Neurosurgery Coding Alert

Coding for definitive skull-base procedures is complicated by the number of codes, the difficulty in understanding the terminology, and multiple and/or co-surgeon billing issues. Communication between surgeon and coder as well as basic knowledge of the medical terms can help coders to interpret operative reports and aid in code selection.
 
Sometimes a secondary repair may be needed following skull-base surgery, but  because these repairs are not always necessary, coders must be able to recognize when they are performed and can be legitimately claimed.

 
Skull-base surgeries are long, complex procedures that often require the expertise of several surgeons of various specialties, says Benjamin Vallo, MD, professor of neurosurgery at New York University. Unlike most surgical procedures, skull-base surgeries are not described by one code. When performing a craniectomy for excision of a brain tumor, for instance, the neurosurgeon reports a single code (e.g., 61518) to describe the approach (i.e., the craniectomy), removal of the tumor and closure.
 
But because of the complexity of skull-base surgeries, CPT contains codes to describe each portion of the operation -- approach, definitive procedure and secondary closure/repair.
 
The definitive portion of the surgery describes the biopsy, resection, excision or repair of the lesion and, when appropriate, primary closure of the dura, skull, mucous membranes and skin, Vallo says.
 
Like the approach codes, these are grouped according to the area of the skull base -- anterior (61600-61601), middle (61605-61613) or posterior (61615-61616) cranial fossa -- in which the lesion to be removed rests. Abnormalities most commonly addressed at the skull base include tumors, and abnormalities of the blood vessels of the brain.
 
When coding for skull-base surgeries, the approach and definitive procedure code must match. Therefore, an anterior approach (e.g., 61586) should accompany a code describing, for instance, removal of a lesion in the same portion of the skull (the anterior cranial fossa). Likewise, an intradural approach code (e.g., 61583) must accompany an intradural definitive procedure code (e.g., 61601).
 
Note: For a complete review of coding skull-base surgery approaches, see Neurosurgery Coding , September 2001.

Anterior Fossa Procedures

 
One of two codes (61600 or 61601) may be used to describe definitive procedures in the anterior cranial fossa, the portion of the skull base lying to the front of the cranium, approximately above the eyes. Each code describes resection or excision of [a] neoplastic, vascular or infectious lesion of base of anterior cranial fossa. The procedures are differentiated according to whether the dura -- the thick membrane surrounding the brain that maintains cerebrospinal fluid (CSF) pressure -- has been entered. An intradural procedure (61601) requires that the membrane be cut, releasing the CSF. An extradural procedure (61600) leaves the dura intact.  
 
If "intradural" or "extradural" is not specified in the operative report, the coder may look further in the documentation for evidence of a watertight closure (e.g., "The dura was repaired") -- which is necessary to restore CSF pressure. All intradural definitive procedures include repair of the dura. The repair/reconstruction codes (61618-61619) may not be separately billed for this procedure. In some cases, however, an intradural procedure may require a secondary repair, which may be billed separately, Vallo says.

 
The middle fossa is an irregularly shaped area resembling a butterfly that centers on the pituitary gland and cradles the temporal lobes of the brain. The definitive procedure codes for this area are differentiated according to intra- or extradural and the precise location of the middle skull base accessed. These are the lateral parapharyngeal space, petrous apex (61605, extradural, and 61606, intradural) and the parasellar area, cavernous sinus, clivus or midline skull base (61607, extradural, and 61608, intradural).
 
The lateral parapharyngeal space and petrous apex lie to the outside of the skull, or near the "edges" of the middle fossa. The parasellar area, cavernous sinus, clivus and midline skull base lie centrally, toward the middle of the skull near the pituitary gland. Choosing the correct code to report the procedure performed depends, in large part, on the surgeon's documentation. Coders should encourage surgeons to adapt CPT terminology whenever possible to ease code selection. In some cases, the surgeon may not indicate landmarks (e.g., clivus, petrous sinus, etc.) noted in CPT, or may use terminology unfamiliar to the coder. Always consult the surgeon prior to submitting a claim if documentation does not clearly indicate the area of the middle fossa from which the lesion is removed, or if the proper code is not obvious. For example, the surgeon may indicate that a specific nerve is encased in the tumor, and depending on which nerve is listed the location may be identifiable from that.

Add-On Codes for Middle Fossa Procedures
 
 
Codes 61609-61612 are add-on codes that may only be used with the middle fossa definitive procedure codes. Codes 61609 (transection or ligation, carotid artery in cavernous sinus; without repair [list separately in addition to code for primary procedure]) and 61610 (... with repair by anastomosis or graft ...) are applied to 61607 and 61608, while 61611 (... in petrous canal; without repair ...) and 61612 (... with repair by anastomosis or graft ...) are applied to 61605 and 61607. Documentation must clearly support billing for these procedures (see note, below). Do not append modifier -51 (multiple procedures) to 61609-61612, as the fee has already been reduced to reflect their status as add-on procedures.
 
Note: Arterial ligation is normally performed for patients who have severe neurologic deficits that result from blunt trauma.

 
Occasionally, the surgeon may use the skull-base codes to clip (remove) an aneurysm. The only applicable code for this is 61613 (obliteration of carotid aneurysm, arteriovenous malformation, or carotid-cavernous fistula by dissection within cavernous sinus), although treatment of other aneurysms would come under the definition of "vascular lesion," which is common to all definitive code descriptions. Note that the skull-base-approach codes may be billed with 61613 for clipping a carotid aneurysm in the cavernous sinus but may not be used with aneurysmremoval codes 61697-61702, which already include an approach procedure. Reporting a separate approach with 61697-61702 is double billing and may lead to denials, audits and charges of fraud.

 
The posterior, or rearmost, fossa rests below the brainstem and cerebellum, says Steven Hysell, MD, of Central California Faculty Medical Group (CCFMG), an organization of faculty physicians and staff headquartered in Fresno, Calif. As with the anterior procedures, there are two posterior cranial fossa definitive procedures codes, 61615 (resection or excision of neoplastic, vascular or infectious lesion of base of posterior cranial fossa, jugular foramen, foramen magnum, or C1-C3 vertebral bodies ...) and 61616, differentiated according to intra- (61616) or extradural (61615).  
 
Again, coders should look to the operative report for evidence of closure of the dura, as well as to the selected approach (which, in this case, should be from the 61595-61598 series) when selecting a code.

 
The repair/reconstruction codes (61618-61619) are "reported separately if extensive dural grafting, cranioplasty, local or regional myocutaneous pedicle flaps or extensive skin grafts are required," according to CPT. These codes are accessed only if a secondary repair or reconstruction is necessary, e.g., due to a dural leak, Hysell says. Such procedures will occur during a later operative session.
 
If the secondary repair/reconstruction occurs during the definitive procedure's global period and was planned at the time of that procedure, report the appropriate repair code with modifier -58 (staged or related procedure by the same physician during the postoperative period) appended. If the repair was not planned at the time of the definitive procedure, report the appropriate code and append modifier -78 (return to the operating room for a related procedure during the postoperative period), Hysell says.

Additional Procedures
 
 
When appropriate, other procedures may be reported with the definitive procedure codes.
 
Code 69990 (use of operating microscope) is an add-on code that may be used to report microdissection. Use of the operating microscope is common with these procedures.
 
A tracheostomy may be needed to maintain airway control during certain approach/definitive procedures, particularly those that are anterior. This is coded 31600 (tracheostomy, planned [separate procedure]). Similarly, lumbar puncture code 62272 (spinal puncture, therapeutic, for drainage of spinal fluid [by needle or catheter]) may be used when regulating CSF pressure.
 
When a myocutaneous flap repair is performed during closure, 15732 (muscle, myocutaneous, or fasciocutaneous flap; head and neck [e.g., temporalis, masseter, sternocleidomastoid, levator scapulae]) -- rather than the secondary repair codes above -- may also be used for each separate muscle flap. Likewise, if a portion of the fascia lata is harvested to repair the dura (as may happen with a diagnosis of meningioma), 20920 (fascia lata graft; by stripper) or 20922 (... by incision and area exposure, complex or sheet) may be claimed. Code 20926 (tissue grafts, other [e.g., paratenon, fat, dermis]) may also be reported for separately harvested grafts such as when fat is placed to obliterate a large defect, with 15770 used for the placement of a derma-fat-fascia graft.
 
Note: Codes 20920 and 20922 are modifier -51 exempt.
 
As always, be sure documentation supports the billing of these additional services.

 
Because skull-base surgeries are divided into three distinct parts, and several surgeons may take part, modifier use can be confusing. If the neurosurgeon performs the definitive procedure but does not perform the approach, he or she may bill for the definitive portion of the surgery with no modifiers.
 
For example, an otolaryngologist or other specialist performs an approach to the middle fossa (61590-61592). The neurosurgeon removes an intradural lesion from the petrous apex. In this case, report 61606 for the neuro-surgeon's portion of the surgery.
 
If the neurosurgeon performs both an approach and the definitive procedure, the secondary portion of the surgery must be billed with modifier -51 attached. It is best to apply modifier -51 to the procedure with the lower payment amount because definitive procedures can pay more or less than their associated approach codes.
 
For instance, the neurosurgeon in the above example performs the approach, followed by removal of the lesion. Code the approach (61590-61592) and 61606-51. In some cases, the neurosurgeon may act as a co- or assistant surgeon during an approach by an ENT surgeon, and perform the definitive procedure alone. In this case, modifier -51 must be attached to the definitive procedure code, along with modifier -62 (two surgeons) or -80 (assistant surgeon) on the approach code, as appropriate.
 
Note: When submitting a claim with modifier -62, each surgeon must prepare his or her own operative report.
 
Sometimes, two surgeons may work together during the definitive portion of the surgery. In this case, each surgeon should apply modifier -62 to the appropriate procedure code, with modifier -51 if either surgeon also performed an earlier portion of the surgery. Generally, however, these surgeries are sequential, i.e., a single surgeon will perform distinct portions of the total procedure.