Coding Medically Necessary Code Description CPT
95940 Continuous intraoperative neurophysiology monitoring in the operating room, one on one monitoring requiring personal attendance, each 15 minutes (List separately in addition to code for primary procedure)
95941 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 (List separately in addition to code for primary procedure)
G0453 Continuous intraoperative neurophysiology monitoring, from outside the operatingroom (remote or nearby), per patient, (attention directed exclusively to one patient) each 15 minutes (list in addition to primary procedure)
Introduction
Tests can be done on specific nerves during complex brain, spine, and neck surgeries to help make sure the nerves are not being harmed. This is known as intraoperative neurophysiologic monitoring (IONM). There are a number of ways to perform this monitoring. It often involves the use of sophisticated medical devices to assess the muscle or electrical response when a nerve is stimulated. The goal is to provide the surgeon with immediate feedback about whether a nerve is at risk of being injured. The surgeon can make a correction right away to avoid permanent damage. This type of monitoring is well proven in specific types of surgeries. Some surgeons are using IONM during surgery for nerves located outside of the brain and spinal cord (the peripheral nerves). There is not enough medical evidence to show whether IONM leads to better health results when used for the peripheral nerves. For this reason, IONM is considered not medically necessary for peripheral nerve surgery.
Note: The Introduction section is for your general knowledge and is not to be taken as policy coverage criteria. The rest of the policy uses specific words and concepts familiar to medical professionals. It is intended for providers. A provider can be a person, such as a doctor, nurse, psychologist, or dentist. A provider also can be a place where medical care is given, like a hospital, clinic, or lab. This policy informs them about when a service may be covered.
Intraoperative Monitoring
Medical Necessity
* Somatosensory-evoked potentials
* Motor-evoked potentials using transcranial electrical stimulation
* Brainstem auditoryevoked potentials
* Electromyography (EMG)of cranial nerves
* Electroencephalography
* Electrocorticography
The types of Intraoperative neurophysiologic monitoring, listed on the left, may be considered medically necessary when there is significant risk of nerve or spinal cord injury during the following spinal, intracranial, vascular or recurrent laryngeal nerve surgical procedures: (this list may not be all inclusive)
* Aortic, thoracic, and abdominal aneurysm repair
* Aortic cross-clamping
* Arteriovenous malformation repair of the spinal cord
* Brachial plexus surgery
* Cerebral vascular surgery (eg, carotid endarterectomy, cerebral aneurysm)
* Clipping of intracranial aneurysms
* Cortical localization
* Interventional neuroradiology
* Pelvic fracture surgery
* Release of a tethered cord
* Repair of coarctation of the aorta
* Resection of fourth ventricular cyst
* Resection of intracranial vascular lesions
* Resection of spinal cord tumor, cyst, or vascular lesion
* Scoliosis correction with instrumentation
* Surgical stabilization of spine fractures
* Stereotactic surgery of the brain or brain stem, thalamus, or cerebral cortex
* Thalamus tumor resection or thalamotomy
* Thyroid surgery
* Anterior cervical spinal fusions
* Thoracic spine surgery
Intraoperative neurophysiologic monitoring for ANY other indication, including during lumbar surgery below L1/L2 is considered not medically necessary. (see Related Information)
* EMG The types of intraoperative neurophysiologic monitoring,
Intraoperative Monitoring Medical Necessity
* Nerve conduction velocity monitoring listed on the left during surgery on the peripheral nerves are considered not medically necessary. Intraoperative Monitoring Investigational
* Somatosensory-evoked potentials
* Motor-evoked potentials using transcranial electrical stimulation
* Brainstem auditoryevoked potentials
* Electromyography (EMG) of cranial nerves
* Electroencephalography
* Electrocorticography
The types of intraoperative neurophysiologic monitoring, listed on the left during the following surgical procedure is considered investigational:
* Esophageal surgeriesMotor-evoked potentials using transcranial magnetic stimulation
Due to the lack of monitors approved by the U.S. Food and Drug Administration, intraoperative monitoring of motorevoked potentials using transcranial magnetic stimulation is considered investigational.
Related Information
These policy statements refer only to use of these techniques as part of intraoperative monitoring. Other clinical applications of these techniques, such as visual-evoked potentials and
EMG, are not considered in this policy. Intraoperative neurophysiological monitoring is indicated in select spine surgeries when there is risk for additional spinal cord injury. Intraoperative monitoring has not been shown to be of clinical benefit for routine lumbar or cervical nerve root decompression (AANEM 2014), or during routine lumbar or cervical laminectomy or fusion (AANEM, 1999a) in the absence of myelopathy or other complicating conditions, which could increase the potential risk of damage to the nerve root or spinal cord, Resnick et al (2005) in published guidelines for the performance of fusion procedures for degenerative disease of the lumbar spine reported that based on the medical evidence of the literature reviewed there did not appear to be support for the hypothesis that any form of intraoperative monitoring improves patient outcomes following lumbar decompression or fusion procedures for degenerative spinal disease. The authors concluded in a 2014 update there was no evidence that intraoperative monitoring can prevent injury to the nerve roots.
Intraoperative neurophysiologic monitoring including somatosensory-evoked potentials and motor-evoked potentials using transcranial electrical stimulation, brainstem auditory-evoked potentials, electromyography of cranial nerves, electroencephalography, and electrocorticography has broad acceptance, particularly for spine surgery and open abdominal aorta aneurysm repairs. Additionally, this policy addresses monitoring of the recurrent laryngealnerve during neck surgeries and monitoring of peripheral nerves.
Intra-operative monitoring is considered reimbursable as a separate service only when a licensed physician, other than the operating surgeon, performs the monitoring while in attendance in the operating room or present by means of a real-time remote mechanism and is immediately available to interpret the recording and advise the surgeon throughout the procedure.
Intra-operative monitoring consists of a physician monitoring not more than three cases simultaneously. Constant communication between surgeon, neurophysiologist, and anesthetist are required for safe and effective intraoperative neurophysiologic monitoring.
Evidence Review
Description
Intraoperative neurophysiologic monitoring (IONM) describes a variety of procedures used to monitor the integrity of neural pathways during high-risk neurosurgical, orthopedic, and vascular surgeries. It involves the detection of electrical signals produced by the nervous system in response to sensory or electrical stimuli to provide information about the functional integrity of neuronal structures. This policy does not address established neurophysiologic monitoring (ie, somatosensory-evoked potentials, motor-evoked potentials using transcranial electrical stimulation, brainstem auditory-evoked potentials, electromyography of cranial nerves, electroencephalography, electrocorticography), during spinal, intracranial, or vascular procedures.
Background
Intraoperative Neurophysiologic Monitoring
The principal goal of intraoperative neurophysiologic monitoring (IONM) is identification of nervous system impairment on the assumption that prompt intervention will prevent permanent deficits. Correctable factors at surgery include circulatory disturbance, excess compression from retraction, bony structures, hematomas, or mechanical stretching. The technology is continuously evolving with refinements in equipment and analytic techniques, including recording, with several patients monitored under the supervision of a physician who is outside the operating room.
The different methodologies of monitoring are described next.
Sensory-Evoked Potentials
Sensory-evoked potential (SEP) describes the responses of the sensory pathways to sensory or electrical stimuli. Intraoperative monitoring of SEPs is used to assess the functional integrity of central nervous system (CNS) pathways during surgeries that put the spinal cord or brain at risk for significant ischemia or traumatic injury. The basic principles of SEP monitoring involve identification of a neurologic region at risk, selection and stimulation of a nerve that carries a signal through the at-risk region, and recording and interpretation of the signal at certain standardized points along the pathway. Monitoring of SEPs is commonly used during the following procedures: carotid endarterectomy, brain surgery involving vasculature, surgery with distraction compression or ischemia of the spinal cord and brainstem, and acoustic neuroma surgery. SEPs can be categorized by type of simulation used, as follow.
Somatosensory-Evoked Potentials
Somatosensory-evoked potentials (SSEPs) are cortical responses elicited by peripheral nerve stimulations. Peripheral nerves, such as the median, ulnar, or tibial nerves, are typically stimulated, but, in some situations, the spinal cord may be stimulated directly. Recording is done either cortically or at the level of the spinal cord above the surgical procedure. Intraoperative monitoring of SSEPs is most commonly used during orthopedic or neurologic surgery to prompt intervention to reduce surgically induced morbidity and/or to monitor the level of anesthesia. One of the most common indications for SSEP monitoring is in patients undergoing corrective surgery for scoliosis. In this setting, SSEP monitors the status of the posterior column pathways and thus does not reflect ischemia in the anterior (motor) pathways. Several different techniques are commonly used, including stimulation of a relevant peripheral nerve with monitoring from the scalp, from interspinous ligament needle electrodes, or from catheter electrodes in the epidural space
Brainstem Auditory-Evoked Potentials
Brainstem auditory-evoked potentials (BAEPs) are generated in response to auditory clicks and can define the functional status of the auditory nerve. Surgical resection of a cerebellopontine angle tumor, such as an acoustic neuroma, places the auditory nerves at risk, and BAEPs have been extensively used to monitor auditory function during these procedures.
Visual-Evoked Potentials
Visual-evoked potentials (VEPs) with light flashes are used to track visual signals from the retina to the occipital cortex. VEP monitoring has been used for surgery on lesions near the optic chiasm. However, VEPs are very difficult to interpret due to their sensitivity to anesthesia, temperature, and blood pressure.
Motor-Evoked Potentials
Motor-evoked potentials (MEPs) are recorded from muscles following direct or transcranial electrical stimulation of motor cortex or pulsed magnetic stimulation provided using a coil placed over the head. Peripheral motor responses (muscle activity) are recorded by electrodes placed on the skin at prescribed points along the motor pathways. MEPs, especially when induced by magnetic stimulation, can be affected by anesthesia. The Digitimer electrical cortical stimulator received U.S. Food and Drug Administration (FDA) premarket approval in 2002. Devices for transcranial magnetic stimulation have not been approved by the FDA for this use. Multimodal IONM, in which more than 1 technique is used, most commonly with SSEPs and MEPs, has also been described.
Electromyogram Monitoring and Nerve Conduction Velocity Measurements
Electromyography (EMG) monitoring and nerve conduction velocity measurements can be performed in the operating room and may be used to assess the status of the cranial or peripheral nerves (eg, to identify the extent of nerve damage before nerve grafting or during resection of tumors). For procedures with a risk of vocal cord paralysis due to damage to the recurrent laryngeal nerve (ie, during carotid artery, thyroid, parathyroid, goiter, or anterior cervical spine procedures), monitoring of the vocal cords or vocal cord muscles has been performed. These techniques may also be used during procedures proximal to the nerve roots and peripheral nerves to assess the presence of excessive traction or other impairment. Surgery in the region of cranial nerves can be monitored by electrically stimulating the proximal (brain) end of the nerve and recording via EMG activity in the facial or neck muscles. Thus, monitoring is done in the direction opposite that of SEPs, but the purpose is similar—to verify that the neural pathway is intact.
Electroencephalogram MonitoringSpontaneous electroencephalography (EEG) monitoring can also be used during surgery and can be subdivided as follows:
* EEG monitoring has been widely used to monitor cerebral ischemia secondary to carotid cross-clamping during a carotid endarterectomy. EEG monitoring may identify those patients who would benefit from the use of a vascular shunt during the procedure to restore adequate cerebral perfusion. Conversely, shunts, which have an associated risk of iatrogenic complications, may be avoided in those patients with a normal EEG. Carotid endarterectomy may be done with the patient under local anesthesia so that monitoring of cortical function can be directly assessed.
* Electrocorticography (ECoG) is the recording of the EEG activity directly from a surgically exposed cerebral cortex. ECoG is typically used to define the sensory cortex and map the critical limits of a surgical resection. ECoG recordings have been most frequently used to identify epileptogenic regions for resection. In these applications, ECoG does not constitute monitoring, per se.
Intraoperative neurophysiologic monitoring, including SSEPs and MEPs using transcranial electrical stimulation, BAEPs, EMG of cranial nerves, EEG, and ECoG, has broad acceptance, particularly for spine surgery and open abdominal aorta aneurysm repairs. These indications have long been considered standard of care, as evidenced by numerous society guidelines, including those from the American Academy of Neurology, American Clinical Neurophysiology Society, American Association of Neurological Surgeons, Congress of Neurologic Surgeons, and American Association of Neuromuscular & Electrodiagnostic Medicine.1-7 Additionally, this policy addresses monitoring of the recurrent laryngeal nerve during neck and esophageal surgeries and monitoring of peripheral nerves.
