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ICAR SINONASAL TUMORS

blood supply to the orbital bones. Orbital contents include the globe, extraocular muscles (EOMs), and a myriad of neurovascular structures contained within the fat-filled space. The EOMs, arising from attachment at the orbital apex, divide the orbital compartment into intraconal and extraconal spaces, wherein the intraconal space contains the complex neurovascular network leading to the globe including the optic nerve. With regard to the medial and inferior extraconal versus intraconal spaces, these regions are of notable importance when considering orbital inva sion from sinonasal tumors, since the depth of invasion often dictates the feasibility of surgical approach. 327,328,332 Lastly, though the bones of the orbit and periorbita serve as robust barriers to orbital invasion, orbital involvement from sinonasal tumors can proceed via direct invasion, extension through existing foramina or fissures, and per ineural spread. 164 It is worth noting that most sinonasal tumors gain access into the orbit in the medial aspect, where the lamina papyracea of the ethmoid bone may be breached. There has been a progression of grading systems for stag ing orbital involvement of sinonasal tumors (Table XI.1). In 1996, McCary et al. graded orbital involvement from A to D, with A classifying tumors adjacent to or abutting the orbit and D classifying tumors with full-thickness periorbital invasion. 325 Subsequently in 2005, Iannetti et al. graded orbital involvement from 1 to 3, with grade 1 being erosion of the medial orbital wall and grade 3 displaying invasion of EOMs, optic nerve, or eyelid skin. 324 In 2019, Turri-Zanoni et al. expanded on the criteria laid forth by Iannetti et al. by including four grades of orbital invasion, with grade 4 defined by involvement of the orbital apex. 165 Clinically, although ocular symptoms such as epiphora, diplopia, and visual changes can indicate orbital involve ment, the absence of clinical findings does not necessarily rule out orbital invasion, which emphasizes the impor tance of imaging. Both CT and/or MRI of the paranasal sinuses and orbits are critical for delineating the pres ence and degree of orbital invasion. 333,334 Though CT is often the preferred assessment tool for evaluation of the bony orbital compartment, determining the status of the periorbita and extraconal fat is often critical in determin ing feasibility of orbital preservation. Normal periorbital lining is hypointense on T1 and T2 sequences on MRI, and can often be considered intact in cases where this lining is preserved and a visible delineation between tumor and orbital fat is seen. 333 Unfortunately, despite the substantial improvement in MRI and CT resolution since the mid-1990s, imaging can sometimes overestimate EOM or intraconal involvement, highlighting the impor tance of intraoperative examination and use of frozen sections. 220,325,333,334

Intervention EEA should be the first-line surgical

technique for the resection of most IP confined to the maxillary sinus to reduce morbidity and recovery times while achieving similar outcomes to open surgery. Endoscopic maxillary surgical approaches should be considered on a case-by-case basis for malignancies and other benign tumors in the maxillary according to the tumor location, surgeon experience, patient preference, and tumor grade, with consideration of the risk–benefit ratio of alternative treatment options.

XI MANAGEMENT OF THE ORBIT Benign and malignant pathology of the nasal cavity, paranasal sinuses, and skull base often involves the orbit, which can significantly impact surgical management options. Malignancies of the sinonasal cavity have been shown to involve the orbit to some degree in 40%–80% of cases. 174,175,323,324 Historically, orbital invasion portends a worse overall prognosis with respect to RFS and DFS; however, given its critical function, there remains some debate over the optimal management of sinonasal tumors with orbital involvement. 175,177,325,326 With advancements in surgical techniques, improved understanding of orbital anatomy, and innovation in nonsurgical treatments, strate gies for orbital management in treating sinonasal tumors have continued to evolve. This section presents the current evidence on general principles in management of cases of orbital involvement from sinonasal and skull base tumors, as well as growing experience in minimally invasive endo scopic approaches to orbital management in the treatment of sinonasal tumors. Histopathology-specific management of specific orbital pathologies is covered in Section XIX. Given the proximity of the orbital compartment to the nasal cavity and paranasal sinuses, it is imperative to understand the orbital structures and contents in consid ering surgical management. Though many of the specific nuances of orbital anatomy is beyond the scope of this sec tion, this represents an overview of the relevant elements when considering orbital management. 327–331 The orbit is a conical-shaped cavity that is encased by a sheath of perior bita, which is a connective tissue membrane that inserts at the orbital apex and serves as a support structure for A Orbital structures and grading orbital invasion