89.Maxillectomy_Mandibulectomy Flashcards
what are the four main muscles of mastication
- masseter2. temporalis3. pterygoideus4. digastricus
blood supply to the mandible
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
innervation to the mandible
mandibular nerve (branch of trigeminal) provides sensory informationtravels through mandibular foramen and exits mental foramina as mental nerves
3 bones of the muzzle
- maxilla: LARGEST2. incisive (premaxilla)3. nasal
main blood supply to the maxilla
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
innervation of the maxilla
infraorbital nerve (branch of trigeminal)travels through maxillary foramen into infraorbital canal and exits at infraorbital foramen
most common oral tumors in dogs in DESCENDING order of frequency
- melanoma2. SCC (nontonsillar)3. fibrosarcoma (hi-low variant exists)4. OSA5. acanthomatous ameloblastoma
T/Fsurvival time after surgical resection of oral OSA appear to be superior to survival times observed from amputation for appendicular OSA
TRUEsurvival time after surgical resection of oral OSA appear to be superior to survival times observed from amputation for appendicular OSA
nomenclature for the epulides
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
behavior and treatment for ossifying and fibromatous epulides
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
behavior and treatment for ancanthomatous ameloblastoma
non metastatic, locally invasive that frequently affects the underlying bone, typically rostral treated with maxillectomy, mandibulectomy(recent papers on “rim excision”)
percentage of oral tumors arising from the gingiva that have boney lysis
60-80%
study on LN size SN/SP in dogs with oral malignant melanoma
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)
% owner statisfied with mandibulectomy and/or maxillectomy procedure
85%
local block for rostral mandibulectomy
mental foramenlevel of second premolar (laterally)mental nerve branches of mandibular nerve (branch of trigeminal)
local block for extensive mandibulectomies
mandibular nerve entering the mandibular foramen palpable on the MEDIAL aspect of the bone at the level of the angel of the mandible
local block for rostral maxillectomy
infraorbital nerve (branch of trigeminal) as it exits infraorbital foramen LATERAL 4th upper PM
local block for entire maxillary region
block maxillary nerve (branch of trigeminal)rostral to ramusbelow ventral border zygomatic archcaudal to lateral canthus of the eye
major blood vessel to be cauterized or ligated during mandibulectomy vs maxillectomy
mandibulectomy: mandibular arterymaxillectomy: infraorbital artery, major palatine arterynasal cavity will bleed from turbinatesif bleeding is severe can temporarily or permanently ligate common carotid
bone margin to include when resecting a neoplasm
at least 1 cm
goal of closure of a mandibulectomy
tension freemucosal apposition and maintain mucosal integritycover free ends of the bone
why is rostral mandibulectomy prone to dehiscence over the transected bone ends
thinness of gingivamotiontrauma during eating
how to gain exposure for a central or caudal mandibulectomy
–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)
ways to minimize hemorrhage from nasal turbinates during maxillectomy
–gelfoam/gelatin sponges–digital pressure–electrocautery–topical epinephrine
method to achieve more exposure for caudal maxillectomy with dorsal extension
intra-oral approach with a rostral caudal skin incision over the dorsolateral maxilla
post op complications
- 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
post op considerations
- 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!
summary of historical data on common oral tumors and prognosis
–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
recurrence rates for tumors with complete vs incomplete margins
complete 15-20% recurincomplete 60-65% recur
oral best oral tumors with low local recurrence and best survival data
nontonsillar SCC (especially if rostral)acanthomatous ameloblastoma
tumor associated with higher recurrence rates
FSA
highly metastatic oral tumor
malignant melanoma
patients considered for adjuvant therapy
–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
most common feline oral tumors
- SCCFSA and OSA also occur
risk factors reported in cats with oral SCC
fed canned foodfed canned tuna food regularlyflea collarstobacco smoke environment
T/Fthe only surgical procedure performed frequently for cats with oral malignancy is mandibulectomy
TRUEcats can tolerate small maxillectomies howeverinappetance likely occurs with >50% mandible removed (consider feeding tube)
prognosis with cats and mandibulectomies for various tumors (Northrup et al 2006 JAAHA)
50% incomplete margins40% local recur hard to get good margins in catsSCC had a shorter survival time that FSA and OSA
