HSS Journal

, Volume 2, Issue 1, pp 19–21 | Cite as

EMG: Myths and Facts

  • Joseph Feinberg
Original Article

Electrodiagnostic testing, more commonly known as the EMG test, to many is a “black box.” It is a commonly ordered test that can provide very definitive information that is often not well understood. A large amount of information is usually provided, yet most clinicians rely primarily on the concluding statements, which may or may not be well substantiated. Added insight into this test demands understanding some basic facts about the “EMG” test and dispelling some of the myths.

The timing for ordering an EMG study

One of the most common myths about EMG tests is that one must wait 2–3 weeks following a nerve injury before reliable information can be obtained. It is true that the degree of muscle denervation that occurs after nerve injury can not be determined until Wallerian degeneration is complete and this can take as short as 1 week or as long as 4 weeks [1]. This is a length-dependent process so that the longer the length of the injured axon, the longer Wallerian degeneration will...


Motor Unit Nerve Conduction Study Axonal Regeneration Neurological Recovery Motor Unit Recruitment 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


  1. 1.
    Dumitru, D, Zwarts, MJ 2005Needle electromyographyDumitru, DAmato, AAZwarts MJ, MJ eds. Electrodiagnostic medicineHanley and BelfusPhiladelphia257292Google Scholar
  2. 2.
    Herbison, GJ 1984Neuropathic Needle Examination. AAEM Course A: Fundamentals of EMGAmerican Association of Electrodiagnostic MedicineRochester, MN2125Google Scholar
  3. 3.
    Berenberg, RA, Forman, DS, Wood, DK,  et al. 1977Recovery of peripheral nerve function after axonotomy. Effect of triiodothyronineExp Neurol57349363CrossRefPubMedGoogle Scholar
  4. 4.
    Forman, BS, Berenberg, RA 1978Regeneration of motor axons in the rat sciatic nerve studied by labeling with axonally radioactively proteinBrain Res156387436CrossRefGoogle Scholar
  5. 5.
    Wohlfart, G 1958Collateral regeneration in partially denervated musclesNeurology8175180PubMedGoogle Scholar
  6. 6.
    Brown, MC, Ironton, R 1978Sprouting and regression of neuromuscular synapses in partial denervated mammalian musclesJ Physiol278325348PubMedGoogle Scholar
  7. 7.
    Thompson, W, Jansen, JKS 1977The extent of sprouting of remaining motor units in partially denervated immature and adult soleus muscleNeuroscience2523535CrossRefPubMedGoogle Scholar
  8. 8.
    Kraft, GH 1990Fibrillation potential amplitude and muscle atrophy following peripheral nerve injuryMuscle Nerve13814821PubMedGoogle Scholar
  9. 9.
    Buchthal, F 1982Fibrillations: clinical electrophysiologyCulp, WJOchoa, J eds. Abnormal nerves and muscle generatorsOxford University PressNew York632662Google Scholar
  10. 10.
    Campbell WW (2002) Electrophysiological approaches to the diagnosis and assessment of ulnar neuropathy. 2002 AAEM Plenary Session Toronto, Ontario, American Association of Electrodiagnostic Medicine, pp. 13–22Google Scholar
  11. 11.
    Dumitru, D, Zwarts, MJ 2002Focal peripheral neuropathiesDumitru, DAmato, AAZwarts, MJ eds. Electrodiagnostic medicineHanley and BelfusPhiladelphia10431126Google Scholar
  12. 12.
    Kimura, J 1979The carpal tunnel syndromeBrain102619635PubMedGoogle Scholar

Copyright information

© Hospital for Special Surgery 2006

Authors and Affiliations

  1. 1.Physiatry Department at the Hospital for Special SurgeryHospital for Special SurgeryNew YorkUSA

Personalised recommendations