Current Procedural Terminology (CPT) codes are a standardized language maintained by the American Medical Association (AMA) used across the healthcare system to describe medical services and procedures. This uniform system ensures that services are accurately documented, billed, and reimbursed between healthcare providers and insurance payers. CPT Code 64635 is a specific code designated for a focused pain management procedure targeting chronic low back pain.
Defining Radiofrequency Neurolysis (CPT 64635)
CPT Code 64635 identifies the procedure known as Destruction by neurolytic agent, paravertebral facet joint nerve(s), with imaging guidance, for a lumbar or sacral, single facet joint. The neurolytic agent most commonly employed is thermal radiofrequency energy, often called Radiofrequency Ablation (RFA) or Radiofrequency Neurolysis (RFN). This minimally invasive technique manages chronic pain originating from the facet joints of the lower spine.
The mechanism of RFA involves inserting a specialized needle-like probe, guided precisely by fluoroscopy or Computed Tomography (CT) imaging, near the medial branch nerves that innervate the facet joints. Radiofrequency current is then passed through the probe, generating heat at the tip. This controlled heat creates a thermal lesion on the targeted nerve tissue, a process called neurolysis, which effectively disrupts the nerve’s ability to transmit pain signals to the brain.
CPT 64635 covers the lumbar spine and the sacral region. These facet joints, also known as zygapophyseal joints, can cause chronic pain (facet joint syndrome) due to arthritis, injury, or degenerative changes. Ablating the medial branch nerves that supply sensation to these joints provides long-term pain relief, typically lasting six to twelve months before the nerve tissue regenerates. This targeted nerve destruction offers a therapeutic option for patients whose chronic low back pain has not responded adequately to conservative treatments.
Billing and Reporting Standards for Facet Neurolysis
The description of CPT 64635 is highly specific and governs how the procedure must be reported for billing purposes. The code represents the destruction of nerves for a single facet joint and is inherently unilateral, covering a procedure performed on only one side of the spine at one vertebral level. This precision is necessary because facet joints are paired, occurring on both the left and right sides of the spine at each vertebral segment.
When the procedure is performed at more than one level, the primary code 64635 is used only for the first joint treated in the lumbar or sacral region. Any subsequent joint treated in the same region during the same session must be reported using the corresponding add-on code, CPT 64636. This add-on code, which covers “each additional facet joint,” must always be listed separately and reported in conjunction with the primary code 64635.
For example, treating the facet joints at the L3-L4 and L4-L5 levels on the left side requires reporting CPT 64635 once for the first level and CPT 64636 once for the second level. Reporting a procedure performed bilaterally (on both the left and right sides of the spine) requires the use of anatomical modifiers. For procedures performed in a physician’s office or hospital setting, the standard practice is to append Modifier 50 (Bilateral Procedure) to the applicable CPT code(s).
Alternatively, some payers, particularly for procedures performed in an Ambulatory Surgical Center (ASC), require reporting the procedure on two separate lines. In this scenario, the procedure on the right side is reported with the modifier -RT (Right Side), and the procedure on the left side is reported with the modifier -LT (Left Side). Regardless of the fact that each facet joint is innervated by two medial branch nerves, the codes are reported per joint treated. Therefore, only one unit of service is reported per joint denervated, ensuring accurate claim submission.
Establishing Medical Necessity and Coverage
Gaining insurance coverage for radiofrequency neurolysis requires establishing clear medical necessity by meeting specific payer criteria that document the facet joint as the definitive source of the patient’s pain. Before RFA is considered, patients must typically have exhausted a period of conservative management, including physical therapy, anti-inflammatory medications, and other non-surgical interventions. A documented trial of failed conservative treatment, often lasting six to twelve weeks, is a prerequisite for authorization.
The most stringent requirement for proving medical necessity is the response to diagnostic facet joint injections, specifically medial branch blocks (MBBs). Insurance payers typically require two positive diagnostic MBBs, performed on separate days, using a local anesthetic without a steroid. A positive response is generally defined as achieving a specific threshold of pain relief, often 80% or greater reduction in the index pain, for the expected duration of the local anesthetic used.
Documentation submitted for prior authorization must be comprehensive, including objective measures of pain and functional impairment. This often includes standardized pain scales, such as a Visual Analog Scale (VAS) or Numerical Rating Scale (NRS), demonstrating a high level of pain related to the facet joints prior to the procedure. The duration of the patient’s chronic pain, typically defined as lasting longer than 12 weeks, must also be clearly noted in the medical record.
The goal of these prerequisite steps is to confirm that the facet joint is the primary pain generator and that the patient has a high probability of benefiting from the longer-term pain relief provided by RFA. If the diagnostic blocks do not achieve the required pain relief threshold, or if the documentation is incomplete or inconsistent, the payer will likely deny coverage, finding that medical necessity has not been adequately demonstrated.