eMedicine Specialties > Neurology > Electromyography and Nerve Conduction Studies

Single-Fiber EMG: Multimedia

Author: David E Stickler, MD, Assistant Professor, Department of Neurosciences, Director of Electromyography Laboratory, Director of MDA Clinic, Director of Neuromuscular Service, Director of ALS Clinic, Medical University of South Carolina
Coauthor(s): Donald B Sanders, MD, EMG Laboratory Director, Professor of Medicine (Neurology), Division of Neurology, Duke University Medical Center
Contributor Information and Disclosures

Updated: Jan 15, 2009

Multimedia

Diagram of a single-fiber electromyography electr...
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Media file 1: Diagram of a single-fiber electromyography electrode within a motor unit. Light-colored symbols indicate muscle fibers belonging to one motor unit. The electrode is positioned to record the action potential from one muscle fiber with maximum amplitude. In this example, no other muscle fibers from the same motor unit are within the recording territory of the electrode (yellow semicircle).
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Diagram of a single-fiber electromyography electr...

Diagram of a single-fiber electromyography electrode within a motor unit. Light-colored symbols indicate muscle fibers belonging to one motor unit. The electrode is positioned to record the action potential from one muscle fiber with maximum amplitude. In this example, no other muscle fibers from the same motor unit are within the recording territory of the electrode (yellow semicircle).

Diagram of fiber density measurements in single-f...
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Media file 2: Diagram of fiber density measurements in single-fiber electromyography (SFEMG). Semicircles represent the recording territories of the SFEMG electrode when it is positioned to record, respectively, the signals in the adjacent outer quadrants of the figure.
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Diagram of fiber density measurements in single-f...

Diagram of fiber density measurements in single-fiber electromyography (SFEMG). Semicircles represent the recording territories of the SFEMG electrode when it is positioned to record, respectively, the signals in the adjacent outer quadrants of the figure.

Electrode setup for single-fiber electromyography...
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Media file 3: Electrode setup for single-fiber electromyography (SFEMG) during intramuscular axonal stimulation. The stimulating electrode is inserted into the muscle near an intramuscular nerve fiber, and the recording electrode is inserted distally near muscle fibers innervated by this nerve. During repetitive stimulation of the nerve, the latency between stimulus and action potentials (APs) varies among successive responses (ie, the neuromuscular jitter).
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Electrode setup for single-fiber electromyography...

Electrode setup for single-fiber electromyography (SFEMG) during intramuscular axonal stimulation. The stimulating electrode is inserted into the muscle near an intramuscular nerve fiber, and the recording electrode is inserted distally near muscle fibers innervated by this nerve. During repetitive stimulation of the nerve, the latency between stimulus and action potentials (APs) varies among successive responses (ie, the neuromuscular jitter).

Recording position of the single-fiber electromyo...
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Media file 4: Recording position of the single-fiber electromyography electrode during jitter analysis with voluntary muscle activation. The electrode is positioned to record action potentials (APs) from 2 muscle fibers that are innervated by the same motor nerve fiber.
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Recording position of the single-fiber electromyo...

Recording position of the single-fiber electromyography electrode during jitter analysis with voluntary muscle activation. The electrode is positioned to record action potentials (APs) from 2 muscle fibers that are innervated by the same motor nerve fiber.

Single-fiber electromyography. Action potentials ...
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Media file 5: Single-fiber electromyography. Action potentials recorded from 2 muscle fibers with normal jitter during voluntary muscle activation. Ten consecutive discharges are superimposed. The oscilloscope is triggered by the rising portion of the first potential, which falls at the same position with each discharge. The second potential falls at slightly varying positions among successive discharges, demonstrating the neuromuscular jitter.
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Single-fiber electromyography. Action potentials ...

Single-fiber electromyography. Action potentials recorded from 2 muscle fibers with normal jitter during voluntary muscle activation. Ten consecutive discharges are superimposed. The oscilloscope is triggered by the rising portion of the first potential, which falls at the same position with each discharge. The second potential falls at slightly varying positions among successive discharges, demonstrating the neuromuscular jitter.

Single-fiber electromyography. Calculation of the...
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Media file 6: Single-fiber electromyography. Calculation of the mean difference between consecutive discharges (MCD). IPI is the interpotential interval or stimulus-to-response latency during axonal stimulation jitter analysis.
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Single-fiber electromyography. Calculation of the...

Single-fiber electromyography. Calculation of the mean difference between consecutive discharges (MCD). IPI is the interpotential interval or stimulus-to-response latency during axonal stimulation jitter analysis.

Single-fiber electromyography. A pair of action p...
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Media file 7: Single-fiber electromyography. A pair of action potentials recorded from a patient with myasthenia gravis during voluntary activation of the muscle. Consecutive discharges are superimposed. The sweep is triggered on the first potential, and increased jitter is seen in the second potential.
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Single-fiber electromyography. A pair of action p...

Single-fiber electromyography. A pair of action potentials recorded from a patient with myasthenia gravis during voluntary activation of the muscle. Consecutive discharges are superimposed. The sweep is triggered on the first potential, and increased jitter is seen in the second potential.

Single-fiber electromyography. A pair of action p...
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Media file 8: Single-fiber electromyography. A pair of action potentials recorded from a patient with myasthenia gravis during voluntary activation of the muscle. Ten consecutive discharges are shown. The oscilloscope is triggered on the first potential, and increased jitter is seen in the second potential. In 3 discharges (arrows), the second potential does not occur (ie, blocking).
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Single-fiber electromyography. A pair of action p...

Single-fiber electromyography. A pair of action potentials recorded from a patient with myasthenia gravis during voluntary activation of the muscle. Ten consecutive discharges are shown. The oscilloscope is triggered on the first potential, and increased jitter is seen in the second potential. In 3 discharges (arrows), the second potential does not occur (ie, blocking).

Graphical display of the results of a normal sing...
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Media file 9: Graphical display of the results of a normal single-fiber electromyography (SFEMG) study. This is a nonsequential histogram of the jitter values that were recorded from 20 potential pairs during voluntary activation. The upper limit of normal for individual-paired jitter is shown. Summary statistics are listed at right.
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Graphical display of the results of a normal sing...

Graphical display of the results of a normal single-fiber electromyography (SFEMG) study. This is a nonsequential histogram of the jitter values that were recorded from 20 potential pairs during voluntary activation. The upper limit of normal for individual-paired jitter is shown. Summary statistics are listed at right.

Graphical display as in Image 9 of a jitter study...
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Media file 10: Graphical display as in Image 9 of a jitter study from a patient with myasthenia gravis (MG). The asterisk indicates a potential pair in which blocking was seen.
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Graphical display as in Image 9 of a jitter study...

Graphical display as in Image 9 of a jitter study from a patient with myasthenia gravis (MG). The asterisk indicates a potential pair in which blocking was seen.

More on Single-Fiber EMG

References
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References

  1. Benatar M, Hammad M, Doss-Riney H. Concentric-needle single-fiber electromyography for the diagnosis of myasthenia gravis. Muscle Nerve. Aug 2006;34(2):163-8. [Medline].

  2. Bromberg MB, Scott DM. Single fiber EMG reference values: reformatted in tabular form. AD HOC Committee of the AAEM Single Fiber Special Interest Group. Muscle Nerve. Jul 1994;17(7):820-1. [Medline].

  3. Gilchrist JM, Ad hoc Committee. Single fiber EMG reference values: a collaborative effort. Ad Hoc Committee of the AAEM Special Interest Group on Single Fiber EMG. Muscle Nerve. Feb 1992;15(2):151-61. [Medline].

  4. Gilchrist JM, Massey JM, Sanders DB. Single fiber EMG and repetitive stimulation of the same muscle in myasthenia gravis. Muscle Nerve. Feb 1994;17(2):171-5. [Medline].

  5. Harris AJ, Duxson MJ, Butler JE, Hodges PW, Taylor JL, Gandevia SC. Muscle fiber and motor unit behavior in the longest human skeletal muscle. J Neurosci. Sep 14 2005;25(37):8528-33. [Medline].

  6. Kouyoumdjian JA, Stalberg EV. Reference jitter values for concentric needle electrodes in voluntarily activated extensor digitorum communis and orbicularis oculi muscles. Muscle and Nerve. 2008;37:694-699. [Medline].

  7. Sanders DB, Howard JF. AAEE minimonograph #25: Single-fiber electromyography in myasthenia gravis. Muscle Nerve. Nov-Dec 1986;9(9):809-19. [Medline].

  8. Sanders DB, Stalberg EV. AAEM minimonograph #25: single-fiber electromyography. Muscle Nerve. Sep 1996;19(9):1069-83. [Medline].

  9. Sarrigiannis PG, Kennett RP, Read S, Farrugia ME. Single-fiber EMG with a concentric needle electrode: validation in myasthenia gravis. Muscle Nerve. Jan 2006;33(1):61-5. [Medline].

  10. Stalberg E, Ekstedt J, Broman A. The electromyographic jitter in normal human muscles. Electroencephalogr Clin Neurophysiol. Nov 1971;31(5):429-38. [Medline].

  11. Stalberg E, Schwartz MS, Trontelj JV. Single fibre electromyography in various processes affecting the anterior horn cell. J Neurol Sci. Apr 1975;24(4):403-15. [Medline].

  12. Stalberg E, Trontelj JV. Single Fiber Electromyography. Studies in Healthy and Diseased Muscle. New York: Raven Press; 1994.

  13. Stickler DE, Massey JM, Sanders DB. MuSK-antibody positive myasthenia gravis: clinical and electrodiagnostic patterns. Clin Neurophysiol. Sep 2005;116(9):2065-8. [Medline].

  14. Trontelj JV, Mihelin M, Fernandez JM, Stalberg E. Axonal stimulation for end-plate jitter studies. J Neurol Neurosurg Psychiatry. Jun 1986;49(6):677-85. [Medline].

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Further Reading

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Keywords

single-fiber electromyography, SFEMG, fiber density, muscle fiber density, myasthenia gravis, neuromuscular jitter, neuromuscular transmission

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Contributor Information and Disclosures

Author

David E Stickler, MD, Assistant Professor, Department of Neurosciences, Director of Electromyography Laboratory, Director of MDA Clinic, Director of Neuromuscular Service, Director of ALS Clinic, Medical University of South Carolina
David E Stickler, MD is a member of the following medical societies: American Academy of Neurology and American Association of Neuromuscular and Electrodiagnostic Medicine
Disclosure: Nothing to disclose.

Coauthor(s)

Donald B Sanders, MD, EMG Laboratory Director, Professor of Medicine (Neurology), Division of Neurology, Duke University Medical Center
Donald B Sanders, MD is a member of the following medical societies: American Academy of Neurology, American Association of Neuromuscular and Electrodiagnostic Medicine, American Neurological Association, and New York Academy of Sciences
Disclosure: Nothing to disclose.

Medical Editor

Aashit K Shah, MD, Associate Professor of Neurology, Wayne State University; Program Director, Clinical Neurophysiology Fellowship, Department of Neurology, Detroit Medical Center
Aashit K Shah, MD is a member of the following medical societies: American Academy of Neurology, American Clinical Neurophysiology Society, and American Epilepsy Society
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Agapito S Lorenzo, MD, Laboratory Director, Associate Professor, Departments of Neurology, Creighton University and University of Nebraska Medical Center
Agapito S Lorenzo, MD is a member of the following medical societies: American Academy of Neurology and American Association of Neuromuscular and Electrodiagnostic Medicine
Disclosure: Nothing to disclose.

CME Editor

Matthew J Baker, MD, Consulting Staff, Collier Neurologic Specialists, Naples Community Hospital
Matthew J Baker, MD is a member of the following medical societies: American Academy of Neurology
Disclosure: Nothing to disclose.

Chief Editor

Nicholas Y Lorenzo, MD, Chief Editor, eMedicine Neurology; Consulting Staff, Neurology Specialists and Consultants
Nicholas Y Lorenzo, MD is a member of the following medical societies: Alpha Omega Alpha and American Academy of Neurology
Disclosure: Nothing to disclose.

 
 
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