Neurosurgery Coding Alert

You need these three guides: Fossa, dura, and resected structures.

When reporting skull base procedures, you need to adopt the following three steps to make your way to the right code:

1. Confirm the fossa
2. Ascertain intradural or extradural work
3. List the structures mobilized

Why skull base surgeries? Surgeons perform skull- base surgery to remove/treat a lesion - such as cancerous tissue, vascular malformation or aneurysm - from the undersurface of the brain.  “A principle of skull base surgery is to remove bone in order to create an access pathway that reduces the need or extent of brain retraction to get to the target lesion,” says Gregory Przybylski, MD, director of neurosurgery at the New Jersey Neuroscience Institute, JFK Medical Center in Edison.

What is skull base? The skull base is a thick, complex bony structure on which the brain rests, and which separates the brain from the remainder of the head, face and neck.

Attempt these 3 questions to assess how well you can navigate your way to the right code for skull base approach procedures.

Question 1: Which of the following codes do you submit for orbital exenteration during anterior cranial fossa approach?

a) 61584
b) 61585
c) 61586
d) 61580

Question 2: Which of the following codes for posterior cranial fossa approach do you submit for transtemporal approach?

a) 61595
b) 61596
c) 61597
d) 61598

Question 3: Which of the following codes applies to an orbitocranial zygomatic approach to the middle cranial fossa?

a) 61590
b) 61591
c) 61592
d) All of the above

Here are answers to the above questions on skull base approach.

Answer 1: The correct answer is option b, 61585.

Orbital exenteration implies 61585 (Orbitocranial approach to anterior cranial fossa, extradural, including supraorbital ridge osteotomy and elevation of frontal and/or temporal lobe[s]; with orbital exenteration).

What is orbital exenteration? In the procedure of orbital exenteration, the entire orbit(s) is removed. “A reconstructive orbit procedure may subsequently be performed to provide a better cosmetic result.  Orbital exenteration is typically reserved for significant malignancy in which preservation of the eye is not feasible,” says Gregory Przybylski, MD, director of neurosurgery at the New Jersey Neuroscience Institute, JFK Medical Center in Edison.

Code 61584 (Orbitocranial approach to anterior cranial fossa, extradural, including supraorbital ridge osteotomy and elevation of frontal and/or temporal lobe[s]; without orbital exenteration) does not include orbital exenteration. This approach describes the bifrontal supraorbital osteotomy for the subfrontal extradural access without orbital exenteration. You report code 61584 when your physician removes just the eye brows or possibly the superior part of the orbit.

Code 61580 (Craniofacial approach to anterior cranial fossa; extradural, including lateral rhinotomy, ethmoidectomy, sphenoidectomy, without maxillectomy or orbital exenteration) for the extradural craniofacial approach with ethmoidectomy or sphenoidectomy but without orbital exenteration.

Code 61586 (Bicoronal, transzygomatic and/or LeFort I osteotomy approach to anterior cranial fossa with or without internal fixation, without bone graft) is specific for LeFort osteotomy in which your surgeon makes a horizontal incision into the bone at the base of the maxilla above the apices of the teeth. You may read that your surgeon incised a cm above gum line, from third molar of one side to that on another side and identified the location of bone cuts above roots of teeth extending from the piriform aperture to the pterygoid plates. You report the same code if the surgeon adopts the bicoronal or transzygomatic approach. You should look for ‘removal of the zygoma’ in the operative note to confirm the transzygomatic approach.

Answer 2: The correct answer is option a, 61595.

Each of the codes include resection of bone in the posterior aspect of the skull. Yet each of the codes specify a unique approach.

Code 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) implies a transtemporal approach. You submit code 61595 when your surgeon enters through the temporal bone behind the ear and proceeds rearward. This is the simplest approach to the posterior cranial fossa.

Code 61596 (Transcochlear approach to posterior cranial fossa, jugular foramen or midline skull base, including labyrinthectomy, decompression, with or without mobilization of facial nerve and/or petrous carotid artery) implies a transcochlear approach. This involves removal of vital ear structures, including the tympanic bone, labyrinth and cochlea. This approach is not frequently adopted for posterior fossa access.

Code 61597 (Transcondylar [far lateral] approach to posterior cranial fossa, jugular foramen or midline skull base, including occipital condylectomy, mastoidectomy, resection of C1-C3 vertebral body[s], decompression of vertebral artery, with or without mobilization) implies a transcondylar approach. This may include resection of the upper cervical vertebra(e). Your surgeon creates a point of entry in the occipital bone, low and to the side of the back of the skull. “This approach allows access to lesions such as a meningioma lying anterior to the brainstem and upper cervical cord, where a posterior approach alone would provide insufficient access,” Przybylski says.

Code 61598 (Transpetrosal approach to posterior cranial fossa, clivus or foramen magnum, including ligation of superior petrosal sinus and/or sigmoid sinus) implies a transpetrosal approach.

Answer 3: The correct answer is option c, 61592.

You submit code 61592 (Orbitocranial zygomatic approach to middle cranial fossa [cavernous sinus and carotid artery, clivus, basilar artery or petrous apex] including osteotomy of zygoma, craniotomy, extra- or intradural elevation of temporal lobe) for an oribitocranial zygomatic approach to the middle cranial fossa.

In this approach, your surgeon performs an osteotomy of the zygoma, removes the cheekbone, and progresses backward towards the middle cranial fossa. This code includes intra- or extradural elevation of the temporal lobe to reach the underlying structures. “This is a common middle fossa approach that allows access to many lesions including tumors and aneurysms,” Przybylski says.

Codes 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) and 61590 (Infratemporal pre-auricular approach to middle cranial fossa [parapharyngeal space, infratemporal and midline skull base, nasopharynx], with or without disarticulation of the mandible, including parotidectomy, craniotomy, decompression and/or mobilization of the facial nerve and/or petrous carotid artery) describe an approach to the temporal behind and in front of the ear, respectively.

An additional useful cue to these codes can be looking at what structures your surgeon mobilized during the procedure. When you read in the operative note that your surgeon dislocated the mandible or mobilized the facial nerve, you submit code 61590. When you read that your surgeon mobilized the ossicular chain or other contents of the auditory canal, you submit code 61591. During any of these approaches, your surgeon may resect the orbits, sinus, temples and posterior cheekbones and decompress/mobilize the petrous carotid artery.