Neurosurgery Coding Alert

Question: May I append the bilateral modifier 50 to unlisted procedure code 64999?

Nebraska Subscriber

Answer: No. AMA's CPT Assistant (September 2005) states, "It is not appropriate to append modifiers to unlisted procedure codes because the unlisted procedure codes in the CPT codebook do not describe specific procedures." That includes

64999 (Unlisted procedure, nervous system).

Keep in mind: The purpose of a modifier is to indicate that a service or procedure identified by a specific CPT code has been changed by some circumstance but not changed in its definition. An unlisted procedure like 64999 doesn't indicate one

specific procedure in the code description, so it should not have any modifiers appended, including the bilateral modifier.

Tip: When you report an unlisted code to describe a procedure, include supporting documentation such as a procedure report to provide a clear description of the nature, extent, need for the procedure, time, effort, and equipment necessary for

your neurologist to provide the service.