89.Maxillectomy_Mandibulectomy

Question 1

what are the four main muscles of mastication

Answer 1

1. masseter2. temporalis3. pterygoideus4. digastricus

Question 2

blood supply to the mandible

Answer 2

mandibular alveolar artery (branch of the maxillary artery) which enters the mandible through the mandibular foramen (on the medial surface near the angle of the mandibleexits through the mental foramina–lateral and caudal to the canine tooth**must be ligated or cauterized during mandibulectomy

Question 3

innervation to the mandible

Answer 3

mandibular nerve (branch of trigeminal) provides sensory informationtravels through mandibular foramen and exits mental foramina as mental nerves

Question 4

3 bones of the muzzle

Answer 4

1. maxilla: LARGEST2. incisive (premaxilla)3. nasal

Question 5

main blood supply to the maxilla

Answer 5

BRANCHES OF MAXILLARY ARTERY1. major palatine artery –through caudal palatine foramen2. infraorbital artery–through maxillary foramen and infraorbital canal, exits laterally at infraorbital foramen @ level of first carnassial tooth

Question 6

innervation of the maxilla

Answer 6

infraorbital nerve (branch of trigeminal)travels through maxillary foramen into infraorbital canal and exits at infraorbital foramen

Question 7

most common oral tumors in dogs in DESCENDING order of frequency

Answer 7

1. melanoma2. SCC (nontonsillar)3. fibrosarcoma (hi-low variant exists)4. OSA5. acanthomatous ameloblastoma

Question 8

T/Fsurvival time after surgical resection of oral OSA appear to be superior to survival times observed from amputation for appendicular OSA

Answer 8

TRUEsurvival time after surgical resection of oral OSA appear to be superior to survival times observed from amputation for appendicular OSA

Question 9

nomenclature for the epulides

Answer 9

historically, epulides were (fibromatous, ossifying and acanthomatous) thought to arise from periodontal ligamentBUT acanthomatous version arises from ODONTOGENIC epithelium and was renamed ACANTHOMATOUS AMELOBLASTOMAfibromatous epulis is the only one that truly comes from the periodontal ligament

Question 10

behavior and treatment for ossifying and fibromatous epulides

Answer 10

non malignant, slow growing, firm local excision with extraction of the tooth and a small rim of alveolar bone (to rid the periodontal ligament origin) results in excellent long term control

Question 11

behavior and treatment for ancanthomatous ameloblastoma

Answer 11

non metastatic, locally invasive that frequently affects the underlying bone, typically rostral treated with maxillectomy, mandibulectomy(recent papers on “rim excision”)

Question 12

percentage of oral tumors arising from the gingiva that have boney lysis

Answer 12

60-80%

Question 13

study on LN size SN/SP in dogs with oral malignant melanoma

Answer 13

LN size was only 70% SN 50%SP for detecting metsneed to sample LN regardless of size (FNA, biopsy)mandibular node is the only accessible node but parotid LN and medial retropharyngeal also drain oral cavity (36% have mets at one of those 3 nodes and only 50% of those were mandibular)

Question 14

% owner statisfied with mandibulectomy and/or maxillectomy procedure

Answer 14

85%

Question 15

local block for rostral mandibulectomy

Answer 15

mental foramenlevel of second premolar (laterally)mental nerve branches of mandibular nerve (branch of trigeminal)

Question 16

local block for extensive mandibulectomies

Answer 16

mandibular nerve entering the mandibular foramen palpable on the MEDIAL aspect of the bone at the level of the angel of the mandible

Question 17

local block for rostral maxillectomy

Answer 17

infraorbital nerve (branch of trigeminal) as it exits infraorbital foramen LATERAL 4th upper PM

Question 18

local block for entire maxillary region

Answer 18

block maxillary nerve (branch of trigeminal)rostral to ramusbelow ventral border zygomatic archcaudal to lateral canthus of the eye

Question 19

major blood vessel to be cauterized or ligated during mandibulectomy vs maxillectomy

Answer 19

mandibulectomy: mandibular arterymaxillectomy: infraorbital artery, major palatine arterynasal cavity will bleed from turbinatesif bleeding is severe can temporarily or permanently ligate common carotid

Question 20

bone margin to include when resecting a neoplasm

Answer 20

at least 1 cm

Question 21

goal of closure of a mandibulectomy

Answer 21

tension freemucosal apposition and maintain mucosal integritycover free ends of the bone

Question 22

why is rostral mandibulectomy prone to dehiscence over the transected bone ends

Answer 22

thinness of gingivamotiontrauma during eating

Question 23

how to gain exposure for a central or caudal mandibulectomy

Answer 23

–commissuroplastyincised full thickness at the level of the commissure, can advance rostrally at closure to prevent tongue hanging out–removal of zygomatic arch (may or may not need to replace)

Question 24

ways to minimize hemorrhage from nasal turbinates during maxillectomy

Answer 24

–gelfoam/gelatin sponges–digital pressure–electrocautery–topical epinephrine

Question 25

method to achieve more exposure for caudal maxillectomy with dorsal extension

Answer 25

intra-oral approach with a rostral caudal skin incision over the dorsolateral maxilla

Question 26

post op complications

Answer 26

1. dehiscence (usually over bone ends (mandible) or labial to palatine mucosa (maxilla)2. chronic oronasal fistula3. inadvertant trauma to adjacent teeth may lead to tooth death4. mandibular drift +/- inadvertant gingival/palatal trauma (may need to remove or shorten teeth) rom map occlusion5. rise and fall over nasal cavity +/- SQ emphysema (self limiting)6. infection (not common bc vascular tissue)7. sublingual sialocele8. facial swelling9. recurrence

Question 27

post op considerations

Answer 27

1. remove blood/gauze from back of throat2. consider feeding tube if needed 3. analgesics4. e collar5. soft food 2-3 weeks before transition6. fascial, sublingual swelling7. rise and fall/SQ emphysema8. monitor!

Question 28

summary of historical data on common oral tumors and prognosis

Answer 28

–one year survival rates 70-90% –most reported recurrences are < 50% –tumor type influences survival rates (melanoma, OSA have a poorer px than FSA, nontonsillar SCC)–tumor location influences recurrence (caudal is bad)–incomplete incision–poorer prognosis

Question 29

recurrence rates for tumors with complete vs incomplete margins

Answer 29

complete 15-20% recurincomplete 60-65% recur

Question 30

oral best oral tumors with low local recurrence and best survival data

Answer 30

nontonsillar SCC (especially if rostral)acanthomatous ameloblastoma

Question 31

tumor associated with higher recurrence rates

Answer 31

FSA

Question 32

highly metastatic oral tumor

Answer 32

malignant melanoma

Question 33

patients considered for adjuvant therapy

Answer 33

–incomplete margins obtained–tumors with hi potential to spread–tumors that tend to recur locally–caudally located tumors originallyadjuvant radiation can provide control once cytoreduction performedchemotherapy for melanoma bc hi met potentialimmunotherapy for melanoma

Question 34

most common feline oral tumors

Answer 34

1. SCCFSA and OSA also occur

Question 35

risk factors reported in cats with oral SCC

Answer 35

fed canned foodfed canned tuna food regularlyflea collarstobacco smoke environment

Question 36

T/Fthe only surgical procedure performed frequently for cats with oral malignancy is mandibulectomy

Answer 36

TRUEcats can tolerate small maxillectomies howeverinappetance likely occurs with >50% mandible removed (consider feeding tube)

Question 37

prognosis with cats and mandibulectomies for various tumors (Northrup et al 2006 JAAHA)

Answer 37

50% incomplete margins40% local recur hard to get good margins in catsSCC had a shorter survival time that FSA and OSA