Neurosurgery Coding Alert

Any one of 14 codes (61580-61598) can describe the approach during skull-base surgery. Applying the appropriate code is complicated not only by the number of choices and the difficult terminology involved but because more than one approach may be required -- or because elements of several approaches may be combined. Payment for these procedures ranges from a high of 77.16 relative value units (RVUs), or about $3,000 on average, to a low of 46.39 RVUs, or about $1,800, according to Medicare's 2001 Physicians Fee Schedule. Therefore, inaccurate coding can alter reimbursement significantly.
Identify the Area To Be Accessed  
The skull base is the foundation of the cranium-- a thick, complex structure on which the brain rests, and which separates the brain from the remainder of the head, face and neck. The approach for skull-base surgeries, which are usually performed to remove a tumor on the undersurface of the brain, gains access to one of three areas: the anterior (frontal) cranial fossa (61580-61586), middle (temporal) cranial fossa (61590-61592), or posterior (cerebellur) cranial fossa (61595-61598). The anterior fossa lies approximately above the eyes. The middle fossa, an irregularly shaped area resembling a butterfly and centered on the pituitary gland, encompasses the temporal lobes of the brain. The posterior fossa rests below the brainstem and cerebellum.
 
"The surgeon may access any of the fossae via one of several entry points," says Vallo Benjamin, MD, professor of neurosurgery at New York University. Because different entry points can lead to the same destination, however, the direction of dissection -- rather than the point of entry -- determines which internal structures are revealed and therefore dictates initial code selection. In simple terms, when first choosing the code, the destination matters more than how you got there.
 
Ideally, the surgeon will clearly dictate in the operative report the fossa(e) he or she approached. Alternatively, the coder may apply his or her knowledge of anatomy to determine the area(s) of the skull base accessed and narrow the code selection accordingly. The location of the tumor (or other reason for surgery) -- which should always be documented -- can provide guidance. For instance, the documentation might specify, "A tumor at the clivus was approached via the sphenoid sinus." The clivus lies just in front of the brain stem, toward the rear of the skull, and is therefore located in the rear portion of the middle cranial fossa. In this case, the correct approach code should be chosen from the 61590-62592 range. Always confer with the surgeon if documentation is unclear or if there is any doubt that the proper code range has been selected.

Intra- or Extradural?  
The next step in narrowing code selection is to determine whether the dissection occurs intra- or extradurally. The [...]