My question surrounds nerve block which is being done with a physician order. (cpt codes 64400 – 64450). We are following the guidelines with regards to giving the pain management pre or post op, and not during anesthesia and we have a managed care payor asking us to prove medical necessity. What is medical necessity for pain. Can anyone tell me if they are doing this in their hospital and if they have had any challenges getting it reimbursed.