well, obliterated means to "blot out" & "leaving no traces." So the CSF space evidently cannot be seen due to the disc herniation. You're right - this doesn't sound good!
I hope the Neuro can explain things to you in detail -- MAKE him do it. Sometimes they are so "short" and pre-occupied that they don't tell us things that we need to know!
Keep us posted as to what he says. Good lucki! Hugs, Lee