Sue C:
64633-64636 codes would not be a diagnostic procedure, the definition of the procedure states using ultrasound guidance the paravertebral facet joint nerve is destroyed using a neurolytic agent, therefore; this is a therapeutic injection.
64490-64495 The physician first performs the diagnostic facet joint injection using a local anesthetic to identify the specific area generating the pain. If the patient experiences pain relief for a significant period of time following a diagnostic injection, the physician will perform a therapeutic injection on a subsequent date of service using a long-acting local anesthetic in conjunction with a steroid.
I hope this clarifies when the code is diagnostic verses therapeutic for you Sue. Good Luck.
Rhonda