Keep in Step with SEP and MEP

CPT® 2012 revises intraoperative neurophysiologic monitoring code usage for surgery.

By Gloria Galloway, MD, FAAN

Use of intraoperative neurophysiologic monitoring (IONM) has increased over the last decade due to evidence of its role in reducing or preventing the incidence of paralysis or paraparesis in certain types of surgeries. Changes to CPT® 2012 affect codes used to bill monitoring for surgeries involving motor evoked potentials (MEP) and somatosensory evoked potentials (SEP).

Certified Inpatient Coder CIC

Turn to 95938, 95939 for Combined Limb Studies

Since January 2012, four-limb SEP tests are reported using 95938 Short-latency somatosensory evoked potential study, stimulation of any/all peripheral nerves or skin sites, recording from the central nervous system; in upper and lower limbs for short-latency SEP studies; code 95939 Central motor evoked potential study (transcranial motor stimulation); in upper and lower limbs is now used for central MEP studies.

The addition of 95938 and 95939 to CPT® 2012 reflects that all four limbs are tested together in virtually all cases. Per CPT® parenthetical instructions, do not report 95925 Short-latency somatosensory evoked potential study, stimulation of any/all peripheral nerves or skin sites, recording from the central nervous system; in upper limbs with 95926 Short-latency somatosensory evoked potential study, stimulation of any/all peripheral nerves or skin sites, recording from the central nervous system; in upper limbs, or 95928 Central motor evoked potential study (transcranial motor stimulation); upper limbs with 95929 Central motor evoked potential study (transcranial motor stimulation); lower limbs to describe four limb studies.

Although 95925-95926 and 95928-95929 are still active, they do not properly describe four-limb studies, and should be used to indicate studies of only the upper or lower limbs, as appropriate.

Codes 95938 and 95939 may be applied in inpatient or outpatient labs when testing four limbs, as shown in the following example.

Case 1: A 17-year-old female has a history of tingling in the left leg and blurred vision over the past six months, on and off. She is otherwise healthy and on no current medications. A diagnosis of multiple sclerosis is considered and further workup is scheduled to include a lower extremity SEP and visual evoked response (VER).

Coding for VER is 95930 Visual evoked potential (VEP) testing central nervous system, checkerboard or flash; the four-limb SEP is reported with 95938.

SEP and MEP May Be IONM Base Procedures

Codes 95938 and 95939 also may serve as “base procedures” when reporting IONM, as described by +95920 Intraoperative neurophysiology testing, per hour (List separately in addition to code for primary procedure).

Prior to performing IONM, the monitoring physician may first conduct one or more studies to establish a patient’s “baseline” responses. You may report these studies in addition to IONM. CPT® provides a list of approved baseline studies for use with IONM, which includes four-limb SEP or MEP, as well as electromyography (EMG), nerve conduction studies, and others.

Code 95920 is time based: For each hour of monitoring, you may report one unit. You cannot count “standby time” or time spent conducting baseline studies as IONM time, and you must report a minimum of 31 minutes of monitoring to bill for the next hour of service, as demonstrated:

Monitoring time

30 minutes or less: Not reported separately

31-90 minutes: 95920 x 1

91-150 minutes: 95920 x 2

151-210 minutes: 95920 x 3

Only a dedicated physician with the sole task of monitoring the patient during the surgery should separately claim IONM services.

Recent guidelines in intraoperative spinal monitoring have been published in Neurology®, helping to clarify the role of transcranial electric motor and SEP in spinal surgeries presenting an injury risk to spinal motor and sensory tracts. These guidelines indicate IONM can prevent the risk of paralysis or paraparesis by alerting the surgical team to the presence of changes in time for intervention. This intervention may include removal of hardware, loosening of hardware, raising blood pressure parameters, adjustments to anesthesia, or a variety of other possible interventions during the surgical procedure.

 Coding Examples Show You the Way

Appropriate use of the new four-limb SEP and MEP codes within 95920 can be shown using more example cases:

Case 2: A 15-year-old female with a history of scoliosis is to undergo anterior and posterior spinal fusion with instrumentation. Due to the risk of motor and sensory track injury during surgery, IONM is performed. Transcranial motor evoked potentials (TcEP) and SEP are monitored during this case, and monitoring continues for six hours. Some changes in SEP occur as a result of blood pressure (BP) changes, and medication changes were made to raise the mean arterial blood pressure (MAP) with improvement of the BP.

Proper CPT® coding is 95939 (1 unit includes all four limbs) and 95938 (1 unit includes all four limbs), plus 95920 x 6 (hourly code times number of hours).

Case 3: A 14-year-old patient is scheduled for repair of tethered cord and spinal fusion. He has a history of refractory seizures, which are poorly controlled, and he is on a three-drug antiepileptic regimen. Because of this patient’s epilepsy history, the monitoring and surgical teams decide that TcEP will not be obtained during the surgical procedure; although EMG monitoring, as well as SEP testing, will be obtained.

Proper coding for the EMG is 95870 Needle electromyography; limited study of muscles in 1 extremity or non-limb (axial) muscles (unilateral or bilateral), other than thoracic paraspinal, cranial nerve supplied muscles, or sphincters because fewer than four muscles were tested in each extremity, and nerve conduction studies were not done. SEP is reported using 95938 for all four limbs. Hourly IONM is reported using 95920, multiplied by the number of hours monitoring occurs.

In all cases, the diagnosis(es) linked to the IONM and baseline study codes should match the diagnosis(es) that the surgeon uses to justify the primary surgical procedure.

Be sure to append modifier 26 Professional component to 95920, as well as any baseline study code(s) billed. The facility will bill separately for the technical portion (equipment and supplies) of the services.


Gloria Galloway, MD, FAAN, is a professor of neurology at Ohio State University Medical Center, in Columbus, Ohio.


Latest posts by admin aapc (see all)

Leave a Reply

Your email address will not be published. Required fields are marked *