Ch 100 Palate Flashcards

1
Q

Palate

A
  • palate separates the nasal passages, choanae, and nasopharynx from the oral cavity and oropharynx
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2
Q

How may pairs of pharyngeal arches are there in the embryo?
What arches form the mandibular and maxillary prominences?

A

6 pharyngeal arches
The first arch forms the mandibular and maxillary prominences

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3
Q

Embryology

A
  • secondary palate is formed from bilateral palatal shelves that grow out from the maxillary processes.
  • These palatal shelves then elevate rapidly above the tongue and join with each other and the developing nasal septum
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4
Q

What form of epithelium forms in the nasal cavity and the oral cavity?

A

Nasal - pseudostratified ciliated columnar
Oral - stratified squamous

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5
Q

What bones form the hard palate?

A

Palatine
Maxillary
Incisive bones

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6
Q

Name the following bones

A
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7
Q

blood supply

A
  • major palatine artery exits through the major palatine foramen
  • major palatine branch of the maxillary division of the trigeminal nerve
  • Blood to the soft palate is principally supplied by the minor palatine arteries (which branch off of the maxillary arteries
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8
Q

What is the normal level of extension of the soft palate?

A

Extends just caudal to last maxillary molar teeth in normal dogs

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9
Q

List the muscles of the soft palate and their function

A
  • Palatinus - shortens the palate rostrocaudally
  • Tensor veli palatini - Stretched the soft palate between the pterygoid bones
  • Levator veli palatini - Elevates the caudal soft palate
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10
Q

What are the 2 functions of the soft palate during swallowing?

A
  • Stimulation of sensory nerves in the palate are part of the mechanism that triggers swallowing
  • Closure of intrapharyngeal opening suring swallowing and vomiting to prevent food entering the nasopharynx and subsequently being aspirated
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11
Q

Palate defects

A
  • Congenital lip and palate defects in cats and dogs can be inherited or are a sequela of intrauterine trauma or stress
  • Causes of palate defects acquired after birth include: infections, trauma, neoplasms, and surgical and radiation therapy.

congenital hypoplasia of the soft palate,
- restoration of a palatopharyngeal sphincteric ring and normal swallowing function may not be achieved because of the lack of functional soft palate musculature

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12
Q

What side do unilateral cleft lips most commony form?

A

left

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13
Q

At what time in foetal development does an insult need to occur to result in a palatal defect?

A

between day 25-28 in dogs

trauma; stress; corticosteroids, nutritional, hormonal, viral, or toxic

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14
Q

timing of surgery

A
  • Most performed between 3 and 4 months of age.
  • Surgery before 2 months of age is challenging
  • Postponing surgery until after 5 months of age may result in a wider cleft as the animal grows and compounded management problems, which are not desirable
  • prognosis without surgical repair for large defects reported to be guarded because of the risk of aspiration

trauma
- may take several days before the extent of local injury is clearly defined.

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15
Q

List some basic principles of surgical correction of palate defects

A
  • Teeth at the surgical site or those which could damage the repair are removed 6-8 weeks prior to definitive repair
  • Laser, electrosurgical and radiosurgical devices not used for haemostasis
  • Flap should be at least 1.5x as wide as the defect they are going to cover
  • 2-layer closure
  • Suture lines preferable not overlying a void
  • Injured tissue left to fully declare itself prior to repair

anaesthesia
- Regional analgesia (maxillary, infraorbital, and major palatine nerve blocks)

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16
Q

Repair of Rostral Defects

A
  • congenital defects of the primary palate, attempts to close the lip and most rostral hard palate defects by simple sliding procedures are rarely successful
  • Repair is achieved with advancement, rotation, transposition (from labial and buccal mucosa), or overlapping flaps, followed by reconstructive cutaneous surgery to provide symmetry
17
Q

What is the standard closure technique for a:
- Congenital hard palate defect
- Traumatic hard palate “split” as with highrise syndrome
- Soft palate midline cleft

A

Congenital hard palate - Overlapping flap
Traumatic highrise syndrome - Medially positioned flap
Soft palate - medially positioned flap

18
Q

name this flap

A

Overlapping flap
- There is less tension on the suture line,
- the suture line is not located directly over the defect,
- area of opposing connective tissues is larger, which results in a stronger scar.
- It provides more reliable results
- the major palatine artery must not be transected during flap
- major palatine foramen at the palatine shelf of the maxilla approximately 0.5 to 1.0 cm medial to the maxillary fourth premolar
- Granulation and epithelialization of exposed bone generally are completed in 3 to 4 weeks

19
Q

name this flap

A

medially positioned flap
- making relieving incisions approximately 1 to 2 mm away from the maxillary cheek teeth on one or both sides is often necessary unilaterally or bilaterally so that the flaps can be moved medially
- trauma > proper occlusion can be accomplished by approximating displaced bony structures with digital pressure and placing a twisted orthopedic wire between the two maxillary canines and covering it with a self-curing composite resin.
- if the relieving incisions are long and gape, a lateral oronasal defect may result

20
Q

List options for surgical correction of congenital hypoplasia of the soft palate

A
  • Bilateral tonsillectomy and extension
  • Bilateral buccal mucosal flaps (one rotated, one rotated and overlapped)
  • Bilateral pharyngeal advancement flaps and one overlapping hard palate flap
21
Q

How do you repair an oronasal fistula?

A

Labial-based mucoperiosteal flap

22
Q

How can you close a large caudal hard palate defect?

A

split palatal U-flap

23
Q

List options for large palatal defects

A
  • Removal of teeth 6-8 weeks prior
  • Local axial pattern flaps (based on major palatine and infraorbital arteries)
  • Distant axial pattern flaps (angularis oris, caudal auricular, superifical temporal etc)
  • Tongue flap
  • Grafting of auricular cartilage
  • Corticocancellous tibial bone
  • Myoperitoneal microvascular flaps
  • Prostheses (obturator) > Fabrication and placement of a palatal obturator usually requires two anesthetic episodes (metal alloy, nonaqueous elastomeric impression material, or synthetic resin.)

Halitosis is a common complication with palatal obturators. Dogs and cats with palatal obturators should be reexamined under general anesthesia every 6 to 12 months to remove the obturator, flush the nose, clean the edges of the palatal defect, and scale and polish the obturator before it is placed back into position.

24
Q

complications

A

wound dehiscence
- result of tension on suture lines because of insufficient flap mobilization before closure
- compromised blood supply of flaps as a result of severe trauma or multiple previous surgeries
- follow-up surgeries should not be attempted before healing of all tissues involved

25
Q

What % or airway resistance is due to the nose in normal dogs?

26
Q

BOAS

A
  • primary components: stenotic nares, hypoplastic trachea, redundant pharyngeal tissue and aberrant conchae
  • eversion of the mucosa of the lateral ventricles occurs secondary to chronic subatmospheric pressure in the airway that is generated to overcome resistance to airflow.
  • The turbulent airflow over the mucosa causes edema and swelling.
  • Over time, the laryngeal cartilage frame can weaken and the larynx can progressively collapse
27
Q

What is Poiseuille’s law?

A

Q = π(pressure difference)(r^4)/8nl

Q - rate of flow
r - radius
n - viscosity of the gas
l - length of airway

Flow is proportional to radius to the fourth power

28
Q

Pathophysiology

A
  • Stenotic nares and abnormal intranasal turbinate > stertorous breathing due to increased resistance to nasal airflow.
  • overlong soft palate projects into the larynx and causes stridor
  • causes a fixed-type upper airway obstruction in the majority of brachycephalic dog studies
  • increased resistance to airflow is caused largely by a decrease in airway radius as illustrated by Poiseuille’s law
  • inspiratory muscles contract for a longer time during each breath cycle in response to increasing upper airway resistance, thus prolonging inspiration
  • decreases (PaO2) and increases (PaCO2), stimulates increased respiratory effort when compensation by other mechanisms is inadequate
  • Inspiratory and expiratory muscle work generates substantial heat. The work of breathing, combined with hot weather and exercise, often precipitates decompensation in brachycephalic dogs
  • funtional dz may contribute > Fibrosis of pharyngeal dilator muscles or Pharyngeal collapse
  • are at risk of developing noncardiogenic pulmonary edema
  • Presumably, subatmospheric intrapleural pressure required to overcome chronic partial upper airway obstruction in affected dogs predisposed them to hiatal hernia, gastroesophageal reflux, and subsequent esophagitis.
29
Q

What is the Hering-Breuer reflex?

A

A stretch reflex mediated by vagal fibres that control the rate and depth of respiration.

Causes a longer contraction of the inspiratory muscles during each breath cycle in response to increased upper airway resistance

30
Q

What functional disorders may also contribute to BOAS?

A

Fibrosis of the pharyngeal dilator muscles
Pharyngeal collapse

31
Q

What % of dogs with BOAS have moderate to severe GI signs?

32
Q

What is the normal tracheal diameter?

A

20% of thoracic inlet

33
Q

What should be given before or at induction for upper airway exam?

A

Anticholinergic to minimise risk of severe bradycardia from vagal discharge during pharyngoscopy
- glycopyrrolate over atropine when needed.
Monitor airway function closely, as thickened secretions and tachycardia can worsen respiratory issues.

34
Q

Clinical Signs and Diagnosis

A
  • Animals in severe respiratory distress need to be evaluated quickly and intubated if respiratory arrest is imminent
  • cold intravenous fluids, sedation with acetylpromazine (0.01 mg/kg IV), oxygen supplementation, and dexamethasone (0.05 to 0.1 mg/kg IV)
  • Concurrent cardiac disease has been reported in dogs with overlong soft palates,28 and Bulldogs are particularly prone to congenital pulmonic stenosis.
  • radiographs of the neck and thorax to evaluate possible concurrent cardiac disease, aspiration pneumonia, pulmonary edema, and tracheal diameter.
35
Q

staphalectomy

A
  • proposed level of palate resection, the caudal border of the palatine tonsils
  • excessive rostral retraction of the soft palate can make judging the appropriate level of palate resection difficult.
  • Clinical experience is therefore often used to determine the appropriate palate length.
  • resection is performed with scissors,a carbon dioxide laser, or bipolar sealing device
  • caudal pharynx and area surrounding the endotracheal tube must be covered by saline-soaked gauze sponges for protection form laser
36
Q

folded flap palatoplasty

A
  • by reducing the soft palate’s length and thickness
  • removed together with underlying connective tissue and parts of the palatinus and levator veli palatini muscles.
  • suture knots will be located more rostral and farther from the pharynx

post op
- Corticosteroids (dexamethasone, 0.05 to 0.1 mg/kg IV
- respiratory rate and effort and arterial hemoglobin oxygen saturation are monitored frequently.
- Food and water are withheld for 12
- postoperative GI signs are aggressively treated with a proton pump inhibitor (omeprazole [0.7 mg/kg PO q24h]), or metoclopramide constant rate infusion [1 to 2 mg/kg/d IV])

dupre and finji

37
Q

What setting should be used for CO2 laser staphylectomy?

A

5-6W
Continuous mode

38
Q

What is the prognosis following soft palate resection?

A

Good to excellent in 90%

Persistent or recurrent signs should prompt a skull CT and retroflexed nasopharyngeal endoscopy to assess for nasopharyngeal turbinates or progression of laryngeal collapse