Neurosurgery Coding Alert

Question: Can you help me with this operative report for a parietooccipital craniotomy? I am thinking of reporting 61518 (Craniectomy for excision of brain tumor, infratentorial or posterior fossa; except meningioma, cerebellopontine angle tumor, or midline tumor at base of skull) but need confirmation that this would be correct.

Description: The patient received a stereotactic-planning MRI. Data was entered into the StealthStation and preoperative planning was performed, outlining the enhancing mass in the left parietooccipital region. The patient is a 57 year old gentleman who had received stereotactic radiosurgery to an AVM to this location nearly 20 years ago, and preoperatively the question was whether he had vascular malformation or a lesion, radiation necrosis or a tumor. The patient's head was fixated to the operative table in the lateral position with the left side up, and the patient's left parietooccipital temporal cranium was prepped & draped in the usual manner.

After prep & drape, a skin incision was made in a C-shaped fashion in the parietooccipital region on the left. This was carried down through the underlying galea. Hemostatis was obtained with the use of Raney clips. A small amount of termporalis muscle was incised, and the entire flap was turned with the pericranium inferiorly and held to the operative table with suture elastic bands & a stockinette. StealthStation was used throughout the case to confirm localization. Burr holes were placed in 2 locations in the cranium with the craniotomy attachment and with the craniotome the craniotomy flap was turned in the standard fashion at this location. Epidural vessels were coagulated. Oxycel cotton was used in the epidural space for hemostasis. The dura was incised & turned inferiorly as well.

The surface of the brain showed that at the surface and slightly adherent to the dura with some crossing fibrous tissue was a purple mass consistent with a type of venous malformation. The brain around it was hemosiderin state. A plane was developed around this protruding purple mass which then widened & became deeper as one went, but a plane could be developed through hemosiderin-laden tissue. At some points, the tissue appeared much firmer than normal white matter, and as one went through the hemosiderin-laden tissue, one would approach normal white matter. In this fashion, a plane could be developed around this lesion. The lesion in itself did not have any arterial color or component to it but did have various pockets of venous bleeding within it. The gross appearance would be that of cavernous malformation. A plane was developed circumferentially around the lesion, which then was removed in toto & sent to Pathology.

Frozen sections were sent of some of the surrounding tougher tissue that was hemosiderin laden also to the lesion, and the frozen sections do not show any necrosis or any significant abnormality that would be considered tumor. More permanent sections were sent from this area as well. With the major lesion removed from the bed, the bed was inspected & several other areas suspicious for venous cavernous lesion were removed until the entire bed was either normal edematous white matter or slightly hemosiderin laden & tougher tissue. The brain appeared relaxed.

Answer: Due to the presence of the venous blood and the history of the previous AVM, this is most likely some type of venous malformation or hemangioma. Since the surgeon reports this grossly as a cavernous malformation (a form of AVM), consistent with the intraoperative findings, you would report the procedure with 61680 (Surgery of intracranial arteriovenous malformation; supratentorial, simple) Although these are often performed with microdissection using the operating microscope (69990, Microsurgical techniques, requiring use of operating microscope [List separately in addition to code for primary procedure]), this was not described in the operative note.

Code 61518 would not be applicable since this is for a neoplasm in the infratentorial or posterior fossa. The posterior fossa is part of the intracranial cavity, located between the foramen magnum and tentorium cerebella; it contains the brainstem and cerebellum. The parieto-occipital lobes are part of the supratentorial region. The supratentorial region contains the cerebrum, while the infratentorial region contains the cerebellum.