Clinical UM Guideline

This document addresses the use of electromyography (EMG) and nerve conduction studies (NCS) in the outpatient setting. Needle EMG and NCS typically comprise the electrodiagnostic (EDX) evaluation of function of the motor neurons, nerve roots, peripheral nerves, neuromuscular junction and skeletal muscles. This document also addresses neuromuscular junction testing regardless of place of service.

Note: For information about other related topics, see:

• CG-MED-50 Visual, Somatosensory and Motor Evoked Potentials
• CG-SURG-112 Carpal Tunnel Decompression Surgery
• MED.00082 Quantitative Sensory Testing
• MED.00092 Automated Nerve Conduction Testing

Note: For a high-level overview of this document, please see “Summary for Members and Families” below. 

Medically Necessary:

1. Needle EMG when performed with NCS at the same time of testing are considered medically necessary for diagnosing neuropathy with sensory loss, weakness or muscle atrophy for any of the following indications (1 through 5):
   1. Unexplained peripheral neuropathy with pain of a neuropathic pattern, demonstrated sensory loss, or motor loss on physical examination; or
   2. Neuropathy suspected to be due to trauma; or
   3. When test results are expected to guide the management of conditions known to cause neuropathy, including but not limited to (a through d):
      1. HIV-positive individuals with symptoms of neuropathy; or
      2. Mononeuropathies, such as Bell’s palsy of the facial nerve; or
      3. Diabetics with persistent or progressive symptoms refractory to conventional treatments; or
      4. Individuals on dialysis or those considering dialysis;
         or
   4. Suspected neural impingement or entrapment where symptoms are persistent or unresponsive to initial conservative treatments, as indicated by any of the following (a through g)
      1. Carpal tunnel syndrome (when clinical documentation shows impingement symptoms refractory to activity modification and at least 4 weeks of wrist splint use)*; or
      2. Ulnar neuropathy at the elbow or wrist (when clinical documentation shows impingement symptoms refractory to activity modification and at least 4 weeks of elbow pad use)*; or
      3. Cervical or lumbar radiculopathy (when clinical documentation shows 4-6 weeks of failed conservative therapy, including physical therapy and where the etiology of the radicular symptoms is not explained by MRI or other diagnostic studies); or
      4. Tarsal tunnel syndrome (when clinical documentation shows pain and numbness isolated to the foot); or
      5. Peroneal palsy with foot drop; or
      6. Suspected brachial or lumbosacral plexus impingement; or
      7. Other peripheral nerve entrapment syndromes;
         or
   5. Significant clinical suspicion for any of the following conditions (a through g):
      1. Amyotrophic lateral sclerosis; or
      2. Guillain-Barre syndrome; or
      3. Hereditary myopathies, (for example, muscular dystrophy); or
      4. Hereditary neuropathies, (for example, Charcot-Marie-Tooth disease); or
      5. Inflammatory myopathies, (for example, polymyositis, chronic inflammatory demyelinating polyneuropathy [CIDP]); or
      6. Inflammatory or idiopathic brachial or lumbosacral plexopathy; or
      7. Post-polio syndrome.

*Note: In cases of carpal tunnel syndrome or ulnar neuropathy, the requirement for a period of conservative treatment may be waived if the physical exam demonstrates significant atrophy or weakness or sensory loss.

2. Needle EMG when performed with NCS at the same time of testing are considered medically necessary for diagnosis of individuals with significant clinical suspicion for any of the following neuromuscular junction diseases (1 through 3):
   1. Myasthenia gravis; or
   2. Eaton-Lambert syndrome; or
   3. Botulism.
       
3. NCS performed without needle EMG at the same time of testing is considered medically necessary for any of the following clinical indications (1 through 7):
   1. Evaluation of suspected carpal or tarsal tunnel syndrome; or
   2. Evaluation of suspected acute nerve injury (that is within 3 weeks of occurrence); or
   3. For individuals on anticoagulant therapy (not merely anti-platelet treatments); or
   4. For individuals with significant lymphedema; or
   5. Evaluation of suspected peroneal palsy; or
   6. Evaluation of thoracic outlet syndrome; or
   7. For facial nerve monitoring in Bell’s palsy.
       
4. Needle EMG performed without NCS at the same time of testing is considered medically necessary for the evaluation of suspected radiculopathy.

Not Medically Necessary:

Needle EMG performed with NCS at the same time of testing are considered not medically necessary when the criteria listed above are not met, including as a screening tool for the general population, in the absence of related symptoms.

NCS performed without needle EMG at the same time of testing is considered not medically necessary except the limited clinical indications listed above.

Needle EMG performed without NCS at the same time of testing is considered not medically necessary when the criteria listed above are not met.

Testing for neuromuscular junction diseases with needle EMG or NCS is considered not medically necessary when the criteria above are not met, and for all other indications.

Needle EMG or NCS is considered not medically necessary for all other conditions, including but not limited to, back pain without radiculopathy, or headaches when there is no suspicion of an underlying disorder of the cranial nerves.

This document describes clinical studies and expert recommendations, and explains whether electromyography (EMG) and nerve conduction studies (NCS) studies are clinically appropriate. The following summary does not replace the medical necessity criteria or other information in this document. The summary may not contain all of the relevant criteria or information. This summary is not medical advice. Please check with your healthcare provider for any advice about your health.

Key Information

EMG and NCS are tests that help evaluate how nerves and muscles work. EMG uses a small needle placed into muscles to measure electrical activity. NCS involves the use of small electrical signals placed on the skin to measure how well nerves send messages. These tests can help doctors diagnose nerve injuries, muscle diseases, nerve problems such as carpal tunnel syndrome, and conditions that affect communication between nerves and muscles, such as myasthenia gravis. EMG and NCS are often done together because they provide different types of information. The tests may help guide treatment decisions when symptoms such as numbness, weakness, muscle wasting, or pain suggest a nerve or muscle disorder. The tests have some risks and limits. Needle EMG may cause discomfort, bruising, or bleeding. NCS may cause mild pain or tingling during stimulation. Studies show these tests are most useful when symptoms and physical examination findings suggest a nerve or muscle problem.

What the Studies Show

Studies and expert recommendations from the American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM) support the use of EMG and NCS together in many situations because the tests provide information that are helpful when looked at together. EMG can help identify muscle or nerve damage and may help distinguish between short-term and long-term nerve problems. NCS can help show whether nerve damage affects sensory nerves, motor nerves, or both. Research shows that using both tests together may improve the ability to correctly diagnose a problem and may help avoid incorrect treatment decisions, including unnecessary surgery. Studies also show that the tests are most helpful when a doctor first performs a medical history and neurologic examination to determine whether nerve or muscle disease is likely.

Research supports EMG and NCS for a wide number of conditions. Evidence also suggests EMG may help evaluate lumbar spine problems when magnetic resonance imaging (MRI) findings do not clearly explain symptoms. However, studies show these tests are less useful for conditions such as headaches without suspected nerve involvement or back pain without signs of nerve damage. Unnecessary or unproven testing can lead to needless worry, or to treatment that does not help. Some newer testing methods, such as surface electromyography (sEMG) combined with walking analysis, are still being studied. Better studies are needed to know if these newer methods improve health.

When are EMG and NCS Clinically Appropriate?

EMG and NCS may be appropriate in these situations:

• Unexplained nerve damage causing numbness, weakness, muscle wasting, or nerve-type pain; or
• Suspected nerve injury caused by trauma; or
• Conditions known to cause nerve damage, including:
  • Human immunodeficiency virus (HIV) with symptoms of nerve damage; or
  • Single nerve disorders such as Bell palsy; or
  • Diabetes with symptoms that continue despite treatment; or
  • Kidney failure requiring dialysis or consideration for dialysis; or
• Suspected nerve compression problems that continue despite conservative treatment, including:
  • Carpal tunnel syndrome; or
  • Ulnar neuropathy, including cubital tunnel syndrome; or
  • Cervical or lumbar radiculopathy; or
  • Tarsal tunnel syndrome with foot pain or numbness; or
  • Peroneal palsy with foot drop; or
  • Suspected brachial plexus or lumbosacral plexus problems; or
  • Other nerve entrapment disorders.

Significant suspicion for conditions including:

• Amyotrophic lateral sclerosis (ALS); or
• Guillain-Barré syndrome; or
• Inherited muscle diseases such as muscular dystrophy; or
• Inherited nerve diseases such as Charcot-Marie-Tooth disease; or
• Inflammatory muscle diseases such as polymyositis or chronic inflammatory demyelinating polyneuropathy (CIDP); or
• Inflammatory or unexplained plexus disorders; or
• Post-polio syndrome; or
• Suspected neuromuscular junction diseases including:
• Myasthenia gravis; or
• Lambert-Eaton syndrome; or
• Botulism.

NCS alone may also be appropriate in limited situations, including suspected carpal tunnel syndrome, acute nerve injury, thoracic outlet syndrome, Bell palsy, significant lymphedema, anticoagulant use, or suspected peroneal palsy.

EMG alone may be appropriate for suspected radiculopathy.

When is this not Clinically Appropriate?

EMG or NCS is not clinically appropriate when symptoms or examination findings do not suggest a nerve or muscle disorder. This includes use as a screening test for the general population without symptoms. Studies show these tests provide limited useful information in people without signs of nerve disease.

EMG and NCS are also not clinically appropriate for conditions such as headaches without suspected cranial nerve disease or back pain without signs of radiculopathy. Research shows the tests usually do not change diagnosis or treatment in these situations.

Some testing approaches are also not recommended because studies have not shown clear benefit. These include certain surface EMG methods, repeated EMG testing at the same location for botulinum toxin (Botox) injections, and some specialized carpal tunnel testing methods with lower accuracy. Better studies are needed to know if these approaches improve health.

EMG or NCS is not clinically appropriate in scenarios other than those listed above.

Return to Description

The following codes for treatments and procedures applicable to this document 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.

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 or for situations designated in the Clinical Indications section as not medically necessary.

Summary

Electromyography (EMG) and nerve conduction studies (NCS) are electrodiagnostic (EDX) tools used to assess the functional integrity of the motor neuron, nerve root, peripheral nerve, neuromuscular junction, and muscle. EMG involves needle electrode insertion to record muscle electrical activity, aiding in the differentiation of various neuromuscular disorders, including inflammatory, chronic, and inherited myopathies, and acute versus chronic denervation. NCS uses surface electrodes (occasionally needles for deep nerves) to evaluate neuropathies and determine sensory versus motor involvement and axonal versus demyelinating patterns. The American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM) recommends combined use of EMG and NCS in most cases for diagnostic accuracy. Optimal use of EMG/NCS relies on clinical context and physician-guided test selection based on history, examination, and diagnostic suspicion.

Discussion

In EMG, electrical potentials are detected by a needle electrode inserted directly into a skeletal muscle. This test is useful in the outpatient evaluation of the motor neuron, nerve root, peripheral nerve, neuromuscular junction and the muscle itself. It is helpful in distinguishing between inflammatory and chronic, metabolic or inherited muscle diseases, and in differentiating between acute, recovering, and chronic denervation. While EMG may not necessarily provide a clinical diagnosis, patterns of EMG abnormalities may suggest specific pathologic entities.

NCS performed in the outpatient setting provides information regarding the presence, severity, and location of a peripheral neuropathy, mononeuropathy, or disorders affecting the neuromuscular junction. Additional information suggested by NCS includes the functional modality most involved (sensory or motor) and the predominant pattern of pathology, for example, axonal, demyelinating, or both.

EMG and NCS tests require needle insertion and then repositioning at multiple sites and at anatomically critical areas, in order to assist in clinical diagnosis, prognosis, and clinical management decisions. In NCS, surface electrodes are usually used for both stimulation and recording of the electrical responses. However, needle electrodes are sometimes needed to evaluate a deep nerve, such as the sciatic or the femoral nerve.

EMG and NCS are most effective when preliminary investigation (including history and neurologic examination) is suggestive of a significant probability of pathology. EMG and NCS should be performed and interpreted by individuals with appropriate training and expertise and should be evaluated in the context of the individual clinical scenario.

The AANEM, states in their “Recommended Policy for Electrodiagnostic Medicine” (2017), that the selection of the number and type of specific EMG and NCS tests to be performed on an individual is best determined by the testing physician, based on multiple factors, including: the referral diagnosis, presenting symptoms, medical history, findings on prior clinical examination or diagnostic testing, and suspected etiology. In 2023, AANEM updated this position statement which states:

Electrodiagnostic testing is used to evaluate the integrity and function of the peripheral nervous system (most cranial nerves, spinal roots, plexi, and nerves), neuromuscular junction (NMJ), muscles, and the central nervous system (brain and spinal cord). Electrodiagnostic testing is performed as part of an electrodiagnostic evaluation for diagnosis or as follow-up of an existing condition. Electrodiagnostic studies can provide information to:

1. Identify normal and abnormal nerve, muscle, motor or sensory neuron, and NMJ functioning.
2. Localize region(s) of pathology.
3. Characterize the pathology.
4. Determine the distribution of abnormalities.
5. Determine the severity of abnormalities.
6. Estimate the chronology of the disease.
7. Determine the progression and/or recovery from abnormal function.
8. Aid in diagnosis and prognosis of disease.
9. Aid in selecting treatment options.
10. Aid in following response to treatment by providing objective evidence of change in neuromuscular function.
11. Localize correct locations for injection of intramuscular agents (e.g., botulinum toxin).

In the 2020 position statement “Proper Performance and Interpretation of Electrodiagnostic Studies”, AANEM states that except for unique situations, needle EMG and NCS should be performed together in a study design determined by a trained physician, in order that healthcare decisions are based on complete diagnostic information. The AANEM position statement also reiterated the importance of the physician performing a history and physical prior to any testing and designing the NCS and EMG testing based upon the information obtained during that exam. Some excerpted comments follow:

Because needle EMG studies offer information needed for an accurate diagnosis, except in unique situations, it is the AANEM's position that NCSs and needle EMGs should be performed together in the same setting. It is the opinion of the AANEM that utilizing only NCSs provides incomplete diagnostic information, potentially leading to inadequate or inappropriate treatment (including inappropriate surgery) and increased health care costs.

Using a predetermined or standardized battery of NCSs for all patients is inappropriate because it may be possible to obtain the data needed to reach a diagnosis with fewer studies. Alternatively, a pre-determined battery may not include the appropriate NCSs and/or EMG tests to determine the diagnosis.

Another AANEM document, the “Model Policy for Needle Electromyography and Nerve Conduction Studies” (2017, updated 2022), identified the following indications for EDX testing to evaluate the integrity and function of the peripheral nervous system (most cranial nerves, spinal roots, plexi, and nerves, neuromuscular junction, muscles) and its connection with the central nervous system. AANEM states that a typical EDX examination includes:

Development of a differential diagnosis by the EDX physician, based upon appropriate history and physical examination and the referring physician’s concerns if applicable

NCSs of a number of nerves by recording and studying the electrical responses from peripheral nerves or the muscles they innervate, following electrical stimulation of the nerve. Usually surface electrodes are used for both stimulation and recording, though needle electrodes may be required in special cases.

Needle EMG testing of selected muscles. This is accomplished by inserting a needle electrode into appropriate muscles, one at a time.

 Indications for EDX testing include the following scenarios:

1. Focal neuropathies, entrapment neuropathies, or compressive lesions/syndromes such as carpal tunnel syndrome, ulnar neuropathies, or root lesions, for localization
2. Traumatic nerve lesions, for diagnosis and prognosis
3. Generalized neuropathies, such as metabolic (for example, diabetic, uremic, etc.), toxic, hereditary or immune-mediated
4. Neuromuscular junction disorders such as myasthenia gravis, myasthenic syndrome or botulism
5. Symptom-based presentations such as “pain in limb”, weakness, cramping/twitching, disturbance of skin sensation or “paresthesia” when appropriate pre-test evaluations are inconclusive and the clinical assessment unequivocally supports the need for the study
6. Radiculopathy-cervical, thoracic, lumbosacral
7. Plexopathy- including idiopathic, traumatic, inflammatory or infiltrative, radiation-induced
8. Myopathy-including inflammatory myopathies like polymyositis and dermatomyositis, myotonic disorders, and congenital myopathies
9. Precise muscle location for injections such as botulinum toxin, phenol, etc.

Nerve Conduction Studies

1. NCSs are performed to assess the integrity and diagnose diseases of the peripheral nervous system. Specifically, they assess action potentials resulting from peripheral nerve stimulation which are recordable over the nerve or from an innervated muscle, the speed (conduction velocity and/or latency), size (amplitude), and shape of the response. Pathological findings include conduction slowing, conduction block, or reduced response. Results of the NCS reflect on the integrity and function of: (I) the myelin sheath, and (II) the axon of a nerve. Interruption of axon and dysfunction of myelin will both affect NCS results. This portion of EDX evaluation is performed by the physician alone or by a trained allied health professional under direct supervision of a physician trained in electrodiagnostic medicine. 
2. Motor, sensory, and mixed NCSs and late responses (F-wave and H-reflex studies) are frequently complementary and performed during the same patient evaluation.
3. Although the stimulation of nerves is similar across all NCSs, the characteristics of motor, sensory, and mixed NCSs are different and are discussed separately below. In each case, an appropriate nerve is stimulated and recording is made either from the appropriate nerves or from a muscle supplied by the motor nerve.
   • Motor NCSs are performed by applying electrical stimulation at various points along the course of a motor nerve while recording the electrical response from an appropriate muscle. Response parameters include amplitude, latency, configuration, and motor conduction velocity.
   • Sensory NCSs are performed by applying electrical stimulation near a nerve and recording the response from a distant site along the nerve. Response parameters include amplitude, latency, configuration, and sensory conduction velocity.
   • Mixed NCSs are performed by applying electrical stimulation near a nerve containing both motor and sensory fibers (a mixed nerve) and recording from a different location along that nerve that also contains both motor and sensory nerve fibers. Response parameters include amplitude, latency, configuration, and both sensory and motor conduction velocity.
   • NCSs performed with preconfigured electrode arrays utilize anatomically specific electrodes to perform both motor and sensory nerve conduction testing. Devices that utilize preconfigured electrode arrays are highly automated.
4. NCS reports should document the nerves evaluated, the distance between the stimulation and recording sites, the conduction velocity, latency, and amplitude. The temperature of the studied limbs should be included. A final diagnosis, which, in some cases, may be a symptom diagnosis or a diagnosis of normal, is then made.

The policy also states:

The necessity and reasonableness of the following uses of needle EMG studies have not been established:

1. exclusive testing of intrinsic foot muscles in the diagnosis of proximal lesions
2. definitive diagnostic conclusions based on paraspinal EMG in regions bearing scar of past surgeries (e.g., previous laminectomies)
3. needle EMG testing shortly after trauma, before needle EMG abnormalities would have reasonable time to develop
4. surface and macro EMGs
5. multiple uses of needle EMG in the same patient at the same location for the purpose of optimizing botulinum toxin injections.

Additionally, current literature does not support the use of EMG and NCS for conditions like headaches without suspected cranial nerve involvement or back pain without suspected radiculopathy, as these tests do not provide meaningful diagnostic value in such cases.

Carpal Tunnel Syndrome (CTS)

The 2023 AANEM Recommended Policy for Electrodiagnostic Medicine in patients suspected of CTS, states that the following studies are recommended:

• Perform a median sensory NCS across the wrist with a conduction distance of 13 cm to 14 cm. If the result is abnormal, comparison of the result of the median sensory NCS to the result of a sensory NCS of one other adjacent sensory nerve in the symptomatic limb (Standard).
• If the initial median sensory NCS across the wrist has a conduction distance greater than 8 cm and the result is normal, one of the following additional studies is recommended:
  • comparison of median sensory or mixed nerve conduction across the wrist over a short (7 cm to 8 cm) conduction distance with ulnar sensory nerve conduction across the wrist over the same short (7 cm to 8 cm) conduction distance (Standard), or
  • comparison of median sensory conduction across the wrist with radial or ulnar sensory conduction across the wrist in the same limb (Standard), or
  • comparison of median sensory or mixed nerve conduction through the carpal tunnel to sensory or mixed NCSs of proximal (forearm) or distal (digit) segments of the median nerve in the same limb (Standard).
• Motor NCS of the median nerve recording from the thenar muscle and of one other nerve in the symptomatic limb to include measurement of distal latency (Guideline).
• Supplementary NCS: comparison of the median motor nerve distal latency (second lumbrical) to the ulnar motor nerve distal latency (second interossei); median motor terminal latency index; median motor nerve conduction between wrist and palm; median motor nerve compound muscle action potential wrist-to-palm amplitude ratio to detect conduction block; median sensory nerve action potential wrist to-palm amplitude ratio to detect conduction block; short segment (1 cm) incremental median sensory nerve conduction across the carpal tunnel (Option).
• Needle electromyography of a sample of muscles innervated by the C5 to T1 spinal roots, including a thenar muscle innervated by the median nerve of the symptomatic limb (Option).

The AANEM 2023 position statement does not recommend the following tests for confirmation of CTS; multiple median F-wave parameters, median motor nerve residual latency, or sympathetic skin response, due to inferior sensitivity and specificity compared to standard studies. Additionally, median NCS using the following methods: limb ischemia, dynamic hand exercises, or brief or sustained wrist positioning are not recommended due to inferior diagnostic accuracy or lack of established clinical efficacy compared to standard EDX tests.

In 2024 the American Academy of Orthopedic Surgeons (AAOS) updated their “Management of Carpal Tunnel Syndrome Evidence-Based Clinical Practice Guidelines.” Regarding using the Carpal Tunnel Syndrome-6 (CTS-6), a 6-question evaluation tool, their guidance states:

Strong evidence suggests that CTS-6 can be used to diagnose carpal tunnel syndrome, in lieu of routine use of ultrasonography or NCV/EMG.
Quality of Evidence: High.
Strength of Recommendation: Strong

AAOS based their recommendations upon the findings in 10 high and 5 moderate quality studies supporting the use of either the CTS-6, nerve conduction velocity/ electromyography (NCV/EMG), or ultrasonography. Although there was heterogeneity present in both the study populations and comparisons for the different studies, there was strong and consistent evidence supporting all modalities in diagnosing CTS. There was no evidence of clinical superiority between diagnostic tools, therefore the guideline does not promote one test over another or change previous recommendations for NCV/EMG testing.

Ulnar Neuropathy/Cubital Tunnel Syndrome:

Ulnar neuropathy is a disorder or dysfunction of the ulnar nerve, usually caused by compression, irritation, stretching, or injury to the nerve. The most common form is ulnar neuropathy at the elbow (UNE), also called cubital tunnel syndrome, where the nerve becomes compressed at the cubital tunnel behind the medial epicondyle (“funny bone”). Less commonly, compression occurs at the wrist in Guyon’s canal, also called the ulnar tunnel, a narrow fibro-osseous passageway located at the wrist on the ulnar side of the hand through which the ulnar nerve and ulnar artery pass into the hand (ulnar tunnel syndrome). Diagnosis is based on clinical history and examination, NCS, EMG, and sometimes ultrasound or magnetic resonance imaging (MRI). Electrodiagnostic testing helps confirm the presence of neuropathy, the site of compression, the severity of nerve injury, and whether there is axonal loss versus demyelination.

Cubital tunnel syndrome is a specific subtype of ulnar neuropathy occurring at the elbow. Cubital tunnel syndrome is caused by compression or irritation of the ulnar nerve as it passes through the cubital tunnel at the elbow. Diagnosis is based on clinical history and physical examination, provocative maneuvers (for example, Tinel sign at elbow, elbow flexion test), and EMG and NCS. EMG/NCS can help confirm ulnar neuropathy, localize compression at the elbow, assess severity, and exclude cervical radiculopathy or other neuropathies. The AANEM describes cubital tunnel syndrome as the second most common compressive neuropathy of the upper extremity after carpal tunnel syndrome.

The AANEM Practice Parameter for Electrodiagnostic Studies in Ulnar Neuropathy at the Elbow Summary Statement (1997, reaffirmed 2015), made the following relevant recommendations for the electrodiagnostic evaluation of individuals with suspected UNE:

• Ulnar sensory and motor NCSs should be performed with surface stimulation and recording. Limb temperatures should be monitored and maintained in a reference range and should be reported if outside a reference range. Corrections in conduction for temperature, if any, should be indicated in the report, although warming cool limbs and repeating the studies is preferable when possible. This recommendation is a practice standard.
• If ulnar sensory or motor NCSs are abnormal, further NCSs should be carried out to exclude a diffuse process. This recommendation is a practice standard.
• Ulnar motor NCS reports should specify the elbow position used during the performance of the studies and the reference values employed. The technique used should be the same as that used to determine the reference values. The same elbow position should be employed during both stimulation and measurement. This recommendation is a practice standard.

Other considerations:

In 2019, Callaghan published a cross-sectional observational study that analyzed testing patterns in incident peripheral neuropathy. A random national sample of 83693 Medicare claims data was analyzed. Diabetes prevalence was 59% (n=46,476). The inclusion criteria were age greater than or equal to 65 years, no diagnosis of peripheral neuropathy in the 30 months prior, and continuous Medicare enrollment 30 months before and 6 months after the incident peripheral neuropathy diagnosis. The tests utilized were vitamin B₁₂: 28.3%, SPEP (serum protein electrophoresis) 13.4%, fasting glucose 10.6%, glucose tolerance test (GTT) 1.0%, hemoglobin A1c 50.3%, EMG: 22.6%, and MRI 25.7%. The results demonstrated that persistent overuse of EMGs and MRIs continued at high rates with incremental increases over time despite their limited impact on management. Concurrently, there was continued underuse of SPEP and GTT, which are recommended by AAN guidelines for identifying reversible causes of peripheral neuropathy. The study was limited by restricted generalizability beyond the Medicare population, the lack of data on test appropriateness, and potential misclassification bias due to reliance on claims data. The author concluded that despite robust clear guideline recommendations, the diagnostic approach to peripheral neuropathy remains suboptimal, and that clinical practice has not significantly shifted toward guideline-concordant testing strategies, with persistent overuse of neurodiagnostic procedures and underuse of simple, recommended blood tests. The author emphasized the need for system-level quality improvement strategies including peer comparison mechanisms within the electronic health record to curb EMG/MRI overuse, and the development of order sets in electronic health records promoting guideline-concordant testing.

Recent evidence regarding electrodiagnostic evaluation of lumbar spinal canal stenosis (LSCS) indicates that electrodiagnostic testing may provide complementary functional assessment in individuals with suspected neurogenic compromise, particularly when clinical findings are incongruent with MRI-defined anatomic stenosis. MRI remains the standard imaging modality for identifying central canal and foraminal narrowing. However, multiple studies demonstrate poor correlation between radiographic severity and symptom burden, functional limitation, or neurologic impairment. Electrodiagnostic testing may assist in determining the physiologic significance of imaging abnormalities and in differentiating symptomatic from incidental degenerative findings.

Needle EMG remains the most established modality for evaluation of radiculopathy associated with LSCS. Needle EMG can identify evidence of active or chronic denervation corresponding to compressed nerve roots and may support localization of lumbosacral root dysfunction when clinical examination is equivocal. Paraspinal mapping and evaluation of limb muscles innervated by the suspected affected roots may improve diagnostic specificity for radiculopathy. Electrodiagnostic testing may also help distinguish LSCS-related radiculopathy from alternative peripheral neurologic disorders, including peripheral polyneuropathy, plexopathy, entrapment neuropathies, or motor neuron disease.

NCS are primarily useful to exclude coexisting peripheral neuropathic conditions rather than to directly diagnose LSCS, as sensory NCS are frequently normal in isolated radiculopathy. Additional electrophysiologic modalities, including somatosensory evoked potentials (SSEPs) and motor evoked potentials (MEPs) demonstrate inconsistent diagnostic performance and are not routinely recommended for standard evaluation of LSCS.

Duarte (2026) published a review of 13 studies that demonstrated EMG abnormalities, including denervation and abnormal spontaneous activity, may correlate with clinically significant neural compression and redundant nerve roots identified on MRI. However, correlations between MRI severity and EMG-confirmed radiculopathy were inconsistent across studies, highlighting that radiographic stenosis alone is not a reliable predictor of physiologic nerve dysfunction. EMG findings may also localize abnormalities to levels different from the apparent anatomic stenosis, particularly in multilevel or central canal stenosis where multiple nerve roots may be affected. Studies cited within the review demonstrated high specificity and moderate-to-high sensitivity for paraspinal mapping in identifying nerve root involvement. No recent studies specifically evaluated paraspinal mapping, which suggests a shift toward alternative and less invasive approaches. Concerns regarding invasiveness, operator dependence, and limited routine clinical adoption may contribute to their reduced use despite prior guideline endorsement. An emerging area of investigation involves sEMG integrated with gait and kinematic analysis. The mor recent studies consistently demonstrated altered paraspinal and lower extremity muscle activation patterns, compensatory gait adaptations, reduced walking speed, and abnormal postural control in symptomatic individuals with LSCS which may allow physiologic assessment during ambulation, when neurogenic claudication symptoms are most pronounced. The authors concluded that although promising, these techniques and their clinical diagnostic utility and standardization have not yet been established. Overall, the evidence supports the use of needle EMG, particularly paraspinal mapping, as an adjunctive diagnostic tool for confirming radiculopathy and functional nerve root involvement in LSCS when clinical and imaging findings are inconclusive. sEMG combined with gait analysis although a promising noninvasive modality, lacks sufficient validation for routine clinical application.

Electromyography/nerve conduction studies (EMG/NCS): Electromyography and nerve conduction studies, collectively referred to as electrodiagnostic (EDX) testing, are diagnostic procedures used to evaluate the functional integrity of motor neurons, nerve roots, peripheral nerves, neuromuscular junctions, and skeletal muscles (AANEM, 2024).

Electrophysiological studies: Diagnostic tests that evaluate the electrical activity and functional integrity of the nervous system, muscles, or cardiac conduction system, most commonly refer to diagnostic procedures such as NCS, EMG, evoked potentials, and repetitive nerve stimulation studies, which are used to assess peripheral nerves, nerve roots, neuromuscular junctions, and muscles (AANEM, 2024).

Motor evoked potentials (MEPs): Electrophysiologic recordings of muscle responses generated following stimulation of the motor pathways within the central nervous system. MEPs are used to assess the functional integrity of descending corticospinal motor tracts and may help detect abnormalities involving central motor conduction pathways. They are commonly utilized in intraoperative neuromonitoring and in the evaluation of neurologic disorders affecting the spinal cord or motor pathways (National Center for Biotechnology Information [NCBI], 2023).

Needle electromyography (EMG) is a diagnostic technique in which a needle electrode is inserted into selected muscles to record electrical activity at rest and during voluntary contraction. EMG is used to identify abnormalities consistent with denervation, reinnervation, myopathy, or disorders affecting the motor unit (Mayo Clinic, 2019).

Nerve conduction studies (NCS) are diagnostic tests that are usually done in conjunction with an EMG. A NCS measures the nerve’s ability to send a signal, as well as the speed (nerve conduction velocity) and size of the nerve signal (National Institute of Neurological Disorders and Stroke [NINDS], 2024).

Nerve conduction velocity (NCV) Studies: Electrodiagnostic tests that measure the speed at which electrical impulses travel along peripheral motor or sensory nerves used to evaluate peripheral nerve function and help identify disorders such as peripheral neuropathy, focal nerve entrapment, demyelinating disease, or nerve injury. NCV testing is typically performed as part of a NCS and often in conjunction with EMG (Mayo Clinic, 2019).

Somatosensory evoked potentials (SSEPs): Electrophysiologic studies that measure the electrical responses generated within the peripheral nerves, spinal cord, brainstem, and cerebral cortex following stimulation of a sensory peripheral nerve. They are used to evaluate the functional integrity of sensory pathways and may help detect abnormalities involving the peripheral or central nervous system. They are commonly used in intraoperative neuromonitoring and in the assessment of neurologic disorders affecting sensory conduction pathways (NCBI, 2023).

Surface EMG (sEMG): A noninvasive electrophysiologic technique that records the electrical activity generated by skeletal muscles using electrodes placed on the surface of the skin overlying the muscle of interest. sEMG is used to evaluate muscle activation patterns, timing, and relative muscle activity during rest or movement and may be applied in rehabilitation medicine, biomechanics, ergonomics, and neuromuscular assessment, sEMG does not evaluate individual motor units or deep muscle structures (NCBI, 2023).Top of Form

Peer Reviewed Publications:

1. Callaghan BC, Price RS, Feldman EL. Distal symmetric polyneuropathy: a review. JAMA. 2015; 314(20):2172-2181.
2. Callaghan BC, Reynolds EL, Muthukumar L, et al. Diagnostic testing for patients with peripheral neuropathy. JAMA Neurol. 2025; 82(4):420-421.
3. Chang MH, Liu LH, Lee YC, et al. Comparison of sensitivity of transcarpal median motor conduction velocity and conventional conduction techniques in electrodiagnosis of carpal tunnel syndrome. Clin Neurophysiol. 2006; 117(5):984-991.
4. Dabbagh A, MacDermid JC, Yong J, et al. Diagnostic accuracy of sensory and motor tests for the diagnosis of carpal tunnel syndrome: a systematic review. BMC Musculoskelet Disord. 2021; 22(1):337.
5. Duarte G, Hupp M, Spirig J, et al. The role of electrophysiological workup in lumbar spinal canal stenosis (LSCS): a systematic review. Spine. 2026; 51(6):E143-E153.
6. Katz JN, Simmons BP. Carpal tunnel syndrome. N Engl J Med. 2002; 346(23):1807-1812.
7. Lazaro RP. Electromyography in musculoskeletal pain: A reappraisal and practical considerations. Surg Neurol Int. 2015; 6:143.
8. Megerian JT, Kong X, Gozani SN. Utility of nerve conduction studies for carpal tunnel syndrome by family medicine, primary care, and internal medicine physicians. J Am Board Fam Med. 2007; 20(1):60-64.
9. Mendell JR, Sahenk Z. Clinical Practice. Painful sensory neuropathy. N Engl J Med. 2003; 348(13):1243-1255.
10. Mondelli M, Aretini A, Arrigucci U, et al. Clinical findings and electrodiagnostic testing in 108 consecutive cases of lumbosacral radiculopathy due to herniated disc. Neurophysiol Clin. 2013; 43(4):205-215.
11. Tankisi H, Pugdahl K, Euglsang-Frederiksen A, et al. Pathophysiology inferred from electrodiagnostic nerve tests and classification of polyneuropathies. Suggested guidelines. Clin Neurophysiol. 2005; 116(7):1571-1580.

Government Agency, Medical Society, and Other Authoritative Publications:

1. American Academy of Neurology (AAN), American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM) and the American Academy of Physical Medicine and Rehabilitation (AAPM&R). Practice parameter: Electrodiagnostic studies in ulnar neuropathy at the elbow. Neurology. 1999; 52(4):688-690.
2. American Academy of Orthopaedic Surgeons (AAOS), Management of carpal tunnel syndrome. Evidence-based clinical practice guideline. May 18, 2024. Available at: https://www.aaos.org/globalassets/quality-and-practice-resources/carpal-tunnel/carpal-tunnel-2024/cts-cpg.pdf. Accessed on July 31, 2026.
3. American Association of Electrodiagnostic Medicine, American Academy of Neurology, and American Academy of Physical Medicine and Rehabilitation. Practice parameter for electrodiagnostic studies in carpal tunnel syndrome: summary statement. Muscle Nerve. 2002; 25(6):918-922.
4. American Association of Electrodiagnostic Medicine; So YT. Guidelines in electrodiagnostic medicine. Practice parameter for needle electromyographic evaluation of patients with suspected cervical radiculopathy. Muscle Nerve Suppl. 1999;8:S209-S221. Reaffirmed 2020.
5. American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM). Available at: https://www.aanem.org/clinical-practice-resources. Accessed on July 31, 2026.
   • Model Policy for Needle Electromyography and Nerve Conduction Studies. Updated and reapproved December 2022.
   • Policy Statement on Electrodiagnosis for Distal Symmetric Polyneuropathy. July 2017, modified and approved May 2024.
   • Position Statement. Overview of Electrodiagnostic Medicine. May 1999, revised and reapproved November 2024.
   • Practice Parameter For Electrodiagnostic Studies In Ulnar Neuropathy At The Elbow: Summary Statement. October 1997, reaffirmed June 2015.
   • Proper Performance and Interpretation of Electrodiagnostic Studies. Muscle Nerve. August 2020; 61(5):567-569.
   • Recommended Policy for Electrodiagnostic Medicine. Updated January 2023. Endorsed by the American Academy of Neurology (AAN), the American Academy of Physical Medicine and Rehabilitation (AANEM).
   • Referral Indications for Primary Care Providers. January 7, 2020, and July 2025.
   • Reporting the results of needle EMG and nerve conduction studies: An educational report. Updated and approved August 2019, and December 2024.
6. Cho SC, Ferrante MA, Levin KH, Harmon RL, So YT. Utility of electrodiagnostic testing in evaluating patients with lumbosacral radiculopathy: an evidence-based review. Muscle Nerve. 2010; 42(2):276-282. Reaffirmed 2017.
7. Doyal A, Schoenherr JW, Flynn DN. Motor Evoked Potential. StatPearls Publishing; Jan. 2026. Available at: https://www.ncbi.nlm.nih.gov/books/NBK580548/?report=reader. Accessed on July 31, 2026.
8. England JD, Gronseth GS, Franklin G, et al. Distal symmetric polyneuropathy: a definition for clinical research: report of the American Academy of Neurology (AAN), the American Association of Neuromuscular and Electrodiagnostic Medicine (AAEM) and the American Academy of Physical Medicine and Rehabilitation (AAPM&R). Neurology. 2005; 64(2):199-207. Reaffirmed October 19, 2024.
9. Kang PB, McMillan HJ, Kuntz NL, et al; Professional Practice Committee of the American Association of Neuromuscular & Electrodiagnostic Medicine. Utility and practice of electrodiagnostic testing in the pediatric population: an AANEM consensus statement. Muscle Nerve. 2020; 61(2):143-155.
10. Marciniak C, Armon C, Wilson J, Miller R. Practice parameter: utility of electrodiagnostic techniques in evaluating patients with suspected peroneal neuropathy: an evidence-based review. Muscle Nerve. 2005; 31(4):520-527. Reaffirmed October 2020.

1. American Academy of Orthopedic Surgeons (AAOS). OrthoInfo: Electrodiagnostic Testing. Available at: https://orthoinfo.aaos.org/en/treatment/electrodiagnostic-testing/Accessed on July 31, 2026.
2. Mayo Clinic. Tests & Procedures. Electromyography (EMG). May 21, 2019. Available at: https://www.mayoclinic.org/tests-procedures/emg/about/pac-20393913. Accessed on July 31, 2026.
3. National Institute of Health (NIH). National Library of Medicine. Medical tests. Electromyography (EMG) and nerve conduction studies. Last updated April 10, 2024. Available at: https://medlineplus.gov/lab-tests/electromyography-emg-and-nerve-conduction-studies/. Accessed on July 31, 2026.
4. National Institute of Health (NIH). National Institute of Neurological Disorders and Stroke. Neurological Diagnostic Tests and Procedures Fact Sheet. December 2024. Last Reviewed April 2019. Available at: https://www.ninds.nih.gov/publications/neurological-diagnostic-tests-and-procedures. https://www.ninds.nih.gov/health-information/disorders/neurological-diagnostic-tests-and-procedures. Accessed on July 31, 2026.

Electromyography, Nerve Conduction Studies (EMG/NCS)
Electrophysiological Studies
Motor Evoked Potentials (MEPs)
Nerve Conduction Velocity (NCV) Studies
Somatosensory Evoked Potentials (SSEPs)
Surface EMG (sEMG)

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