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Scientific reports2019; 9(1); 2713; doi: 10.1038/s41598-019-39189-z

Asymmetric recurrent laryngeal nerve conduction velocities and dorsal cricoarytenoid muscle electromyographic characteristics in clinically normal horses.

Abstract: The dorsal cricoarytenoid (DCA) muscles, are a fundamental component of the athletic horse's respiratory system: as the sole abductors of the airways, they maintain the size of the rima glottis which is essential for enabling maximal air intake during intense exercise. Dysfunction of the DCA muscle leads to arytenoid collapse during exercise, resulting in poor performance. An electrodiagnostic study including electromyography of the dorsal cricoarytenoid muscles and conduction velocity testing of the innervating recurrent laryngeal nerves (RLn) was conducted in horses with normal laryngeal function. We detected reduced nerve conduction velocity of the left RLn, compared to the right, and pathologic spontaneous activity (PSA) of myoelectrical activity within the left DCA muscle in half of this horse population and the horses with the slowest nerve conduction velocities. The findings in this group of horses are consistent with left sided demyelination and axonal loss, consistent with Recurrent Laryngeal Neuropathy (RLN), a highly prevalent degenerative disorder of the RLn in horses that predominantly affects the left side. The detection of electromyographic changes compatible with RLN in clinically unaffected horses is consistent with previous studies that identified "subclinical" subjects, presenting normal laryngeal function despite neuropathologic changes within nerve and muscle confirmed histologically.
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Publication Date: 2019-02-25 PubMed ID: 30804428PubMed Central: PMC6389933DOI: 10.1038/s41598-019-39189-zGoogle Scholar: Lookup
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  • Non-U.S. Gov't

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This study investigates how the function and health of the dorsal cricoarytenoid muscles and the recurrent laryngeal nerves in horses can influence their ability to perform athletically. The research finds that slower nerve conduction in these areas, particularly on the left side, can be connected to a degenerative disorder known as Recurrent Laryngeal Neuropathy.

Background and Aim

  • The research aims to understand the relationship between the conduction velocity of recurrent laryngeal nerves (RLn) and the electromyographic (EMG) characteristics of the dorsal cricoarytenoid (DCA) muscles in clinically healthy horses.
  • The DCA muscles play a critical role in a horse’s respiratory system, primarily by controlling the size of the rima glottis, which is essential for a horse’s air intake during intense exercise.
  • Recurrent Laryngeal Neuropathy (RLN) is a common degenerative disorder in horses that often affects the left side, causing dysfunction of the DCA muscle and resulting in poor performance.

Methodology

  • An electrodiagnostic study including electromyography of the DCA muscles and conduction velocity testing of the innervating RLn was performed on horses with normal laryngeal function.
  • The study examined whether differences in conduction velocity of the left and right RLn could signal early, ‘subclinical’ signs of RLN, before overt clinical symptoms were present.

Findings

  • The researchers found reduced nerve conduction velocity of the left RLn in comparison to the right.
  • Pathologic spontaneous activity (PSA), which could indicate RLN, was found in the myoelectrical activity of the left DCA muscle in half of the tested horse population.
  • These findings suggest that the horses with the slowest nerve conduction velocities were experiencing a kind of nerve damage, called demyelination, and loss of nerve cells, particularly on the left side—both of which are consistent with symptoms of RLN.

Conclusion and Implication

  • The study concludes that the identified electromyographic changes are consistent with previous research suggesting RLN could be present in horses even when they appear clinically unaffected.
  • These “subclinical” cases represent horses that maintain normal laryngeal function despite experiencing neuropathological changes in their nerves and muscles.
  • The results could therefore be an indicator that these horses are in the early stages of RLN, which poses a potential risk to their future athletic performance.

Cite This Article

APA
Cercone M, Hokanson CM, Olsen E, Ducharme NG, Mitchell LM, Piercy RJ, Cheetham J. (2019). Asymmetric recurrent laryngeal nerve conduction velocities and dorsal cricoarytenoid muscle electromyographic characteristics in clinically normal horses. Sci Rep, 9(1), 2713. https://doi.org/10.1038/s41598-019-39189-z

Publication

Scientific reports
ISSN: 2045-2322
NlmUniqueID: 101563288
Country: England
Language: English
Volume: 9
Issue: 1
Pages: 2713
PII: 2713

Researcher Affiliations

Cercone, Marta
  • Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA.
Hokanson, Caitlin M
  • Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA.
Olsen, Emil
  • Comparative Neuromuscular Diseases Laboratory, Department of Clinical Sciences and Services, Royal Veterinary College, London, NW1 0TU, UK.
Ducharme, Norm G
  • Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA.
Mitchell, Lisa M
  • Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA.
Piercy, Richard J
  • Comparative Neuromuscular Diseases Laboratory, Department of Clinical Sciences and Services, Royal Veterinary College, London, NW1 0TU, UK.
Cheetham, Jon
  • Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA. jc485@cornell.edu.

MeSH Terms

  • Animals
  • Electromyography
  • Female
  • Horse Diseases / diagnosis
  • Horse Diseases / physiopathology
  • Horses / injuries
  • Horses / physiology
  • Laryngeal Muscles / innervation
  • Laryngeal Muscles / physiopathology
  • Male
  • Physical Conditioning, Animal
  • Recurrent Laryngeal Nerve / physiopathology
  • Recurrent Laryngeal Nerve Injuries / diagnosis
  • Recurrent Laryngeal Nerve Injuries / physiopathology
  • Recurrent Laryngeal Nerve Injuries / veterinary

Conflict of Interest Statement

The authors declare no competing interests.

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Citations

This article has been cited 3 times.
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