43 Transmaxillary Approaches Lesions involving the clival area, the middle and posterior skull base, and the upper cervical spine represent a significant challenge for neurosurgeons, ENT surgeons, and maxillofacial surgeons, due to the troublesome exposure of the surgical site. Neoplastic, degenerative or inflammatory lesions can arise in this peculiar region, involving and compressing the cervico-medullary junction and inducing craniocervical instability. Surgical decompression and subsequent craniocervical stabilization represent the gold standard of treatment. Although aggressive surgical resection has been advised for some of these local aggressive lesions, such as chordomas and chondrosarcomas, wide exposure of this region is difficult to obtain because of the surrounding anatomy and potential neurologic morbidity. Multiple approaches have been described to gain adequate surgical exposure. The choice of the correct surgical approach depends on several factors, such as patient’s age and general health condition, tumor histopathology, extension and growth rate, and the exact location of the lesion. Four different broad categories of surgical techniques have been proposed in literature: open-transfacial, microsurgical, endoscopic, and robotic techniques provide all good visualization of this hard-to-reach anatomical area, each one of them obviously showing definite pros and cons. In particular, the Le Fort I transmaxillary approach and the following downward displacement of the maxilla provides a wide exposure of the posterior nasopharynx, from the sphenoid sinus to the clivus and the anterior part of the foramen magnum. This technique allows obtaining an acceptable cranio-caudal exposure of the clival and paraclival region, associated to a reduced lateral vision. • Neoplastic, degenerative or inflammatory lesions involving the clival area, the middle and posterior skull base and the upper cervical spine. • Position: The patient is positioned supine with the head fixed on a horseshoe head holder. • Body: The trunk and the head are slightly elevated to facilitate the venous backflow. • Head: The head is placed in neutral position. • Neck: The neck is slightly extended (about 20°), to facilitate further brain relaxation after dural opening. • Intubation: Submental orotracheal intubation. (Fig. 43.1). • Mucoperiosteal incision is performed at the superior vestibular fornix of the oral cavity. • Incision is carried out 1 cm above the gingival reflection, along the upper alveolar margin between the bilateral first molars. Fig. 43.1 Submental orotracheal intubation. Fig. 43.2 Mucosal incision. • Branches of the superior alveolar artery. • Pericranial layer ◦ A subperiosteal dissection of soft tissues is carried out using an elevator instrument. • Bone exposure ◦ Bone exposure is accomplished through the exposure of the anterior wall of the maxilla, the piriform aperture, the infraorbital foramen and the infraorbital nerve at the exit of its canal. ◦ Then, the surgeon must detach the cartilaginous portion of the nasal septum from the nasal spine and the vomer (Figs. 42.3, 43.4). • Osteotomy has to be performed 1 cm above the teeth roots, using an oscillating saw or the piezosurgery. • In order to avoid postoperative loss of individual occlusion, premodeling of 4 miniplates on both sides is accomplished. At the end of surgery, exact position of the maxilla is guaranteed by replacing the premodeled plates by screws insertion in the previous driven holes.
43.1 Introduction
43.2 Indications
43.3 Patient Positioning
43.4 Mucosal Incision (Fig. 43.2)
Abbreviations: SMI = submental incision; VT = ventilation tube.
Abbreviations: C = chin; FT = frontal teeth; G = gingiva; T = tongue.
43.4.1 Critical Structures
43.5 Soft Tissue Dissection
43.6 Osteotomy (Figs. 43.5, 43.6)
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