Histological and ultrastructural evidence that recurrent laryngeal neuropathy is a bilateral mononeuropathy limited to recurrent laryngeal nerves

Hahn, Caroline; Matiasek, Kaspar; Dixon, Padraic; Molony, V.; Rodenacker, Karsten; Mayhew, I. G.

doi:10.2746/042516408x335711

Cited by 33 publications

(67 citation statements)

References 26 publications

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“…Finally, we found no evidence that horses with RLN develop right-sided ACC over time, despite the fact that RLN has been confirmed to be a bilateral mono neuropathy [5]. Left-sided progression of RLN has been previously reported in approximately 15% cases over a median of 12 months [4].…”

Section: Discussionmentioning

confidence: 43%

“…Mean age on presentation was 7.2 years (range [3][4][5][6][7][8][9][10][11][12][13][14] and athletic use included 8 eventers (one Irish Draught 2 pure English Thoroughbreds and 5 Thoroughbred crossbreds) and 22 Thoroughbred racehorses (5 flat and 17 National Hunt jump horses).…”

Section: Resultsmentioning

confidence: 99%

“…The video recordings were reviewed to confirm the diagnosis and the following criteria were assessed: 1) Grade of left and right arytenoid abduction. This was graded [1][2][3][4][5] according to the scale previously described by Dixon et al [21]. 2) Presence/absence of vocal cord collapse (VCC) and whether this was unilateral or bilateral.…”

Section: Methodsmentioning

confidence: 99%

“…The condition arises due to a progressive degenerative distal axonopathy [4] affecting both recurrent laryngeal nerves [5]. However, the left side is more severely affected.…”

Section: Introductionmentioning

confidence: 99%

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Retrospective study investigating causes of abnormal respiratory noise in horses following prosthetic laryngoplasty

Compostella

Tremaine

Franklin

2012

Equine Veterinary Journal

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SummaryReasons for performing the study: To investigate causes of respiratory noises in horses following prosthetic laryngoplasty (with or without a ventriculocordectomy) and to examine potential associations between degree of arytenoid abduction and the presence of other upper respiratory tract (URT) abnormalities, including right-sided collapse. Methods: Clinical records and dynamic videoendoscopic recordings were examined from horses presented between 1995 and 2010 for investigation of respiratory noise during exercise, following a prosthetic laryngoplasty (+/-a ventriculocordectomy). Relationships between the degree of left arytenoid cartilage abduction and the presence of other URT disorders were investigated. Results: Thirty horses matched the inclusion criteria. All horses had previously undergone a prosthetic laryngoplasty in different hospitals and in 63% (19/30) of these horses a left-sided ventriculocordectomy had also been performed. The majority of cases (87%) had multiple respiratory abnormalities and only 13% had a single URT disorder. Palatal dysfunction was the most common diagnosis (83%), followed by axial deviation of the aryepiglottic folds (60%) and vocal cord collapse (43%). The right arytenoid cartilage was fully abducted in all cases and no statistically significant correlation between the degree of left arytenoid abduction and any other URT disorders was detected. Conclusions: Multiple forms of dynamic URT disorders were diagnosed in horses that presented with abnormal respiratory noise following laryngoplasty. There was no association between degree of left arytenoid abduction and other URT abnormalities. Furthermore, horses with suboptimal left arytenoid cartilage abduction were not predisposed to right-sided laryngeal collapse. Clinical relevance: Our results demonstrate the fundamental role of dynamic endoscopy in correctly diagnosing dynamic airway collapse in horses that have undergone surgical treatment of the upper respiratory tract.

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Section: Discussionmentioning

confidence: 43%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…The condition arises due to a progressive degenerative distal axonopathy [4] affecting both recurrent laryngeal nerves [5]. However, the left side is more severely affected.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Retrospective study investigating causes of abnormal respiratory noise in horses following prosthetic laryngoplasty

Compostella

Tremaine

Franklin

2012

Equine Veterinary Journal

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“…There is now considerable evidence that this condition results from loss of large-diameter myelinated axons that is most profound distally (described as a distal axonopathy) in the left recurrent laryngeal nerve (Duncan et al 1974;Cahill and Goulden 1986a;Hahn et al 2008). The subsequent laryngeal muscle denervation and atrophy, which gives rise to the clinical signs of incomplete abduction of the arytenoid cartilage and vocal cord, is therefore typically left-sided.…”

mentioning

confidence: 99%

Immunohistochemical Analysis of Laryngeal Muscles in Normal Horses and Horses With Subclinical Recurrent Laryngeal Neuropathy

Rhee

Steel

Derksen

et al. 2009

J Histochem Cytochem.

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Michigan (FJD,NER)S U M M A R Y We used immunohistochemistry to examine myosin heavy-chain (MyHC)-based fiber-type profiles of the right and left cricoarytenoideus dorsalis (CAD) and arytenoideus transversus (TrA) muscles of six horses without laryngoscopic evidence of recurrent laryngeal neuropathy (RLN). Results showed that CAD and TrA muscles have the same slow, 2a, and 2x fibers as equine limb muscles, but not the faster contracting fibers expressing extraocular and 2B MyHCs found in laryngeal muscles of small mammals. Muscles from three horses showed fiber-type grouping bilaterally in the TrA muscles, but only in the left CAD. Fiber-type grouping suggests that denervation and reinnervation of fibers had occurred, and that these horses had subclinical RLN. There was a virtual elimination of 2x fibers in these muscles, accompanied by a significant increase in the percentage of 2a and slow fibers, and hypertrophy of these fiber types. The results suggest that multiple pathophysiological mechanisms are at work in early RLN, including selective denervation and reinnervation of 2x muscle fibers, corruption of neural impulse traffic that regulates 2x and slow muscle fiber types, and compensatory hypertrophy of remaining fibers. We conclude that horses afflicted with mild RLN are able to remain subclinical by compensatory hypertrophy of surviving muscle fibers. (J Histochem Cytochem 57:787-800, 2009)

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Genetics of Equine Neurologic Disease

Finno

Aleman

2013

Equine Genomics

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Histological and ultrastructural evidence that recurrent laryngeal neuropathy is a bilateral mononeuropathy limited to recurrent laryngeal nerves

Abstract: Genetic and local factors specifically affecting the recurrent laryngeal nerves in RLN-affected horses should now be investigated further.

Cited by 33 publications

References 26 publications

Retrospective study investigating causes of abnormal respiratory noise in horses following prosthetic laryngoplasty

Retrospective study investigating causes of abnormal respiratory noise in horses following prosthetic laryngoplasty

Immunohistochemical Analysis of Laryngeal Muscles in Normal Horses and Horses With Subclinical Recurrent Laryngeal Neuropathy

Genetics of Equine Neurologic Disease

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