This document addresses use of automated, noninvasive nerve conduction testing devices, (e.g., the NC-stat^® System; NeuroMetrix, Inc.) as an alternative to conventional methods of performing nerve conduction testing.

The NC-stat^® System (NeuroMetrix, Inc., Waltham, MA) is a portable, hand-held, noninvasive, automated nerve conduction testing device that has been marketed for use in an office or clinic setting to assess nerves of the upper and lower extremities to assist in the diagnosis of peripheral nerve disorders, such as carpal tunnel syndrome and diabetic peripheral neuropathy.

Note: For information related to conventional electromyography and nerve conduction velocity studies (EMG/NCS), see the following document:

• CG-MED-24 Electromyography and Nerve Conduction Studies (EMG/NCS)

Investigational and Not Medically Necessary:

Electrodiagnostic testing with automated, noninvasive nerve conduction testing devices, such as the NC-stat^® System, is considered investigational and not medically necessary for all indications, including as an alternative method of performing nerve conduction velocity studies.

The NC-stat^® System received U.S. Food and Drug Administration (FDA) clearance in 1998, through the 510(k) approval process, for measurement of neuromuscular signals that are useful in diagnosing and evaluating systemic and entrapment neuropathies.  This original approval was for use as an adjunct to, and not as a replacement for, conventional electrodiagnostic testing.  Although the device has been modified since the original FDA approval to extend its nerve testing capability, the intended use of the device has not changed (FDA, 1998; 2000; 2001; 2002; 2004).  In 2008, another device from NeuroMetrix, Inc. obtained FDA clearance.  This device, the NeuroMetrix ADVANCE^™ lists the NC-stat as the predicate device, but it also involves needle EMG, as part of the device's testing capability in real time as follows:

A device that features a high-resolution touch-screen display panel with a stylus. The device has a cable that connects to disposable surface electrodes for performance of nerve conduction studies. The device communicates via Bluetooth with an accessory EMG module that connects to electromyography needles for performance of invasive needle electromyography studies. The device amplifies, digitizes and stores nerve and muscle signals. It delivers electrical stimuli through the electrodes for nerve conduction studies. Nerve conduction and needle electromyography waveforms are displayed in real time.  The device reports standard nerve conduction parameters based on operator or computer assigned waveform cursors. Nerve conduction parameters include motor and sensory latency, motor and sensory conduction velocity, F-wave response parameters, A-waves, motor and sensory amplitude and waveform configuration. The device may optionally upload stored data to the Communications Hub (FDA, 2008).

Another similar device, the NeuMed^® Brevio^® Nerve Conduction Monitoring System (Neurotron Medical, Inc., Pennington, NJ) received FDA 510 (k) clearance in 2001 as a hand-held automated device intended for measurement of nerve response latency and amplitude in the diagnosis and monitoring of peripheral neuropathies.  According to the FDA approved labeling, the Brevio device has the same technological characteristics, indications and target population as the NC-stat^® device (predicate device; FDA, 2001).

To date, there has been very limited published evidence to demonstrate the safety and efficacy of automated, noninvasive nerve conduction testing devices, as compared to conventional "Gold standard" electrodiagnostic testing using needle electromyography (EMG) and nerve conduction velocity studies (NCS).  Most of the published clinical studies have evaluated use of this type of device for assessment of the median and ulnar nerves only (Katz, 2006; Kong, 2006).

In 2005, the Washington State Department of Labor and Industries conducted a technology assessment of the NC-stat^® System to evaluate the available peer-reviewed literature on this device, following inquiries from physicians in the local practice community, as well as from staff of the Department of Labor and Industries.  This technology assessment reviewed results from six articles in May of 2005, and an additional two articles were reviewed in 2006 to update the review.  The report concluded that the NC-stat^® System is not equivalent to conventional methods for nerve conduction velocity testing (Morse, 2006).

In an updated position statement on the Proper Performance and Interpretation of Electrodiagnostic Studies from the American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM, 2006), although no specific reference to portable, automated nerve conduction testing devices, (e.g., the NC-stat^® device) is made, the following comments were noted:

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.

Also,

Individuals without medical education in neuromuscular disorders and without special training in electrodiagnostic procedures typically are not qualified to interpret the waveforms generated by NCS and needle EMG or to correlate the findings with other clinical information to reach a diagnosis.

The NC-stat^® System consists of four components which include single-use biosensors, a battery powered monitor that connects to the sensors and stores information, a docking station for the monitor, and the onCall^™ Information System, (which is a remote report generation system to which test data are transmitted for analysis).  A computerized system interprets the data, which is suggested by the manufacturer, to be available and capable of being transmitted to the treating physician within minutes.

Although portable, automated, noninvasive testing of nerve conduction has been suggested as an easier method for providers to obtain rapid results, the AANEM recommends that electrodiagnostic studies of EMG and NCS be performed together, except in unique situations, in a study design determined (and interpreted) by a trained physician, so that healthcare decisions are based on complete diagnostic information (AANEM, 2004).  Currently, there is insufficient evidence in the published data to demonstrate how use of automated nerve conduction testing devices, such as the NC-stat^® System, will guide treatment management and ultimately impact clinical outcomes.

Electromyography:  (EMG) refers to the recording and study of the electrical activity of specific muscles through the use of a needle electrode which is inserted directly into a skeletal muscle; EMG testing is used to exclude, diagnose, describe and follow-up on diseases of the peripheral nervous system and the associated muscles

Nerve Conduction Studies: (NCS) involve the application of surface electrodes, in order to assess the integrity of, and diagnose diseases of the peripheral nervous system; NCS assess the speed (conduction velocity/latency), size (amplitude), and shape of the electrical responses elicited from the targeted nerve and the muscle stimulated by that nerve

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 or these services as it applies to an individual member.

When Services are Investigational and Not Medically Necessary:
For the procedure code listed below, or when the code describes a procedure indicated in the Position Statement section as investigational and not medically necessary.

Peer Reviewed Publications:

1. Elkowitz SJ, Dubin NH, Richards BE, et al. Clinical utility of portable versus traditional electrodiagnostic testing for diagnosing, evaluating and treating carpal tunnel syndrome.  Am J Orthop. 2005; 34(8):362-364.
2. Hilburn JW. General principles and use of electrodiagnostic studies in carpal and cubital tunnel syndrome. With special attention to pitfalls and interpretation. Hand Clin. 1996; 12(2):205-221.
3. Jabre JF, Salzsieder BT, Gnemi KE.  Criterion validity of the NC-stat automated nerve conduction measurement instrument.  Physiol Meas. 2007; 28(1):95-104.
4. Katz, J, Simon B. Carpal Tunnel Syndrome. New England Journal of Medicine. 2002; 346:1807-1812.
5. Katz RT. NC-stat as a screening tool for carpal tunnel syndrome in industrial workers.  J Occup Environ Med. 2006; 48(4):414-418.
6. Kong X, Gozani SN, Hayes MT, Weinberg DH.  NC-stat sensory nerve conduction studies in the median and ulnar nerves of symptomatic patients.  Clin Neurophysiol. 2006; 117(2):405-413. 
7. Leffler CT, Gozani SN, Cros D.  Median neuropathy at the wrist: diagnostic utility of clinical findings and an automated electrodiagnostic device.  J Occup Environ Med. 2000; 42(4):398-409.
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. Perkins BA, Grewal J, Ng E, et al.  Validation of a novel point-of-care nerve conduction device for the detection of diabetic sensorimotor polyneuropathy.  Diabetes Care. 2006; 29(9):2023-2027.
10. Vinik AL, Emley MS, Megerian JT, et al.  Median and ulnar nerve conduction measurements in patients with symptoms of diabetic peripheral neuropathy using the NC-stat system.  Diabetes Technol Ther. 2004; 6(6):816-824.

Government Agency, Medical Society, and Other Authoritative Publications:

1. American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM, formerly AAEN). Recommended Policy for Electrodiagnostic Medicine. Rochester, MN. September 1997 and updated 2004.  Endorsed by the American Academy of Neurology, the American Academy of Physical Medicine and Rehabilitation, and the American Association of Neuromuscular and Electrodiagnostic Medicine. Available at: http://www.aanem.org/documents/recpolicy.pdf.  Accessed on December 9, 2009.
2. American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM).  Proper performance and interpretation of electrodiagnostic studies.  Position statement.  Approved September 2005.  Muscle Nerve. 2006; 33:436-439.  Available at: http://www.aanem.org/documents/ProperPerformance.pdf.  Accessed on December 9, 2009.
3. Bolton C, Walker FO. Electromyography and nerve conduction study (EMG/NCS). Sensory nerve conduction study workshop. American Academy of Neurology, Annual Meeting, Workshop #250. Washington, DC: May 2, 1994; pp. 250-254.
4. Chapell R, Bruening W, Mitchell MD, et al. Diagnosis and treatment of worker-related musculoskeletal disorders of the upper extremity. Agency for Healthcare Research and Quality (AHRQ).  Evidence Report/Technology Assessment No. 62. Rockville, MD:2002.
5. England JD, Gronseth GS, Franklin G, et al. Distal symmetric polyneuropathy: A definition for clinical research.  Report of the American Academy of Neurology, the American Association of Neuromuscular and Electrodiagnostic Medicine (AAEN) and the American Academy of Physical Medicine and Rehabilitation. Neurology. 2005; 64:199-207.
6. Jablecki CK, Andary MT, Floeter MK, et al. American Academy of Neurology, America Association of Neuromuscular and Electrodiagnostic Medicine and the American Academy of Physical Medicine and Rehabilitation. Practice parameter: Electrodiagnostic studies in carpal tunnel syndrome. Neurology. 1993; 43(11): 2404-2405.
7. Morse, J.  Office of the Medical Director, Department of Labor and Industries. Washington State Department of Labor and Industries. Technology Assessment: NC-stat System, NeuroMetrix, Inc. June 8, 2006.  Available at: http://www.lni.wa.gov/ClaimsIns/Files/OMD/taNCSTAT0506.pdf.  Accessed on December 9, 2009.
8. U.S. Food and Drug Administration 510(k) Premarket Notification Database.  NeuroMetrix NC-stat.^® No. K041320.  Rockville, MD: FDA. Aug. 12, 2004.  Available at: http://www.accessdata.fda.gov/cdrh_docs/pdf4/K041320.pdf.  Accessed on December 9, 2009.
9. U.S. Food and Drug Administration 510(k) Premarket Notification Database.  Brevio. Summary No. K012069. Rockville, MD:FDA. June 29, 2001. Available at: http://www.accessdata.fda.gov/cdrh_docs/pdf/K012069.pdf.  Accessed on December 9, 2009.
10. Work Loss Data Institute. Carpal tunnel syndrome (acute & chronic). Corpus Christi, TX: Work Loss Data Institute; 2006.

1. Consumer information available at the manufacturer's web site.  NeuroMetrix, Inc., Waltham, MA.  Available at: http://www.neurometrix.com/products.htm.  Accessed on December 9, 2009.

Automated Nerve Conduction Testing
NC-stat^® System
Nerve Conduction Studies, Electromyography
Nerve Conduction Velocity Studies
NeuMed^® Brevio^® Nerve Conduction Monitoring System

The use of specific product names is illustrative only.  It is not intended to be a recommendation of one product over another, and is not intended to represent a complete listing of all products available.