 'harmless' cyst I was probably born with or perhaps an atypical MS plaque, but he said this would not account for all of the symptoms I was experiencing. He did a lumbar puncture (spinal tap) to further investigate for MS, which showed increased protein and white blood cells, but at a low level which, in his opinion would also not account for my symptoms but still did not rule out nor prove MS. Two years later in 1997, I started having more headaches and the MRI was repeated. It showed no change in the cerebellar lesion, and my neurologist now felt it was not MS and was probably congenital and harmless. Two years ago in 2008 I was having headaches of a different kind and losing weight for no apparent reason so a new neurologist did another MRI. It showed now that I have 3 lesions in my cerebellum, which the radiologist felt were there since birth and harmless. I explained that I had one lesion years ago, but the neurologist said he trusted the radiologist's opinion that they have been there since birth. I told the neurologist that I saw the MRI films with my own two eyes back in 1995 and 1997 and I am positive there was only one lesion at that time. He said, "Well, we have better machines now." and that's the end of that. The headaches stopped eventually. I'm still otherwise as sick as always, but they say it has nothing to do with the cyst or cysts in my cerebellum. I will say that when I had my sudden onset of CFS in 1995 I had profound dizziness and could not even sit in a chair without holding on or I would fall in the floor. This persisted for a month before it gradually diminished to where I was only dizzy when I turned my head fast or repeatedly as when grocery shopping and looking at both sides of the aisle as I go. That's pretty much better now. The only problems I have with balance now are that I can not spin around in a circle (as when dancing) without feeling like everything keeps spinning (but since I don't find myself really needing that skill, I don't feel my quality of life is diminished by that) and also, I can not balance in complete darkness or with my eyes closed. I have concluded that my brain has learned a new way of keeping my balance which is mainly by visual input, and when visual input is removed, I will certainly fall down if I am not holding on to something. I just keep night lights on here and there in the house and I don't have any trouble getting around the house in the 'dark'.