3.14\ Paranasal Sinus Stents

Paranasal sinus stents can be used to improve intranasal drainage and to maintain patency and drainage after sinus surgery, particularly when the neo-ostium measures less than 5 mm. Most stents are self-retaining and can be inserted endoscopically. The stents are usually a temporary measure, but occasionally remain for over 1 year. Potential complications include dislodgment and obstruction, especially for long-term stents. In particular, stents can predispose to scarring. Sinus stents are hollow tubular structures with a relatively wide flange or “mushroom” at one end in order to secure the device in position. CT is useful for evaluating the position of the stent and associated complications, if needed (Fig. 3.43).

Frontal sinus trephination consists of creating a defect in the sinus and is performed to provide access for drainage or culture of infected material, particularly if there is intracranial involvement. The procedure can also be performed in conjunction with functional endoscopic sinus surgery for enhanced visualization and irrigation of the frontal sinus and for resection of type IV frontal cells, which cannot be attained from an endonasal approach. The trephination defect is usually located approximately 1 cm lateral to the midline, and an external drainage catheter can be left in position (Fig. 3.44).

3.16\ Decompression, Enucleation,

and Ostectomy

3.16.1\ Discussion

Ostectomy and drainage can be used to treat cystic lesions that involve maxillary sinuses. This involves creating a Caldwell-Luc-type defect in the maxillary antrum and inserting a drainage tube in order to decompress the lesion (Fig. 3.45). Alternatively, surgical enucleation can be used to

a

treat keratocystic odontogenic tumors, which originate in the maxillary alveolus and extend into the maxillary sinus. In order to minimize the recurrence rate, adjunctive measures such as ostectomy orenblocresectioncanbeperformed.Furthermore, cryotherapy and instillation of the cyst cavity with Carnoy’s solution or balsam of Peru after enucleation can be used to ablate residual tissue (Fig. 3.46). Recurrent odontogenic cysts manifest as gradual scalloping of the maxillary bone at the resection site on follow-up imaging (Fig. 3.47).

b

Fig. 3.45  Decompression and drainage. The patient is status post unroofing of a left maxillary odontogenic keratocyst via decompression and irrigation. Coronal CT image (a) demonstrates a right maxillary sinus drain that

passes across a wide antrostomy. Coronal CT (b) image obtained 1 year later demonstrates interval removal of the drain and resolution of the lesion

Fig. 3.46  Enucleation and ostectomy. Preoperative coronal CT image (a) shows an odontogenic keratocyst (*) projecting into the left maxillary sinus. The cyst is air filled due to prior spontaneous drainage into the oral cav-

ity. Postoperative coronal CT image (b) obtained 1 year following enucleation and packing with balsam of Peru shows soft tissue filling the space previously occupied by the cyst (arrow)

Fig. 3.47  Residual/recurrent lesion. The patient is status post enucleation and ostectomy for a left maxillary odontogenic keratocyst. Initial postoperative coronal CT image

(a) shows the left maxillary sinus ostectomy site (arrow). Follow-up CT at 1 year (b) demonstrates interval scalloping of the maxillary bone (arrow)

3.17\ Maxillectomy

and Palatectomy

3.17.1\ Discussion

Maxillectomy consists of removing at least a portion of the maxillary sinus. The degree of resection ranges from partial/lateral maxillectomy, total maxillectomy, maxillectomy with palatectomy, and pterygoid plate resection to craniofacial resection, depending on the extent of disease (Figs. 3.48 and 3.49). Obturators are often used to occlude the oronasal communication that results from palatectomy (Fig. 3.50). Many of these devices contain metal parts and should be removed prior to imaging in order to minimize artifact. Obturators otherwise have variable appearances on CT, ranging from hyperattenuating to heterogeneous to air-filled components. Bone and soft tissue flaps can also be used to reconstruct the surgical resection defects (Figs. 3.51 and 3.52). In addition, titanium mesh, plates and screws, and plastic slings are often used to support the constructs. Both CT and MRI with contrast are useful for follow-up, particularly to asses for recurrent tumor. With extensive resections,

a

the pterygopalatine­ fossa becomes altered by scar tissue (Fig. 3.53), which should not be confused with tumor recurrence on imaging, since these can feature enhancing soft tissue on imaging. Recurrent tumors can have variable appearances, but most commonly appear as growing mass lesions located at the surgical margins (Fig. 3.54). Comparison with prior studies, short-term follow-up, PET-CT, or biopsy should be considered in ambiguous cases. Of note, synthetic materials, such as polytetrafluoroethylene, that are sometimes used as slings in reconstruction of the soft tissues overlying the maxillectomy can produce foreign body granulomas, which can mimic tumor recurrence (Fig. 3.55). Similarly, dacryocystoceles in patients treated for sinonasal cancer can mimic recurrent tumor. However, these lesions characteristically appear as fluid-filled structures in the anteromedial orbit (Fig. 3.56). Dacryocystoceles may form secondary to obstruction by recurrent tumor, ablative surgery, radiation therapy, or certain chemotherapeutic agents. Finally, infected maxillectomy sites may be treated with implantation of antibiotic impregnated methyl methacrylate beads, which appear as hyperattenuating on CT (Fig. 3.57).

b

Fig. 3.48  Partial maxillectomy and total palatectomy. The patient has a history of leukemia status post bone marrow transplant with graft-versus-host disease invasive fungal infection involving the hard palate and maxillary sinuses. Bilateral partial maxillectomy was performed. Coronal (a) and 3D CT (b) images show resection of the

bilateral medial maxillary sinus walls and the hard palate, resulting in continuity between the oral cavity, maxillary sinuses, and nasal cavity. There are mandibular dental amalgam artifacts that should not be confused for a prosthesis related to the surgery

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b

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Fig.3.52  Palatectomy and maxillectomy with osteomyocutaneous flap reconstruction. The patient has a history of desmoplastic ameloblastoma extending into the right maxillary sinus. Coronal (a) and 3D (b) CT images show right partial maxillectomy and palatectomy. Fibular graft

(arrows) has been used to reconstruct the contours of the maxillary alveolus, and the myocutaneous portion of the graft forms the floor of the maxillary sinus and nasal cavity, creating a neoantrum (*)

Fig. 3.53  Postoperative pterygopalatine fossa. The patient underwent maxillectomy for breast cancer metastasis. Axial CT image (a) shows amorphous fibrovascular tissue at the posterior margin of the left partial maxillec-

tomy (arrows). Axial T2-weighted (b) and post-contrast T1-weighted (c) MR images show that this tissue has low T1 and T2 signal, but enhances (arrows)

Fig. 3.54  Flap reconstruction with tumor recurrence. The patient has a history of squamous cell carcinoma and is status post right total maxillectomy with flap reconstruction. Axial CT image shows a necrotic mass (arrow) at the reconstruction flap margin

Fig. 3.55  Foreign body reaction. Axial CT image shows soft tissue surrounding a polytetrafluoroethylene sling (encircled)

Fig. 3.56  Postoperative dacryocystocele. Coronal CT image shows postoperative findings related to left sinonasal surgery, with dilatation of the lacrimal sac (arrow)

Fig. 3.57  Antibiotic-impregnated beads. 3D CT image shows numerous hyperattenuating beads in the bilateral maxillectomy cavities in a patient who underwent prior odontogenic myxoma debulking with superimposed infection of the surgical bed