Variation in Coding Practices for Vestibular Schwannoma Surgery^[*]

Thank you to the authors for this interesting article. The findings were certainly discouraging to me as a consultant who has worked with hundreds of neurosurgeons to optimize coding, documentation, and reimbursement during my 20-year tenure as a faculty for the American Association of Neurological Surgeons (AANS) coding courses. That 35% of the institutional cohort's vestibular schwannoma procedures were incorrectly coded is also disappointing. Fortunately, the results are better for the National Surgical Quality Improvement Program (NSQIP) database where only 24% are incorrectly coding but that number is still too high. Obviously my education attempts have failed as so many neurosurgeons are coding incorrectly for vestibular schwannoma surgery.

The bottom line is that it was, and still is, correct to use 61520 and 61526 and incorrect to use the skull base surgery codes for the majority of vestibular schwannoma surgical procedures performed via the retrosigmoid/suboccipital and translabyrinthine/transmastoid approaches.

The descriptions for each Current Procedural Terminology (CPT) code are noted below:

61520	Craniectomy for excision of brain tumor, infratentorial, or posterior fossa; cerebellopontine angle (CPA) tumor (commonly called the retrosigmoid or suboccipital removal code)
61526	Craniectomy, bone flap craniotomy, transtemporal (mastoid) for excision of CPA tumor (commonly called the translabyrinthine or transmastoid removal code)

The skull base surgery CPT codes (61580–61619) were implemented in 1994 while 61526/61520 were included in CPT prior to 1990. The Winter's 1993 CPT Assistant states the following about the new, at the time, skull base surgery codes (italics added for emphasis):

“In CPT 1994, new codes were added to describe skull base surgery. This surgery is unique in that it involves operating on a portion of the skull which was inaccessible prior to the development of innovative surgical approaches to lesions affecting the deep facial structures that are adjacent to the undersurface of the cranium (i.e., the base of the skull).”

CPT 61526/61520 were in CPT prior to 1990 which means these procedures were performed prior to the advent of the skull base surgery codes. In fact, retrosigmoid/suboccipital and translabyrinthine/transmastoid excision of vestibular schwannoma surgery had been performed for decades prior to the skull base surgery codes in 1994. Therefore, most vestibular schwannoma surgery is not considered “innovative approaches” for use of the skull base surgery codes.

The same CPT Assistant ends with this statement (italics added for emphasis):

“These codes have been formulated to be utilized specifically by those performing skull base surgery for extensive lesions which are often transcranial in nature and should not be used to describe limited surgical procedures for isolated lesions of the cranial vault or head and neck that can be adequately described by other CPT codes.”

Again, there were “other” CPT codes, 61520 and 61526, to describe the removal of a CPA tumor (e.g., acoustic neuroma) prior to the implementation of the skull base surgery codes. In fact, additionally, the March 2018 CPT Assistant Newsletter states the following:

Question: When performing a translabyrinthine approach for the resection of a vestibular schwannoma, is it correct to report codes 61595 and 61616, or code 61526?

Answer: This is a CPA (CPA) tumor, and should be reported with code 61526, Craniectomy, bone flap craniotomy, transtemporal (mastoid) for excision of CPA tumor. Code 61526 was established specifically for translabyrinthine vestibular schwannoma removal. If both an otolaryngologist and neurosurgeon worked as a team to perform their respective portions of the procedure, each surgeon would report code 61526 with modifier 62, two surgeons, appended. Skull base codes 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, and 61616, resection or excision of neoplastic, vascular or infectious lesion of base of posterior cranial fossa, jugular foramen, foramen magnum, or C1–C3 vertebral bodies; intradural, including dural repair, with or without graft, should not be reported.

Therefore, 61526 and 61520 continue to be the correct codes for translabyrinthine/transmastoid and suboccipital/retrosigmoid, respectively, vestibular schwannoma excision procedures.

As we all know the relative value units (RVUs) for the skull base surgery codes are higher than 61520 or 61526 though these codes are highly valued as well. Curiously, something happened in the institutional cohort as the coding pattern dramatically changes, in 2009 to 2010, from correctly using a single CPT code to incorrectly using dual skull base codes. One wonders if the surgeon compensation formula changed to one that is RVU-based?

It is also unfortunate that eight incorrect stand-alone CPT codes were in the institutional and ACS-NSQIP (American College of Surgeons-National Surgical Quality improvement Program) databases for vestibular schwannoma resection as clearly these do not represent vestibular schwannoma removal procedures. The table below shows the eight incorrectly used codes, the respective CPT description and the rationale for why it is an incorrect code for this type of surgery.

Incorrectly Used Code	CPT Description	Rationale
61305	Craniectomy or craniotomy, exploratory; infratentorial (posterior fossa)	This is a generic exploratory code and does not represent tumor removal.
61345	Other cranial decompression, posterior fossa	This is a generic code for decompression, not a tumor removal.
61458	Craniectomy, suboccipital; for exploration or decompression of cranial nerves	This code is for decompression of a cranial nerve, not excision of a cranial nerve tumor such as a vestibular schwannoma.
61500	Craniectomy; with excision of tumor or other bone lesion of skull	The code is for excision of a bone tumor of the skull which does not include a vestibular schwannoma.
61516	Craniectomy, trephination, bone flap craniotomy; for excision or fenestration of cyst, supratentorial	This code is for excision of a cyst, not a tumor such as a vestibular schwannoma.
61510	Craniectomy, trephination, bone flap craniotomy; for excision of brain tumor, supratentorial, except meningioma	This code is used for excision of a tumor in a lobe, not at the cerebellopontine angle.
61518	Craniectomy for excision of brain tumor, infratentorial or posterior fossa; except meningioma, cerebellopontine angle tumor, or midline tumor at base of skull	The code says “except” “cerebellopontine angle tumor.”
61521	Craniectomy for excision of brain tumor, infratentorial or posterior fossa; midline tumor at base of skull	A vestibular schwannoma is in the cerebellopontine angle and not midline base of skull.

Abbreviation: CPT, current procedural terminology.

^* This article is an editorial comment on “Variation in Coding Practices for Vestibular Schwannoma Surgery” by Bi et al (J Neurol Surg B 2019; doi: 10.1055/s-0038-1667124).