Chapter 33: Endoscopic Sinus Surgery

Introduction

• There has been an evolution in the theories of pathogenesis and clinical management of sinonasal inflammatory disease that has revolutionized the practice of otolaryngologists.

• Diseases previously managed with open procedures are now widely managed with endoscopic approaches as the technology too has greatly improved.

• Further, the advancement of topical therapies and in-office procedures has created opportunities to manage disease, while creating cost-saving techniques and possibly improving patient safety.

• However, the variability of the anatomy and their critical relationship with the sinonasal cavities still remain true and a detailed knowledge of the embryology, and anatomy of the paranasal sinuses is necessary to avoid potentially disastrous surgical complications.

Embryology of Paranasal Sinuses

Ethmoturbinals

• Development heralded by the appearance of a series of ridges or folds on the lateral nasal wall at approximately the eighth week (Figure 33-1).

• Six to seven folds emerge initially but eventually only three to four ridges persist.

• Persistant ridges are referred to as ethmoturbinals from an ethmoid origin:

  • First ethmoturbinal—rudimentary and incomplete in humans

    • – Ascending portion forms the agger nasi.

    • – Descending portion forms the uncinate process.

  • Second ethmoturbinal—forms the middle turbinate

  • Third ethmoturbinal—forms the superior turbinate

  • Fourth and fifth ethmoturbinals—fuse to form the supreme turbinate

• Furrows form between the ethmoturbinals and ultimately establish the primordial nasal meati and recesses.

  • First furrow (between the first and second ethmoturbinals)

    • – Descending aspect forms the ethmoidal infundibulum, hiatus semilunaris, and middle meatus.

      • The primordial maxillary sinus develops from the inferior aspect of the ethmoid infundibulum.

    • – Ascending aspect contributes to the frontal recess.

  • Second furrow (between the second and third ethmoturbinals) forms the superior meatus.

  • Third furrow (between the third and fourth ethmoturbinals) forms the supreme meatus.

Contemporary Sinus Embryology Theory

• In addition to the traditional ridge and furrow concept of development, a cartilaginous capsule surrounds the developing nasal cavity and plays a role in sinonasal development.

• At 8 weeks, three soft-tissue elevations or preturbinates are seen that correlate to the future inferior, middle, and superior turbinates.

• At 9 to 10 weeks a soft-tissue elevation and underlying cartilaginous bud emerges that corresponds to the future uncinate process.

• By 13 to 14 weeks a space develops lateral to the uncinate anlagen that corresponds to the ethmoidal infundibulum.

• By 16 weeks, the future maxillary sinus begins to develop from the inferior aspect of the infundibulum.

• All three turbinates and each paranasal sinus arise from the cartilaginous nasal capsule which resorb or ossify over time.

Anatomic Considerations in Endoscopic Sinus Surgery (ESS)

The Lamellae

• The basal or ground lamella of the middle turbinate divides the anterior and posterior ethmoid air cells.

• The frontal, maxillary, ...