**Abstract:**  
National Government Services (NGS) expects healthcare professionals who
perform electrodiagnostic (ED) testing will be appropriately trained and/or
credentialed, either by a formal residency/fellowship program, certification
by a nationally recognized organization, or by an accredited post-graduate
training course covering anatomy, neurophysiology and forms of
electrodiagnostics (including both NCS and EMG) acceptable to this Contractor,
in order to provide the proper testing and assessment of the patient's
condition, and appropriate safety measures.  
  
The electrodiagnostic evaluation is 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 of knowledge about clinical diagnostic and management aspects of
neuromuscular diseases, may not be adequate for proper performance of an
electrodiagnostic evaluation and correct interpretation of electrodiagnostic
test results. Without awareness of the patterns of abnormality expected in
different diseases and knowledge that the results of nerve conduction studies
(NCS) and electromyography (EMG) may be similar in different diseases,
diagnosis solely by EMG-NCS findings may be both inadequate and ultimately be
detrimental to the patient.  
  
Guidelines about proper qualifications for qualified health care professionals
performing electrodiagnostic evaluations have been developed and published by
AANEM (American Association of Neuromuscular and Electrodiagnostic Medicine)
and other medical organizations, including the AMA, the American Academy of
Neurology, the American Academy of Physical Medicine and Rehabilitation,
American Neurological Association, the American Board of Physical Therapy
Specialties (ABPTS) in Clinical Electrophysiology, and the Department of
Veterans Affairs.  
  
Both EMGs and NCSs 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.  
  
Nerve conduction studies 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.  
  
Neuromuscular junction testing involves the stimulation of an individual motor
nerve by means of repetitive electrical impulses with measurement of the
resulting electrical activity of a muscle supplied by that nerve. Supramaximal
electrical stimuli are delivered to the nerve. A surface electrode over, or
percutaneous electrode placed in, a corresponding muscle records the evoked
muscle action potentials using standard nerve conduction study techniques. The
nerve is then stimulated electrically in a repetitive train at 2-3 Hz, or in
special circumstances at higher rates up to 50 Hz. In diseases of the
neuromuscular junction, characteristic changes of a progressive decrease
(decrement) in the compound action potential amplitude may be seen during the
repetitive stimulation.  
  
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
based knowledge of clinical diagnosis 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
muscle's 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
EMGs, and myelin and axonal involvement are best detected by NCSs.  
  
 **Indications:**  
 **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.

1\. Focal neuropathies or compressive lesions such as carpal tunnel syndrome,
ulnar neuropathies or root lesions, for localization. 2\. Traumatic nerve
lesions, for diagnosis and prognosis. 3\. Diagnosis or confirmation of
suspected generalized neuropathies, such as diabetic, uremic, metabolic or
immune 4\. Repetitive nerve stimulation in diagnosis of neuromuscular junction
disorders such as myasthenia gravis, myasthenic syndrome. 5\. 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. The Contractor 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 NCV 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 EMGs and NCSs 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 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 either wrong or detrimental to the
patient.  
  
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.

a. Motor. 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.

b. Sensory. 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.

c. 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."

d. Nerve conduction studies performed using automated devices (for example
devices such as NC-stat System) cannot support testing of other locations and
other nerves as needed depending on the concurrent results of testing.

When the beneficiary has a high pre-test or a prior probability for having the
diagnosis of Carpal Tunnel Syndrome, the NC-stat System (alone) will be
allowed, one service per arm.  
  
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.  
  
 **Neuromuscular Junction Testing**  
Neuromuscular junction testing by repetitive stimulation may be reasonable and
necessary to diagnose patients with fatiguable weakness who are being
evaluated for possible disease of the neuromuscular junction. These diseases
may include myasthenia gravis or Lambert Eaton myasthenic syndrome (LEMS), as
well as Botulinum toxicity. Rarely, exposure to certain drugs such as
aminoglycoside antibiotics can potentiate myasthenic symptoms. Patients in
intensive care unit (ICU) settings who experience continued weakness after a
critical illness which has required being paralyzed for mechanical ventilation
may also be candidates for this type of testing.  
  
 **Electromyography**  
Neurogenic disorders can be distinguishable from myopathic disorders by a
carefully performed EMG. For example, both polymyositis and ALS (Amyotrophic
Lateral Sclerosis) produce manifest weakness. The former carries a very
different prognosis and treatment than the latter. An EMG is very 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:

1\. Nerve compression syndromes, including carpal tunnel syndrome and other
focal compressions.

2\. Radiculopathy - cervical, lumbosacral.

3\. Mono/polyneuropathy - metabolic, degenerative, hereditary.

4\. Myopathy - including poly-and dermatomyositis, myotonic and congenital
myopathies.

5\. Plexopathy - idiopathic, trauma, infiltration.

6\. Neuromuscular junction disorders - myasthenia gravis. Single fiber EMG is
of especial value here.

7\. At times, immediately prior to Botulinum A toxin injection, for
localization.

8\. 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 one study performed per anatomic
location of injection, if needed. Please refer to the NGS LCD for Botulinum
Toxins, L33646, and related Article, A52848, for further coverage and coding
guidance.  
  
 **Limitations:**  
  
 **Nerve Conduction Studies**  
 **Routine testing for polyneuropathy of diabetes or endstage renal disease
(ESRD)** is not considered medically necessary and is not covered. Testing for
the sole purpose of monitoring disease intensity or treatment efficacy in
these two conditions is also not covered.  
  
Nerve conduction studies must provide a number of response parameters in a
real-time fashion to facilitate provider interpretation. Those parameters
include amplitude, latency, configuration and conduction velocity. Medicare
does not accept diagnostic studies that do not provide this information or
those that provide delayed interpretation as substitutes for Nerve conduction
studies. Raw measurement data obtained and transmitted trans-telephonically or
over the Internet, therefore, does not qualify for the payment of the
electrodiagnostic service codes included in this LCD.  
  
Medicare does not expect to receive claims for nerve conduction testing
accomplished with discriminatory devices that use fixed anatomic templates and
computer-generated reports used as an adjunct to physical examination
routinely on all patients.  
  
 **Neuromuscular Junction Testing**  
Neuromuscular junction testing by repetitive stimulation is not considered
reasonable and necessary for the diagnosis or treatment of diabetic
neuropathy.  
  
Neuromuscular junction testing by repetitive stimulation is not considered
reasonable and necessary for the diagnosis or treatment of carpal or tarsal
tunnel syndrome.  
  
Neuromuscular junction testing by repetitive stimulation is indicated for
specific physical signs and symptoms (e.g. diplopia, dysphagia, weakness,
fatigue) only if there is actual clinical suspicion that a neuromuscular
junction disorder is the cause.  
  
  
 **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 EMG's  multiple uses of EMG in the same patient at the same location of
the same limb for the purpose of optimizing Botulinum toxin injections.