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The rules say that plans must pay for a medical service or item if regular Medicare would pay for it in this case. 
You can find this rule at 42 Code of Federal Regulations (CFR) Section 422.101. 
 
The rules state that Both EMG and NCS are usually required for a clinical diagnosis of peripheral nervous 
system disorders. Performance of one type of testing does not eliminate the need for the other. The intensity 
and extent of testing with EMG and NCS are matters of clinical judgment developed after the initial pre-test 
evaluation, and later modified during the testing procedure. 
 
Decisions to continue, modify or conclude a testing rely on knowledge of anatomy, physiology and 
neuromuscular diseases. Ongoing real-time assessment of data is required during the clinical diagnostic 
evaluation and especially during EMG examination. 
 
Nerve conduction studies (NCS) are used to measure action potentials resulting from peripheral nerve 
stimulation which are recordable over the nerve or from an innervated muscle. With this technique, responses 
are measured between two sites of stimulation, or between a stimulus and a recording site. 
 
NCS are of two general types: sensory and motor. Either surface or needle electrodes can be used to stimulate 
the nerve or record the response. Axonal damage or dysfunction generally results in loss of nerve or muscle 
potential response amplitude; whereas demyelination leads to prolongation of conduction time and slowing of 
conduction velocity. 
 
Obtaining and interpreting NCS results requires extensive interaction between the performing qualified health 
care professional and patient and is most effective when both obtaining raw data and interpretation are 
performed concurrently on a real-time basis. 
 
Results of the NCS reflect on the integrity and function of: 
 
        (I) the myelin sheath (Schwann cell derived insulation covering an axon), and 
        (II) the axon (an extension of neuronal cell body) of a nerve. 
 
Interruption of axon and dysfunction of myelin will both affect NCS results. 
 
It is often also valuable to test conduction status in proximal segments of peripheral nerves. This assessment 
can be accomplished by H-reflex, F-wave and blink reflex testing. These proximal segments include the first 
several centimeters of a compound nerve emerging from the spinal cord or brainstem. H-reflex, F-waves and 
Blink reflex testing accomplish this task better than distal NCS.  
Electromyography (EMG) is the study and recording of intrinsic electrical properties of skeletal muscles. This 
is carried out with a needle electrode. Generally, the needles are of two types: monopolar or concentric. EMG 
is undertaken together with NCS. Unlike NCS however, EMG testing relies on both auditory and visual 
feedback to the electromyographer. This testing is also invasive in that it requires needle electrode insertion and 
adjustment at multiple sites, and at times anatomically critical sites. As in NCS, during EMG studies the 
electromyographer depends on ongoing real-time interpretation of clinical diagnoses being evaluated to decide 
whether to continue, modify, or conclude a test. This process requires knowledge of anatomy, physiology, and 
neuromuscular diseases. 
 
EMG results reflect not only on the integrity of the functioning connection between a nerve and its innervated 
muscle but also on the integrity of a muscle itself. The axon innervating a muscle is primarily responsible for 
the muscles volitional contraction, survival, and trophic functions. Thus, interruption of the axon will alter the 
EMG. A few prime examples of conditions in which EMG is potentially helpful are disc disease producing 
spinal nerve dysfunction, advanced nerve compression in peripheral lesions, Amyotrophic Lateral Sclerosis 
(ALS), polyneuropathy, etc. After an acute neurogenic lesion, EMG changes may not appear for several days to 
weeks in the innervated muscles. Primary muscle disease such as polymyositis will also alter a normal EMG 
pattern. Myotonic disorders may show a pattern of spontaneous repetitive discharges on needle exploration. 
 
In summary, axonal and muscle involvement are most sensitively detected by EMG, and myelin and axonal 
involvement are best detected by NCS. 
 
  A. Nerve Conduction Studies 
 
            The dichotomy into axonal and demyelinating neuropathies provides a practical means of correlating 
electrical abnormalities with major pathophysiologic changes in the nerve. Electrical studies can be of help in 
localization of an abnormality, and in distinguishing one variety of neuropathy from another: for example, 
diffuse vs. multifocal; axonal vs. demyelinating. Such distinction has diagnostic value. Specific classification 
of nerve injuries into neuropraxia and axonotmesis can be made on the basis of conduction studies and 
electromyography. Such classification has a bearing on prognosis and treatment. 
 
            Focal neuropathies or compressive lesions such as carpal tunnel syndrome, ulnar neuropathies or root 
lesions, for localization. 
            Traumatic nerve lesions, for diagnosis and prognosis. 
            Diagnosis or confirmation of suspected generalized neuropathies, such as diabetic, uremic, metabolic or 
immune. 
            Repetitive nerve stimulation in diagnosis of neuromuscular junction disorders such as myasthenia 
gravis, myasthenic syndrome. 
            There may be other instances, not detailed here, where NCS may be of use. Not all possible or potential 
indications are addressed here. 
 
The broad diagnostic scope of NCS is recognizable by the foregoing description. There may be instances where 
questions about an indication, or need for a study, will arise. The clinical history and examination, carried out 
before the study, must always describe and document clearly and comprehensibly the need for the planned test. 
A "rule-out" diagnosis is typically not acceptable. Noridian is cognizant of the fact that patients are not always 
referred with a definite diagnosis in mind. Often, pain, paresthesia, or weakness in an extremity is the reason 
for an NCS or EMG. These common symptoms result not only from axonal and myelin dysfunction but also 
from systemic, non-neurological illnesses. EMG and NCS may help in making this distinction. Therefore, 
symptom-based diagnoses such as "pain in limb", "weakness", "disturbance in skin sensation" or "paresthesia" 
are acceptable, provided the clinical assessment unequivocally supports the need for a study. To cite but one 
example of many, an EMG or NCS is irrelevant as a first order diagnostic test for limb pain resulting from 
immediate antecedent trauma or acute bone injury.  
Both EMG and NCS are required for a clinical diagnosis of peripheral nervous system disorders. EMG results 
reflect on the integrity of the functioning connection between a nerve and its innervated muscle and also on the 
integrity of a muscle itself. Performance of one does not eliminate the need for the other. The intensity and 
extent of testing with EMG and NCS are matters of clinical judgment developed after the initial pre-test 
evaluation, and later modified during the testing procedure. 
 
Decisions to continue, modify or conclude a test also rely on a knowledge base of anatomy, physiology and 
neuromuscular diseases. There is a requirement for ongoing real-time clinical diagnostic evaluation, especially 
during EMG examination. Also, EMG examination is invasive. Needle placement in the exact muscle of 
interest is essential. It requires needle exploration near vital structures as the pleura, femoral neurovascular 
bundle, peritoneum, intraspinal spaces, carotid artery, orbit and brachial plexus. Risk of infection from AIDS, 
Hepatitis B-E, Creutzfeldt-Jakob encephalopathy, and hemorrhage from anticoagulation can be managed by 
proper techniques. 
 
The electrodiagnostic evaluation is actually an extension of the neurologic portion of the physical examination. 
Both require a detailed knowledge of a patient and his/her disease. Training in the performance of 
electrodiagnostic procedures, in isolation without awareness and ability to diagnose and manage neuromuscular 
diseases, is not always adequate for electrodiagnostic consultation. Recognition and experience in the 
management of disparate diseases that produce common electrodiagnostic findings may be necessary. For 
example, EMG-NCS findings may overlap in the following pairs of disorders: inflammatory myopathies and 
ALS, ALS and multi-level radiculopathies, myotonia of channelopathies (periodic paralyses) and myotonic 
dystrophies, focal neuropathies such as Carpal Tunnel Syndrome and proximal plexopathies. Other instances 
where knowledge of disease behavior is crucial are Chronic Inflammatory Demyelinating Neuropathy (CIDP) 
and Multifocal Motor Neuropathy. These entities display electrodiagnostic features that resemble generalized 
polyneuropathies. Neuromuscular transmission disorders require separation based on clinical presentation and 
electrical features. Treatment will depend on differentiating among them. Without awareness of the disease 
spectrum, diagnosis solely by EMG-NCS findings may be wrong, detrimental to the patient or both. 
 
The following definitions are from the American Association of Neuromuscular & Electrodiagnostic Medicine 
Recommended Policy for Electrodiagnostic Medicine. 
 
"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 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, and configuration. 
            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 motor 
conduction velocity." 
 
Nerve conduction studies performed independent of needle electromyography (EMG) may only provide a 
portion of the information needed to diagnose muscle, nerve root, and most nerve disorders. When the nerve 
conduction study (NCS) is used on its own without integrating needle EMG findings or when an individual 
relies solely on a review of NCS data, the results can be misleading, and important diagnoses may be missed. 
 In most instances, both NCS and usually EMG are necessary to perform diagnostic testing. While a provider 
may choose to perform just an NCS, when performed alone it is usually considered not medically necessary. 
The only exception to this is a situation when a provider may consider it appropriate to perform an NCS 
without doing an EMG for the diagnosis of carpal tunnel syndrome with a high pre-test probability. 
 
B. Electromyography 
 
Neurogenic disorders can be distinguishable from myopathic disorders by a carefully performed EMG. For 
example, both polymyositis and ALS produce manifest weakness. The former carries a very different prognosis 
and treatment than the latter. An EMG is valuable in making this distinction. Similarly, classification of nerve 
trauma into axonal vs. demyelinating categories, with corresponding differences in prognoses, are possible with 
EMG. Below is a list of common disorders where an EMG, in tandem with properly conducted NCS, will be 
helpful in diagnosis:  
 
            Nerve compression syndromes, including carpal tunnel syndrome and other focal compressions. 
            Radiculopathy - cervical, lumbosacral. 
            Mono/polyneuropathy - metabolic, degenerative, hereditary. 
            Myopathy - including poly-and dermatomyositis, myotonic and congenital myopathies. 
            Plexopathy - idiopathic, trauma, infiltration. 
            Neuromuscular junction disorders - myasthenia gravis. Single fiber EMG is of special value here. 
            At times, immediately prior to botulinum toxin injection, for localization. 
            At times, immediately prior to injection of phenol or other substances for nerve blocking or 
chemodenervation. 
 
 
There may be other instances, not detailed here, where EMG may be of use. 
 
Use of EMG with Botulinum Toxin Injection 
EMG may be used to optimize the anatomic location of botulinum toxin injection. It is expected there will be 
no more than one study performed per anatomic location of injection, if needed. (Please see the separate LCD 
"Botulinum Toxin Types A and B.") 
 
Electromyography 
The necessity and reasonableness of the following uses of EMG studies have not been established: 
 
        exclusive testing of intrinsic foot muscles in the diagnosis of proximal lesions  
        definitive diagnostic conclusions based on paraspinal EMG in regions bearing scar of past surgeries (e.g., 
previous laminectomies)  
        pattern-setting limited limb muscle examinations, without paraspinal muscle testing for a diagnosis of 
radiculopathy  
        EMG testing shortly after trauma, before EMG abnormalities would have reasonably had time to develop  
        surface and macro EMGs  
        multiple uses of EMG in the same patient at the same location of the same limb for the purpose of 
optimizing botulinum toxin injections. 
 
You can find this rule in the Local Coverage Determination (LCD) - L36524, Nerve Conduction Studies and 
Electromyography. 
 
If you want to read these Medicare rules, you can go to this website www.medicareappeal.com. 
 
The Plan contract says that the Plan covers items and services in accordance with Medicare rules.