[Endoscopic anatomy involving the extended transsphenoidal approach].

OBJECTIVE

To provide pertinent anatomic data and details for the clinical application of the extended transsphenoidal approach; to probe the anatomic characteristic and method under endoscope;

METHODS

25 adult cadaver heads fixed in formalin were used to dissect, observe, measure and photograph the relationship between the neural and vascular structure and the important anatomic landmarks related to the extended transsphenoidal approach under endoscope.

RESULTS

The posterior and lateral wall of sphenoidal sinus could be well exposed by bilateral approach under endoscope. The clinical application of endoscope could improve the illumination of the operative field, magnify the objects and provide two-dimensional images. The distortion of the images under endoscope depended upon the distance between the lens and the object as well as the angle of the lens. To establish the anatomic vertical compartment under the endoscope might be helpful to the operation. The midline vertical compartment consisted of the planum sphenoidale, tuberculum sella, sella and clival indentation. The paramedian vertical compartment was composed of the medial third of the optic canal and the carotid artery protuberance. The lateral vertical compartment contained four bony protuberances (optic, cavernous sinus apex, maxillary, and mandibular). Endoscopic surgical maneuvering was under non-midline direction. Precise surgical landmarks are essential for a successful operation. These landmarks allowed the surgeon to recognize and approach the surgical target without confusion. The nasopharynx, middle turbinate, and inferior turbinate were some of the landmarks in the nasal cavity. Once the sphenoidal sinus was entered, the anatomic structures of the sphenoidal sinus posterior wall, which were described above, were the unique landmarks that will guide the surgeon to the surgical target.

CONCLUSION

The anatomic characteristics under endoscope were different from those under microscope. The application of the extended transsphenoidal approach under endoscope could provide more extensive vision and satisfied exposure to reach the area of the central skull base.