Endoscopic view of the posterior nasal cavity.

The utility of transnasal endoscopy in the diagnosis and surgical management of sinonasal disease is well described. [1] A systematic approach to transnasal endoscopic examination includes a thorough evaluation of the structures at the posterior nasal cavity.

Figure A is a transnasal telescopic view of the posterior end of the left middle meatus, with the middle turbinate visible superiorly and the inferior turbinate inferiorly. A Lusk ball-tipped probe is in contact with the region of the sphenopalatine foramen. This site is the point of access in the endoscopic approach to ligation of the sphenopalatine artery for posterior epistaxis. [2] A mucosal incision would expose the sphenopalatine neurovascular bundle at the upper end of the perpendicular plate of the palatine bone.

The posterior end of the middle meatus depicted in figure A is also a useful point of retrograde entry into the middle meatus if an anterior approach to the middle meatus is obstructed--for example, when a middle turbinate is deviated toward the lateral nasal wall. Sliding the telescope into the posterior end of the middle meatus between the middle turbinate above and the inferior turbinate below can facilitate visualization of the structures within the middle meatus as the telescope is slowly withdrawn.

Figure B is a transnasal endoscopic view of the ostium of the right sphenoid sinus within the sphenoethmoid recess. The boundaries of the sphenoethmoid recess are the superior turbinate laterally, the roof of the nasal cavity superiorly, and the nasal septum medially. [3] Notice that the inferior aspect of the superior turbinate serves as the lateral border of the sphenoethmoid recess. Obstruction of the sphenoid sinus ostium might therefore occur in the presence of polypoid disease of the superior turbinate.

An important consideration during endoscopic sphenoidectomy is the often-quoted distance of 7 cm from the nasal vestibule to the anterior face of the sphenoid sinus. One should remember that this distance is only an approximation, and it varies from one individual to another. Familiarity with the anatomy at the sphenoethmoid recess should minimize the risk of a catastrophe from an inadvertent entry into the skull base or from an iatrogenic injury to the carotid artery or optic nerve within the lateral wall of the sphenoid sinus.

Sinonasal anatomy can be disorienting, and the posterior nasal cavity is no exception. Figure C is a transnasal telescopic view of the posterior end of the left middle turbinate. Not all structures that look alike are part of the same structure, so proper orientation to the individual variability of each particular patient is important. This can be achieved by systematically moving from one known structure to the next known structure. The nasal septum, middle turbinate, and the lateral nasal wall are all labeled in the figure, and withdrawing the telescope more anteriorly would provide a more familiar view of each structure.

Figure D is a unique view of the posterior aspect of both nasal cavities in a patient with a large septal perforation. The nasal septum is situated at the midline of the figure. The superior, middle, and inferior turbinates are all labeled.

Videography is a useful adjunct to transnasal endoscopy. Figures C and D demonstrate that proper identification of structures along the lateral wall can be difficult with a single snapshot view. Reviewing a telescopic examination captured on videotape provides continuous, moving images that allow the surgeon to rewind and fast forward to distinguish potentially confusing sinonasal anatomic configurations. Videography also provides a complete record of diagnostic endoscopy or therapeutic procedures that might be of educational value to medical students or physicians in training. The accelerated technologic advances in computer storage memory provide another medium with which telescopic examinations can be recorded. From the Southern New England Ear, Nose, Throat, and Facial Plastic Surgery Group and the Hospital of St. Raphael, New Haven, Conn. (Dr. Yanagisawa), and the Section of Otolaryngology, Yale University School of Medicine, New Haven (Dr. Yanagisawa and Dr. Joe).

References

From the Southern New England Ear, Nose, Throat, and Facial Plastic Surgery Group and the Hospital of St. Rapheal, New Haven, Conn. (Dr. Yanagisawa), and the Section of Otolaryngology, Yale University School of Medicine, New Haven (Dr. Yanagisawa and Dr. Joe).

(1.) Stammberger HR. Functional Endoscopic Sinus Surgery: The Messerklinger Technique. Philadelphia: B.C. Decker, 1991.

(2.) Christmas DA, Yanagisawa E, Pastrano JA. Transnasal endoscopic ligation of the sphenopalatine artery. Ear Nose Throat J 1998;77:524-5

(3.) Stammberger HR. Kennedy DW. Paranasal sinuses: Anatomic terminology and nomenclature. The Anatomic Terminology Group. Ann Otol Rhinol Laryngol Suppl 1995;167:7-16.