Question: Our providers commonly perform lumbar sympathetic plexus blocks via single injection, which we code with 64449. Because the code descriptor says continuous infusion by catheter, not single injection, we’ve tried appending modifier 52 to 64449 to show reduced services, but Medicare is denying the whole charge and won’t pay separately. Do you have any suggestions? Michigan Subscriber Answer: The single lumbar plexus injection has been an issue for many years, and there are various recommendations for how to report it. While some have suggested reporting it as you have indicated, this is causing denials. Try this: Since the procedure is a single lumbar injection, consider 64520 (Injection, anesthetic agent; lumbar or thoracic (paravertebral sympathetic)). This is supported by a clinical policy bulletin (CPB) 0863 published by Aetna, indicating this as the correct code for lumbar sympathetic plexus block. When there is not an existing code that applies to the procedure performed, the typical rule is to report an unlisted code, for example, 64999 (Unlisted procedure, nervous system), with thorough documentation that includes an explanation of the services provided.