Documentation and Coding Guidelines for Intraoperative Neurophysiology Monitoring (IONM)

Title: Documentation and Coding Guidelines for Intraoperative Neurophysiology Monitoring (IONM)
Standard #:


Issued: 10/01/2019 Reviewed/Revision Date:


Intraoperative neurophysiologic monitoring (IONM) and testing are medical procedures that allow monitoring of neurophysiologic signals during a surgical procedure.  This standard addresses intraoperative monitoring of surgical cases performed in the operating room and in the neurosurgical radiology suites.

For purposes of reimbursement, IONM must be requested by the operating surgeon and the monitoring must be performed by a physician, other than the operating surgeon, the technical/surgical assistant or the anesthesiologist rendering the anesthesia.  It is also expected that a specifically trained technician, preferably registered with one of the credentialing organizations, will be in continuous attendance in the operating room, recording and monitoring a single surgical case, with either the physical or electronic capacity for real-time communication with a supervising physician who holds hospital privileges to perform intraoperative neurophysiology services.


  1. Ensures that data essential for evaluation of the patient is available
  2. Evaluates and interprets all baseline signals and requests changes in the monitoring procedures, if required;
  3. Interprets all significant changes from baseline recordings (or responses obtained from topographical studies) in real time;
  4. In real time, evaluates context appropriate data and recommends (or suggests) the likely anatomical areas of injury in the context of the surgical procedure when possible.


Assignment of cases:

  • Cases will be logged, tracked and updated for IONM physician monitoring
  • The log will include scheduled and add-on cases
    • Cases will be pre-assigned based on the physician’s predetermined schedule and availability.
    • Confirmation of the assigned IONM physician will occur before the case begins as to incorporate last minute changes in the OR schedule.
    • On-going communication will occur with technician as needed regarding IONM physician assignments and when hand‐offs occur.
    • Physician taking over a case will be responsible for notifying the technician that a hand off will occur.

 Formal tracking grid will include:

  • The day’s cases,
  • IONM physician assignment,
  • Handoffs to another IONM physician
  • Tracking of monitoring time from within the OR and/or monitoring time from outside the OR (remote or nearby).
    • Start and stop of actual monitoring time by physician

Documentation of monitoring report:

  • The technician may initially generate the IONM document with technical details only.
    • Technician must electronically sign the initial draft confirming their contribution and then forward to the IONM physician to complete the documentation.
  • The final medical record report must include personal documentation by the physician to include:
    • Initial brief clinical history of the patient supporting the reason for the surgery
    • Final interpretation of the baseline test results
    • Description of any neurophysiological changes during surgery
    • Actual monitoring time of the physician after baseline test completion
    • Electronic signature and date of IONM physician


Use of codes 95940, 95941, G0453 and their base procedure codes

IONM is a procedure that describes ongoing electrophysiologic testing, and monitoring performed during surgical procedures. It includes only the time spent during an ongoing, concurrent, real-time electrophysiologic monitoring.  Time spent in clinical activities, other than those above, should not be billed under 95940, 95941 and/or G0453. The time spent performing or interpreting the baseline electrophysiologic studies must not be counted as intraoperative monitoring, but represents separately reportable procedures.

  • For example 95940, 95941 and G0453 are distinct from performance of specific types of pre-procedural baseline electrophysiologic studies (95860, 95861, 95867, 95868, 95907-95913. 95933, 95937) or other interpretation of specific types of baseline electrophysiologic studies (95985, 95922, 95925-95930, 95938, 95939).
  • Note that the supervision requirements for each underlying test or primary test modality vary, and must be met (Medicare Benefit Policy Manual). For example, cortical mapping during monitoring requires personal supervision.

CPT and HCPCS codes for IONM billing

Codes that may be utilized when professional oversight is employed for IONM.  Professional oversight of IONM may be provided in two different ways:

  1. Monitoring oversight within the O.R. (95940)
  2. Monitoring oversight remotely from outside the O.R. (95941, G0453) which requires real-time remote connection

Codes 95940, 95941, and G0453 must always be billed in conjunction with the applicable base (primary) procedure code(s).

  • Each base (primary) code should be applied once per operative session.
  • Time spent after the procedure performing or interpreting neurophysiologic studies should not be counted as IONM, but reported as a separate procedure.
  • The monitoring professional must be monitoring in real-time and be solely dedicated to performing the monitoring.
  • Throughout the monitoring, there must be provisions for continuous and immediate communication directly with the operating room team in the surgical suite.
  • For procedures that last beyond midnight, report services using the day on which the monitoring began and using the total time monitored.

Add-on CPT codes 95940 and 95941:

CPT 95940 (Applicable to Medicare, Medi-Cal and some Commercial Insurance)

Continuous intraoperative neurophysiology monitoring in the operating room, one-on-one monitoring requiring personal attendance, each 15 minutes –

  • Billed in whole units and should be rounded to the next unit if at least 8 minutes of service is provided.
  • Code 95940 requires one-on-one monitoring. Simultaneous cases cannot be coded with 95940.
  • Code 95940 requires reporting only the portion of time the monitoring professional was physically present in the operating room providing one-on-one patient monitoring and no other cases may be monitored at the same time. Report continuous intraoperative neurophysiologic monitoring in the operating room (95940) in addition to the services related to monitoring from outside the operating room (95941).
  • The supervising physician time spent in the operating room includes the time from entering until leaving the operating room, except for the time spent interpreting the baseline testing.

CPT 95941 (Applicable to Most Commercial Insurance)

Continuous intraoperative neurophysiology monitoring, from outside the operating room (remote or nearby) or for monitoring of more than one case while in the operating room, per hour –

  • Billed in whole units and should be rounded up to the next unit if at least 31 minutes of service is provided.
  • For remote monitoring, it includes time from initiating to discontinuing monitoring except for the time spent interpreting the baseline testing.
  • Throughout the monitoring, there must be provisions for continuous and immediate communication directly with the operating room team in the surgical suite. One or more simultaneous cases may be reported (95941). When monitoring more than one procedure, there must be the immediate ability to transfer patient monitoring to another monitoring professional during the surgical procedure should that individual’s exclusive attention be required for another procedure. Report 95941 for all remote or non-one- on-one monitoring time connected to each case regardless of overlap with other cases.
  • Code 95941 allows for reporting simultaneous cases without division of time between them. The number of cases monitored at any one time will vary, but should not exceed the requirements for providing adequate attention to each. Payer policies should be reviewed to determine if individual insurers impose any limits on the number of overlapping cases that can be provided and billed.
  • Do not report 95941 if the monitoring lasts 30 minutes or less.

Intraoperative neurophysiology monitoring codes 95940 and 95941 are each used to report the total duration of respective time spent providing each service, even if that time is not in a single continuous block.

HCPCS CODE G0453 (Applicable to Medicare, Medi-Cal and Some Commercial Insurance)

Continuous intraoperative neurophysiology monitoring, from outside the operating room (remote or nearby), per patient, (attention directed exclusively to one patient), each 15 minutes

  • HCPCS code G0453 is billed in whole units and should be rounded up to the next unit if at least 8 minutes of service is provided, not to exceed 4 units per hour.
  • Multiple cases may be monitored simultaneously, but the monitoring professional can only bill one case at a time.
  • Monitoring professionals may use the method of their choice to allocate time to patients being simultaneously monitored, but only one unit of service can be billed for one patient for a 15-minute time period.
  • The monitoring professional may add up non-continuous time directed at one patient to determine how many units may be billed.
  • Monitoring professionals must account for the exclusive, non-continuous time spent monitoring Medicare patients when billing Medicare.
  • For remote monitoring, it includes time from initiating to discontinuing monitoring except for the time spent interpreting the baseline testing.


  • When standby care is requested, both the requesting physician and providing physician must document the need for standby care regardless of whether a claim for reimbursement is submitted
  • CPT guidelines for 99360, include:
    • The requesting physician must document in writing the request for the standby service.
      • This could be accomplished by the surgeon entering into the medical record or operative note to request the IONM services and the delay in the start of the services as originally scheduled.
    • The standby physician must not provide care to other patients during the standby period.
    • The standby physician should not submit 99360 for any service of less than 30 minutes total on that date of service.
    • You may report an additional unit of 99360 for each additional 30 minutes, meaning another full 30 minutes of standby service.
    • To report time spent waiting on standby for a case to start, use 99360.


Working With Residents and Fellows (Non-credentialed, non-billable Fellows)

  • Time-Based Codes: For procedure codes determined on the basis of time, the teaching physician must be present for the entire period of time for which the claim is made. Time spent by the resident in the absence of the teaching physician cannot be reported for billing purposes.

 Working With Fellows (Credentialed, Billing Fellows)

  • Certain IONM Fellows may have previously completed fellowship in neurophysiology and may be credentialed to bill independently for basic IONM procedures. They are not credentialed and cannot bill for complex IONM procedures for which they are currently in training.

Please reference policies B-406 Billing for Teaching Physicians and B-407 Billing for Fellows Participating in Private Practice for complete policy information.



AMA CPT Professional Edition, Intraoperative Neurophysiology section

AAN Policy  Model Coverage Policy – American Academy of Neurology