According to the AMA CPT Assistant publication, a block at the spinal instrumentation would be unlisted CPT 64999
AMA CPT Assistant May 2012
Surgery: Nervous System
Question: What code(s) may be reported for injection of 0.5% Marcaine and 80 mg of Depo-Medrol to existing spinal hardware (eg, pedicle screws) at L4, L5, and S1 bilaterally?
May code 64483 be reported?
Answer: No. Code 64483, Injection, anesthetic agent and/or steroid, transforaminal epidural; lumbar or sacral, single level, represents transforaminal epidural nerve root injection
performed in the lumbar region. There is no specific CPT code for the injection of spinal hardware. CPT code 64999, Unlisted procedure, nervous system, would be most appropriate
to describe the injections for pain performed outside the foramen, as indicated in the clinical scenario provided in this inquiry. Although three spinal level (L4, L5, S1
bilaterally) injections were performed, code 64999 should be reported only once to represent the multiple injections