Hi mary, As far as strength, they are supposed to be roughly equal as far replacing one with the other and not experiencing negative side effects.
The real difference is in ther mechanism of action and their half life.
Xanax is often preferred as a PRN "as needed" med for anxiety because it works fast and has a short hlaf life, It also only works on a particular part of your brain.
Where valium is the Only muscle relaxer that works both on your brain and on smooth muscle fiber, It's by far the vbest med for muscle spasm, but many docs don't use it due to the high abuse rate, not that Xanax isn't abused too. Valium would work better on muscle spasm, It would also work for anxiety and you would be less prone for rebound problems with valium as Xanax wears off fast. Valium has a long half life so you mantain some in your system, more of a prevenative for panic attacks or a longterm treatment for anxiety and a great treatment for muscle spasm. Any benzo will increase the CNS depression from opiates so you have to be careful. It's really better to start a new med on the weekend when it's OK to sleep, rather than at your desk.
The conversion is fine, It really just depends on the purpose of taking it. Another Long acting or long half life benzo is Klonopin, which is the preferred drugg for anxiety problems that haven't reposned to conventional therapy, SSRI's and short acting anti anxiety meds. Klonopin also has antiseizure properties, may help with neuro pain, does help greatly with restless leg, so th reason your taking it should really determine the choice of which med would b best for what problem.
Panic attacks are nothing to be ashamed off, A huge flair can certainly feel like a panic attck too, pain so bad you can't catch your breath. Anxiety, like depression, can go hand in hand with CP and doesn't mean anyone will label you Crazy Mary.LOL Simply because you take a Benzo either Xanax, Klonopin or Valium. Often a dose of "any" benzo will help me more than BT meds when I hurt so bad I can't seem to catch my breath.
For spasm, I would choose valium and you still get the anti-axnxiety effect, Xanax is solely an anti anxiety med. Or used to promote sleep without a hangover due to it's short action. Benzo's used for sleep tend to loose their effetiveness over time, where meds like elevil continue to work without the same type of tolerance you develop to opiates.
Good luck, Dave C