The first time you use RSD type the whole name out with a slash or in parenthesis oh heck try it this way

Reflex Sympathetic Dystroph (RSD), also known as Complex Regional Pain Syndrome (CRPS),

Then maybe as far as using the letters only

RSD/CRPS

I know if you use one name only the insurance people can be so damn dense.

Also Maybe for their convenience ask your doctor if she ever uses the Diagnosis Codes &/or Procedure Codes within her letters to insurance companies. The less work they have to do as far as researching, maybe the more likely they would be to give the go ahead???

I am just throwing out suggestions here & I could be way off line.

DebbyV