Current Procedural Terminology (CPT) codes are standardized five-digit identifiers used by healthcare providers and payers to describe specific medical services and procedures performed on a patient. CPT 64490 is a highly specific code located within the nervous system section of the CPT manual, designated for interventional pain management procedures targeting the spine. This code serves as the primary identifier for a particular type of injection procedure used to diagnose and treat pain originating in the upper back and neck regions.
The Specific Procedure: Medial Branch Blocks in the Upper Spine
CPT 64490 specifically describes the injection of a diagnostic or therapeutic agent into a paravertebral facet joint or the nerves that innervate it. Facet joints (zygapophyseal joints) are small, paired joints on the back of the spine that stabilize motion between vertebrae. When these joints become arthritic or injured, they can cause chronic back or neck pain, known as facet joint syndrome. The procedure involves targeting the medial branch nerves, which transmit pain signals exclusively from these facet joints.
The code is explicitly designated for procedures performed in the cervical (neck) or thoracic (mid-back) spinal regions. A medial branch block involves injecting a local anesthetic near these nerves; significant pain relief confirms the facet joint as the pain source (diagnostic tool). For therapeutic purposes, a corticosteroid may be injected along with the anesthetic to provide longer-lasting relief by reducing inflammation. Precise localization is achieved using imaging guidance, typically fluoroscopy or computed tomography (CT), which is considered an inclusive component of this CPT code and is not billed separately.
Why Levels Matter: First Level Designation
The designation “single level” in the CPT 64490 code description reflects the segmental anatomy of the spine and is a fundamental concept in spinal procedure billing. The code applies to the initial vertebral level treated in the cervical or thoracic region during a single session. Since a single facet joint is innervated by multiple medial branch nerves, the code reports the blocking of all nerves necessary to anesthetize that specific joint level.
This initial level treatment is considered a base procedure, reported once per side, per level. CPT 64490 is inherently a unilateral code, covering the procedure on one side of the spine at that first level. The CPT coding structure uses “add-on” codes for more extensive procedures. If a second, adjacent level is treated, the add-on code 64491 is used, and a third or any additional level is reported with code 64492.
Navigating Billing and Frequency Rules
Accurate claim submission for CPT 64490 requires adherence to specific rules regarding laterality and procedure frequency. When the procedure is performed on both the right and left sides of the spine at the same vertebral level, it is considered a bilateral procedure. In this case, CPT 64490 is reported once with the addition of Modifier 50, which signifies that the service was performed bilaterally.
Insurance payers, including Medicare, impose frequency limits on these injections, typically restricting them to three or four injection sessions per spinal region per year. This limitation ensures medical necessity is met. Comprehensive documentation is mandatory for reimbursement, requiring clear records of the imaging guidance used, the specific vertebral level treated, and the medical necessity supporting the procedure. Furthermore, a specific modifier, such as KX, may be required by some payers when the injection is purely diagnostic to confirm the source of the patient’s pain.