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: A Triple Coding Challenge  
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 [...]