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Small Animal Surgical Diseases > Laryngeal Paralysis > Flashcards

Laryngeal Paralysis Flashcards

1
Q

what are the 4 cartilages of the larynx?

A
  1. epiglottic
  2. arytenoid
  3. thyroid
  4. cricoid
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2
Q

what nerve is most important associated with the larynx and innervates the cricoarytenoid muscle?

A

recurrent laryngeal nerve

this nerve originates from the vagus nerve

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3
Q

what muscle is most important that is associated with the larynx?

A

cricoarytenoideus dorsalis muscle

dilates the glottic cavity by abducting the vocal folds

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4
Q

why is the larynx important?

A
  1. prevents aspiration
  2. controls airway resistance
  3. voice production
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5
Q

Which of the following statements is FALSE about laryngeal paraylsis?
A. can occur due to injury to the cricoarytenoideus nerve
B. can be unilateral or bilateral
C. can be congenital or acquired
D. occurs in dogs and cats
E. occurs in male dogs more frequently than female

A

A. can occur due to injury to the cricoarytenoideus nerve

It occurs due to injury/damage to the vagus or recurrent laryngeal nerves

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6
Q

What 4 breeds are at risk for CONGENITAL laryngeal paralysis that is manifested in dogs <1 yo?

A
  1. bouvier des flandres
  2. dalmatians
  3. huskies
  4. rottweilers

these animals usually have a concurrent progressive neurologic degeneration

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7
Q

which 4 breeds are at risk for ACQUIRED laryngeal paralysis?

A
  1. labrador retrievers*
  2. golden retrievers
  3. st. bernards
  4. irish setters

the acquired form has an onset of avg 9 years of age.

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8
Q

What are the 5 potential causes of acquired laryngeal paralysis?

A
  1. idiopathic (often accompanied by a generalized polyneuropathy, talk to client about this)** most commonly
  2. neoplasia (thyroid tumor, mediastinal mass – invasive into nerve)
  3. endocrine polyneuropathy (hypothyroidism association)
  4. immune-mediated polyneuropathy (immune-med destruction of nervous system)
  5. iatrogenic (in surgery, cut RLN)
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9
Q

What are the clinical signs of laryngeal paralysis?

A

EARLY on: voice changes, gagging, coughing with food and water intake

LATER on: exercise intolerance, inspiratory stridor, acute respiratory distress secondary to exacerbation of disease (warm temps –> heat stroke)

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10
Q

T/F: progression of laryngeal paralysis is fairly quick

A

false - slow

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11
Q

what diagnostics should you run on a dog that presents to your clinic with inspiratory stridor, gagging, coughing, and exercise intolerance?

A
  1. CBC/Chem/UA
  2. T4, TSH
  3. thoracic + cervical xrays
  4. esophagram / swallow studies
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12
Q

T/F: dogs with laryngeal paralysis are at risk for aspiration pneumonia

A

true

because they cannot control their airway well. Radiographs are a great way to screen for causes of LP like masses, but also can check for aspiration pneumonia. 7.9% dogs with LP have aspiration pneumonia. You should take radiographs prior to surgery and DELAY the surgery if detect asp. pneumonia because anesthesia increases risks.

AFTER surgical correction of LP, there is a 21% risk of developing asp. pneumonia.

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13
Q

What medications should you avoid in your anesthesia protocol for a patient with laryngeal paralysis?

A

medications that cause panting (hydromorphone)

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14
Q

What type of things are you looking for during your laryngeal exam?

A
  1. masses
  2. Soft palate appearance
  3. edema, erythema
  4. arytenoids, vocal folds abducting during inspiration
  5. match timing of inspiration with arytenoid motion
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15
Q

How would you handle an emergent case of laryngeal paralysis?

A
  • cooling (if temps >105)
  • supplemental oxygen
  • IV sedation (ace, butorphanol) calms patient down
  • IV corticosteroids (dexamethasone)
  • cautious fluid therapy
  • intubate (if severe)
  • temporary tracheostomy (very severe cases)
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16
Q

T/F: some patients with laryngeal paralysis can be managed without surgery

A

true
if they are asymptomatic AT REST, then you could recommend things such as weight loss, stress reduction, exercise restriction, avoiding hot temps.
however, you must inform the client that this is a progressive disease and surgery is the treatment of choice in most cases.

17
Q

what is the GOAL of surgery to correct laryngeal paralysis?

A

decrease airway resistance

18
Q

what surgeries are available for the treatment of laryngeal paralysis?

A
  1. arytenoid lateralization (standard technique, unilateral lateralization of one of the arytenoids tying it to the cricoid cartilage or thyroid cartilage)

Other/Salvage options:
2. ventricular cordectomy, partial arytenoidectomy
3. modified castellated laryngofissure
4. permanent tracheostomy (salvage)

19
Q

what is the standard surgical APPROACH to laryngeal paralysis correction?

A

left lateral cervical approach
the incision should be parallel and ventral to the jugular vein

20
Q

how big do you want to make the glottic opening when surgically correcting laryngeal paralysis?

A

no larger than ET tube

21
Q

what are potential complications of surgical correction of laryngeal paralysis?

A
  1. aspiration pneumonia
  2. persistent clinical signs (cough, gag, stridor)
  3. suture failure
  4. cartilage fracture
22
Q

T/F: bilateral arytenoid lateralization is preffered over unilateral

A

false unilateral is preffered.

23
Q

what are signs of feline laryngeal paralysis?

A
  1. tachypnea
  2. dyspnea
  3. dysphonia
  4. dysphagia
  5. anorexia
  6. cough
  7. weight loss

feline LP is not as common as canine

24
Q

What drug can we pre-treat patients with if we want to decrease risk of developing aspiration pneumonia?

A

metoclopromide – increases GI motility and decreases risk of regurg and aspiration.

25
Q

When and how should you do your laryngeal exam?

A

just prior to intubation in sternal recumbency.
Use propofol for induction

look for masses, look at soft palate, look for edema, erythema, etc.

26
Q

what medication should you have on-hand for laryngeal examination prior to surgical correction?

A

Doxapram to stimulate respiration
propofol can make them not breathe and this impedes your exam. We do not want to misdiagnose LP when its just propofol effects creating minimal or shallow breathes.

27
Q

What direction should arytenoids go during inspiration?

A

abduct – open

28
Q

why is it important to match the timing of inspiration with arytenoid movement?

A

Paradoxical motion.
Arytenoids are flaccid in case of LP, but when the dog breathes out, the force of the breath causes the arytenoids to open passively.
You could miss the diagnosis of LP.

29
Q

what is the “viscous cycle” that can occur as a result of laryngeal paralysis?

A

The dog goes into the heat, gets excited and respirations increase.
This creates trauma to the arytenoid mucosa and causes inflammation, swelling, and further dyspnea.

30
Q

what is the first cartliage you see when performing surgical correction of LP?

A

thyroid cartilage

place stay suture through it to retract it out of the way
(make sure NOT to take bite through ET tube)

31
Q

What suture should you use to tie the arytenoid to the cricoid cartilage?

A

non-absorbable (polypropylene) with taper needle

2-0 in dogs

32
Q

How tight should you tie the suture when lateralizing the arytenoid cartilage?

What size glottic opening are you aiming for?

A

Tight enough to stay in place
but not too tight to where it has a lot of tension and fractures the cartilage

based on feel. you are aiming for the final glottic opening to be no larger than the ET tube. Do not over-abduct.

33
Q

what is the outcome (in terms of prognosis) of LP corrective surgery?

A

90% patients have improvement after undergoing unilateral arytenoid lateralization

but dogs are at higher risk of asp pneumonia (not allowed to swim)

34
Q

T/F: laryngeal paralysis is a progressive disease

A

true – while patients who are asymptomatic at rest may benefit from weight loss, stress reduction, exercise restriction, and avoiding heat stress, the condition will continue to progress and surgery is the ultimate treatment of choice for this condition.

Small Animal Surgical Diseases (20 decks)

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