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Neurology

Electrodiagnostic Testing for Diagnosing Polyneuropathy

Educational Objective
To understand how to interpret the results of diagnostic tests and apply them clinically.

1 Credit CME

JAMA

Published Online: November 16, 2021

JAMA Diagnostic Test Interpretation

Article Information and Disclosures

Ryan D. Jacobson, MD¹;

Michelle Glantz, DO¹

Author Affiliations

¹Department of Neurological Sciences, Rush University, Chicago, Illinois

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A 50-year-old woman with a history of seizures presented to the electromyography laboratory with progressive lower extremity pain and gait imbalance for approximately 5 years. A neurological examination demonstrated reduced pinprick sensation in both feet and absent vibratory sensation at the first toes. Mild weakness of ankle dorsiflexion and absent ankle jerk reflexes were noted bilaterally. She had a slightly wide-based gait, high-arched feet, and hammer toes. She had no known family history of polyneuropathy and no history of diabetes, alcohol misuse, known vitamin deficiency, hypothyroidism, or HIV. Nerve conduction studies (NCS) and needle electromyography (EMG) were performed. The results are shown in Table 1 and Table 2.

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A. Results are consistent with axonal polyneuropathy

Electrodiagnostic testing typically includes NCS and needle EMG. NCS involves application of an electrical stimulus to the skin above a nerve and use of surface electrodes to record waveform responses from individual sensory and motor nerves. The action potential generated after electrical stimulation represents the number of fibers depolarized. The amplitude, distal latency, and conduction velocity of an action potential help distinguish whether a neuropathy is axonal or demyelinating. Needle EMG involves placement of a small recording needle electrode into a muscle to evaluate for abnormal insertional activity or spontaneous activity upon needle insertion and to assess voluntary motor units with volitional activation of the muscle. EMG can help distinguish neurogenic or myopathic weakness.¹

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Article Information

Corresponding Author: Ryan D. Jacobson, MD, Department of Neurological Sciences, Rush University, 1725 W Harrison St, Ste 1118, Chicago, IL 60612 (ryan_jacobson@rush.edu).

Conflict of Interest Disclosures: None reported.

References

Choi JM , Di Maria G . Electrodiagnostic testing for disorders of peripheral nerves. Clin Geriatr Med. 2021;37(2):209-221. doi:10.1016/j.cger.2021.01.010 PubMed Google Scholar Crossref

Tankisi H , Pugdahl K , Beniczky S , Andersen H , Fuglsang-Frederiksen A . Evidence-based recommendations for examination and diagnostic strategies of polyneuropathy electrodiagnosis. Clin Neurophysiol Pract. 2019;4:214-222. doi:10.1016/j.cnp.2019.10.005 PubMed Google Scholar Crossref

Centers for Medicare and Medicaid Services. Physician fee schedule look-up tool. Accessed August 19, 2021. https://www.cms.gov/Medicare/Medicare-Fee-for-Service-Payment/PFSlookup

Callaghan BC , Price RS , Feldman EL . Distal symmetric polyneuropathy in 2020. JAMA. 2020;324(1):90-91. doi:10.1001/jama.2020.0700 PubMed Google Scholar Crossref

Siao P , Kaku M . A clinician’s approach to peripheral neuropathy. Semin Neurol. 2019;39(5):519-530. doi:10.1055/s-0039-1694747 PubMed Google Scholar

Callaghan BC , Burke JF , Feldman EL . Electrodiagnostic tests in polyneuropathy and radiculopathy. JAMA. 2016;315(3):297-298. doi:10.1001/jama.2015.16832 PubMed Google Scholar Crossref

Pareyson D , Scaioli V , Laurà M . Clinical and electrophysiological aspects of Charcot-Marie-Tooth disease. Neuromolecular Med. 2006;8(1-2):3-22. doi:10.1385/NMM:8:1-2:3 PubMed Google Scholar Crossref

Reilly MM , Murphy SM , Laurá M . Charcot-Marie-Tooth disease. J Peripher Nerv Syst. 2011;16(1):1-14. doi:10.1111/j.1529-8027.2011.00324.x PubMed Google Scholar Crossref

Stuppia G , Rizzo F , Riboldi G , et al. MFN2-related neuropathies: clinical features, molecular pathogenesis and therapeutic perspectives. J Neurol Sci. 2015;356(1-2):7-18. doi:10.1016/j.jns.2015.05.033 PubMed Google Scholar Crossref

Chung KW , Kim SB , Park KD , et al. Early onset severe and late-onset mild Charcot-Marie-Tooth disease with mitofusin 2 (MFN2) mutations. Brain. 2006;129(Pt 8):2103-2118. doi:10.1093/brain/awl174 PubMed Google Scholar

AMA CME Accreditation Information

Credit Designation Statement: The American Medical Association designates this Journal-based CME activity activity for a maximum of 1.00  AMA PRA Category 1 Credit(s)™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Successful completion of this CME activity, which includes participation in the evaluation component, enables the participant to earn up to:

1.00 Medical Knowledge MOC points in the American Board of Internal Medicine's (ABIM) Maintenance of Certification (MOC) program;;
1.00 Self-Assessment points in the American Board of Otolaryngology – Head and Neck Surgery’s (ABOHNS) Continuing Certification program;
1.00 MOC points in the American Board of Pediatrics’ (ABP) Maintenance of Certification (MOC) program;
1.00 Lifelong Learning points in the American Board of Pathology’s (ABPath) Continuing Certification program; and
1.00 CME points in the American Board of Surgery’s (ABS) Continuing Certification program

It is the CME activity provider's responsibility to submit participant completion information to ACCME for the purpose of granting MOC credit.