Clinical UM Guideline

This document addresses non-operative uses of the following evoked potential (EP) studies:

• visual evoked potentials (VEPs);
• somatosensory evoked potentials (SSEPs or SEPs);
• motor evoked potentials (MEPs).

Evoked potentials (EPs) or evoked responses are electrical waves created in the central nervous system by peripheral stimulation of a sensory organ. EPs are used to identify abnormal central nervous system function that may not be detected clinically.

Note: This document does not address intra-operative uses for VEPs, SSEPs, or MEPs. Please see the following related documents for additional information:

• CG-MED-94 Vestibular Function Testing;
• CG-SURG-104 Intraoperative Neurophysiological Monitoring.

I.  Visual Evoked Potentials:

Medically Necessary:

Visual evoked potentials are considered medically necessary for the diagnosis, evaluation, or monitoring of any of the following conditions:

1. Multiple sclerosis or neuromyelitis optica, or other demyelinating disorders of the optic nerve; or
2. Suspected disorder of the optic nerve, optic chiasm or optic radiations not explained by magnetic resonance imaging, computerized tomography, infectious diseases or metabolic disorders.

Not Medically Necessary:

Visual evoked potentials are considered not medically necessary for all other uses, including but not limited to glaucoma testing and routine screening of infants.

II.  Somatosensory Evoked Potentials:

Medically Necessary:

Somatosensory evoked potentials are considered medically necessary when the results will be used to guide clinical management for the following conditions:

1. Acute (within 72 hours of onset) anoxic encephalopathy; or
2. Coma following traumatic, hypoxic-ischemic and other diffuse brain injuries; or
3. Central nervous system deficit identified on clinical exam when not explained by appropriate imaging studies; or
4. Demyelinating disease (such as multiple sclerosis) when diagnosis is uncertain and clinical suspicion exists based on neurologic symptoms or cerebrospinal fluid evaluation; or
5. Myelopathy, unexplained; or
6. Spinocerebral degeneration (such as Friedreich’s ataxia); or
7. Spinal cord lesions secondary to trauma when the need for surgical intervention is uncertain; or
8. Suspected brain death.

Not Medically Necessary:

Somatosensory evoked potentials are considered not medically necessary for all other uses.

III.  Motor Evoked Potentials:

Medically Necessary:

Motor evoked potentials are considered medically necessary for evaluation of suspected hysterical or factitious paralysis.

Not Medically Necessary:

Motor evoked potentials are considered not medically necessary in the non-operative setting when the above criteria are not met.

The following codes for treatments and procedures applicable to this guideline are included below for informational purposes. Inclusion or exclusion of a procedure, diagnosis or device code(s) does not constitute or imply member coverage or provider reimbursement policy. Please refer to the member's contract benefits in effect at the time of service to determine coverage or non-coverage of these services as it applies to an individual member.

Visual evoked potentials, non-operative
When services may be Medically Necessary when criteria are met:

When services are Not Medically Necessary:
For the procedure codes listed above when criteria are not met, for all other diagnoses not listed, or for situations designated in the Clinical Indications section as not medically necessary.

When services are also Not Medically Necessary:
For the following procedure codes; or when the code describes a procedure designated in the Clinical Indications section as not medically necessary.

Somatosensory evoked potentials, non-operative
When services may be Medically Necessary when criteria are met:

When services are Not Medically Necessary:
For the procedure codes listed above when criteria are not met.

Motor evoked potentials, non-operative
When services may be Medically Necessary when criteria are met:

When services are Not Medically Necessary:
For the procedure codes listed above when criteria are not met.

Evoked Potentials are recordings of the nervous system's electrical response to the stimulation of specific sensory pathways. These recordings have the ability to provide information relative to the functional integrity of pathways within the nervous system. Only a few evoked potentials are used on a routine basis and those most frequently encountered include VEPs and SSEPs.

Visual Evoked Potentials (VEPs)

VEPs track signals from the retina to the visual cortex and determine how a visual system reacts to light. A common indication for VEPs is to help confirm the diagnosis of MS, or to evaluate and monitor MS. In general, myelin plaques that occur in MS slow the speed of VEP wave peaks. Over time, VEPs in individuals with MS become progressively slower, eventually attenuating in amplitude as demyelination increases (Creel, 2012). The American Academy of Neurology (AAN) (Gronseth, 2000) recommends VEPs as probably useful to identify those at increased risk for clinically definite MS.

VEPs have also been used for other conditions including neuromyelitis optica (NMO) or other demyelinating disorders of the optic nerves, or for a suspected disorder of the optic nerve, optic chiasm, or optic radiations not explained by magnetic resonance imaging (MRI), computerized tomography (CT), infectious diseases, or metabolic disorders.

The U.S. Preventive Services Task Force (USPSTF) (2017) has not recommended vision screening for infants and young children. The USPSTF concludes that the evidence is insufficient to assess the balance of benefits and harms of vision screening for children less than 3 years of age.

van Laerhoven and colleagues (2013) published a systematic literature review to investigate the prognostic value of clinical tests used for evaluation of long-term neurodevelopmental outcomes of neonates with perinatal asphyxia and hypoxic-ischemic encephalopathy (HIE). A total of 29 studies were included in the review describing 13 prognostic tests performed 1631 times in 1306 term neonates. Considerable heterogeneity was noted in test performance, cut-off values, and outcome measures. The VEP was found to have relatively high diagnostic accuracy (sensitivity 0.90 [0.74-0.97]; specificity 0.92 [0.68-0.98]). This review reported on diagnostic accuracy of VEP; well-designed prospective studies examining clinical utility are needed before standardized clinical use is advocated.

Several small studies (Horn, 2012; Pillai, 2013) have investigated the use of VEP technology to differentiate between normal healthy eyes and eyes with early to advanced visual field loss resulting from glaucoma. The authors indicated that VEP signals may discriminate between normal eyes and glaucomatous eyes. However, larger studies are needed to confirm these findings. Additionally, VEP has not been shown to be as good as or superior to standard visual field testing in managing clinical outcomes for persons with glaucoma.

Somatosensory Evoked Potentials (SSEPs)

SSEPs are electrical waves that are generated by the response of sensory neurons to stimulation. An abnormal SSEP finding demonstrates that there is dysfunction within the somatosensory pathways.

SSEP studies may be useful for helping to assess the extent of injury and predict outcomes in persons with traumatic, hypoxic-ischemic and other diffuse brain injuries, including those who are comatose. A 2020 systematic review by Sandroni and colleagues identified 94 studies evaluating factors associated with a poor neurological outcome in comatose individuals following cardiac arrest. Among other factors identified in the review, the bilateral absence of N20 waves of short latency SSEP within 7 days of the return of spontaneous circulation, examined in 18 studies, was associated with a poor neurological outcome in most of the 18 studies.

Wijdicks and colleagues (2006) for the Quality Standards Subcommittee of the American Academy of Neurology issued a practice parameter on "Prediction of outcome in comatose survivors after cardiopulmonary resuscitation (an evidence-based review)." The authors recommended that the assessment of poor prognosis can be guided by the bilateral absence of cortical SSEPs (N20 response) within 1 to 3 days (recommendation level B).

The American Academy of Neurology (AAN) (Gronseth, 2000) recommends SSEPs as possibly useful to identify those at increased risk of for developing clinically definite MS.

Additional indications for SSEPs include: acute anoxic encephalopathy; deficit of the central nervous system identified on exam, but not explained by appropriate imaging studies; demyelinating diseases under certain conditions; unexplained myelopathy; spinocerebral degeneration (such as Friedreich’s ataxia); spinal cord lesions secondary to trauma when the need for surgical intervention is uncertain; or suspected brain death.

Motor Evoked Potentials (MEPs)

MEPs evaluate motor pathways located in the anterolateral spinal tracts perfused by the anterior spinal artery. Single- or repetitive-pulse stimulation of the brain causes the spinal cord and peripheral muscles to produce neuroelectrical signals known as MEPs. In a case series, Cantello and colleagues (2001) examined the use of MEPs for diagnosing psychogenic or hysterical paralysis. The series found that MEP studies assisted in the diagnosis of psychogenic paralysis and the authors noted that if nerve trunks and muscles were found to be intact, a psychogenic cause for paralysis may be implied.

A systematic review by Siow and colleagues in 2019 examined published literature on the MEPs as a potential biomarker for hereditary spastic paraplegia (HSP). The authors identified 32 studies on MEPs and HSP published between 1987 and 2016. Studies were primarily case series/case reports or case-control studies. No pooled analyses of study data were performed due to differences in study methodologies and heterogeneity among study results. The most common finding of the included studies, according to the review’s authors, was absent or prolonged lower limb center motor conduction time (CMCT) in individuals with HSP (this was true for 78% of  study participants). However, studies varied widely in their findings on the correlation between CMCT and clinical outcomes, such as disease severity and gait abnormalities. Prospective studies with long-term follow-up are needed to clarify the utility of MEPs as a prognostic biomarker for HSP.

Friedreich's ataxia: A rare genetic disease that affects the muscles and heart.

Hysterical paralysis: An uncommon psychogenic, nonorganic loss of motor function.

Visually evoked potential (VEP), (visually evoked response [VER] and visually evoked cortical potential [VECP] are equivalent): These terms refer to electrical potentials, initiated by brief visual stimuli, which are recorded from the scalp overlying the visual cortex. VEP waveforms are extracted from the electro-encephalogram (EEG) by signal averaging. VEPs are used primarily to measure the functional integrity of the visual pathways from the retina via the optic nerves to the visual cortex of the brain. Evoked potentials, whether auditory, visual or somatosensory, are extracted from the EEG by a simple computer program that saves a defined time period of EEG activity following a visual stimulus and isolates the VEP. Transient pattern VEPs have components that can be followed during maturation, pathological conditions and changes of visual acuity.

Peer Reviewed Publications:

1. Cantello R, Boccagni C, Comi C, et al. Diagnosis of psychogenic paralysis: the role of motor evoked potentials. J Neurol. 2001; 248(10):889-897.
2. Chen XW, Zhao YX. Comparison of isolated-check visual evoked potential and standard automated perimetry in early glaucoma and high-risk ocular hypertension. Int J Ophthalmol. 2017(a); 10(4):599-604.
3. Chen X, Zhao Y. Diagnostic performance of isolated-check visual evoked potential versus retinal ganglion cell-inner plexiform layer analysis in early primary open-angle glaucoma. BMC Ophthal. 2017(b); 17(1):77.
4. Djuric S, Djuric V, Zivkovic M, et al. Are somatosensory evoked potentials of the tibial nerve the most sensitive test in diagnosing multiple sclerosis? Neurol India. 2010; 58(4):537-541.
5. Fan X, Wu LL, Di X, et al. Applications of isolated-check visual evoked potential in early stage of open-angle glaucoma patients. Chin Med J (Engl). 2018; 131(20):2439-2446.
6. Horn FK, Kaltwasser C, Jünemann AG, et al. Objective perimetry using a four-channel multifocal VEP system: correlation with conventional perimetry and thickness of the retinal nerve fiber layer. Br J Ophthalmol. 2012; 96(4):554-559.
7. Pillai C, Ritch R, Derr P, et al. Sensitivity and specificity of short-duration transient visual evoked potentials (SD-tVEP) in discriminating normal from glaucomatous eyes. Invest Ophthalmol Vis Sci. 2013; 54(4):2847-2852.
8. Sand T, Kvaløy MB, Wader T, Hovdal H. Evoked potential tests in clinical diagnosis. Tidsskr Nor Laegeforen. 2013; 133(9):960-965.
9. Sandroni C, D'Arrigo S, Cacciola S, et al. Prediction of poor neurological outcome in comatose survivors of cardiac arrest: a systematic review. Intensive Care Med. 2020; 46(10):1803-1851.
10. Siow SF, Cameron Smail R, Ng K, et al. Motor evoked potentials in hereditary spastic paraplegia-a systematic review. Front Neurol. 2019; 10:967.
11. van Laerhoven H, de Haan TR, Offringa M, et al. Prognostic tests in term neonates with hypoxic-ischemic encephalopathy: a systematic review. Pediatrics. 2013; 131(1):88-98.
12. Wang X, Li RS, Wei YH, et al. Applications of the isolated-check visual evoked potential in primary open angle glaucoma with or without high myopia. Int J Ophthalmol. 2021; 14(5):704-713.
13. Xu LJ, Zhang L, Li SL, et al. Accuracy of isolated-check visual evoked potential technique for diagnosing primary open-angle glaucoma. Doc Ophthalmol. 2017; 135(2):107-119.
14. Young B, Eggenberger E, Kaufman D. Current electrophysiology in ophthalmology: a review. Curr Opin Ophthalmol. 2012; 23(6):497-505.

Government Agency, Medical Society, and Other Authoritative Publications:

1. American Clinical Neurophysiology Society. Guideline 9A: Guidelines on evoked potentials. J Clin Neurophysiol. 2006; 23(2):125-137.
2. Centers for Medicare and Medicaid Services (CMS). National Coverage Determination for Evoked Response Tests. NCD #160.10. Effective January 15, 1980. Available at: https://www.cms.gov/medicare-coverage-database/view/ncd.aspx?ncdid=200&ncdver=1&bc=0. Accessed on January 13, 2024.
3. Creel DJ. Visually Evoked Potentials. 2012 Mar 01. In: Kolb H, Fernandez E, Nelson R, editors. Webvision: The Organization of the Retina and Visual System [Internet]. Salt Lake City (UT): University of Utah Health Sciences Center; 1995. Available at: http://www.ncbi.nlm.nih.gov/books/NBK107218/pdf/CreelVEP.pdf. Accessed on January 13, 2024.
4. Gronseth GS, Ashman EJ. Practice parameter: the usefulness of evoked potentials in identifying clinically silent lesions in patients with suspected multiple sclerosis (an evidence-based review): Report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology. 2000; 54(9):1720-1725.
5. U.S. Preventive Services Task Force. Screening for visual impairment in children ages 1 to 5 years. January 2017. Available at: https://www.uspreventiveservicestaskforce.org/Page/Document/RecommendationStatementFinal/vision-in-children-ages-6-months-to-5-years-screening. Accessed on January 13, 2024.
6. Wijdicks EF, Hijdra A, Young GB, et al; Quality Standards Subcommittee of the American Academy of Neurology. Practice parameter: prediction of outcome in comatose survivors after cardiopulmonary resuscitation (an evidence-based review): report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology. 2006; 67(2):203-210.

1. American Academy of Ophthalmology. Glaucoma Diagnosis. Available at: https://www.aao.org/eye-health/diseases/glaucoma-diagnosis. Accessed on January 13, 2024.
2. National Multiple Sclerosis Society. Diagnosing MS. Available at: https://www.nationalmssociety.org/Symptoms-Diagnosis/Diagnosing-MS. Accessed on January 13, 2024.

Motor Evoked Potential
Motor Evoked Response
Somatosensory Evoked Potential
Somatosensory Evoked Response
Visual Evoked Potential
Visual Evoked Response

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