CPT code 64999: Unlisted procedure, nervous system

What is CPT code 64999?

CPT code 64999 is used to report a nervous system procedure that does not have a more specific CPT code. This unlisted procedure code serves as a catch-all for new, uncommon, or complex interventions that involve the central or peripheral nervous system but are not described by existing CPT codes.

Common clinical applications include erector spinae plane blocks, ultrasound-guided peripheral nerve injections, or novel techniques involving specific nerve targets when no designated CPT code exists. Because 64999 is a miscellaneous code, payers require thorough documentation to support medical necessity and to compare the service with similar, listed procedures for reimbursement purposes.

Documentation requirements

Detailed documentation is essential when billing CPT 64999 to ensure proper review and consideration by payers. The lack of a defined procedural description makes strong clinical justification even more critical.

Clinical indication and medical necessity

Clearly describe the patient’s condition, symptoms, or diagnosis that required the procedure. Medical necessity should be well-supported, such as cases involving pain syndromes that require nerve blocks or instances where conventional treatments have failed. Indicate why no specific code exists for the procedure performed.

Procedure description

Provide a full procedural note detailing the anatomy involved, the technique used, and whether tools like ultrasound guidance were utilized. Mention any comparison to existing, similar procedures to help justify relative value during claims review.

Supporting documentation

Include operative reports, prior authorization (if applicable), and any clinical guidelines that support the decision to use an unlisted code. If the procedure is analogous to an existing CPT code, indicate the reference code used for pricing and review.

Billing guidelines

CPT 64999 requires manual review by insurers and must be submitted with extensive supporting information to avoid denial or reimbursement delays.

Cannot be billed with another code

64999 should not be billed in combination with a specific CPT code for the same procedure. If a valid, active code exists for the service rendered, that code must be used instead.

Submit with a cover letter or comparison

When submitting 64999, many payers require a cover letter or pricing reference, such as another CPT code of similar complexity and relative value unit (RVU). This helps the payer determine reimbursement and validate coding and billing practices.

Check for prior authorization

Because 64999 is unlisted, some insurers require prior authorization, particularly for procedures like erector spinae blocks or advanced peripheral nerve interventions. Always verify payer-specific requirements in advance.

Other related CPT codes

• 64483 – Injection, anesthetic agent; lumbar or sacral (transforaminal epidural)
• 64450 – Injection, anesthetic agent; other peripheral nerve or branch
• 64490 – Injection(s), diagnostic or therapeutic agent; paravertebral facet joint