Abstract
In this chapter, we will discuss the key components of performing an endoscopic maxillary antrostomy. This will include anatomic considerations, preoperative considerations, surgical instrumentation needed, pearl and pitfalls, the actual surgical dissection steps, and finally postoperative considerations.
Keywords
chronic sinusitis, FESS, maxillary antrostomy, maxillary sinus, sinus surgery
Introduction
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The maxillary antrostomy is the first step in performing functional endoscopic sinus surgery.
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Based on a good working knowledge of the anatomy and using proper visualization and mucosa-sparing techniques, a well-performed maxillary antrostomy will not only address maxillary sinus disease but properly set up the remaining portions of the sinus surgery.
Anatomy ( Figs. 6.1, 6.2, and 6.3 )
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The uncinate process is composed of thin bone covered by mucosa. It has attachments superiorly to the agger nasi cell or skull base.
Fig. 6.1
(A) Drawing in coronal view of the middle turbinate, uncinate, and ostiomeatal complex. Dashed circles represent the ostiomeatal complexes. Local anesthetic should be infiltrated at both X s, which correspond to the axilla of the middle turbinate as it attaches to the lateral nasal wall, and injected into the anterior face of the middle turbinate itself. (B) Coronal CT scan showing bilateral conchae bullosae, which are air cells inside the middle turbinate.
Fig. 6.2
Drawing in sagittal view showing the curvature of the uncinate process, location of the natural ostium, and nasolacrimal duct and sac (dashed line).
Fig. 6.3
Drawing in axial view showing the relationship between the uncinate process, ethmoid bulla, and middle turbinate. Dashed circle represents the ostiomeatal complex.
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The uncinate process covers the infundibulum—the functional area where the maxillary sinus, anterior ethmoids, and frontal sinus drain.
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The uncinate process attaches anteriorly to the lacrimal bone and is in the shape of a quarter moon. The posterior-inferior portion of the uncinate runs in a horizontal plane toward the posterior fontanelle.
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The maxillary line is the attachment of the uncinate process to the lacrimal bone. The natural os of the maxillary sinus can be visualized at the junction of the lower 1⁄3 and upper 2⁄3 on the maxillary line ( Fig. 6.4 ). The ostiomeatal complex is a functional area not an anatomic area. Opening the ostiomeatal complex involves removing the uncinate process and ethmoid bulla as well as enlarging the natural maxillary ostium.
Fig. 6.4
Endoscopic photograph illustrating how to locate the maxillary os.
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The middle turbinate serves to humidify inspired air. Care should be taken to preserve the middle turbinate if possible when performing a maxillary antrostomy. If removal is necessary, consider amputating only the anterior inferior quadrant of the turbinate.
Radiographic Considerations
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Look at the axial and coronal computed tomographic (CT) scans
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Identify the uncinate process and its relation to the medial orbital wall.
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Beware of an uncinate process that is lateralized against the medial orbital wall ( Fig. 6.5 ). If identified, make sure to take great caution in using a sickle knife or microdébrider against the uncinate to prevent inadvertent orbital entry.
Fig. 6.5
Coronal CT scan showing a lateralized left uncinate process (asterisk). With the decreased maxillary volume and low orbital floor, this CT scan is consistent with maxillary atelectasis or silent sinus syndrome.
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Identify the presence of any Haller cells, also called infraorbital ethmoid cells, that may be contributing to the obstruction of the middle meatus.
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Identify the presence of any pathologic process along the floor and/or anterolateral walls of the maxillary sinus. If a retention cyst or polyp is present, make preparations to have angled instruments and endoscopes available to address these hard-to-reach locations.
Instrumentation ( FIG. 6.6 )
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0-degree and 30-degree endoscopes
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45-degree or 70-degree endoscopes if lesions must be removed along the floor or anterior wall
Fig. 6.6
Photographs of instruments used in maxillary antrostomy. (A) Downbiter and backbiter forceps. (B) Ball-tip probe and 45-degree Blakesley forceps.
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Ball-tip probe
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Backbiter
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Downbiter
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Angled microdébrider
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Straight through-cutter
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120-degree giraffe
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Used for removal of retention cysts along the anterior and/or floor of the maxillary sinus
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Preoperative Considerations
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The first 15 minutes after anesthesia induction is often a time when the patient’s heart rate and blood pressure are at their highest. Starting to operate before proper mucosal decongestion and local injection have been accomplished will often result in mucosal trauma and excess mucosal bleeding, especially in the areas of the anterior septum, anterior middle turbinate, and lateral nasal wall. Trauma to these areas will add to the difficulty of the remainder of the procedure.
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Take at least 5 minutes to allow the vasoconstrictive pledgets to decongest the mucosa and local injections to take effect.
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It is important to accurately place the nasal pledgets to optimize the visual field. A common mistake is to place the pledgets low in the nose, failing to decongest the nasal swell bodies, which can obscure endoscopic visualization of the middle meatus and frontal recess ( Fig. 6.7 ).
