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The choice of open versus an endoscopic approach depends on the exposure needed and on the surgeon’s training and experience.

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Primary surgery for chronic rhinosinusitis is now almost exclusively performed endoscopically.

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Functional endoscopic sinus surgery aims to re-establish physiologic sinus ventilation and mucociliary clearance.

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Surgery for chronic rhinosinusitis is adjunctive to medical therapy; the ostiomeatal complex is its primary target.

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Identification of anatomic landmarks and variations helps limit complications.

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Inadvertent penetration of the orbit or the skull base may occur in the following situations: lamina papyracea lying medial to maxillary ostium or dehiscence of the lamina; maxillary sinus hypoplasia; low or sloping fovea ethmoidalis; sphenoid sinus septations attached to the carotid canal; and carotid canal or optic nerve dehiscence.

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The anterior skull base is highest anteriorly and slopes downwards posteriorly.

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The anterior wall of the sphenoid sinus is convex toward the surgeon; the skull base is concave, sloping away from the surgeon.

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The maxillary antrostomy helps identify the medial orbital wall; intranasal herniation of orbital fat upon pressing of the eyeball increases chances of orbital trauma.

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Major complications of endoscopic sinus surgery are cerebrospinal fluid leak, blindness, diplopia, and internal carotid artery injury.

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Functional endoscopic sinus surgery provides significant improvement in overall general health.

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Common causes of failure of endoscopic sinus surgery are lateralized middle turbinate, missed middle meatal antrostomy, maxillary ostium stenosis, frontal recess scarring, residual ethmoidal air cells, and adhesions.

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Endoscopic approaches may be used for sinonasal tumors and skull base surgery.