Difference between revisions of "Laryngeal Hemiplegia"

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(Created page with "*In Horses: *Unilateral paralysis of arytenoids *Common 2-13% training thoroughbreds *Damaged/ dysfunctional recurrent laryngel nerve (branch of vagus) *Mostly left side affected...")
 
 
(One intermediate revision by the same user not shown)
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**Trauma
 
**Trauma
  
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* These horses are also known as "'''roarers'''"
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* Equine laryngeal hemiplegia is a very common condition.
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===Pathogenesis===
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# The disease starts with an idiopathic degeneration of the left recurrent laryngeal nerve.
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# This leads to atrophy of the left dorsal cricoarytenoid muscle.
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# Without the use of this muscle, the horse is unable to abduct the left arytenoid cartilage and vocal fold.
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# Airways are therefore partially obstructed on inspiration.
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 +
[http://w3.vet.cornell.edu/nst/nst.asp?Fun=F_KSsrch&kw=HEMIPLEGIA View images courtesy of Cornell Veterinary Medicine]
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Idiopathic Laryngeal Hemiplegia:
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:Progressive loss of fibres (esp. large diameter) within left recurrent laryngeal nerve compared to right
 +
:Dying back axonopathy with myelin sheath involvement:
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:Degenerating fibres
 +
:Regenerating clusters
 +
:De/Re-myelination
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:Flattening of nerve between aorta & trachea
 +
:Inspiratory 'roaring' noise - flapping of vocal fold
 +
:'Slap test' - adduction of contralateral arytenoid during expiration
 +
:Endoscopic examination - assymetric arytenoids, poor abduction of left vocal fold.
 +
:Palpable atrophy of laryngeal musculature
 +
:Laryngeal Ventriculectomy (Hobday procedure)
 +
:'Tie Back'
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:Laryngeal muscle prosthesis
 +
:Prognosis usually good
  
 
==Test yourself with the Larynx Pathology Flashcards==
 
==Test yourself with the Larynx Pathology Flashcards==
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[[Category:Larynx - Pathology]]
 
[[Category:Larynx - Pathology]]
 
[[Category:Respiratory System - Degenerative Pathology]]
 
[[Category:Respiratory System - Degenerative Pathology]]
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[[Category:Respiratory Diseases - Horse]]
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[[Category:Central Nervous System - Degenerative Pathology]]
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[[Category:Peripheral Nervous System - Pathology]]

Latest revision as of 14:10, 9 March 2011

  • In Horses:
  • Unilateral paralysis of arytenoids
  • Common 2-13% training thoroughbreds
  • Damaged/ dysfunctional recurrent laryngel nerve (branch of vagus)
  • Mostly left side affected, occasionally also the right nerve
  • Demyelination of nerve fibres, and leading to atrophy of intrinsic laryngeal muscles particularly the adductor (cricoarytenoid) which allows the left arytenoid cartilage to lean into the laryngeal lumen
  • The 'roaring' is noticeable after exercising
  • The aetiology is not properly established but suggested factors are:
    • Length of the left recurrent nerve
    • Extension neuritis in guttural pouch mycosis
    • Neurotoxins - organophosphorus compounds may produce similar degenerative changes in the nerves
    • Enlarged retropharyngeal lymph nodes
    • Neoplasia
    • Trauma
  • These horses are also known as "roarers"
  • Equine laryngeal hemiplegia is a very common condition.

Pathogenesis

  1. The disease starts with an idiopathic degeneration of the left recurrent laryngeal nerve.
  2. This leads to atrophy of the left dorsal cricoarytenoid muscle.
  3. Without the use of this muscle, the horse is unable to abduct the left arytenoid cartilage and vocal fold.
  4. Airways are therefore partially obstructed on inspiration.

View images courtesy of Cornell Veterinary Medicine

Idiopathic Laryngeal Hemiplegia:

Progressive loss of fibres (esp. large diameter) within left recurrent laryngeal nerve compared to right
Dying back axonopathy with myelin sheath involvement:
Degenerating fibres
Regenerating clusters
De/Re-myelination
Flattening of nerve between aorta & trachea
Inspiratory 'roaring' noise - flapping of vocal fold
'Slap test' - adduction of contralateral arytenoid during expiration
Endoscopic examination - assymetric arytenoids, poor abduction of left vocal fold.
Palpable atrophy of laryngeal musculature
Laryngeal Ventriculectomy (Hobday procedure)
'Tie Back'
Laryngeal muscle prosthesis
Prognosis usually good

Test yourself with the Larynx Pathology Flashcards

Larynx Pathology Flashcards