BlueCross BlueShield of Tennessee Medical Policy Manual

Nerve Conduction Studies


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 Electrodiagnostic (EDX) examination includes the following:

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:

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.


See also:



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 or per-configured 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, BCBST concurs with 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). This specialized training is comprehensive including presentation of didactic materials by an experienced EDX consultant, a lengthy preceptorship under the supervision of an experienced EDX consultant, and the completion of a specified number of EDX evaluations  (general 200 or more). BCBST does not recognize 2-3 day training courses (e.g. Vendor/manufacturer/distributor provided training, device specific training, week-end workshops, DVD training) as meeting the standards for specialized training in the field of EDX. 

BCBST agrees with the current interpretation of the Committee on Electrodiagnosis of the American Chiropractic Association Council on Neurology 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.


American Academy of Orthopaedic Surgeons. (2007). American Academy of Orthopaedic Surgeons clinical guideline on the diagnosis of carpal tunnel syndrome. Retrieved August 8, 2012 from

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

American Association of Neuromuscular & Electrodiagnostic Medicine. (2010, September). Model policy for needle electromyography and nerve conduction studies. Retrieved September 21, 2010 from

American Association of Neuromuscular & Electrodiagnostic Medicine. (2010, September). Responsibilities of an electrodiagnostic technologist (Endorsed by the American Association of Electrodiagnostic Technologists.  Retrieved September 21, 2010 from

American Society of Electroneurodiagnostic Technologists. (2011). National competency skill standards for performing nerve conduction studies. Retrieved August 8, 2012 from

BlueCross BlueShield Association. Medical Policy Reference Manual. (6:2012). Automated point-of-care nerve conduction tests (2.01.77). Retrieved August 8, 2012 from BlueWeb. (22 articles and/or guidelines reviewed)

Complete Guide to Medicare Coverage Issues [Computer software]. (2012, July). Sensory nerve conduction threshold test (sNCT) (NCD 160.23, p. 2-81). Ingenix.

Daroff, R., Fenichel, G., Jankovic, J., & Mazziotta, J. (Eds.). (2012). Bradley’s Neurology in Clinical Practice (6th ed., pp. 394-419). Philadelphia: Elsevier Inc.   

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)

Kim, N.H. & Kim, D.H. (2012). Ulnar neuropathy at the wrist in a patient with carpal tunnel syndrome after open carpal tunnel release. Annals of Rehabilitation Medicine, 36 (2), 291-296. (Level 4 Evidence - Independent study)

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

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




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