Maxillary Swing
Jimmy Yu-Wai Chan
INTRODUCTION
Nasopharyngeal carcinoma (NPC) is unique among other head and neck malignancies with regard to its epidemiology, pathology, and treatment outcome. It is endemic in southern China and Southeast Asia, with a reported annual incidence of 10 to 50 per 100,000 population. The primary treatment modality for NPC is radiotherapy for early-stage cancers and concomitant chemoradiation for more advanced NPC. Surgical resection is usually reserved for persistent or recurrent cancer after the initial treatment.
Anatomically, the nasopharynx is located at the central skull base in the center of the head, which is over 10 cm from the skin surface in all directions. As a result, adequate exposure for surgical resection of cancers involving this region is often difficult, especially when the cancer has infiltrated the nearby structures.
The maxillary swing approach originated from the observation that during maxillectomy for carcinoma of the maxillary antrum, the nasopharynx was widely exposed when the maxilla was removed. During the maxillary swing operation, the maxillary antrum, including the lateral walls and the floor attached to the anterior cheek flap, is swung laterally as an osteocutaneous flap, in order to expose the pathology in the nasopharynx. After removal of the cancer, the maxillary antrum was returned to its original position and fixed to the rest of the facial skeleton.
HISTORY
A detailed history, physical examination, and imaging studies are crucial for precise preoperative planning in order to achieve the best oncologic and functional outcome. Details of the patient’s general health should be sought, including a history of major cardiac or neurologic comorbidities and the need for antiplatelet or anticoagulant consumption. Information such as the initial stage of the cancer on presentation and the subsequent treatment protocol, including the use of induction chemotherapy, concomitant chemoradiation, as well as the type and dosage of external radiation given, is important. The history of recurrent cancer and its subsequent treatment, such as a second course of external radiotherapy, brachytherapy, or surgery, should be obtained. The spectrum of complications from previous treatment, including xerostomia, trismus, hearing problem, loss of smell and taste, velopharyngeal incompetence, and dysphagia, should be thoroughly assessed, as these symptoms may deteriorate further after surgery.
PHYSICAL EXAMINATION
The general status of the patients should be assessed for their fitness for surgery under general anesthesia. Neurologic status, including cranial nerve palsy (such as the abducens nerve), should be noted, as this may signify intracranial tumor extension and, hence, inoperability. The degree of preexisting trismus should be measured,
as severe trismus will decrease exposure and increase the difficulty of surgery. The general dental health is assessed, and if necessary, a preoperative dental consultation will be arranged. The neck should be thoroughly examined for cervical lymphadenopathy, and further investigation has to be performed if there is any clinical suspicion of lymph node metastasis. Otoscopy should be carried out since middle ear effusion is a common finding.
as severe trismus will decrease exposure and increase the difficulty of surgery. The general dental health is assessed, and if necessary, a preoperative dental consultation will be arranged. The neck should be thoroughly examined for cervical lymphadenopathy, and further investigation has to be performed if there is any clinical suspicion of lymph node metastasis. Otoscopy should be carried out since middle ear effusion is a common finding.
INDICATIONS
Pathology of the anterior skull base, including
Persistent or recurrent NPC after chemoradiation
Adenocarcinoma or minor salivary gland tumor of the nasopharynx as primary treatment
Chordoma
Schwannoma
CONTRAINDICATIONS
Patients whose medical condition is not fit for general anesthesia
Persistent or recurrent NPC with significant intracranial extension
Significant parapharyngeal extension with encasement of the petrosal internal carotid artery
Patients who have had previous surgery via the midface degloving approach
PREOPERATIVE PLANNING
Routine ultrasound examination of the neck is necessary, and if suspicious lymphadenopathy is evident, ultrasound-guided fine needle aspiration should be performed. Cross-sectional imaging study of the nasopharynx and the skull base using MRI with intravenous contrast offers the best spatial resolution allowing accurate assessment of the extent of the cancer, the presence of invasion of the parapharyngeal space, retropharyngeal lymph node metastasis, as well as the relationship with the petrosal internal carotid artery and the skull base.
The plasma level of Epstein-Barr virus DNA should be measured, and if it is more than 500 copies per milliliter, systemic metastasis should be suspected and whole body [18F]-FDG PET-CT scan should be performed. If necessary, preoperative pulmonary and cardiac optimization should be arranged.
Dental assessment must be performed, and an obturator should be fabricated for each patient before the maxillary swing procedure; this is used to clip onto the teeth on the upper jaw upon return of the swung maxilla, ensuring correct repositioning and precise dental alignment.
Endoscopic examination should be performed before surgery. Biopsy of the lesion of concern is done for histologic confirmation. It also maps the extent of the disease and determines which side of the face to swing during the subsequent surgery.
SURGICAL TECHNIQUE
The operation is carried out under general anesthesia with the patient in the supine position. The head is placed on a soft head ring to allow mobility, and support behind the shoulders should be inserted to extend the neck if a neck dissection or neck exploration is necessary. Endotracheal intubation is carried out through the mouth if possible as this avoids disturbance of the cancer in the nasopharynx. A temporary tracheostomy is then performed, and the endotracheal tube is withdrawn. This avoids the risk of damage to the endotracheal tube during osteotomy, and the tracheostomy protects the airway should postoperative bleeding or edema occur.
Protective eye ointment is used in the contralateral eye, which is draped out of the operative field. The oral cavity and the nasal cavities are irrigated with copious amount of antiseptic solution such as chlorhexidine. Intravenous antibiotics are given on induction of anesthesia, and this usually includes a metronidazole for anaerobic bacteria and a cephalosporin for aerobic bacteria.
The Weber-Ferguson facial incision is used as it is for maxillectomy; the horizontal limb of the incision is placed at the subciliary region 5 mm below and parallel to the lower eyelid margin (Fig. 35.1; Video 35.1). The incision over the lip is designed to be zigzag to prevent postoperative contracture, and the horizontal limb curves down laterally along the skin crease to stop at about 0.5 cm above the lower edge of the zygomatic arch. Tarsorrhaphy is done for the eye on the side of the swing to avoid inadvertent trauma to the cornea.
 FIGURE 35.1 A: Weber-Ferguson-Longmire incision for right maxillary swing operation. B: After skin incision, the underlying osteotomy sites (blue line) are exposed. By maintaining the attachment of the maxilla to the overlying soft tissue, the blood supply of the underlying bone is secured. |
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