Unlisted CPT 64999 is the correct selection. There has not been a change in the AMA guidance for this procedure.
AMA CPT Assistant.
September 2007 page 10
Coding Communication:Surgery: Nervous System
Question
What is the appropriate CPT code to report for a ganglion impar sympathetic block?
AMA Comment
Code 64999, Unlisted procedure, nervous system, should be reported. When reporting an unlisted code to describe a procedure or service, it will be necessary to submit supporting documentation (eg, a procedure report) along with the claim to provide an adequate description of the nature, extent, and need for the procedure and the time, effort, and equipment necessary to provide the service.