What Is CPT 64491 and When Is It Used?

CPT 64491 is an add-on code used to report a second-level facet joint injection in the cervical or thoracic spine. These injections are guided by fluoroscopy or CT to ensure the medication — typically an anesthetic, steroid, or both — reaches the correct joint or nerves surrounding it.

The purpose of these injections is twofold:

• Diagnostic: to confirm if a specific joint is the source of the patient’s pain.
  
  
• Therapeutic: to relieve inflammation and reduce discomfort in patients with confirmed facet-related pain.
  
  

Importantly, 64491 is never used on its own. It always follows 64490, which is the code for the first level injected in the same spinal region. If injections are given at more than two levels, 64492 is used for the third or any additional levels.

Understanding the Facet Injection Code Set

Let’s put 64491 into perspective by comparing it with the other codes in its family. Here’s how they’re organized by region and injection level:

So, when a provider performs injections at two cervical levels, such as C4-C5 and C5-C6, 64491 would be used in conjunction with 64490 to indicate that two different vertebral levels were treated.

Billing Example: Applying 64491 Correctly

Let’s say a patient undergoes injections at C4-C5 and C5-C6 on the right side only, under fluoroscopy:

• You would report 64490 for the first level.
  
  
• Then 64491 for the second level.
  
  

If injections were done bilaterally (both right and left sides) at those same levels, then things shift slightly:

• 64490-50 for bilateral injection at the first level
  
  
• 64491 x2 to reflect the second level injected on both sides (without modifier 50)
  
  

Keep in mind that payer policies differ. For example, Medicare typically requires modifier 50 for bilateral injections, while some commercial insurers prefer reporting each side separately with RT and LT modifiers. Always check payer-specific pain management billing guidance.

Imaging Requirements and Why They Matter

Imaging guidance is not optional when reporting 64491. The CPT descriptor itself specifies fluoroscopy or CT must be used to ensure accurate needle placement. If the provider does not document the use of imaging, or if ultrasound is used instead, 64491 is not billable.

Fluoroscopy or CT imaging must also be performed in real time and documented clearly in the report. Missing or unclear documentation here is one of the most common reasons payers deny these claims.

Modifier Use With 64491

Modifier usage around 64491 can be a little complex, especially when bilateral procedures are involved. Here’s a simplified breakdown:

• Use modifier 50 with 64490 if both sides of the same level are injected.
  
  
• Report 64491 twice (with no modifier) if the second level is injected bilaterally.
  
  
• Use RT/LT only if the payer requires it in place of modifier 50.
  
  
• Never use modifier 51 with 64491. It is an add-on code and automatically exempt from multiple-procedure reductions.
  
  

In ambulatory surgical centers (ASCs), additional rules may apply. For example, the facility may need to bill bilateral injections as two separate lines with RT and LT, even if the physician uses modifier 50 on a single line.

What Payers Expect in Documentation

To justify CPT 64491, documentation must clearly establish:

• The medical necessity for multiple level injections.
• The exact levels and sides treated (e.g., right C4-C5, left C5-C6).
• The use of image guidance and type of modality (fluoroscopy or CT).
• A detailed pain history, duration of symptoms, prior treatments, and why conservative options failed.
• The goal of the injection — whether diagnostic (to confirm facet pain) or therapeutic (to relieve inflammation).

Without this level of detail, the claim may be flagged or denied, especially by Medicare or other payers that follow strict coverage determinations.

Reimbursement Snapshot

While reimbursement can vary based on location and contracts, here are some national averages for CPT 64491 in common settings:

Rates can swing dramatically — from under $100 to over $600 — based on payer contracts, facility vs. office setting, and geographic region. Knowing your local rate benchmarks can help during payer contract negotiations.

Avoid These Common Mistakes

Errors in coding or documentation can delay payments or trigger audits. Here are the mistakes you want to avoid:

• Reporting 64491 without 64490
  Remember, 64491 is an add-on code. It can’t be reported alone.
  
  
• Missing imaging documentation
  If fluoroscopy or CT use isn’t clearly documented, the claim may be denied.
  
  
• Incorrect modifier usage
  Using modifier 50 on add-on codes like 64491, or stacking codes improperly, is a red flag.
  
  
• Confusing nerve count with level count
  No matter how many nerves are injected, the code reflects vertebral levels, not the number of nerve branches.
  
  

Final Thoughts

Understanding when and how to report CPT 64491 is essential for any practice that performs facet joint injections in the cervical or thoracic spine. It’s not just about getting the right code — it’s about using it in the right sequence, with the right modifiers, and supporting it with clear documentation.

This code may be short, but it plays a big role in pain management billing. Take time to review payer-specific rules, especially for Medicare, and make sure your documentation templates and coding protocols align with current standards.

Whether you’re billing for the first time or correcting past claim issues, mastering 64491 can lead to cleaner submissions, fewer denials, and more predictable revenue for your practice.

Frequently Asked Questions

What does CPT 64491 represent
CPT 64491 is an add on code used to report a second level facet joint injection in the cervical or thoracic spine performed with fluoroscopy or CT guidance.

Can CPT 64491 be billed by itself
No. CPT 64491 must always be billed with the primary code 64490. It cannot be reported as a standalone service.

How is CPT 64491 different from CPT 64492
CPT 64491 is used for the second injected level. CPT 64492 is used when a third or additional level is injected during the same session.

Is imaging guidance required for CPT 64491
Yes. Fluoroscopy or CT imaging must be used and clearly documented. Without imaging guidance the code is not payable.

Do I use modifier 50 with CPT 64491
In most cases modifier 50 is applied to the primary code 64490. CPT 64491 is usually reported as two units for bilateral injections depending on payer rules.

Does Medicare cover CPT 64491
Yes when medical necessity is met. Medicare requires documentation of chronic pain failed conservative treatment and proper imaging guidance.