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7: Digestive System > Chapter 89 Mandibulectomy and Maxillectomy > Flashcards

Chapter 89 Mandibulectomy and Maxillectomy Flashcards

1
Q

What is the origin and insertion of the masseter

A
  • Origin: Zyogomatic arch
  • Insertion: Masseter fossa of mandible (lateral and ventral surface of caudal mandible)
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2
Q

What is the origin and insertion of the temporal m.

A
  • Origin: Temporal region of skull
  • Insertion: Coronoid process of mandible
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3
Q

What is the origin and insertion fo the digastricus m?

A

Origin: Occipital region of skull

Insertion: Ventral border of body of mandible

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4
Q

What is the origin and insertion of the pterygoid muscle?

A

Origin: Pterygoid, palatine and sphenoid bones

Insertion: Angular process of ramus

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5
Q

What vessel supplies the majority of blood to the mandible?

A

Inferior alveolar

(Branch of maxillary)

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6
Q

Label the diagram

A
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7
Q

What is the name of the foramina through which inferior alveolar artery enters and exists mandible?

Which nerve provides sensory innervation to mandible and lower teeth?

A

Enters through mandibular formen (medial side, caudal mandible)

Exits through mental formen (lateral side, rostrally)

Mandibular nerve (branch of trigeminal). Trabels with inferior alveolar artery - see below re nomenclature.

  • Mandibular nerve as it enters mandibular foramen
  • Inferior alveolar nerve as it travells within mandible
  • Mental nerves as it exits at mental foramen
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8
Q

Which nerve provides sensory innervation to mandible and lower teeth?

What foramina does it travel thorugh

A

Mandibular nerve (branch of trigeminal). Trabels with inferior alveolar artery - see below re nomenclature.

  • Mandibular nerve as it enters mandibular foramen
  • Inferior alveolar nerve as it travells within mandible
  • Mental nerves as it exits at mental foramen
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9
Q

Where is mental foramen located?

A

Just caudal to lower canine tooth

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10
Q

What bones make up the muzzle

A

Incisive (contains inscisors)

Nasal

Maxilla

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11
Q

What is the major blood supply to the muzzle?

A

Major palatine and infraorbital arteries

(branches of maxillary arteries)

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12
Q

The major blood supply to the muzzle is via the major palatine and infraorbital arteries.

What formanina does each vessel pass through

A

Major palatine: opens onto caudal palate via caudal palatine foramen

Infraorbital: Through maxillary foramen and exits infraorbital foramen

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13
Q

Where is the infraorbital foramen located?

A

Rostral margin of upper 4th premolar (carnassial)

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14
Q

What nerve supplies the upper teeth?

And hard palate

A

Infraorbital n

(branch of maxiallary which is branch of trigeminal)

Hard palate = major palatine nerve

I.e. matching the names of the arteries

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15
Q

What are the 5 most common canine oral neoplasms, in order

And 3 in cats

A

Malignant melanoma > SCC > Fibrosarc > Osteosarc > Canine acanthomatous ameloblastoma (CAA)

SCC > Fibrosarc > Lymphoma

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16
Q

What is a good overall met rate of canine oral scc

A

20%

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17
Q

Name a unique entity of FSA

A

N.B. Histologically low grade, biologically high grade

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18
Q

HOw does MST or canine oral OSA compare with appendicular?

A

Better

5-17m MST

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19
Q

What is typical presentation of the following canine oral tumours?

Malignant melanoma

SCC

Fibrosarcoma

A

Malignant melanoma

  • Small-breed
  • Old
  • Cocker, Poodle, Chow chow
  • Gingiva

SCC

  • Large breed
  • Old
  • Flat/ulcerative

Fibrosarcoma

  • Golden ret, Lab
  • Middle-aged
  • Maxillary gingiva, near carnassial
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20
Q

List 3 non-malignant oral canine masses

A
  • CAA: Canine Acanthomatous Ameloblastoma
  • POF: Peripheral Odontogenic Fibroma
  • FFH: Focal Fibrous Hyperplasia
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21
Q

How do CAA and POF differ?

A

CAA:

  • CAA invades surrounding bone!
  • Tx: mandibulactomy/maxillectomy
  • Often rostal, esp mandible.

POF:

  • POF doesnt invade bone
  • Tx: Excise. Improved cure if remove associated teeth and remove small margin of surrounding alveolar bone
  • Pre-maxillary region
22
Q

What is thorugh to be cause of focal fibrous hyperplasia

A

Irritation from calculus/plaque

23
Q

List 9 specific mass ddx for oral mass in dog (not cyst etc)

A
  • Malignant melanoma
  • SCC
  • Fibrosarc
  • Osteosarc
  • CAA
  • POF
  • FFH
  • MLO
  • PNST
24
Q

Name 2 specifics re oral mass biopsy

A

Plan excision

Deep biopsy

25
Q

Of dogs with oral tumour and LN mets, what % were mets so ipsilateral mandibular?

A

55%

i.e. if you only take the ipsilateral mandibular will miss HALF of LN mets

26
Q

What nerve block can be performed for mandubulaectomy and maxillectomy and what region do they cover?

What exactly is injected

A

0.5-1.0 ml 0.5% bupi

Mandibulectomy:

  • Mental foramen: Inscisor region
  • Mandibular foramen: Entire mandibualr body + STs

Maxillectomy:

  • Infraorbital formamen: Rostral maxilla
  • Maxillary foramen: Entire maxillar
    • Inject rostral to ramus, below ventral border of zygomatic arch, just caudal to lateral canthus of eye
27
Q

Name a back up for extensive haemorrhage during mandibulactomy/maxillectoym

A

Temporary or permanat occlusion of carotid

(i.e. clip + prep + drape area)

28
Q

What vessel has to be controlled suring mandibulectomy?

And maxillectomy:

A

Mandibular: Inferior alveolar

Maxillectomy: Major palatine and infraorbital

29
Q

How can bleeding be minimised during maxillectomy (7 steps/methods)

A
  • Ostectomy of caudal extent last
  • Electrocautery
  • Direct pressure
  • Gelantin sponges
  • Cold saline
  • Topical epinephrine (1mg/ml in 10ml saline)
  • Carotid artery occlusion
30
Q

What margins are recommended for mandibulectomy/maxillectomy

A

>1cm

31
Q

Name the mandibulectomy types

A

A, Rostral hemimandibulectomy (unilateral rostral mandibulectomy).

B, Rostral mandibulectomy (bilateral rostral hemimandibulectomy).

C, Central hemimandibulectomy.

D, Caudal hemimandibulectomy.

E, Total hemimandibulectomy.

F, Three-quarter mandibulectomy.

32
Q

Name the maxillectomy types

A

A, Hemimaxillectomy.

B, Rostral hemimaxillectomy.

C, Rostral maxillectomy (premaxillectomy or bilateral rostral hemimaxillectomy).

D, Central hemimaxillectomy.

E, Caudal hemimaxillectomy.

33
Q

Aside form ‘proper’ mandibulectomy, how can a tumour not invading ventral cortex potentially be managed?

A

Mandibular rim excision

(i.e. crescent/square section removed –> ventral cortex remains in situ and intact)

34
Q

How can access to the ramus of the mandible be improved?

And caudal maxillay

A

Mandibulectomy

  • Inscise cheek full thickness from commisure caudally
  • Renove portion of zygomatic arch

Maxillectomy

  • Inscise cheek full thickness from commisure caudally
  • Make rostrocaudal longitudinal inscision in skin over dorsolateral maxilla (–> essentailly a bipedicle skin flap)
35
Q

How can cosmesis be improved after caudal hemi mandibulaectomy

A

Shift comissure of lip rostrally

36
Q

How can nose drooping be prevented after rostral maxillectomy

A

Sutures between dorsal nasal cartilage and holes drilled in nasal bone

37
Q

Name 2 axial pattern flaps that can be used for closure of large caudal oral defects

A
  • Angularis oris
  • Omocervical (aka superficial cervical) - reaches canine teeth
  • Recent case report of superior labial artery for repair of midline secondary palate defect - used mucomuscular i.e. not skin)
38
Q

List potenatial complications of maxillectomy/mandibulectomy (10)

A
  • Haemorrhage
  • Dehisence
  • Oronasal fistula (maxillectomy)
  • Recurrence
  • Sublingual swelling (mandibulectomy)/generalised swelling of area
  • Skin movement with repoiration (maxillectomy)
  • Anorexia (i..e consider placig feeding tube - ALWAYS in cat)
  • Altered cosmesis
  • Drooling
  • Need for assisted feeding/drinking
  • Mandibular drif + malocclusion (mandibulectomy)
  • Medially displaced lip margin
39
Q

List 3 techniques for management of mandibular drift

A
  • Extraction of remaining canine
  • Orthodontic rubber chaains between lower caninen and ipsilateral upper PM4 (carnassial)
  • MAndibular regeneration/immediate reconstruction:
    • Titanium plate + rh-BMP2 +- calcium-collgen matric
    • Reported for canine rostral and segmental mandibulectomy (all had solid bone after 2-6 months)
      • 2/5 rostral ones –> dehisence + plate exposure, fine after revision.
    • N.B. rh BMP2 contraindicated if tumour cells remain so best to ensure clean margins first
40
Q

Describe post-discharge follwo up for mand/maxillectomy

A

Inspect site 2 weeeks post -op. Then q 3-4 months + rads up to 2 years post op

(checking for recurrence!)

41
Q

See these broad recommendation , just FYI

A
  • Aggressive surgical management does improve the survival prospects for dogs with oral malignancies. One-year survival rates of 70% to 90% have been reported commonly, and most reported local recurrence rates are well below 50%.
  • The tumor type strongly influences survival. Tumors with a high metastatic potential, such as malignant melanoma and osteosarcoma, are generally associated with poorer survival than tumors with lower metastatic potential, such as fibrosarcoma and squamous cell carcinoma.
  • The tumor location strongly influences local recurrence rates. Tumors that are located in the caudal aspect of the oral cavity are generally associated with a poorer prognosis than tumors located more rostrally. In addition to being inherently more difficult to resect than tumors in the rostral aspect of the mouth, caudally located tumors are less likely to be noticed at an early stage by owners and veterinarians and are typically larger at the time of surgical resection.
  • As with most malignancies, histologically incomplete excision of oral tumors is a negative prognostic indicator, largely because of its association with increased local recurrence rates. In two large reports of dogs undergoing mandibulectomy or maxillectomy, local recurrence rates were 15% to 22% for tumors with complete histologic margins and 62% to 65% for tumors with incomplete margins.
  • Overall, local recurrence rates and survival data are best for squamous cell carcinoma and acanthomatous ameloblastoma. Squamous cell carcinoma, particularly in rostral locations, has a reasonable likelihood of being cured by aggressive surgery alone, and acanthomatous ameloblastomas are almost invariably cured with appropriate surgery. Fibrosarcomas are associated with comparatively high local recurrence rates, partly because of their frequent location in the central or caudal maxilla. Although malignant melanoma is highly metastatic, reported median survival times approach 1 year, suggesting that metastatic disease often progresses relatively slowly. Some evidence suggests that the prognosis for patients with mandibular osteosarcoma may be superior to that for appendicular osteosarcoma; however, it is unclear whether this difference is attributable to a lower prevalence of micrometastases at the time of presentation or to a slower progression of metastatic disease.
42
Q

List 4 negative prognostic indicators for canine oral mass

A
  • Incomplete margins
  • Location (caudal or calvarium)
  • Histologic grade
  • Mitotic Index
43
Q

How are malignant melanomas managed with radiotherapy

A

Hypofractionated (i.e. fewer times, higher doses)

55-70% complete remission

44
Q

How do acanthomatous amelobastomas respond to radiotherapy

A

Well1

But if small sx still preferable

45
Q

What family of drugs tends to be used for oral tumours

A

Platinum based

46
Q

What was result of adding chemo to malignant melamnoma tx?

A

No difference vs sx alone

47
Q

List 2 less conventional options for tx of malignant melanoma

A
  • Tyrosinase targeting vaccine
  • Biologic response modifiers aka immunotherapy (Corynebacterium parvum and liposome-encapsulated muramyl tripeptide-phosphatidylethanolamine (L-MTP-PE)
48
Q

How does bahviour of feline SCC difer to dogs

A

V locally invasive!

Often occur caudally

49
Q

WHat % mandibulectomy is more likely to lead to anorexia in cats?

A

>50%

50
Q

What was median duration of o-tube feeding in cats undergoing mandibulectomy?

A

74d!

51
Q

Outcome and prognostic factors following curative intent surgery for oral tumours in dogs: 234 cases (2004 – 2014) (Sarowitz, JSAP, 2017)

What were 3 main findings?

A
  • Worst MST malignant melanoma (206d) and OSA (209d)
  • Worst mets malignant melanoma (30%)
  • Worst recurrence FSA (54%)
52
Q

Main complications after bilateral caudal maxillectom y

(Tuohy, VetSurg, 2019)

A

Dehisence –> oronasal fistula - fixed with angularios oris flap in one, split thickness flap)

Post-op swelling

7: Digestive System (12 decks)

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