during my Chiari decompression in Aug. of 1999 they found 2 "cysts" the cysts did not show up on ANY MRI's I had including the MRI I had the week prior to decompression..when they discovered these cysts they gathered all my MRI's to compare..NOTHING was on them ..The one was a lipoma in the foramen magnum and the other was an epithelial cyst. They Think they got all of the lipoma as it was attatched to the herniated part of my cerebellum which they told me was dead tissue so they had to remove part of the herniated cerebellum. One was just above the incision (back of head, center) and was seen using a mirror it was the size of a quarter...they took snips of that and lipoma and sent it to pathology and waited for results before closing me...because they weren't sure if they were cancer or not since nothing was shown on prior MRI's...they were found to be congenital. Why wouldn't they show up on MRI's?? and my question is....is it possible for the lipoma to grow back?? I am having alot of symptoms of "chiari".. headaches, pressure in head....it's like a BP cuff has been placed around my neck and pumped up....I feel like I am choking, my head gets tight like a blown up ballon, pain, and there are the noises...."whooshing" " humming" buzzing" I can sometimes change the loudness of the noises temporarily by moving my head from left to right and up and down. If my cysts do not show up on MRI's....how do we know that they are or are not causing problems?? How can we find out other than cutting me open....would a CINE MRI show an obstruction by watching the flow of CSF ?? My latest MRI says I have low lying cerebral tonsils associated with Chiari malformation....does that mean I'm back to where I started....that the cerebellum is back to where it was before...My neurosurgeon says that I now have "chiari syndrome" and there is nothing else we can do for it.....because he performed the decompression surgery I am now cured of the chiari malformation. I'm confused!!!