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.

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.

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.

Evaluation and Management Service on the Same Date as an Office Procedure

Question:

A patient came into the office for a balloon sinus ostia catheterization and dilation of the maxillary, sphenoid and frontal sinuses bilaterally. My surgery scheduler has already obtained pre-certification for the procedure as it is covered in the office setting. I performed an examination and then did the procedure. I then performed a sphenoid, frontal, and maxillary dilation bilaterally. Can I bill an E/M service since I examined the patient?

Answer:

No, since the focus of the visit was the procedure and you have already obtained precertification for the procedures on the sphenoid and frontal sinus dilation (CPT 31298-50) and the maxillary dilation (31295-50), the E/M service is inherent to the procedure and should not be reported separately.  In this situation there is not a significant separate identifiable justification for an E/M service.

*This response is based on the best information available as of 7/03/25.

Ablation of Thyroid Nodules

Question:

My physician performed a percutaneous radiofrequency ablation of 3 thyroid nodules, one in the lower part of the left lobe and 2 in the right lobe. I am not sure what CPT code I should report. Can you help?

Answer:

Certainly. There are 2 new CPT codes to report percutaneous radiofrequency ablation of thyroid nodules: CPT code 60660 (Ablation of 1 or more thyroid nodule(s), one lobe or the isthmus, including imaging guidance, radiofrequency) and CPT code 60661, an add-on code for the additional lobe. In this instance, you will report 60660 for the left lobe and 60661 for the right lobe. Keep in mind that imaging guidance is included and should not be reported separately.

*This response is based on the best information available as of 6/19/25.