Maxillectomy

Maxillectomy is a surgical procedure involving the partial or complete resection of the maxilla (upper jaw) to remove neoplastic, traumatic, or infectious lesions that are not amenable to conservative management. The procedure is classified based on the extent of resection: marginal maxillectomy (removal of a portion of the alveolar margin), partial maxillectomy (removal of a segment of the maxilla, including the palate), and total maxillectomy (removal of the entire maxilla, typically performed for extensive tumors). The surgery aims to achieve complete excision of the diseased tissue with adequate margins while preserving as much normal anatomy and function as possible. Maxillectomy is commonly performed in dogs and cats for the treatment of oral tumors, such as fibrosarcoma, melanoma, and squamous cell carcinoma, as well as for severe trauma or osteomyelitis. The procedure requires careful preoperative planning, including advanced imaging to determine tumor extent and involvement of adjacent structures, and meticulous surgical technique to minimize complications such as hemorrhage, oronasal fistulas, and wound dehiscence.

The primary indications for maxillectomy include: 1) Neoplastic diseases: Oral tumors such as squamous cell carcinoma, fibrosarcoma, melanoma, osteosarcoma, and chondrosarcoma are the most common indications. These tumors may arise from the gingiva, palate, or bone. 2) Trauma: Severe maxillary fractures that are comminuted, infected, or associated with significant bone loss may require partial maxillectomy for debridement and reconstruction. 3) Infectious diseases: Chronic osteomyelitis of the maxilla that is unresponsive to medical therapy may necessitate surgical resection. 4) Congenital or developmental anomalies: Rarely, severe palatal defects or malformations may require maxillectomy as part of reconstructive surgery. 5) Iatrogenic causes: Previous unsuccessful surgeries or radiation therapy may lead to tissue necrosis and necessitate resection. The underlying etiology determines the extent of resection and the need for adjunctive therapies such as radiation or chemotherapy.

Maxillectomy is most commonly performed in dogs and cats, with a higher incidence in older animals due to the increased risk of neoplasia. In dogs, certain breeds such as Boxers, Golden Retrievers, and Rottweilers are predisposed to oral tumors, particularly fibrosarcoma and melanoma. Cats are more commonly affected by squamous cell carcinoma, especially in the sublingual and tonsillar regions, but maxillary tumors are also seen. There is no significant sex predilection, although some studies suggest a slight male predominance. The procedure is less common in other species but may be performed in exotic animals or horses for similar indications. The incidence of maxillectomy is relatively low compared to other oral surgeries, but it is a critical procedure for managing aggressive oral pathology.

The pathophysiology of conditions requiring maxillectomy varies with the underlying disease. For neoplasia, tumor growth leads to local invasion of bone and soft tissues, causing pain, loosening of teeth, and difficulty eating. Malignant tumors may metastasize to regional lymph nodes or distant organs. For trauma, maxillary fractures disrupt the normal occlusion and can lead to oronasal fistulas, hemorrhage, and infection. Chronic osteomyelitis results from bacterial infection, leading to bone necrosis and sequestration. The surgical resection itself removes the diseased tissue, but the resulting defect can cause functional and cosmetic deficits. The maxilla is a complex structure that supports the teeth, forms the hard palate, and contributes to the nasal cavity and orbit. Resection can lead to oronasal communication, altered mastication, and changes in facial contour. Understanding the anatomy and pathophysiology is essential for planning the surgical approach and reconstruction.

Predisposing factors for conditions requiring maxillectomy include: 1) Age: Older animals are more prone to neoplasia. 2) Breed: Certain breeds have a higher incidence of oral tumors, such as Boxers (fibrosarcoma), Golden Retrievers (melanoma), and Siamese cats (squamous cell carcinoma). 3) Environmental factors: Exposure to tobacco smoke or other carcinogens may increase the risk of oral tumors. 4) Dental disease: Chronic periodontal disease may predispose to oral tumors or osteomyelitis. 5) Trauma: Animals with access to roads or high-risk environments are more prone to maxillary fractures. 6) Genetic factors: Some breeds have inherited predispositions to specific tumor types. 7) Previous radiation therapy: Radiation can induce secondary tumors or tissue necrosis. 8) Immunosuppression: Immunocompromised animals may be more susceptible to infections and tumors.

Clinical signs associated with conditions requiring maxillectomy include: 1) Oral mass: A visible or palpable mass on the gingiva, palate, or maxilla. 2) Dysphagia: Difficulty eating or dropping food. 3) Halitosis: Bad breath due to tumor necrosis or infection. 4) Oral bleeding: Bleeding from the mouth, especially with trauma or tumors. 5) Loosening of teeth: Teeth may become loose or displaced due to tumor invasion or fracture. 6) Facial swelling: Swelling of the face, particularly under the eye or along the maxilla. 7) Nasal discharge: Unilateral or bilateral nasal discharge, often with blood or pus, due to tumor invasion or oronasal fistula. 8) Pain: Signs of oral pain, such as pawing at the mouth, reluctance to eat, or aggression when the mouth is touched. 9) Weight loss: Due to decreased food intake. 10) Sneezing: May occur if the nasal cavity is involved. 11) Exophthalmos: If the tumor extends into the orbit. 12) Neurological signs: Rarely, if the tumor invades the brain or cranial nerves.

Differential diagnoses for conditions requiring maxillectomy include: 1) Oral tumors: Benign tumors such as epulis (fibromatous, ossifying, acanthomatous) may mimic malignant tumors but are less invasive. 2) Osteomyelitis: Bacterial infection of the maxilla can cause bone lysis and swelling, but is typically associated with a history of trauma or dental disease. 3) Dental abscess: A periapical abscess can cause facial swelling and draining tracts, but is usually localized to a tooth root. 4) Oronasal fistula: A communication between the oral and nasal cavities, often due to trauma or dental disease, can cause nasal discharge and halitosis. 5) Foreign body: A foreign body in the oral cavity or nasal passage can cause similar signs. 6) Eosinophilic granuloma complex: In cats, this condition can cause oral ulcers and masses. 7) Cryptococcosis: A fungal infection that can cause nasal and oral masses. 8) Trauma: Maxillary fractures can cause swelling, pain, and malocclusion. 9) Osteosarcoma: A malignant bone tumor that can arise in the maxilla. 10) Chondrosarcoma: A malignant cartilage tumor that can also affect the maxilla. 11) Fibrosarcoma: A malignant tumor of fibrous tissue that is common in the oral cavity. 12) Melanoma: A malignant tumor of melanocytes that can be oral or cutaneous.

The diagnostic algorithm for a patient suspected of requiring maxillectomy involves: 1) Complete history and physical examination, including thorough oral examination under anesthesia. 2) Dental radiographs to assess tooth roots and bone involvement. 3) Advanced imaging: Computed tomography (CT) is the preferred modality to evaluate the extent of the lesion, bone lysis, and involvement of adjacent structures such as the nasal cavity, orbit, and lymph nodes. Magnetic resonance imaging (MRI) may be used for soft tissue detail. 4) Biopsy: A tissue sample is essential for histopathological diagnosis. This can be obtained via incisional biopsy or fine-needle aspiration. 5) Staging: For malignant tumors, thoracic radiographs or CT to check for pulmonary metastases, and lymph node aspiration or biopsy to assess regional metastasis. 6) Preoperative assessment: Complete blood count, serum biochemistry, urinalysis, and coagulation profile to evaluate overall health and surgical risk. 7) Surgical planning: Based on imaging and biopsy results, the surgeon determines the extent of resection and the need for reconstruction.

Laboratory findings in patients undergoing maxillectomy are often non-specific but may include: 1) Complete blood count: May show anemia due to chronic bleeding or inflammation, leukocytosis with infection, or thrombocytopenia with bone marrow involvement. 2) Serum biochemistry: May be normal, but elevated liver enzymes or renal parameters may indicate metastatic disease or concurrent illness. 3) Urinalysis: May be normal, but proteinuria or hematuria could indicate systemic disease. 4) Coagulation panel: Prolonged PT/aPTT or abnormal TEG may indicate a bleeding disorder, which is important for surgical planning. 5) Blood gas analysis: May be abnormal if the patient has respiratory compromise due to nasal obstruction. 6) Inflammatory biomarkers: C-reactive protein (CRP) and serum amyloid A (SAA) may be elevated with infection or neoplasia. 7) Synovial fluid analysis: Not typically performed for maxillectomy, but if there is concurrent joint disease, it may be evaluated. 8) Histopathology: The biopsy results are crucial for diagnosis and grading of tumors.

Imaging is essential for preoperative planning of maxillectomy. 1) Radiography: Dental radiographs are useful for evaluating tooth roots and periapical disease. Skull radiographs may show bone lysis or fractures, but are limited by superimposition. 2) Computed tomography (CT): CT is the gold standard for evaluating the extent of maxillary lesions. It provides detailed bone anatomy, allows 3D reconstruction, and helps determine the margins of resection. CT can also assess the nasal cavity, orbit, and regional lymph nodes. 3) Magnetic resonance imaging (MRI): MRI provides superior soft tissue contrast and is useful for evaluating tumor invasion into the nasal cavity, orbit, or brain. 4) Ultrasonography: May be used to evaluate cervical lymph nodes for metastasis. 5) Thoracic radiography or CT: To screen for pulmonary metastases. 6) Fluoroscopy: May be used intraoperatively to guide placement of implants or to assess the extent of resection. 7) Angiography: Rarely used, but may be helpful to identify major vessels if vascular invasion is suspected.

Cytology and histopathology are critical for diagnosis and surgical planning. 1) Fine-needle aspiration (FNA) of the mass or enlarged lymph nodes can provide a preliminary diagnosis. Cytology may show neoplastic cells, inflammatory cells, or infectious agents. 2) Incisional biopsy: A wedge or punch biopsy of the mass is performed to obtain a definitive histopathological diagnosis. The biopsy should be taken from the center of the lesion, avoiding necrotic areas. 3) Histopathology: The biopsy is examined for tumor type, grade, and surgical margins. For malignant tumors, the mitotic index, degree of differentiation, and presence of vascular invasion are important prognostic factors. 4) Special stains: Immunohistochemistry may be used to differentiate tumor types, such as Melan-A for melanoma, cytokeratin for carcinoma, and vimentin for sarcoma. 5) Surgical margins: After resection, the entire specimen is submitted for histopathology to evaluate the completeness of excision. Margins are inked and assessed for tumor cells at the edge.

The treatment of conditions requiring maxillectomy is primarily surgical. 1) Preoperative stabilization: Address any systemic abnormalities, such as anemia or infection. Administer prophylactic antibiotics (e.g., cefazolin 22 mg/kg IV at induction, repeated every 90 minutes intraoperatively). 2) Surgical technique: The patient is positioned in dorsal recumbency with the maxilla exposed. The oral cavity is packed with gauze to prevent aspiration of blood and debris. The surgical approach depends on the location and extent of the lesion. For marginal maxillectomy, an incision is made through the gingiva around the lesion, and the alveolar bone is removed with an oscillating saw or osteotome. For partial maxillectomy, a larger segment of the maxilla is removed, including the palate. The nasal cavity may be entered, and the defect is closed by apposing the buccal mucosa to the palatal mucosa or using a local flap. For total maxillectomy, the entire maxilla is removed, and reconstruction is complex, often requiring a prosthesis or free tissue transfer. 3) Suture materials: The oral mucosa is closed with absorbable monofilament sutures (e.g., polydioxanone, 3-0 or 4-0) in a simple interrupted or continuous pattern. The palate is closed in a single layer if possible, but a two-layer closure may be used. 4) Implants: If the maxilla is reconstructed with bone grafts or plates, titanium miniplates and screws are commonly used. 5) Intraoperative complications: Hemorrhage is controlled with electrocautery, ligation, or bone wax. Oronasal fistulas are closed with tension-free flaps. 6) Postoperative care: Pain management with opioids (e.g., hydromorphone 0.05-0.1 mg/kg IV q4-6h) and NSAIDs (e.g., carprofen 2.2 mg/kg PO q12h). Antibiotics are continued for 7-10 days. The patient is fed a soft diet for 2-4 weeks. 7) Adjunctive therapy: Radiation therapy or chemotherapy may be recommended for malignant tumors with a high risk of recurrence or metastasis.

The prognosis for maxillectomy depends on the underlying disease and the completeness of excision. For benign tumors, the prognosis is excellent if complete resection is achieved. For malignant tumors, the prognosis varies: 1) Squamous cell carcinoma: In cats, the prognosis is poor due to a high rate of local recurrence and metastasis. In dogs, the prognosis is better if the tumor is completely excised. 2) Fibrosarcoma: The prognosis is guarded due to a high rate of local recurrence, but metastasis is less common. 3) Melanoma: The prognosis is poor due to a high rate of metastasis. 4) Osteosarcoma: The prognosis is poor, with a median survival time of 10-12 months even with aggressive therapy. 5) Chondrosarcoma: The prognosis is better than osteosarcoma, with a median survival time of 2-3 years. 6) Overall, the 1-year survival rate for dogs with oral tumors treated with maxillectomy is approximately 50-70%, depending on tumor type and stage. 7) Negative prognostic indicators include incomplete margins, high tumor grade, lymph node metastasis, and distant metastasis.

Postoperative follow-up for maxillectomy patients includes: 1) Immediate postoperative period: Monitor for hemorrhage, swelling, and respiratory distress. The patient is hospitalized for 1-3 days. 2) Suture removal: Oral sutures are typically absorbable and do not require removal, but if non-absorbable sutures are used, they are removed at 10-14 days. 3) Serial examinations: Recheck at 2 weeks, 4 weeks, 8 weeks, and 12 weeks postoperatively to assess healing, eating, and any signs of complications. 4) Radiographic evaluation: Thoracic radiographs are recommended every 3-6 months for the first 2 years to monitor for pulmonary metastases. 5) CT or MRI: May be repeated if there is suspicion of local recurrence. 6) Activity restrictions: The patient should be restricted from vigorous activity for 4-6 weeks to allow healing. 7) Physical therapy: Not typically required for maxillectomy, but if there is significant tissue loss, the patient may need assistance with eating. 8) Long-term monitoring: For malignant tumors, lifelong monitoring is recommended.

Clinical pearls: 1) Preoperative CT is essential for planning the extent of resection and avoiding complications. 2) Use a surgical margin of at least 1 cm for malignant tumors. 3) Pack the oropharynx with gauze to prevent aspiration of blood and debris. 4) Use a tension-free closure to prevent oronasal fistulas. 5) Consider a local flap (e.g., buccal mucosal flap) for large defects. 6) Administer perioperative antibiotics to reduce the risk of infection. 7) Provide adequate pain management to ensure the patient eats postoperatively. Pitfalls: 1) Inadequate margins can lead to tumor recurrence. 2) Excessive hemorrhage can be life-threatening; control bleeding with ligation or electrocautery. 3) Oronasal fistulas can occur if the closure is under tension; use a flap if necessary. 4) Damage to the orbit or eye can occur during maxillectomy; be careful with the caudal maxilla. 5) Postoperative infection can lead to dehiscence; maintain strict aseptic technique. 6) Failure to address lymph node metastasis can lead to poor outcomes; stage the patient preoperatively.

Perioperative drug protocols for maxillectomy based on Plumb's Veterinary Drug Handbook: 1) Prophylactic antibiotics: Cefazolin 22 mg/kg IV at induction, repeated every 90 minutes during surgery. Continue with amoxicillin-clavulanate 13.75 mg/kg PO q12h for 7-10 days postoperatively. 2) Analgesics: Preoperative: Hydromorphone 0.05-0.1 mg/kg IV or IM. Intraoperative: Fentanyl CRI at 5-10 mcg/kg/hr. Postoperative: Hydromorphone 0.05-0.1 mg/kg IV or IM q4-6h for 24-48 hours, then transition to oral opioids such as tramadol 2-5 mg/kg PO q8-12h. NSAIDs: Carprofen 2.2 mg/kg PO q12h or meloxicam 0.1 mg/kg PO q24h, starting after recovery from anesthesia. 3) Local anesthesia: Maxillary nerve block with bupivacaine 0.5% (1-2 mg/kg total dose) or lidocaine 2% (2-4 mg/kg) for intraoperative and postoperative analgesia. 4) Muscle relaxants: Not typically used. 5) Chondroprotectants: Not relevant. 6) Antiemetics: Maropitant 1 mg/kg IV or SC q24h if needed. 7) Gastroprotectants: Omeprazole 0.7-1.5 mg/kg PO q24h if the patient is on NSAIDs. 8) Fluid therapy: Isotonic crystalloids at 5-10 ml/kg/hr during surgery, adjusted based on blood loss.

Key literature on maxillectomy includes: 1) Fossum's Small Animal Surgery (5th edition) provides comprehensive coverage of maxillectomy techniques and outcomes. 2) Tobias & Johnston Veterinary Surgery: Small Animal (2nd edition) includes detailed chapters on oral surgery and maxillectomy. 3) Piermattei's Atlas of Surgical Approaches to the Bones and Joints of the Dog and Cat (5th edition) describes surgical approaches to the maxilla. 4) Studies by Lascelles et al. (2003) and others have reported survival times for dogs with oral tumors treated with maxillectomy. 5) A study by Sarowitz et al. (2017) evaluated complications and outcomes of maxillectomy in dogs, finding a complication rate of 30-40%, with oronasal fistula being the most common. 6) A study by Farcas et al. (2014) compared marginal vs. segmental maxillectomy for oral tumors, showing similar outcomes if margins are complete. 7) Consensus guidelines from the American College of Veterinary Surgeons (ACVS) and the European College of Veterinary Surgeons (ECVS) recommend CT for preoperative planning and a 1 cm margin for malignant tumors. 8) A meta-analysis by Liptak et al. (2004) on oral melanoma showed that surgery alone has a median survival of 5-6 months, but combination with radiation or immunotherapy improves outcomes.