Transoral Inferior Maxillectomy
Paul J. Donald
INTRODUCTION
The inferior maxillectomy is an operation usually employed in the management of malignant tumors that occur below Ohngrens line. The most common cancer is adenocarcinoma of salivary gland origin, followed by squamous cell carcinoma, acinic cell carcinoma, mucoepidermoid carcinoma, and adenoid cystic carcinoma. Less common are malignant melanoma, neuroendocrine tumors, and plasmacytoma. Cancer that invades the maxillary sinus from the oral cavity, primarily from the alveolar ridge or the hard palate, is often accessible to extirpation using an inferior maxillectomy. Mention must be made of one of the most malignant tumors seen arising from the minor salivary glands in the palate, the polymorphous low-grade adenocarcinoma, which is anything but low grade in its behavior. Fortunately, it is rare, but its aggressive behavior belies its blandappearing histology. The advantage of inferior maxillectomy over the standard radical maxillectomy is that it can be done entirely intraorally and should not disturb form or function. If there is an intranasal component to the cancer, this can be managed with either a facial degloving procedure or a separate transfacial alotomy. The alotomy is an exposure of the anterior nasal cavity by incising around the nasal ala down to the underlying pyriform rim, through the nasal mucosa and vestibular skin, and retracting the ala medially.
HISTORY
Like so many malignancies of the upper aerodigestive track, cancers of the nasal cavity and paranasal sinuses begin with subtle symptomatology. Repeated episodes of mild epistaxis may be the presenting symptom. Unilateral purulent nasal drainage may arise from obstruction of the natural ostium of the sinus. Unilateral nasal obstruction usually begins as a subtle change barely noticed by the patient. Large cancers may invade the medial wall of the maxillary sinus or extend from the sinus ostium producing nasal obstruction. Cancers of the palate and alveolar ridge are much easier to detect by the patient in the earlier stages. Cancer of the palate may be the cause of an ill-fitting denture or may ulcerate early in its course causing pain and bleeding. Cancer arising in the alveolar ridge may cause loosening of a tooth/teeth. Their heaped-up character seen on inspection may be thought in the early stages to be due to periodontal disease. Squamous cell carcinoma of the alveolar ridge may initially present as a “dry socket” after tooth extraction or as an extraction site that produces what may appear to be granulation tissue but does not heal.
Among the most insidious of squamous cell carcinomas are those affecting the nasal vestibule. They often present as a small ulcer in the anterior floor of the nose and/or nasal septum. They have a marked tendency to spread posteriorly along the floor of the nose. It is often shocking to see how far posteriorly these cancers will spread along the periosteum of the pre- and central maxilla.
PHYSICAL EXAMINATION
Cancer of the inferior aspect of the maxillary sinus may remain asymptomatic for a long time before it manifests itself. The cancer may present as a mass or swelling of the alveolar ridge or hard palate, often covered by normal appearing mucosa. An ill-fitting denture or change in occlusion in the dentulous patient may be the only symptom.
As the cancer enlarges, the mucosal surface may ulcerate and eventually result in an oral nasal or antral fistula causing nasal regurgitation of ingested liquids and even food. Numbness of the face due to invasion of the infraorbital nerve or orbital symptoms is rarely seen in cancers confined to the inferior aspect of the maxilla. As always, a complete examination of the head and neck is mandated. Examination of the oral cavity may reveal a mass extending from the floor of the maxillary sinus to the alveolar ridge or palate. Cancers primary in the palate may also present as a mucosal covered mass, especially in the case of a benign tumor such as a pleomorphic adenoma or simply as an ulcer that is more common in malignancy. Cancers of the maxillary alveolar ridge may appear as a heaped-up lesion in an empty tooth socket or heaped-up tissue in the gingival collar around a tooth with or without ulceration or, in an edentulous area, as a mass. Examination of the nose may reveal a pink or red irregular mass often with an ulcer that bleeds when touched. Cancer of the nasal vestibule presents as a nodule and/or ulceration in the vestibular skin usually invading the adjacent musculature of the upper lip. This cancer unlike those that arise from the sinuses and present in the nasal cavity is often tender to the touch.
Thorough examination of the neck is vital with special attention to the submandibular triangle where the first echelon of lymph nodes related to the oral cavity is located.
INDICATIONS
The principal indication for inferior maxillectomy is the removal of either benign or malignant tumors. Pleomorphic adenoma is the most frequently encountered benign tumor of the hard palate. The vast majority of these tumors simply require a local resection of the tumor with a narrow margin of healthy tissue. Any bone loss probably results from tumor necrosis, so a light drilling of the adjacent bone is all that is required for complete excision. Even more common than the pleomorphic adenoma is the osteoma of the hard palate that carries the name of torus palatinus. These rarely require excision. The usual indication is to accommodate a denture. A rare benign tumor of the palate, the fibrous myxoma, may require a limited palatectomy and limited inferior maxillectomy. Ameloblastomas are classified as benign tumors of odontogenic origin. Their benign designation is because of their lack of metastases. However, they are locally aggressive and must be resected with a safe margin of healthy tissue. When originating in the maxillary alveolar ridge, adequate resection may require an inferior maxillectomy. A large odontogenic keratocyst of the maxillary alveolus may also require an inferior maxillectomy for adequate clearance. These like the ameloblastoma have frequent local recurrences and need an adequate margin of healthy tissue around the tumor.
The list of various malignant tumors taking origin in the palate and floor of the maxillary sinus is described in the Introduction section with adenocarcinoma and squamous cell carcinomas comprising the majority of malignancies below Ohngrens line.
Another indication for inferior maxillectomy is osteomyelitis. This sometimes is induced by irradiation therapy usually following tooth extractions with or without accompanying infection. Another cause of osteomyelitis of the maxilla that appears to be becoming more common is a complication of taking bisphosphonates. Other infections may be responsible for maxillary osteomyelitis such as actinomycosis. Patients who are on immune suppression or on chemotherapy for leukemia or lymphoma or suffer from HIV/AIDS may require inferior maxillectomy if the hard palate or alveolar ridge becomes nonviable. Chronic conditions such as chronic sclerosing osteomyelitis, which may accompany Romberg disease, may require a conservative type of inferior maxillectomy.
Cervical metastases from cancer originating in the hard and soft palate that would be limited enough to be appropriately treated by inferior maxillectomy are uncommon and are even more unusual with carcinomas originating in the maxillary sinus below Ohngren line. Cancers arising in the hard palate are less likely to metastasize than those taking origin in the soft palate. Soft palate cancers, when they do metastasize, are often bilateral. Cancers in the maxillary sinus metastasize uncommonly, but when they do, they have a different route than those from the palate. Some of the lymphatic radicals drain to the high retropharyngeal nodes and, unless quite large, are difficult to detect on direct clinical examination. CT and MRI scanning are necessary to rule out metastatic cancer at this site. The appearance of metastatic nodes in later follow-up, however, is much more prevalent in palatal malignancies than when these patients first present.
Selective neck dissection is generally not done in the limited cancers described here. The role of selective neck dissection or sentinel lymph node studies is controversial in mucosal melanoma originating in these sites. Modified radical neck dissection of Levels I through V is reserved for those cancers with clinically positive lymph nodes. The addition of retropharyngeal nodal dissection is done in those patients whose primary cancer arose in the maxillary sinus. Treatment with postoperative adjuvant radiation therapy combined with chemotherapy is employed when there is multiple adenopathy, or extracapsular spread or perineural or perivascular spread of the primary cancer.
Editorial Comment
The incidence of occult metastasis from squamous cell carcinoma of the hard palate and maxillary alveolar ridge has not been studied systematically; however, recently several series have been published on the actual incidence of cervical metastasis from these individual subsites. Although the metastatic rate is generally perceived to be low, our own retrospective study published in 2006 indicated that the overall incidence of metastasis to the cervical lymph nodes from squamous cell carcinoma of the hard palate and maxillary alveolar ridge is significant (34.6%). Elective neck dissection may be offered to patients with cancer of the hard palate and alveolar ridge who have an N0 neck, affording the patient and the surgical team the valuable histologic information needed to guide adjuvant therapy. This will reduce the potential need for future hospitalization and morbidity from radical therapies when the neck is not treated in patients with cancer of these sites. Our data suggest that the behavior of the squamous cell carcinoma of the hard palate and alveolar ridge is similar to that of other sites in the oral cavity such as the tongue and floor of the mouth.
Brown et al., in a recent study concluded that squamous cell carcinoma arising in the maxillary alveolus and hard palate has a similar risk for regional metastasis as the rest of the oral cavity, and the lower propensity for elective neck dissection is resulting in higher regional recurrence and lower survival rates. Future management of the N0 neck for patients with squamous cell carcinoma of the maxillary alveolus and hard palate should include the same approach to the neck as in patients with squamous cell carcinoma in other sites in the oral cavity because the risk is equivalent.
Morris et al. studied the incidence of metastasis to the lymph nodes in the neck from squamous cell cancers arising in the hard palate and maxillary alveolus in order to identify factors predictive of regional failure. Their series included 139 patients with squamous cell carcinoma from these primary sites. None of the necks were treated electively. Regional failure occurred in 28.4% of these patients and was significantly associated with pathologic T classification, ranging from 18.7% (pT) to 37.39% (pT4). Most patients (65.6%) with regional recurrence were not able to be salvaged. Thirty-two of the patients (29.5%) who were N0 at presentation had recurrence in the neck. Therefore, it would seem justified to recommend elective neck dissection for the majority of these cancers due to three factors: (1) the high rate of regional recurrence; (2) the limited number of salvageable recurrences; and (3) the poor outcome despite salvage.
Montes et al. reported a series of 146 patients with squamous cancer of the oral cavity. The regional metastatic rate was 31.4%. The regional salvage rate was 52.9%. Surgeons contributing patients to this multicenter study recommend a selective neck dissection of levels I-III as a primary management strategy for patients with T2, T3, and T4 squamous cell cancer of the oral cavity.
CONTRAINDICATIONS
Distant metastasis is a contraindication to inferior maxillectomy. Lack of physical fitness and lack of patient cooperation are also contraindications to surgery. Invasion into the floor of the orbit or invasion of the infraorbital nerve precludes inferior maxillectomy. These patients need more extended resections.
Patients on anticoagulant therapy should discontinue their medication and go on bridging therapy so that they can be reversed at the time of surgery. Patients with severe comorbidities must have their condition optimized prior to surgery.
Prosthetic rehabilitation is essential, and in those instances where some form of dental rehabilitation is not available to the patients, they should be well aware of nasal regurgitation as well as difficult swallowing and speaking.
Invasion of the pterygoid muscle requires a wider exposure than obtainable by inferior maxillectomy, so that total maxillectomy would be a better surgical option.
PREOPERATIVE PLANNING
Imaging Studies
The most valuable imaging study is the CT scan of the sinuses. The scan will demonstrate a mass often accompanied by bone erosion, and examination of the neck is important. Sorting out whether an opacification in one or more sinuses is tumor or retained secretions is better done with MR scanning.
Pathology
Incisional biopsy of a mass in the palate, nasal vestibule, or alveolar ridge will usually reveal the diagnosis. Masses confined to the maxillary sinus will usually be accessible by endoscopic examination and biopsy. A small trephine opening in the anterior wall of the sinus or a limited Caldwell-Luc procedure will provide
excellent access to the sinus cavity for biopsy. If a biopsy or surgery has been done elsewhere, the slides must be acquired and be reviewed by a head and neck pathologist prior to surgery.
excellent access to the sinus cavity for biopsy. If a biopsy or surgery has been done elsewhere, the slides must be acquired and be reviewed by a head and neck pathologist prior to surgery.
Maxillofacial Prosthodontics
It is essential for patients to have a consultation with a maxillofacial prosthodontist prior to surgery. The insertion of a prosthetic device at the time of surgery is essential for early rehabilitation. The ability of the patient to speak and take fluids by mouth in the early postoperative period without significant nasal regurgitation facilitates an early recovery from the surgery.
