Herniation & dura

Hi. I'm getting closer to scheduling surgery, but again i think i may not be informed enough. can anyone tell me what "dura" is? & can anyone please explain herniation? i keep hearing about it here. when i asked my 2nd NS what herniation is, he said i dont have it & told me to be carefull what i hear online. Is it possible to have an extremely large syringomyelia, & have severe symptoms & no herniation? I was just calming down a bit, & i am now reading very bad stories about "dura" & patches? Can anyone please offer me some information? thanx

Thanx beeba. what a nightmare. now that i know what herniation is. how can he say i dont have it when he showed me how much my brain has grown under my skull!? i asked how many millimeters. i saw him measure. we got to talking & i didnt get answer, but i saw 3.5 on the screen. he said i absolutley do have chiari & a very large syringomyelia. i am running out of doctors that accept my insurance, & have no out of network benefits. hopefully i will have some luck tomorrow. my symptoms are bad & getting hard to live with