Nerve Conduction Studies
DESCRIPTION
Nerve conduction studies (NCS) are performed to diagnose diseases of, and the integrity of, the peripheral nervous system. Results may indicate that sensory symptoms are due to an impairment of peripheral nerve function or, when normal, to a lesion proximal to the dorsal root ganglia. Nerve conduction studies assess the speed (conduction velocity, and/or latency), size (amplitude), and shape of the response. Pathological findings include conduction slowing, conduction block, temporal dispersion, low amplitude, and/or no response. Nerve conduction study results can document the existence of neuropathy, quantify its severity, note the distribution (distal, proximal, or diffuse) and assess the degree of demyelination and axon loss in the segments of the nerve studied.
A typical NCS examination includes the following:
Development of a differential diagnosis by the EDX consultant based upon appropriate history and physical examination.
NCS of a number of nerves by recording and studying the electrical responses from peripheral nerves or the muscles they innervate through electrical stimulation of the nerve.
Completion of indicated needle EMG studies to evaluate the differential diagnosis and to complement the nerve conduction studies. The use of invasive needle electrodes requires the skill of a trained EDX consultant who is a MD, DO, or Chiropractic Neurologist.
Motor, sensory and mixed nerve conduction studies and late responses (F-waves and H-reflex studies) are frequently complementary and performed during the same evaluation.
Nerve conductions studies (NCS) and needle electromyography (EMG), when properly performed by a trained practitioner, are considered the gold standard of electrodiagnostic testing. The diagnosis of cervical, thoracic, lumbar, or lumbosacral radiculopathy cannot be made without Needle EMG in conjunction with NCS and/or anatomic imaging studies such as MRI, CT, or myelography. NCS and needle EMG are also critically important in the diagnosis of:
Peripheral Nerve Entrapments (e.g. Ulnar Neuropathy, Peroneal/Fibular Neuropathy)
Peripheral Nerve Injuries
Myopathies and Muscular Dystrophies
Neuromuscular Junction Disorders (e.g. Myaesthenia Gravis)
Motor Neuron Disease (e.g. Amyotrophic Lateral Sclerosis)
Generalized Peripheral Neuropathy (e.g. Diabetic Neuropathy, Alcoholic Neuropathy, Hereditary Neuropathies)
According to the AANEM, nerve conduction studies performed without needle EMG may be missing valuable data that could be essential to determine an accurate diagnosis. Dissociation of Nerve Conduction Studies (NCS) and the EMG into separate reports is generally inappropriate. Performance and interpretation of NCS separately from the needle EMG component of the test should be the exception (e.g. when testing an acute nerve injury or when the individual is on anticoagulants) rather than the established practice pattern.
POLICY
Nerve conduction studies for the diagnosis of motor neuron diseases, myopathies, radiculopathies, plexopathies, neuropathies and neuromuscular junction (NMJ) disorders are considered medically necessary.
Nerve conduction studies performed without needle electromyography studies, unless contraindicated (e.g., individuals on anticoagulant therapy, hemophilia, Von Willibrand’s disease, idiopathic thrombocytopenic purpura [ITP], disseminated intravascular coagulation [DIC]), are considered investigational.
Automated (e.g. pre-configured) nerve conduction testing (e.g., NC-stat®, ADVANCE™) is considered investigational.
Any device utilized for this procedure must have FDA approval specific to the indication, otherwise it will be considered investigational.
See also:
IMPORTANT REMINDER
We develop Medical Policies to provide guidance to Members and Providers. This Medical Policy relates only to the services or supplies described in it. The existence of a Medical Policy is not an authorization, certification, explanation of benefits or a contract for the service (or supply) that is referenced in the Medical Policy. For a determination of the benefits that a Member is entitled to receive under his or her health plan, the Member's health plan must be reviewed. If there is a conflict between the Medical Policy and a health plan, the express terms of the health plan will govern.
ADDITIONAL INFORMATION
Nerve conduction studies are to be performed by the physician alone or by a technologist under direct supervision of the electrodiagnostic (EDX) consultant. The consultant must be trained or certified in the application, performance and interpretation of electrodiagnostic testing and licensed by the state in which the studies are performed. The technician performing the studies must be trained in electrodiagnostic testing and licensed or certified by the state (or by one of the state's health related boards if licensure or certification as a technician does not exist in a given state) in which the studies are performed. Electrodiagnostic testing is not performed in a standard fashion, but must be specifically designed for each individual patient. It is often necessary to modify or add to the procedure during the examination, depending on the findings as they unfold. (Refer to BCBST's Staff Supervision Requirements for Delegated Services policy.)
The decision to perform an NCS must be based upon a history and physical examination findings obtained prior to the performance of the procedure and evident in the individual's record.
In order to perform and interpret electrodiagnostic tests, it is the position of the American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM) that, the EDX consultant be a physician who has had special training in the diagnosis and treatment of neurological and neuromuscular diseases and in the application of particular neurophysiologic techniques to the study of these disorders. This type of training is generally included in the residency or fellowship programs of physicians who specialize in physical medicine and rehabilitation (physiatrists) or neurology (neurologists). Current interpretation of the Committee on Electrodiagnosis of the American Chiropractic Association Council on Neurology is that electrodiagnostic evaluation/interpretation in the assessment of neurological disorders should be performed by a board eligible or board certified Chiropractic Neurologist.
Published scientific evidence in peer-reviewed journals regarding the utilization of automated, non-invasive nerve conduction equipment for diagnosis of disease of the peripheral nervous system is lacking.
SOURCES
American Association of Neuromuscular & Electrodiagnostic Medicine. (2004, June). Recommended policy for electrodiagnostic medicine. (Endorsed by the American Academy of Neurology and American Academy of Physical Medicine and Rehabilitation.) Retrieved September 21, 2010 from http://www.aanem.org/AANEM/media/AANEM/Documents/Practice/Position%20Statements/Recommended_Policy_EDX_Medicine_07152010.pdf.
American Association of Neuromuscular & Electrodiagnostic Medicine. (2010, September). Model policy for needle electromyography and nerve conduction studies. Retrieved September 21, 2010 from http://www.aanem.org/AANEM/media/AANEM/Documents/Practice/Position%20Statements/Model_Policy_NCS_EMG_062810.pdf.
American Association of Neuromuscular & Electrodiagnostic Medicine. (2010, September). Responsibilities of an electrodiagnostic technologist (Endorsed by the American Association of Electrodiagnostic Technologists August 1998.) Retrieved September 21, 2010 from http://www.aanem.org/AANEM/media/AANEM/Documents/Practice/Position%20Statements/responsibilities_of_edx_techs.PDF.
BlueCross BlueShield Association. Medical Policy Reference Manual. (6:2010). Automated point-of-care nerve conduction tests (2.01.77). Retrieved September 21, 2010 from BlueWeb. (19 articles and/or guidelines reviewed)
Gooch, C.L., & Weimer, L., (2007). The electrodiagnosis of neuropathy: Basic principles and common pitfalls. Neurologic Clinics, 25 (1), 1-28. (Level 5 Evidence)
Grant, Peter A., (2010). American Association of Neuromuscular & Electrodiagnostic Medicine, Secretary/Treasurer. October 1, 2010. Physician input. (Level 5 Evidence)
U. S. Food and Drug Administration. (2003, May). Center for Devices and Radiological Health. 510(k) Premarket Notification Database. K070109. Retrieved September 21, 2010 from http://www.accessdata.fda.gov/cdrh_docs/pdf7/K070109.pdf.
U. S. Food and Drug Administration. (2003, May). Center for Devices and Radiological Health. 510(k) Premarket Notification Database. K060584. Retrieved September 21, 2010 from http://www.accessdata.fda.gov/cdrh_docs/pdf6/K060584.pdf.
ORIGINAL EFFECTIVE DATE: 2/1/2001
MOST RECENT REVIEW DATE: 12/9/2010
ID_BT
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