I have a CRNA that did a Brachial plexus block. He wants to bill this with 8 units. CPT says to report 64415 once per nerve plexus regardless of the number of injections performed along the nerve plexus. In the Optum Coding and Payment guide there is no base codes listed for the 64415. I have read several websites and I am getting different answers. Can someone direct me to the correct number on units that should be billed with 64415?