Re: Severe cervical spinal stenosis
The answer to your question about 8mm is, "could be bad, but not necessarily". I was down to 5mm not long ago. Take a look at my MRI from before a 3-level laminoplasty last year:
Also note the "short pedicles" observation. This is likely also part of your problem, in that short pedicles would be one of the components of congenital stenosis. Laminoplasties were really designed for people with congenital spinal canal stenosis, in that they directly address the central problem, which is that you just don't have enough room to start out with.