Neurology & Pain Management Coding Alert

Identify the nerves tested to ease the path, experts say

If you find reporting nerve conduction studies (NCS) confusing, especially when the neurologist stimulates or records multiple nerve fibers, take heart: NCS claims can be a snap with the right tools and a little coding direction. Follow these four expert-approved steps for foolproof NCS claims.

1. Determine the Nerve Fiber Type(s)

Before determining which NCS codes apply, you must first know the types of nerve fibers the neurologist tested.

All nerves contain motor fibers, sensory fibers or a mixture of the two, says Neil Busis, MD, chief of the division of neurology and director of the neurodiagnostic laboratory at the University of Pittsburgh Medical Center at Shadyside, and clinical associate professor of neurology, University of Pittsburgh School of Medicine.

Codes 95900 and 95903 describe motor fiber testing (the former without F-wave study, the latter with F-wave study), while code 95904 describes sensory or mixed fiber testing (see "What's What? A Quick Guide to NCS Terminology"  for an explanation of "motor," "sensory" and "mixed" nerve fibers).

During NCS, the neurologist places a stimulating electrode at one location along the nerve and a recording electrode at another location along the same nerve. The stimulating electrode delivers a low-level electrical charge, while the recording electrode measures the resulting nerve function.

Coding example: The neurologist places stimulation electrodes on the radial motor nerve with recording electrodes at the extensor indicis proprius. He conducts the test without F-waves. Because this nerve contains motor fibers only, you should report one unit of 95900, Busis says. If the neurologist had included an F-wave study, you would be correct to report 95903.

If, however, the neurologist tested a sensory nerve, such as the medium sensory nerve, 95904 would be appropriate. And, had he tested a single nerve containing both sensory and motor fibers (such as the median mixed nerve in the palm, which connects to the lumbrical muscles) you would also report 95904.

2. Count the Billable Units

You should report multiple units of NCS, when appropriate, and failing to do so will seriously compromise your reimbursement.

Don't miss: The number of billable units does not necessarily correspond to the number of nerves the neurologist tests, says Tiffany Schmidt, JD, policy director for the American Association of Electrodiagnostic Medicine (AAEM). Rather, the number of billable units depends on the movement of the stimulating and recording electrodes.

If either the recording or stimulating electrode remains stationary during the study, you may report only one unit of the appropriate NCS code. But if the neurologist moves both the recording and stimulating electrodes - even if to different locations on the same nerve - you may report multiple units of the appropriate code, says Heather Corcoran, coding manager at CGH Billing Services, a medical billing firm in Louisville, Ky. And, if the neurologist does test multiple nerves, you may likewise report multiple units.

Coding example 1: If the neurologist studies the median mixed and median sensory nerves, you should report two units of 95904 (two separate nerves). If the neurologist tests the median motor nerve, then moves both the stimulating and recording electrodes, you should report 95900 x 2 (because the physician moved both electrodes while testing the same nerve). But if the neurologist had moved only the stimulating electrode during the second round of testing, you could report only a single unit of code 95900.

Watch for: Some insurers reject 95900 and 95903 reported during the same session, arguing that 95900 is a component of 95903. The National Correct Coding Initiative (NCCI) does bundle these codes, but the bundle  applies only if you report both codes for the same location. If the neurologist conducts one of each type of study on separate nerves, you may report two separate studies, Busis says.

Coding example 2: The neurologist stimulates the median motor nerve, recorded at the adductor pollicis brevis (without F-waves), and follows by stimulating the anterior interosseous branch of the median motor nerve while recording at the pronator quadratus (with F-waves).

In this case, you should report 95900, 95903 because the neurologist moved both the stimulating and recording electrodes. Therefore, two separate studies occurred (one with F-waves and one without), and you may bill accordingly. However, had the neurologist stimulated the anterior interosseous branch and recorded at the pronator quadratus, first without F-waves and then with F-waves, you should only report 95903 (the study without F-waves is included in the study with F-waves).

Bonus Tip: Turn to the Table of Nerves

As an alternative to counting the number of "moving electrodes" (described in tip #2) to determine the number of billable NCS units, the AMA has developed a list of all the nerve conduction studies that you may report as separate procedures.

The AMA arranged the list of separately reportable studies by type (motor or sensory/mixed) and location (upper extremity, lower extremity, cranial and root stimulation). By comparing the physician's documentation to the list of separately reportable procedures, you can easily identify the correct type and number of NCS codes to bill the studies.

Note: You may access the above list, officially released in CPT Assistant in 2002, by visiting the American Academy of Electrodiagnostic Medicine (AAEM) Web site at www.aaem.net. Click on the "Practice Issues/Advocacy" and "List of Nerves" links.

3. Watch Out for Use/Frequency Limits

When reporting multiple NCS units or testing the same patient on multiple occasions, neurologists and their coders should be aware of payers' use and frequency guidelines.

Payers set limits on the maximum number of NCS units they will reimburse for a given diagnostic category. Generally, payers abide by the AAEM's "Recommended Policy for Electrodiagnosic Testing," which includes a chart listing the "maximum number of tests necessary in 90 percent of cases" for a variety of diagnostic categories and electro-diagnostic tests (including NCS, EMG, etc.).

Take note: The AAEM's chart lists the maximum recommended number of NCS units for radiculopathy as three motor units (either 95900 or 95903) and two sensory units (95904), for example. Although payers may allow you to exceed the AAEM's recommend maximums in some cases, your documentation must clearly support the necessity. "Without a thorough explanation, the insurer's going to reject the claim," Schmidt says.

And major insurers such as Aetna set frequency guidelines, specifying, for instance, that use of 95900-95904 "at a frequency of two times per year would be considered appropriate for most conditions" - including unilateral or bilateral carpal tunnel syndrome, radiculopathy, mononeuropathy, polyneuropathy, myopathy and neuromuscular junction disorders - but that the payer may reject more than two claims per year as excessive.

4. Provide the Documentation to Back It Up

Complete documentation is crucial to receive prompt and appropriate payment for NCS claims, Schmidt says. The AAEM recommends documenting the nerves the physician evaluated, the distance between the stimulation and recording sites, and the conduction velocity, latency values and amplitude for each study.

At a minimum, the physician's documentation should note the number of nerves tested and indicate if he or she tested additional branches of the same nerve separately, Corcoran says.

Without such explanations, insurers are likely to reject multiple units of the same code (for instance, 95904 x 2) as a duplication of services, even if the coding accurately reflects the work the physician performed.