This term includes a wide spectrum of surgical procedures, varying from partial resections of different types in relation to the site of origin of the lesion (inferior maxillectomy, medial maxillectomy, subtotal maxillectomy), to the standard radical maxillectomy, to the extended radical maxillectomies, in which the operation includes clearance or resection of one or more adjacent anatomic structures (orbit, premaxillary soft tissues and skin, zygomatic bone, pterygoid process, pterygomaxillary fossa, infratemporal fossa).
Access to the lesion may be obtained through a transoral approach, as for tumors involving the inferior half of the maxillary sinus, which are amenable to partial inferior maxillectomy (Fig. 5.14).
Medial maxillectomy, which is usually associated to an ethmoidectomy (Fig. 5.15), is indicated for benign (i.e., inverted papilloma) and malignant lesions limited to the lower part of the ethmoid, the nasal cavity,
Fig. 5.15 a,b. Partial medial maxillectomy with ethmoidectomy
Fig. 5.15 a,b. Partial medial maxillectomy with ethmoidectomy and/or the medial wall of the maxillary sinus. In many benign lesions, the operation can also be performed transnasally with a microendoscopic approach, but for most malignant lesions an external approach is still the option of choice. Medial maxillectomy has been traditionally performed through a lateral rhinotomy approach (Fig. 5.16), but in recent years a common tendency to resort to midfacial degloving (Casson et al. 1974) has been observed. This surgical technique is characterized by the association of sublabial and rhi-noplastic incisions, with or without osteotomies at the level of nasal bones and the frontal process of the maxilla (Fig. 5.17).
The first step is a bilateral intercartilaginous incision at the level of the nasal vestibulum; the procedure then proceeds with nasal soft tissue dissection from lateral cartilages and nasal septum by means of an incision that divides it from the columella. The intercar-tilaginous incisions go on bilaterally until the floor of the vestibulum, joining together with the septal incision. The second step is another incision at the level of mucosa of the superior buccal vestibulum extended to the third molar bilaterally, followed by a subperios-teal dissection which exposes the anterior wall of both maxilla, the inferolateral margins of the pyriform fossa, and the infraorbital nerves up to the inferior frame of the orbits. At this point, the nasal-maxillary cavity is entered by entirely resecting the anterior wall of the maxillary sinus. In the case of benign lesions or of malignant lesions not involving the anterior wall, it can be temporarily removed and fixed back at the end of the operation with microplates in titanium or in reabsorb-able material.
Midfacial degloving, which currently represents the gold standard for the surgical treatment also of neoplasms of the nasopharynx (i.e., juvenile angiofibroma) not amenable to microendoscopic surgery, has the advantage of avoiding evident scars and of maintaining good vascularization of the facial flap. Major limitations are, however, an anterior extension of the neoplasm with involvement of the nasal bones, lacrimal pathways, and/or pre-maxillary soft tissues, a superior growth into the frontal sinus, and all the situations in which the inferior and/or the medial walls of the orbit are eroded by the lesion and a careful dissection from the periorbit is therefore required. In all these situations a lateral rhinotomy approach, with or without b
superior lip splitting (Fig. 5.16), which gives an excellent exposure of the surgical field and ensures a good control of the dissection along the inferior and medial orbital walls, is still indicated.
The same access is recommended for radical max-illectomy (Fig. 5.18) and extended radical maxillecto-mies, which may require the association of an infratemporal approach or a frontal craniotomy whenever the lesion extends far posteriorly or superiorly to invade the skull base, respectively.
The goal of modern oncologic surgery of the sino-nasal tract is not only to provide a radical extirpation of the lesion, but also to preserve to the best possible extent functions such chewing, eating, and speaking, as well as aesthetic appearance. Different techniques can be employed principally in relation to the entity of the ablative procedure.
A prosthetic obturator is a simple solution for a small defect after inferior maxillectomy. A clasp-retained obturator can later be substituted by a more stable one based on bone-anchored implants. Problems of prosthetic stability derive from excision of more than half the palate. In such cases, a tripod-like stabilization of the obturator can be obtained by means of bone graft or, even better, with one of the more reliable revascu-larized free osseous flaps (from scapula, iliac crest, fibula, or radium) (Funk et al. 1998). In toothless patients, soft tissue flaps can be sufficient to separate the sinona-sal tract from the oral cavity. For less than half-palate defects, a pedicled temporalis muscle flap can still be considered an option, particularly when in combination with total or extended maxillectomy; it is easy to harvest and the risk of failure is very low (Colmenero et al. 1991). On the other hand, larger palatal excision
without need of dental rehabilitation should be closed by a radial free flap or with the muscular portion of other composite flaps (scapular, fibular, or iliac crest).
Iliac crest, scapula, and fibula, if appropriately harvested and oriented, can be even used to adequately restore the anterior maxillary contour and three-dimensional projection of the face when the anterior wall of the maxillary and zygomatic bones have been removed.
When more than half of the orbital floor needs to be resected, reconstruction with split calvarial bone is mandatory to prevent sequelae such as diplopia or enophthalmos. Moreover, the membranous portion of cranial bones like the parietal one, seems to be reabsorbed less frequently than the endochondral bones previously used (rib and iliac crest), even during radiotherapy (Zins and Whitaker 1993). However, meticulous coverage of the graft by soft tissues should be always obtained.
In the case of extended maxillectomies, a number of different situations can be encountered depending on the specific structures removed. Large cheek or scalp defects can be closed by free flaps (radial, rec-tus abdominis or parascapular) with the appropriate bulk. External nose and auricular defects are usually restored by prostheses; pedicled or free flaps simply play the role of cover for the surgical wound to prepare tissues for prosthesis retention. Orbital exenteration usually poses more challenging problems. A pure soft lining of the orbital cavity can be achieved by the temporalis muscle, over which a prosthesis will be later positioned (Turner et al. 1999). The orbit can be alternatively filled by soft tissue transfer if an adjacent skull base defect demands it or when ocular prosthesis is not desired.
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