Neurosurgery Coding Alert

When reporting stereotactic radiosurgery, also called gamma knife surgery, you may assign up to five units of 61793 per claim. To take advantage of this opportunity, however, the circumstances of the surgery must meet three conditions.

If your surgeon uses stereotactic radiosurgery, targeting either the brain or spine, you should automatically reach for 61793 (Stereotactic radiosurgery [particle beam, gamma ray or linear accelerator], one or more sessions) to report the procedure.

Although the CPT descriptor for 61793 does not state "per lesion," the AMA has provided instructions in its CPT Assistant (January 2006, Vol. 16, No. 1, page 46) recommending that you may report up to five units of 61793 per session. This assumes, of course, that the surgeon must treat multiple lesions.

In other words: You may not report multiple units of 61793 for multiple treatments on the same lesion. Instead, you may report one unit of 61793 for each separate lesion the surgeon treats, up to five lesions.

"Code 61793 describes stereotactic radiosurgery of a single lesion, with one or more isocenters, treated in a single fraction or over several sessions," says Gregory Przybylski, MD, director of neurosurgery at the New Jersey Neuroscience Institute, JFK Medical Center in Edison.

What if the surgeon treats more than five lesions? AMA instructions state directly that you should not report 61793 "more than five times for any session" [emphasis in original]. Therefore, even if the surgeon treats more than five lesions per date of service, you should limit yourself to no more than five units of 61793.

Number of lesions matters, not number of sessions: The descriptor for 61793 does specify "one or more sessions." This is because the surgeon may have to treat the same lesion during more than one session over a period of time to safely treat it. In these cases, which are called "fractionated treatments," you should report 61793 only once per lesion, regardless of how many sessions the surgeon requires to destroy the lesion.

CPT Assistant supports this coding, stating, "Code 61793 is intended to describe the physician work in treating a single lesion regardless of whether that treatment requires multiple isocenters or multiple sessions" [emphasis in original]. The article goes on to confirm, "Any additional sessions for the same lesion(s) are inclusive of code 61793."

Example: The surgeon uses the gamma knife to target and destroy four spinal lesions. During an initial session, the surgeon treats two of the lesions completely but plans to fractionate treatment for two others. During a later session, the surgeon again treats the remaining two lesions.

Because the surgeon treated four separate lesions, you may report 61793 x 4. The number of sessions the surgeon requires to treat the lesions does not factor into the coding.

Especially difficult circumstances may call for modifier 22: "If any lesion requires multiple isocenters and/or requires more complex targeting, then code 61793 should be reported appended by modifier 22 (Increased procedural services)," the January 2006 CPT Assistant says. At the same time, the issue confirms that "61793 is reported once per lesion treated whether one isocenter is used to treat the lesion or multiple isocenters are used to treat the lesion."

Tip: Remember that you should apply modifier 22 only in those truly difficult and unusual circumstances that call for significant additional physician work and/or time. For complete instructions on applying modifier 22 appropriately, see "Follow 3 Tips for Modifier 22 Success Every Time," in Neurosurgery Coding Alert, Vol. 9, No. 4, pages 28-30).

If you report 61793 multiple times for multiple lesions, you must also append modifier 59 (Distinct procedural service) to tell the payer that the neurosurgeon treated several distinct, anatomically separate lesions. This alerts the payer, for instance, that you are not (improperly) reporting multiple units of 61793 to indicate that the surgeon required more than one session to treat a single lesion.

"Based on CMS payment policy, you should describe treatment of additional lesions with 61793 appended with 59 modifier, for up to a total of five lesions in one session," Przybylski says.

Therefore, in the above example in which the surgeon uses the gamma knife to remove four lesions over the course of two sessions, you would report 61793 for the initial lesion, plus 61793-59 x 3 for each of the three additional, anatomically distinct lesions the surgeon targets.

- Better late than never: If the neurosurgeon discovers and treats a new lesion during the 90-day global period of the original stereotactic radiosurgery treatment, you should once again report 61793, but you would append modifier 58 (Staged or related procedure or service by the same physician during the postoperative period) to show that this is a related, "more extensive" procedure.

"In such a case, the pathology is likely the same, and you will require the same ICD-9 as the earlier procedure," Przybylski says.

You should not claim 20660 (Application of cranial tongs, caliper or stereotactic frame, including removal [separate procedure]) or +61795 (Stereotactic computer-assisted volumetric [navigational] procedure, intracranial, extracranial or spinal [list separately in addition to code for primary procedure]) in addition to 61793.

AMA guidelines -- as outlined in the above-referenced CPT Assistant -- and national Correct Coding Initiative (CCI) edits both stress that you should include the planning phase of the stereotactic radiosurgery (61795) and the frame application (20660) as part of the main surgical procedure (61793). Payment for the planning and frame application is already included in reimbursement for 61793.