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Electrodiagnostic Testing for Diagnosing Polyneuropathy

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

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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CME Disclosure Statement: Unless noted, all individuals in control of content reported no relevant financial relationships. If applicable, all relevant financial relationships have been mitigated.

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
1.
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.2021.01.010PubMedGoogle ScholarCrossref
2.
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.2019.10.005PubMedGoogle ScholarCrossref
3.
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
4.
Callaghan  BC , Price  RS , Feldman  EL .  Distal symmetric polyneuropathy in 2020.   JAMA. 2020;324(1):90-91. doi:10.1001/jama.2020.0700PubMedGoogle ScholarCrossref
5.
Siao  P , Kaku  M .  A clinician’s approach to peripheral neuropathy.   Semin Neurol. 2019;39(5):519-530. doi:10.1055/s-0039-1694747PubMedGoogle Scholar
6.
Callaghan  BC , Burke  JF , Feldman  EL .  Electrodiagnostic tests in polyneuropathy and radiculopathy.   JAMA. 2016;315(3):297-298. doi:10.1001/jama.2015.16832PubMedGoogle ScholarCrossref
7.
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:8:1-2:3PubMedGoogle ScholarCrossref
8.
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.xPubMedGoogle ScholarCrossref
9.
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.2015.05.033PubMedGoogle ScholarCrossref
10.
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/awl174PubMedGoogle Scholar
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