Neurosurgery Coding Alert

Append modifier 50 for bilateral procedures.

Do not miss out on an easy code for subtemporal cranial decompression. Once you have confirmed in the operative note that your surgeon did a subtemporal decompression, you can narrow down your focus to a single definitive code. You can learn how to report this procedure with an example of operative procedure note.

Step 1: Confirm the Decompression

You may read that your surgeon treated a patient who had classical symptoms of high intracranial pressure, i.e. headache and visual blurring. Upon investigations, your surgeon will document the confirmation of papilledema and small ventricles. You may also read the spinal or ventricular tap in this patient confirmed a high intracranial pressure and that the high pressure did not respond to medication. In this case, your surgeon may plan a cranial decompression.   “There are a number of treatment options in addition to cranial decompression that include fenestration of the optic nerve sheaths, with the goal of preserving or restoring vision, as well as CSF diversion with shunting,” says Gregory Przybylski, MD, director of neurosurgery, New Jersey Neuroscience Institute, JFK Medical Center, Edison.

Example: Here is an example of an operative note for a subtemporal approach for cranial decompression.

“We made a skin incision 1 cm anterior to the tragus and extended the incision approximately 8 cm perpendicular to the zygoma. We then did a subperiosteal dissection of the temporal bone and achieved a large craniectomy with a 6 cm diameter. Next, we opened the dura in a stellate fashion and drained the subarachnoid fluid. To achieve a watertight closure, we reapproximated the temporalis muscle and fascial layers ensuring that there was minimal cosmetic defect.”

Step 2: Narrow Down to 61340

Once you have confirmed the drainage of cerebrospinal fluid, you report the procedure of subtemporal decompression with code 61340 (Subtemporal cranial decompression [pseudotumor cerebri, slit ventricle syndrome]).

Check for bilateral procedures: For bilateral subtemporal cranial decompression, you report 61340 with modifier 50 (Bilateral procedures).

Step 3: Do Not Forget the Diagnosis Codes

The code descriptor of 61340 specifies that the code applies to subtemporal cranial decompression done for pseudotumor cerebri or slit ventricular syndrome.

Depending upon the type and cause of hydrocephalus, you should report the diagnosis codes, 331.3 (Communicating hydrocephalus) to 331.5 (Idiopathic normal pressure hydrocephalus [INPH]). You do not report other codes for the symptoms, i.e. headache or blurring of vision. 

If your surgeon documents a diagnosis of slit ventricular syndrome, you report code 996.75 (Other complications due to nervous system device implant and graft). “Slit ventricle syndrome can occur with improper CSF drainage from a shunt,” Przybylski says.