Ch 101 - Larynx Flashcards

1
Q

List the cartilages of the larynx

A
  • Epiglottic
  • Thyroid
  • Cricoid
  • sesamoid
  • interarytenoid
  • paired arytenoid
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2
Q

List the processes of the arytenoid cartilages

A
  • Cuneiform
  • Corniculate
  • Vocal
  • Muscular
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3
Q

List the extrinsic and intrinsic muscles of the larynx

A

Extrinsic (constrict the caudal part of the pharynx)
- Thyropharyngeus
- Cricopharyngeus

Intrinsic
- Cricoarytenoideus dorsalis (arytenois abduction)
- Cricoarytenoideus lateralis (Pivots arytenoid inwards to close rima glottidis
- Thyroarytenoideus - Gives rise to ventricularis and vocalis muscles
- Arytenoideus transversus
- Hyoepiglotticus (draws epiglottis downwards)
- Cricothyroideus (tenses the vocal cords)

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4
Q

How does the feline laryngeal anatomy differ from dogs?

A
  • The arytenoid cartilages lack a cuneiform and corniculate process and the aryepiglottic folds are absent (mucosa connects at the sides of epiglottis directly to the cricoid lamina)
  • Vocal cords are thick and rounded
  • Ventricles are absent
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5
Q

List the three functions of the larynx

A
  • Larynx is pulled cranially during swallowing to block laryngeal opening
  • Controls airway resistance
  • Voice production
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6
Q

What % of dogs with BOAS will have:
- Stenotic nares
- Elongated soft palate
- Everted saccules
- Laryngeal collapse

A
  • Stenotic nares 43-85%
  • Elongated soft palate 86-96%
  • Everted saccules 55-66%
  • Laryngeal collapse 8-70%
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7
Q

What are the three stages of laryngeal collapse?

A
  • Stage I - Everted laryngeal saccules
  • Stage II - Cuneiform process losses its rigidity and becomes medially displaced
  • Stage III - Corniculate process collapse, resulting in loss of dorsal arch of rima glottidis
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8
Q

What are the options for a patient with laryngeal collapse who does not respond to surgical management of BOAS and medical management?

A
  • Permanent tracheostomy
  • Laryngeal tieback
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9
Q

Damage to what structures can cause laryngeal paralysis?

A
  • Nucleus ambiguus
  • Vagus nerve or its branches
  • Cricoarytenoideus dorsalis muscle
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10
Q

What causes congenital laryngeal paralysis?
What breeds are overrepresented?

A
  • Progressive degeneration of neurons within the nucleus ambiguus and Wallerian degeneration of laryngeal nerves
  • Bouvier des Flandres, Bull terriers, dalmations, Rottweilers, Leonberger
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11
Q

What breeds are overrepresented for acquired laryngeal paralysis?

A
  • Lab and Golder Retrievers
  • St Bernards
  • Irish Setters
  • Husky
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12
Q

What % of dogs with laryngeal paralysis have pre-op aspiration pneumonia?
Oesophageal dysfunction?

A
  • Aspiration pneumonia 7.9%
  • Oesophageal dysfunction 11.4% - assoc with an increased risk of post-op complications
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13
Q

What is doxapram?

A

CNS stimulant which causes an increased resp rate and tidal volume by increasing the electrical activity in the inspiratory and expiratory centers of the medulla

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14
Q

What are the surgical options for the Tx of laryngeal paralysis?

A
  • Unilateral or bilateral arytenoid lateralisation
  • Ventricular cordectomy and partial arytenoidectomy
  • Modified castellated laryngofissure
  • Permanent tracheostomy
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15
Q

What is the reported increase in rima glottidis opening using cricoarytenoid and thyroarytenoid lateralisation?

A
  • Cricoarytenoid - 207%
  • Thyroarytenoid - 140%
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16
Q

What is the prognosis after tie-back?

A
  • 90% will improve
  • 70% alive at 5yr

Complications 10-58%
- Aspiration pneumonia 8-21%
- Persistent or recurrence of signs in up to 33%
- Failure (suture breakage or cartilage fracture)
- Laryngeal webbing
- etc

Bilateral complication rate 89% with 8/9 dogs developing asp pneumonia and 5/9 dying within 5 months

17
Q

What are the 2 approaches for a partial laryngectomy?

A
  • Intra-oral
  • Ventral (less risk of webbing as can close the mucosa primarily)

Removing vocal cord and corniculate and vocal process of arytenoid (cuneiform process left intact)

18
Q

What is the rate of aspiration pneumonia and laryngeal webbing formation with intraoral partial laryngectomy?

A
  • Aspiration pneumonia 6-33%
  • Laryngeal webbing - 8-14%
19
Q

When is a permanent tracheostomy a good option for laryngeal paralysis?

A

Dogs at a high risk for aspiration pneumonia from myopathy, megaoesophagus, hiatal hernia, GI disorder etc