Selecting Skull Base Surgical Approaches

Question:

How should we bill for a skull base surgery approach when the surgeon accessed both the middle and posterior cranial fossae (e.g., CPT® 61591 and 61595), and the main lesion was resected from the posterior cranial fossa (e.g., CPT® 61616)?

Answer:

Per CPT® guidelines, codes 61591 and 61595 represent distinct surgical approaches to the middle and posterior cranial fossae, respectively. They do not denote which area of the brain is accessed. Each code includes specific required components:

• 61591 – Infratemporal post-auricular approach to middle cranial fossa (internal auditory meatus, petrous apex, tentorium, cavernous sinus, parasellar area, infratemporal fossa) including mastoidectomy, resection of sigmoid sinus, with or without decompression and/or mobilization of contents of auditory canal or petrous carotid artery

• 61595 – Transtemporal approach to posterior cranial fossa, jugular foramen or midline skull base, including mastoidectomy, decompression of sigmoid sinus and/or facial nerve, with or without mobilization

To report both codes, the operative note must clearly support that all required elements of each code were performed as separate and distinct procedures. Importantly, the mastoidectomy is not optional in either code, and the work on the sigmoid sinus must be a resection for 61591 and decompression for 61595. If these elements overlap or are not separately performed, reporting both codes is not supported.

The middle and posterior cranial fossae are anatomically adjacent, and surgical access to one may involve access to the other. Traversing the middle fossa to reach a posterior lesion does not, by itself, justify reporting a separate middle fossa approach code.

In cases involving resection of a vestibular schwannoma, CPT® instructs coders to use the traditional combined approach and resection codes (61520, 61526, or 61530) rather than the skull base code sets (61580–61619). These codes bundle the approach and resection into a single code and are generally more appropriate for cerebellopontine angle tumors like vestibular schwannomas.

If the lesion is confined to the posterior fossa and the middle fossa was only used as a surgical corridor, then 61595 alone is appropriate. Modifier -22 may be considered if additional complexity is well-documented.

While CPT® does not explicitly prohibit reporting two approach codes, it emphasizes the following principles:

• Duplicative work must be avoided

• Each code must be fully supported by documentation

• Overlapping anatomical access does not justify separate approach or resection codes

If documentation does not support all elements of both codes, and duplication exists, then the coding is not clinically supported. In such cases, CPT® guidance suggests that an unlisted procedure code may be more appropriate.

*This response is based on the best information available as of 9/25/25.

Reporting Modifiers with Unlisted Codes

Question:

Can modifiers be reported with unlisted CPT codes?

Answer:

Yes, modifiers can be appended to unlisted CPT codes.

In 2024, CPT clarified this by updating the introduction guidelines for unlisted procedures and services. These updates were further explained in the January 2024 issue of CPT Assistant, which addressed the new and revised text and the standardization of reporting unlisted CPT codes across the CPT code set.

Illustration of modifiers that may be appropriately applied includes:

• Laterality modifiers – e.g., RT (right), LT (left)

• Bilateral procedure modifier – 50

• Role-based modifiers – e.g., 62 (two surgeons), 80 (assistant surgeon), 82 (assistant surgeon when qualified resident not available), AS (non-physician surgical assistant)

• Multiple or distinct procedure modifiers – e.g., 51 (multiple procedures), 59 (distinct procedural service)

• Global modifiers – e.g., 58 (staged or related procedure), 78 (return to operating room for related procedure), 79 (unrelated procedure or service)

This is not an all-inclusive list of modifiers that may be appropriately applied to unlisted CPT codes. For complete and up-to-date information, one should refer to current CPT guidelines and payer-specific policies.

Please note: Modifiers that describe an alteration of a service or procedure, such as modifier 52 (reduced services), are not appropriate for use with unlisted codes. The same applied to modifier 22 (increased procedural services).

*This response is based on the best information available as of 9/22/25.

Bone Anchored Hearing Implants

Question:

What CPT code would I report for implanting a bone anchored osseointegrated implant with a magnetic transcutaneous attachment outside of the mastoid?

Answer:

In 2023 three new CPT were created to report Transcutaneous osseointegrated implants outside of the mastoid. For the implantation the code to report is 69729, for the replacement of the existing device report 69730 and for the removal of the implant report 69728.

*This response is based on the best information available as of 8/28/25.

Coding for Inspire

Question:

How do we go about coding the new Inspire V that has only a stimulation lead and no sensing lead? Also, how would we code a revision from Inspire IV to Inspire V?

Answer:

The new Inspire V system received FDA approval on August 2, 2024 and is coded using CPT 64568, which describes the open implantation of a cranial nerve neurostimulator and pulse generator. This is appropriate because Inspire V includes only a stimulation lead, unlike Inspire IV, which includes both a stimulation and a sensing lead and is coded as 64582.

For revisions from Inspire IV to Inspire V, the correct code is CPT 61885. This code is used for the replacement of a cranial neurostimulator pulse generator with connection to a single electrode array, which accurately reflects the Inspire V configuration. Other revision codes assume the same device architecture and are not appropriate when transitioning from a dual-lead to a single-lead system. Coders can identify the use of Inspire V in the operative note by the absence of a sensing lead, and by the fact that the procedure does not require dissection through the pectoralis muscle both of which you may see involved in an Inspire IV operative note. 

From a reimbursement perspective:

• Medicare has revised NCD 160.18 to allow ICD-10 code G47.33 (Obstructive Sleep Apnea) to be billed with CPT 64568. This change was implemented on July 1, 2025, but is retroactively effective to January 1, 2025. Additionally secondary diagnosis requirement of BMI are still required to support medical necessity.

• While many commercial payers have adopted this coding alignment, some have not, so it is essential to verify coverage and coding acceptance with each payer individually.

The Centers for Medicare & Medicaid Services (CMS) issued Change Request (CR) 13939, documented in:

• MM13939 – ICD-10 & Other Coding Revisions to National Coverage Determinations: July 2025 Update (PDF)

• R13097OTN – CMS Manual System Transmittal

*This response is based on the best information available as of 8/14/25.

Incident-to Billing for Medicare

Question:

We bill incident-to for Medicare patients in our office for our physician assistants. We don’t have a Otolaryngologist in the office on Friday afternoons but our 5 PAs are in seeing patients. Can we bill their services “incident to” the physician they work for?

Answer:

You are not able to bill the service Incident-to when a physician is not in the office suite. A supervising physician must be on-site providing supervision in order to bill “incident to.” In your case, you will bill direct using the PA’s name and NPI (national provider identification) number.

*This response is based on the best information available as of 7/31/25.

Claim Denial with Modifiers 24/58

Question:

I have been getting denied for office visits (99212-99215) billed during a global period. I bill the E/M code with a modifier 24, and/or 58 and the claims still get denied for “separately billed services/tests as they are considered components of the procedure. Separate payment is not allowed.” According to the conferences I have attended for KZA, we’ve been told that we can bill and E/M code with modifier 24, but the insurances do not cover it. Do you have any other suggestions on how to get these claims paid?

Answer:

Thank you for your question. Billing an E/M service during a global period can be tricky, especially when insurers bundle them into the procedure. Here are some strategies to improve claim approvals:

1. Ensure Documentation Supports the Modifier

• Modifier 24: Must show that the E/M service is unrelated to the procedure. If the visit is for post-op care, insurers will likely deny it.

• Modifier 58: Used for staged or related procedures, not routine post-op visits or visits unrelated to the procedure.

2. Check Payor-Specific Guidelines

• Medicare and private payors may interpret what qualifies as an unrelated E/M service differently.

• Some payors require additional documentation proving medical necessity.

3. Use Diagnosis Codes That Support Unrelated Services

• If the diagnosis code is too closely related to the procedure, payors may still bundle the visit.

• Consider adding supporting notes explaining why the visit was medically necessary.

4. Appeal Denied Claims

• If you believe the denial was incorrect, submit an appeal with detailed documentation.

• Include payor guidelines that support separate reimbursement.

*This response is based on the best information available as of 7/17/25.