CPT 64635 & 64636: Lumbar Facet RFA Coding Guide (Levels, Sides, Visits)

Lumbar facet RFA is a therapeutic procedure that targets the medial branch nerves supplying facet joints in the lumbar spine. Using radiofrequency energy, the physician creates thermal lesions to interrupt pain signals.

Unlike diagnostic procedures such as medial branch blocks (MBB), RFA is performed only after confirming the pain source.

• Provide long-term pain relief (6–12 months)
• Reduce reliance on medications
• Improve mobility and quality of life

Understanding the structure of these codes is critical.

64635 – Destruction by neurolytic agent (radiofrequency), lumbar or sacral, single facet joint (first level)

+64636 – Each additional facet joint (add-on code)

These codes are reported based on facet joint levels, not:

• Number of nerves treated
• Number of needles used
• Number of lesions created

• Use 64635 once per session for the first facet joint level
• Use +64636 for each additional level treated

• 64636 is an add-on code and cannot be billed alone
• Do not report more than 3 levels per region (payer dependent)
• Always confirm levels before assigning codes

Accurate coding depends on understanding how facet joints are innervated.

Always code based on facet joint levels, not:

• Medial branch nerves
• Number of lesions
• Number of needles

Each facet joint exists between two vertebrae:

• L3–L4 = 1 level
• L4–L5 = 1 level

Two medial branch nerves supply each joint:

• One from the same level
• One from the level above

Even if both nerves are ablated, it still counts as one level

Documentation:

“RFA performed at L3, L4 medial branches”

Interpretation:

L3 + L4 nerves → L4–L5 joint = 1 level

Documentation:

“RFA at L3, L4, L5 medial branches”

Interpretation:

L3–L4 and L4–L5 = 2 levels

Translate documentation into facet joint levels first, then assign CPT codes.

In addition to identifying levels, correct coding for CPT 64635 and 64636 also depends on accurately reporting laterality—whether the procedure was performed on the right side, left side, or both.

If RFA is performed on only one side:

Right side → RT modifier

Left side → LT modifier

If the same levels are treated on both sides, the procedure is considered bilateral.

There are two common ways to report this:

• Report each side separately
• This is accepted by most payers

Example:

64635 RT

64635 LT

• Some payers allow modifier 50 for bilateral procedures
• Always verify payer guidelines before using

If multiple levels are treated bilaterally:

Example:

L3–L4 and L4–L5 on both sides

Coding:

64635 RT

64635 LT

+64636 RT

+64636 LT

Always clearly identify the side(s) treated and apply modifiers correctly based on payer requirements.

Understanding how CPT 64635 and 64636 apply across visits and sessions is essential for accurate billing and avoiding duplicate or denied claims.

Each procedure session is coded independently, even if the same patient returns for additional treatments.

• Codes are assigned per date of service
• Do not combine multiple visits into a single claim

• Report codes based on all levels treated in that single session
• Do not split levels across multiple claims for the same day

In some cases, physicians treat different levels or sides across multiple visits.

Example:

Visit 1: Right side L3–L4

Visit 2: Left side L3–L4

Each visit is coded separately with appropriate modifiers.

RFA may be repeated if:

• Pain returns
• Previous procedure provided relief

Requirements:

• Document prior success
• Justify medical necessity

• Do not bill the same level again without medical necessity
• Ensure documentation clearly supports each session
• Follow payer frequency guidelines

Code per session, per visit, and ensure each claim is supported by proper documentation and medical necessity.

Proper documentation is essential for reimbursement.

Ensure the procedure note clearly documents:

• Facet joint levels treated
• Laterality (right, left, or bilateral)
• Procedure performed (radiofrequency ablation/neurotomy)
• Imaging guidance used (fluoroscopy or CT)
• Technique details (lesioning, probe placement, etc.)

Most payers require evidence of prior medial branch block (MBB) before RFA.

Documentation should include:

• Number of prior MBBs performed
• Percentage of pain relief achieved
• Duration of relief
• Consistency of pain pattern

To support reimbursement, documentation must show:

• Chronic pain not responding to conservative treatment
• Functional limitations
• Justification for proceeding with RFA

Strong, detailed documentation is essential to justify the procedure and ensure successful reimbursement.

Ensure documentation clearly states:

Radiofrequency ablation

Neurotomy / lesioning

Avoid confusion with injections (MBB).

Translate documentation into joint levels.

Example:

“Ablation at L3, L4, L5 medial branches”

Equals:

L3–L4 joint

L4–L5 joint

= 2 levels

First level → 64635

Additional levels → +64636

Procedure:

L3–L4 and L4–L5

Coding:

64635

+64636

RFA can be:

Unilateral (one side)

Bilateral (both sides)

Many payers prefer:

Separate line items instead of modifier 50

Understanding CPT 64635 and 64636 becomes much easier when applied to real scenarios. Below are common cases you’ll encounter in practice.

Procedure:

RFA performed at L4–L5 (right side)

Coding:

64635 RT

Procedure:

RFA at L3–L4 and L4–L5 (left side)

Coding:

64635 LT

+64636 LT

Procedure:

RFA at L4–L5 on both sides

Coding (preferred method):

64635 RT

64635 LT

Procedure:

RFA at L3–L4 and L4–L5 on both sides

Coding:

64635 RT

64635 LT

+64636 RT

+64636 LT

Procedure Note:

“Ablation performed at L3, L4, L5 medial branches”

Correct Interpretation:

L3–L4 and L4–L5 = 2 levels

Coding:

64635

+64636

Always convert documentation into facet joint levels first, then apply CPT codes and modifiers accurately.

Even experienced coders make errors when billing CPT 64635 and 64636, often leading to denials or compliance issues.

• Counting medial branch nerves instead of facet joint levels
• Assuming more nerves = more billable levels

• Misreading documentation like “L3, L4, L5 medial branches”
• Overcoding levels due to misunderstanding anatomy

• Not applying RT/LT for unilateral procedures
• Incorrect use of modifier 50 for bilateral cases

• Reporting more than 3 levels per region
• Billing levels not clearly documented

• Combining multiple sessions into one claim
• Billing repeat procedures without proper justification

• Missing prior MBB details
• No pain relief percentage documented
• Unclear procedure notes

Most denials occur due to level confusion, modifier errors, or weak documentation—addressing these areas improves claim success.

Maximizing reimbursement for CPT 64635 and 64636 requires more than correct coding—it involves consistency, documentation quality, and payer awareness.

• Verify levels directly from procedure notes
• Avoid undercoding or overcoding due to misinterpretation

• Apply RT/LT consistently
• Follow payer preference for bilateral billing

To better understand how modifiers impact reimbursement accuracy, explore our guide on the Role of Modifiers in Wound Care Coding.

• Clearly state levels and sides
• Include prior MBB results and pain relief %
• Ensure medical necessity is well documented

• Check requirements for diagnostic blocks
• Confirm allowed number of levels
• Stay updated on payer-specific rules

• Track common denial reasons
• Adjust workflows to prevent repeat issues

Accurate coding + strong documentation + payer alignment = higher reimbursement and fewer denials

To see how outsourcing can improve efficiency and reduce costs, check out our guide on the Benefits of Virtual Medical Billing Assistants.

Partner with Summit RCM for comprehensive Medical revenue cycle management services that streamline your billing operations, reduce claim rejections, and improve cash flow. From coding to collections, their team ensures your entire revenue cycle runs efficiently.

Contact Summit RCM today to optimize your revenue cycle and maximize profitability.