Current Procedural Terminology (CPT) codes form a standardized language used across the medical industry to describe services and procedures performed by healthcare providers. These numeric codes ensure clear communication between physicians, hospitals, and insurers, serving as the foundation for accurate medical billing and reimbursement processes. Utilizing the correct code is necessary for documenting the precise nature of the intervention a patient receives. CPT Code 64635 specifically identifies a sophisticated pain management procedure involving the intentional destruction of certain nerves.
Defining CPT Code 64635
The full descriptor for CPT Code 64635 is: “Destruction by neurolytic agent, paravertebral facet joint nerve(s), with imaging guidance (fluoroscopy or CT); lumbar or sacral, single facet joint.” This establishes the procedure’s purpose: stopping pain signals from the lower back or tailbone region. The code is strictly designated for procedures targeting the lumbar or sacral spine.
A neurolytic agent is any substance or method used to destroy or temporarily disable nerve tissue. While chemicals like alcohol or phenol can be used, the procedure most commonly associated with this code is radiofrequency ablation (RFA), a thermal treatment. CPT 64635 is designated as a base code because it represents the intervention performed at a single spinal level.
The CPT definition requires imaging guidance, such as fluoroscopy or Computed Tomography (CT), to ensure precise placement of the needle. This image-guided approach minimizes the risk of damage and confirms the neurolytic agent is delivered directly to the targeted nerve. The code is reported per joint treated, even though two distinct nerves often supply sensation to a single facet joint.
Clinical Context: The Procedure and Targeted Anatomy
The procedure corresponding to CPT 64635 addresses chronic back pain originating from the facet joints of the lower spine. Facet joints (zygapophyseal joints) are small, paired joints that link adjacent vertebrae, allowing movement while maintaining stability. When these joints become arthritic, inflamed, or damaged, they become a significant source of persistent pain.
The sensory information from these joints is transmitted by small nerve branches known as the medial branch nerves. These nerves travel past the facet joints and are the specific targets of the destruction procedure. For a single facet joint, pain signals are supplied by medial branch nerves from the spinal nerve roots both above and below that joint level.
The procedure most commonly used for this nerve destruction is Radiofrequency Ablation (RFA), also known as radiofrequency neurotomy. During this outpatient procedure, a specialized needle is guided by fluoroscopy to the precise location of the medial branch nerve. Once positioned, a thermal lesion is created by heating the needle tip with radiofrequency energy. This heat destroys a segment of the nerve, effectively interrupting the transmission of pain signals from the facet joint to the brain.
Candidates for this intervention must first confirm the pain source through diagnostic injections. These procedures involve temporarily blocking the medial branch nerves with a local anesthetic. A successful block, defined as providing at least 80% pain relief, confirms the facet joint as the source of pain and justifies the subsequent nerve destruction. The RFA procedure aims to provide longer-lasting relief than a temporary nerve block.
Proper Coding and Application Rules
CPT Code 64635 is the primary code for the destruction of facet joint nerves at a single lumbar or sacral level. When the procedure is performed on multiple adjacent levels, CPT 64636 is used as an add-on code to report the additional work involved. The add-on code descriptor specifies its use for “each additional facet joint.”
The base code (64635) is reported once for the first level treated. CPT 64636 is then reported for every subsequent level treated during the same session. For example, if a patient receives treatment at three levels (L3-L4, L4-L5, and L5-S1), the provider submits CPT 64635 once and CPT 64636 twice.
The intervention is considered a single level even if performed bilaterally (on both the left and right sides). To indicate a bilateral procedure, modifier 50 is appended to the code. This modifier alerts the payer that the service was performed on both sides of the patient’s body. Correctly applying the base code, add-on code, and modifier ensures accurate documentation for reimbursement.